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Tuesday, 19 July 2016

The Auk July 2016: Volume 133, Issue 3

The Auk
Published by: The American Ornithologists' Union

July 2016 : Volume 133 Issue 3 


A quantitative analysis of objective feather color assessment: Measurements in the laboratory do not reflect true plumage color 
Iker Vaquero-Alba, Andrew McGowan, Daniel Pincheira-Donoso, Matthew R. Evans and Sasha R. X. Dall

An important driver of the evolution of animal coloration is sexual selection operating on traits that are used to transmit information to rivals and potential mates, which has a major impact on fitness. Reflectance spectrometry has become a standard color-measuring tool, especially after the discovery of tetrachromacy in birds and their ability to detect UV light. Birds' plumage patterns may be invisible to humans, and therefore the establishment of reliable and quantitatively objective ways of assessing coloration not dependent on human vision is a technical need of primary importance. Plumage coloration measurements can be taken directly on live birds in the field, or in the laboratory (e.g., on collected feathers). However, which of these 2 approaches offers a more reliable, repeatable sampling method remains an unsolved question. Using a spectrophotometer, we measured melanin-based coloration in the plumage of Barn Swallows (Hirundo rustica). We assessed the repeatability of measures obtained with both traditional sampling methods to quantitatively determine their reliability. We used an ANOVA-based method for calculating the repeatability of measurements from 2 years separately, and a GLMM-based method to calculate overall adjusted repeatabilities for both years. The results of our study indicate a great disparity between color measurements obtained using both sampling methods and a low comparability across them. Assuming that measurements taken in the field reflect the real or “true” color of plumage, we may conclude that there is a lack of reliability of the laboratory method to reflect this true color in melanin-based plumages. Likewise, we recommend the use of the GLMM-based statistical method for repeatability calculations, as it allows the inclusion of random factors and the calculation of more realistic, adjusted repeatabilities. It also reduces the number of necessary tests, thereby increasing power, and it allows easy calculation of 95% CIs, a measure of the reliability and precision of effect-size calculations.

Male Red-backed Fairywrens appear to enhance a plumage-based signal via adventitious molt
Samantha M. Lantz and Jordan Karubian

Phenotypically plastic signals that can be altered in response to changing environmental conditions provide animals with the ability to dynamically signal their current condition or status. Such flexibility might also provide a means of avoiding potential trade-offs between signal components. Among birds, for example, both the timing of expression and the coloration of nuptial plumage are often thought to be honest signals of condition. However, because plumage is a relatively static signal type, birds that express condition-dependent plumage signals may face a trade-off between timing of signal production and signal quality, in that signals produced relatively early may be of lower quality because of seasonal constraints. A related cost may be increased fading or wear of plumage associated with extended duration of signal expression. Male Red-backed Fairywrens (Malurus melanocephalus) exhibit asynchronous development of nuptial red–black plumage, with some individuals molting into nuptial plumage months earlier than others. We report that male Red-backed Fairywrens that molt into nuptial red–black plumage early during the nonbreeding season appear to increase their plumage coloration by replacing feathers outside of normal molt periods (i.e. adventitious molt). In this way, some male Red-backed Fairywrens may be able to molt into nuptial plumage in the nonbreeding season, which is likely to increase access to mates or resources, and to subsequently enhance the red hue of a plumage-based sexual signal to a putatively more attractive state. We suggest that adventitious molt may be a currently underappreciated mechanism that birds use to improve or maintain the quality of plumage-based signals over time, between periodic full-body molts.

Reproductive biology of the Sapayoa (Sapayoa aenigma), the “Old World suboscine” of the New World 
Sarah A. Dzielski, Benjamin M. Van Doren, Jack P. Hruska and Justin M. Hite

The Sapayoa (Sapayoa aenigma), a low-density resident of Chocó rainforests from Panama to Ecuador, has long perplexed ornithologists. It was originally described as a manakin (Pipridae), but molecular work has revealed its closest living relatives to be Old World suboscines (Eurylaimides) and supported its placement in the monotypic family of Sapayoidae. Despite such phylogenetic intrigue, little is known about the Sapayoa's general life history or reproductive biology; only one nest has been described. We present information on 2 actively attended and 13 inactive Sapayoa nests in Darién National Park, Panama. We provide the first detailed description of individual effort at an active nest, family group dynamics during the nesting period, the plumage of immature birds, and the range of vocalizations produced. We also present the first documentation of cooperative breeding and compile several recent nesting observations, extending the published Sapayoa breeding period by several months. Furthermore, we describe unusual behaviors among provisioning birds, including mounting between individuals of the same sex and mounting of a female by immature male helpers during chick provisioning. The receiving individual gave a conspicuous solicitation display before each mounting. Finally, we highlight elements of the Sapayoa's natural history that echo its Old World relatives and contrast with members of the New World Tyranni. For example, the Sapayoa resembles the eurylaimid broadbills—and differs starkly from the manakins—in diet, nest structure, breeding system, and mode of parental care.

Habitat and social factors influence nest-site selection in Arctic-breeding shorebirds
Jenny A. Cunningham, Dylan C. Kesler and Richard B. Lanctot

Habitat selection theory suggests that shorebirds should choose nest sites that maximize survival and fitness. We investigated how habitat, and proximity to conspecific or heterospecific nesting birds, was related to nest-site selection in American Golden-Plovers (Pluvialis dominica), Dunlin (Calidris alpina), Long-billed Dowitchers (Limnodromus scolopaceus), Pectoral Sandpipers (C. melanotos), Red Phalaropes (Phalaropus fulicarius), and Semipalmated Sandpipers (C. pusilla) in Barrow, Alaska, USA, between 2005 and 2012. We used remote-sensing data to link habitat information to used and unused nest sites, and we measured distances from nests to other nearby nesting shorebird neighbors. Results from an information-theoretic approach to identify best-approximating models indicated that all species selected nest sites on the basis of both habitat and social cues. Macroscale tundra moisture level within 50 m of the nest, which was closely associated with vegetation community, was an informative variable for Dunlin, Long-billed Dowitcher, and Red Phalarope, which all selected wetter habitat. Enhanced tundra microrelief increased the probability of nest-site selection for American Golden-Plover, Long-billed Dowitcher, Pectoral Sandpiper, and Semipalmated Sandpiper. American Golden-Plover, Dunlin, Pectoral Sandpiper, and Semipalmated Sandpiper selected sites farther from conspecific nests than predicted by chance. Our results indicate that shorebirds select nest sites on the basis of habitat features, and that some are also influenced by proximity to other nesting shorebirds. These findings indicate that shorebirds select nests that are likely to aid incubation abilities, reduce predator detection of nesting birds, enhance detection of predators, enhance foraging, and reduce competition from conspecifics. The variable needs of the different Arctic-breeding shorebirds indicate that climate change will have both beneficial and harmful consequences. Our habitat models may be useful for predicting areas of high shorebird importance throughout the Arctic Coastal Plain, allowing mitigation of proposed anthropogenic developments.

Effects of tidal periodicities and diurnal foraging constraints on the density of foraging wading birds
Leonardo Calle, Dale E. Gawlik, Zhixiao Xie, Lauri Green, Brian Lapointe and Allan Strong

In intertidal zones, tidal cycles reduce water depths and provide areas of shallow water where wading birds can forage for aquatic prey (water depths 0–50 cm). However, a bird that forages diurnally can make use of only a portion of the tidal cycle, which can limit fulfillment of energetic demands. Furthermore, daily and biweekly (spring–neap) tides may compound effects on shallow-water availability for foraging birds. However, the relative effects of daily and biweekly tidal periodicities on the foraging ecology of wading birds are seldom investigated due to a lack of appropriate tools. Therefore, we developed a tidal simulation model to provide dynamic spatiotemporal estimates of the availability of water depths that are within the upper and lower bounds of the birds' foraging water depth limits (“shallow-water availability”). We studied two wading bird species, the Little Blue Heron (Egretta caerulea), a daytime-only forager, and the Great White Heron (Ardea herodias occidentalis), which feeds both diurnally and nocturnally, to evaluate the relative effects of daily and biweekly tides on shallow-water availability and on patterns in abundance of foraging birds. Seasonal foraging surveys (n = 38; 2011–2013) were conducted by boat along a 14-km transect adjacent to extensive intertidal flats in the lower Florida Keys, USA. For both species combined, biweekly tides resulted in a 0.61- to 6.09-fold change in abundance, whereas daily tides resulted in a 1.03- to 5.81-fold change in abundance. Diurnal shallow-water availability was not consistently correlated in magnitude or direction with spring–neap tidal cycles because differences in tide height between consecutive low tides were larger than changes in tidal amplitude from spring–neap tide cycles. Thus, the strong response by birds to the spring–neap tide was likely driven by mechanisms other than diurnal shallow-water availability alone.

Ecomorphological differences in foraging and pattering behavior among storm-petrels in the eastern Pacific Ocean
Josh Sausner, Juan Carlos Torres-Mura, Jeanne Robertson and Fritz Hertel

For closely related species, differences in morphology can provide insight into the evolutionary history of a taxonomic group, as well as mechanisms for ecological segregation. Storm-petrels are among the smallest seabirds, and their greatest taxonomic diversity occurs in the eastern Pacific Ocean. Some storm-petrels exhibit a unique foraging behavior, known as “pattering” or “sea-anchor soaring,” in which they appear to walk on the surface of the ocean, but this behavior is used to a varying degree among species. We compared morphological traits related to the pattering behavior in 9 species of storm-petrels that breed in the eastern Pacific. Measurements on the wing (wing loading, aspect ratio), beak (size), and leg (length and foot size) were analyzed using a discriminant function analysis (DFA). A thin-plate spline/relative warp analysis was also used to detect subtle differences in wing shape. Species that patter the most have low wing loading, low foot loading, and a long tarsus and were distinct from the species that were classified as intermediate or least pattering. The DFA and a cluster analysis also identified putative pattering behavior of species based on morphology, for which there was little known observational data. A molecular phylogeny of the mitochondrial ND1 gene revealed that the 2 subfamilies of storm-petrels were not monophyletic. The phylogenetic tree shows that the pattering behavior has a strong evolutionary signal and arose early among storm-petrels.

Molecular analysis of nestling diet in a long-distance Neotropical migrant, the Louisiana Waterthrush (Parkesia motacilla)
Brian K. Trevelline, Steven C. Latta, Leesia C. Marshall, Tim Nuttle and Brady A. Porter

Elucidating the diet of Neotropical migratory birds is essential to our understanding of their ecology and to their long-term conservation. Reductions in prey availability negatively impact Neotropical migrants by affecting their survival as both nestlings and adults. Beyond broad taxonomic or morphological categories, however, the diet of Neotropical migrants is poorly documented. Using the molecular techniques of DNA barcoding and next-generation sequencing, we elucidated the diet of Louisiana Waterthrush (Parkesia motacilla) nestlings in Arkansas and Pennsylvania, USA. Waterthrush have been shown to respond negatively to the reduced availability of aquatic insects in the orders Ephemeroptera, Plecoptera, and Trichoptera (EPT taxa). We hypothesized that Louisiana Waterthrush nestling diet would be primarily composed of these pollution-sensitive aquatic taxa, and that changes in the riparian insect community would be reflected in their diet. Unexpectedly, the orders Lepidoptera (92%) and Diptera (70%) occurred frequently in the diet of Louisiana Waterthrush nestlings. Among EPT taxa, only the order Ephemeroptera (61%) was frequently detected whereas Plecoptera (7%) and Trichoptera (1%) were poorly represented. The frequency at which aquatic Ephemeroptera and terrestrial Lepidoptera were detected in waterthrush nestling diet differed significantly over the nesting period in Pennsylvania but not in Arkansas, suggesting that phenological shifts in the availability of non-EPT prey taxa may be an important yet undescribed factor influencing the foraging ecology of waterthrush on the breeding grounds. Furthermore, these findings suggest that terrestrial insects may be more important to waterthrush nestlings than previously thought, which enhances our understanding of this biological indicator and Neotropical migrant.

Habitat quality and nest-box occupancy by five species of oak woodland birds
Megan C. Milligan and Janis L. Dickinson

Habitat quality can have important consequences for avian communities through impacts on survival and annual reproductive success. However, habitat quality is often hard to measure, leading to the use of occupancy as a proxy. We compared habitat use of 5 avian species that used nest boxes in the oak woodlands of central coastal California, USA, to determine which habitat characteristics best predicted box occupancy. We focused on the relationship between habitat characteristics and occupancy for five species—Ash-throated Flycatcher (Myiarchus cinerascens), House Wren (Troglodytes aedon), Oak Titmouse (Baeolophus inornatus), Violet-green Swallow (Tachycineta thalassina), and Western Bluebird (Sialia mexicana)—for which we had 12 consecutive years of data on nest boxes spread over a 700 ha study area. We also examined whether the physical habitat characteristics and box occupancy rates were good predictors of reproductive success, to infer whether they were useful indicators of habitat quality. The habitat characteristics influencing nest-box occupancy differed among the 5 species. Ash-throated Flycatchers were associated with fragmented habitats with less grassland. House Wrens were associated with riparian vegetation, as were Oak Titmice, which were also associated with chaparral. Violet-green Swallows were associated with chaparral but tended to nest farther from riparian corridors than Oak Titmice. Western Bluebirds nested away from riparian corridors and in areas with more grassland and oak woodland. Finally, occupancy rate was a better predictor than habitat characteristics of reproductive success, which suggests that occupancy can be a valuable proxy for habitat quality for these 5 species.

Effects of current reproductive success and individual heterogeneity on survival and future reproductive success of female Wood Ducks 
Robert A. Kennamer, Gary R. Hepp and Bradley W. Alexander

Estimates of vital rates and their sources of variation are necessary to understand the population dynamics of any organism. These data have been used to test predictions of life history theory as well as to guide decisions of wildlife managers and conservation biologists. Life history theory predicts tradeoffs among life history traits, such that current reproductive effort will be negatively correlated with survival and/or future reproduction. Many studies support this prediction, but others report positive covariation between fitness traits, and attribute positive correlations to differences in individual quality. In this study, we used 11 yr of capture–mark–recapture data of breeding female Wood Ducks (Aix sponsa), along with their breeding histories, to examine sources of variation in annual survival rates and to assess the impact of current reproductive success on probabilities of survival and future reproductive success. Cormack-Jolly-Seber models indicated that apparent survival of female Wood Ducks did not vary annually and was only weakly affected by age class and breeding habitat conditions, but that there was a strong positive relationship between survival and the number of successful nests (0, 1, or 2). Next, we used a multistate analysis to examine the importance of female nest fate (successful or failed) on the probability of surviving and of nesting successfully the next year. Early incubation body mass was used to assess the nutritional status and quality of females. Females that nested successfully in year t were not less likely to nest successfully in year t + 1 than females that had nested unsuccessfully in year t. We also found strong positive covariation between nest success in year t and the probability of surviving. However, being in relatively good or poor condition had no effect on these relationships. Our results are consistent with the idea that female quality is heterogeneous, but body mass was not a good proxy of quality. Therefore, the existence of tradeoffs between female reproductive success and survival or future reproduction was less clear because of our inability to identify and control for differences in female quality.

Target enrichment of thousands of ultraconserved elements sheds new light on early relationships within New World sparrows (Aves: Passerellidae)
Robert W. Bryson Jr., Brant C. Faircloth, Whitney L. E. Tsai, John E. McCormack and John Klicka

Sparrows in the nine-primaried oscine family Passerellidae represent an attractive model for studying avian diversification across North and South America. However, the lack of phylogenetic resolution at the base of the New World sparrow tree has hampered the use of the existing sparrow phylogeny to test questions about the evolution of sparrow traits. We generated phylogenomic data from 1,063 ultraconserved elements to estimate phylogenetic relationships among the major clades of New World sparrows. Concatenated and species-tree analyses of 271,830 base pairs of sequence data converged on a well-supported phylogeny that differs from previous estimates. The resolved backbone of the sparrow phylogeny provides new insight into the biogeography of this radiation by suggesting both a tumultuous biogeographic history, with many colonizations of South America, and several independent ecological transitions to different habitat types.

Do migratory warblers carry excess fuel reserves during migration for insurance or for breeding purposes?
Jennalee A. Holzschuh and Mark E. Deutschlander

Migration is energetically costly, and many passerines prepare for and maintain migration with hyperphagia and increased fuel or fat reserves. During spring migration, as they approach their breeding grounds, passerines may deposit fat in excess of what is needed to complete migration. Individuals may carry excess fuel reserves as insurance against potentially poor environmental conditions in early spring (insurance hypothesis). If this is true, individuals arriving early at northern stopover locations or their breeding grounds should have greater energy reserves than later arrivals. Alternatively, passerines may arrive in spring with excess fat to help offset the demands of breeding (breeding performance hypothesis). Given the energetic requirements of egg production, females may arrive with greater reserves than males if excess fat directly or indirectly offsets breeding costs. We analyzed the energetic condition of 12 warbler species mist-netted during migration from 1999 to 2012 at Braddock Bay Bird Observatory, Monroe County, New York, USA. This northern stopover location is near the breeding range (in relation to total migratory distance) for most of the parulid species we examined and, therefore, is a likely location to show carryover effects between migration and breeding. In 11 of the 12 species, energetic condition was greater in the spring than in the fall for both sexes; and in all 12 species, condition was greater in females than in males in both seasons. Contrary to the insurance hypothesis, condition increased with arrival date for most species during spring migration. Although better condition in females supports the breeding performance hypothesis, the presence of this difference in both seasons suggests that additional factors influence energetic condition in parulids. Given that males arrive in better condition in the spring than when they depart in the fall, individuals of both sexes may carry excess energy reserves during spring migration to potentially use for reproductive efforts.

Variation in egg size, shell thickness, and metal and calcium content in eggshells and egg contents in relation to laying order and embryonic development in a small passerine bird
Grzegorz Orłowski, Lucyna Hałupka, Przemysław Pokorny, Ewelina Klimczuk, Hanna Sztwiertnia and Wojciech Dobicki

Although there are quite a number of studies examining the effect of egg laying order on the levels of elements and various chemical substances, none have taken into account the presence or absence of embryonic development in the eggs. In this study, we measured the morphometry (length, breadth, volume, and mass), shell thickness, and concentrations of calcium and 10 other metals (including 8 essential elements: chromium, copper, nickel, manganese, iron, cobalt, zinc, and magnesium; and 2 nonessential elements: lead and cadmium) in the shells and contents of embryonated and nonembryonated eggs across the laying order of Eurasian Reed-Warblers (Acrocephalus scirpaceus). We found a significant increase in egg volume in both nonembryonated and embryonated eggs, and an increase in egg length and mass in embryonated eggs, with laying order. Analysis confirmed significant differences related to laying order between nonembryonated and embryonated eggs in the concentrations of elements measured in shells (Cu, Cd, Pb, Mn, Fe, and Zn) and egg contents (Pb). Analysis of the relationships between laying order and concentrations of elements revealed a significant increase in Mg and Ca concentrations in the shells of embryonated eggs, and a significant decrease in Ni in the contents of nonembryonated eggs and in Cu, Cd, Mn, and Co in the contents of embryonated eggs. Our results indicate that laying order and the presence of an embryo are critical factors responsible for variation in some features of egg morphometry and element concentrations in eggshells and egg contents. These factors should therefore be taken into consideration in studies of the chemistry and morphometry of avian eggs.

Breeding biology of the Tropeiro Seedeater (Sporophila beltoni)
Márcio Repenning and Carla Suertegaray Fontana

The recently described Tropeiro Seedeater, Sporophila beltoni, is a rare long-distance austral migrant songbird that breeds in upland grasslands of southern Brazil. No aspect of its natural history has been studied previously. We studied the natural history of this seedeater in the grasslands of the Araucarian Plateau from 2007 until 2011, focusing on breeding biology and monitoring 133 nests. The breeding cycle lasts for 3.8 months, and the breeding season is correlated with photoperiod and phenology of the grasses; nesting peaks in November and December; the mean clutch size is 2 eggs (1–3); and only the females brood, for 12 days. The nestling period lasts 10 days, and both parents care for the nestlings, although with different roles. The daily estimated survival rate (DSR) of nests, as modeled by the MARK program, was 0.94 and varied temporally in the breeding season. The estimated reproductive success was 20%. The quadratic model best explained the changes in nest survival, coupled with concealment and nest height from the ground. Other factors tested, including year-to-year variation, age of the nest, and species of support plant, did not significantly affect nest survival. Predation was the main cause of nest failure (48%), followed by desertion of nests and trampling by cattle (37%). Multiple breeding attempts (maximum 3) occurred, averaging 1.75 (SE ± 0.17) nests per female in each breeding season. This information on breeding biology and nest survival will aid in management and conservation efforts in grasslands of southern Brazil.

Phenotypic and genetic analysis support distinct species status of the Red-backed Woodpecker (Lesser Sri Lanka Flameback: Dinopium psarodes) of Sri Lanka
Saminda P. Fernando, Darren E. Irwin and Sampath S. Seneviratne

Hybridization has challenged taxonomy, since hybridizing forms could be stable evolutionary entities or ephemeral forms that are blending together. The island of Sri Lanka has 2 subspecies of the flameback woodpecker D. benghalense: D. b. jaffnense in the north and D. b. psarodes in the south. Red plumage separates the endemic phenotype D. b. psarodes from other subspecies of D. benghalense. Despite these differences, intermediate phenotypes in north-central Sri Lanka discouraged the elevation of D. b. psarodes into a full species. The recent HBW and BirdLife International checklist, however, has elevated D. b. psarodes to a full species (D. psarodes), primarily based on its plumage. To objectively evaluate whether this taxonomic elevation is warranted, we examined the phenotypic and genetic affinities of D. psarodes within the D. benghalense cluster. In doing that we provide the first quantitative phenotypic and genetic analysis across a hybrid zone for an Old World woodpecker group. We sampled woodpeckers along a line transect across the island and measured body shape/size, plumage, and genetic variation in a mitochondrial gene (Cytb). Plumage color ranged from red in the south to yellow in the north, with varying proportions of orange in north-central Sri Lanka (an area of ~66 km). Morphology (body shape/size) and plumage characters showed a clear separation. There are 2 mitochondrial haplotype groups, one in the north and one in the south. A mixture of north and south haplotypes were seen in north-central Sri Lanka. Width of the hybrid zone suggests that some form of selection limits the spread of hybrids into the range of parental forms. Morphological, plumage, and genetic traits are all indicative of limited hybridization in a narrow zone between the 2 taxa, supporting the treatment of D. psarodes as a distinct species. This study provides an illustrative example of extensive hybridization between stable taxonomic entities, discouraging the practice of merging hybridizing forms as single species.

Interspecific competition for nests: Prior ownership trumps resource holding potential for Mountain Bluebird competing with Tree Swallow 
Karen L. Wiebe

Interspecific competition over nest sites is common among cavity-nesting birds, but little is known about what determines the outcome of such contests, particularly whether or not prior ownership plays a role. Using a box removal and replacement experiment, I tested whether Mountain Bluebird (Sialia currucoides) or Tree Swallow (Tachycineta bicolor) had the higher resource holding potential (RHP). A different box-blocking experiment with paired boxes on territories measured the extent to which prior ownership influenced contest outcomes for both species. Behavioral observations in the pre-laying period showed more physical aggression by Mountain Bluebird against Tree Swallow. Nevertheless, Tree Swallow won 70% of boxes when neither species had prior ownership, suggesting Tree Swallow had a higher RHP. When their boxes were blocked, 24% of Tree Swallow usurped boxes from Mountain Bluebird, which did not differ statistically from the 33% of boxes usurped by bluebirds from swallows; thus, prior ownership does not guarantee winning the contest for either species. Currently, Mountain Bluebird arrives earlier in spring than does Tree Swallow and relies more extensively on prior ownership to retain nest sites. This advantage could be jeopardized if the migration schedule of Tree Swallow is accelerated due to climate change, and so it is important to understand the role of prior ownership in contests for nest sites for birds.

Range-wide patterns of geographic variation in songs of Golden-crowned Sparrows (Zonotrichia atricapilla)
Daizaburo Shizuka, M. Ross Lein and Glen Chilton

Discrete geographic variation, or dialects, in songs of songbirds arise as a consequence of complex interactions between ecology and song learning. Four of the five species of Zonotrichia sparrows, including the model species White-crowned Sparrow (Z. leucophrys), have been studied with respect to the causes and consequences of geographic variation in song. Within White-crowned Sparrows, subspecies that migrate farther have larger range size of dialects. Here, we assessed geographic patterns of song variation in the fifth species of this genus, the Golden-crowned Sparrow (Z. atricapilla). We analyzed field-recorded songs from 2 sampling periods (1996–1998 and 2006–2013) covering most of its breeding range in western North America. All songs began with a descending whistle and most songs consisted of 3–4 phrases that contained combinations of whistles, buzzes, and trills. We identified 13 discrete song types based on unique sequences of phrase types and frequency changes between phrases. Over 90% of individuals sang 1 of 5 song types, and we found clear dialect structure composed of these 5 common song types. The geographic range of dialects spanned large distances (500 to 1,700 km), resembling the geographic structure of dialects in the long-distance migrant Gambel's White-crowned Sparrow (Z. l. gambelli), though locations of dialect boundaries differ between species. Because both Golden-crowned Sparrows and Gambel's White-crowned Sparrows migrate similarly long distances, our study provides support to the hypothesis that dialect range size correlates with migration distance. We found little evidence of change in dialect composition in 4 populations that were sampled 15 years apart, which suggests that the dialect structure is stable across multiple generations. Our study opens the door for further comparisons to investigate links between ecology and the emergence of song dialects in this well-studied genus.

Viewing geometry affects sexual dichromatism and conspicuousness of noniridescent plumage of Swallow Tanagers (Tersina viridis)
Ana S. Barreira, Natalia C. García, Stephen C. Lougheed and Pablo L. Tubaro

Some types of plumage color are difficult to characterize spectrophotometrically because the properties of the reflected light change with viewing geometry (i.e. the relative positions of the light source and the observer, and the orientation of the feather). This is the case for the noniridescent plumage coloration of the Swallow Tanager (Tersina viridis), which seems to change from a human perspective as the angle between the light source and the observer varies. In this study, we measured plumage reflectance with different angles of illumination and/or observation, and used avian visual models to evaluate the change in sexual dichromatism and conspicuousness with viewing geometry from a bird's perspective. We also calculated different color parameters to assess how these changed with viewing conditions. Sexual dichromatism showed large changes, with its maximum coinciding with the angle combination between illuminant and observer that produced both the highest conspicuousness for males and the highest crypsis for females. The conspicuousness of males also varied with viewing geometry, and was consistently less when viewed by the visual system of a potential avian predator (VS) than by that of a conspecific (UVS). The change in perceived coloration was mainly related to large variation in hue and chroma in the plumage of males as the relative angle between the illumination and observation probes changed. Our results show that viewing geometry can alter color perception, even for noniridescent plumage coloration. Therefore, the relative position of the light source and the observer should be considered in studies of avian visual communication, particularly for species with plumage coloration similar to that of Swallow Tanagers.

Fifty-seventh Supplement to the American Ornithologists' Union
Check-list of North American Birds 
R. Terry Chesser, Kevin J. Burns, Carla Cicero, Jon L. Dunn, Andrew W. Kratter, Irby J. Lovette, Pamela C. Rasmussen, J. V. Remsen Jr., James D. Rising, Douglas F. Stotz and Kevin Winker

Tuesday, 12 July 2016

Ardeola June 2016 : Volume 63 Issue 1

Published by: Spanish Society of Ornithology/BirdLife


Table of Contents
Jun 2016 : Volume 63 Issue 1


Ardeola, a Scientific Journal of Ornithology: Cooperative Survivorship within the Red Queen Game 
Mario Díaz, Eulalia Moreno, Juan A. Amat, Beatriz Arroyo, Emilio Barba, Jacob González-Solís, Paola Laiolo, Florentino de Lope, Santiago Merino, José Ramón Obeso and Alberto Velando

Ardeola is the scientific journal of the Spanish Ornithological Society. We analyse historical changes in citation, topics and foreign authorship of articles published in Ardeola from its first publication in 1954 up to last year, 2015, to test to what extent the persistence of the journal during the last 61 years has been due to support of authors, Society members, readers, editors or the whole ornithological community. Analyses were done within the context of the Red Queen game played by scientific journals competing for the best and more cited articles. The impact factor of Ardeola has increased from 1985 onwards both in absolute and relative terms. Thematic changes have followed trends of the general ornithological literature, without the journal specialising in particular topics or geographical regions. Foreign authorship decreased from 1954 up to the end of the 20th century, subsequently increasing again, a trend fuelled by coverage by Current Contents and the JCR, the establishment of English as the language of publication and recent Internet access through the BioOne platform. Ardeola is a traditional scientific journal, backed by a scientific society, whose future will be guaranteed by a reputation for rigour and quality sought by authors, reviewers and editors, supported by the members of the Spanish Ornithological Society and retaining its original objective: ‘to be a journal at the level of the best…, looking for a strong collaboration with foreign authors to promote the benefit of the Ornithology’.


What are We Learning about Speciation and Extinction from the Canary Islands? 
Juan Carlos Illera, Lewis G. Spurgin, Eduardo Rodriguez-Exposito, Manuel Nogales and Juan Carlos Rando

Oceanic islands are excellent systems for allowing biologists to test evolutionary hypotheses due to their relative simplicity of habitats, naturally replicated study design and high levels of endemic taxa with conspicuous variation in form, colour and behaviour. Over the last two decades the Canary Islands archipelago has proved an ideal system for evolutionary biologists who seek to unravel how biodiversity arises and disappears. In this review we have evaluated the contribution of the study of Canarian birds to our understanding of how and why species occur and change over time. We focus our attention on both extant and extinct Canarian taxa, and describe how research on these species has filled gaps in our understanding of avian speciation and extinction. In addition, we discuss the necessity of revising the current taxonomy in the Canarian avian taxa, especially the status of the endemic subspecies, some of which might be better treated as full species. An accurate classification of Canarian birds is not only necessary for testing evolutionary, biogeographic and ecological hypotheses, but also for effective decision making about conservation and environmental management. Finally we introduce future avenues of research that we feel will yield the most exciting and promising findings on island evolution in the coming years.

Brood Parasite-Host Coevolution in America Versus Europe: Egg Rejection in Large-Sized Host Species
Manuel Soler

The hosts of brood parasites have evolved egg-discrimination ability as a defence that allows them to reject parasitic eggs laid in their nests. Twenty-five years ago, Stephen Rothstein emphasised that rejection rates differed markedly between potential host species in Europe and America. The much more complete information available today supports Rothstein's conclusions, but also allows new ones, especially when considering host size. For instance, successful resistance, one of the three potential long-term outcomes of brood parasite-host coevolution, is considerably more frequent in small-sized European host species and in medium-sized and large-sized Nearctic host species, while this evolutionary outcome is rare among Neotropical hosts regardless of their size. These results have never before been discussed, despite the differences being spectacular: 17 out of 19 small hosts presenting successful resistance are from Europe and 16 out of 17 medium-sized and 11 out of 13 large hosts presenting successful resistance are from North America. Interestingly, many large Nearctic hosts with a rejection rate close to 100% are corvids. The high rejection capacity shown by large Nearctic potential hosts probably evolved as a response to a highly virulent extinct brood parasite, either a large extinct cowbird or an extinct cuckoo species, which went extinct after losing the arms race against its large hosts.

The Unknown Life of Floaters: The Hidden Face of Sexual Selection 
Juan Moreno

Sexual selection, as a form of social selection based on reproductive resources, is a crucial driver of evolutionary change. Many studies on sexual selection identify potential targets only within the reproductive fraction of populations. Floaters constitute the non-territorial fraction of the population, according to the usual definitions. Floaters have been identified through exhaustive capture and marking programmes, removal and nest-box addition experiments, extra-pair paternity studies, acoustic marking and genetic studies. The literature shows that floaters may represent a considerable fraction of populations, especially among males. There is no clear evidence that size, condition or testosterone level is necessary for explaining floater status generally. However, the literature suggests that ornament size and expression are involved in territorial exclusion and may be either its cause or one of its consequences. There is some evidence that floaters survive and reproduce less well than territorials, and that changes from floater to territorial status are accompanied by changes in survival and reproductive rates. However, certain male floaters may obtain some reproductive success through extra-pair copulations. The possibility that floating constitutes a successful alternative strategy in some species cannot be excluded, although the current preliminary consensus is that floaters are ‘making the best of a bad job’. Floater status may be imposed by limitations in the availability of mates or breeding space resulting in skewed population sex ratios, polygamous mating systems, high population densities and increased demand for specific breeding requirements such as space in colonies or adequate nesting cavities. Predictions concerning the effects of these factors have not been conducted to date. Few studies have been able to clarify the duration of floater status in any population. For short-lived species, floater status in a single breeding season may in fact imply zero lifetime reproductive success. In males, the existence of a considerable fraction of floaters attempting to breed may select for intense territorial behaviour and competitive mate guarding tactics in territory holders and in aggressive extrapair copulation and territory acquisition tactics in floaters. Interference competition from floaters may lead to density-dependent declines in reproductive success. In females, the attempts by floaters to attain breeding opportunities may have contributed to the observed propensities for female prospecting and for female-female aggression and the signalling of female dominance towards other females. Moreover, there may exist selection in females for signalling quality to mates in order to avoid being evicted by rivals. Excluding floaters from the analysis of sexually selected traits may severely affect sexual selection estimates because of biased sampling for large or more intensely expressed ornamentation. The importance of sexual selection may be negated or underestimated when in fact its action on floaters could be maintaining current levels of expression in the territorial fraction. Existing phenotypes should express, in their morphology, physiology and behaviour, the relentless drive through evolutionary time to avoid becoming a floater.

Differential Waterbird Population Dynamics After Long-Term Protection: The Influence of Diet and Habitat Type 
Alejandro Martínez-Abraín, Juan Jiménez, Juan Antonio Gómez and Daniel Oro

Using as a model system a long-term data set (1984–2014) of waterbird counts at nine large wetlands of Eastern Spain (Comunidad Valenciana), we explored the ecological drivers of population fluctuations, both during the wintering (34 species) and breeding (36 species) seasons. Most species showed increasing trends (80% during breeding, 62% in winter), including both initially common and rare species, suggesting a positive effect of site protection policies that were mainly applied in the 1980s. Specialised freshwater species such as diving ducks and coots did not show population recovery, most probably due to the characteristic tendency of shallow lagoons to remain eutrophic even after several decades of the implementation of sewage management and water purification. In fact re-introduction of a diet-specialist (red-knobbed coot) failed but that of a diet-generalist (purple swamphen) succeeded. Waterfowl hunting and the abandonment of rural practices also probably played a role in the lack of recovery by some species. Population trends of breeding species were more dependent on local conditions than trends of wintering populations. Body size could also have some influence on growth rates because some of the smallest species of shorebirds and Laridae (such as Kentish plovers, little terns and black-headed gulls) showed decreasing trends in one or both seasons. Finally, a few species were gained for the system as new wintering species, probably due to climate warming. Our results suggest that growth rates alone are poor descriptors of population fluctuations, especially for birds and other vagile taxa, and that it is more appropriate to interpret trends when considering natural regions spatially, and when growth rates are analysed within the time scale of the theoretical logistic curve.

Individual-Based Tracking Systems in Ornithology: Welcome to the Era of Big Data 
Pascual López-López

Technological innovations have led to exciting fast-moving developments in science. Today, we are living in a technology-driven era of biological discovery. Consequently, tracking technologies have facilitated dramatic advances in the fundamental understanding of ecology and animal behaviour. Major technological improvements, such as the development of GPS dataloggers, geolocators and other bio-logging technologies, provide a volume of data that were hitherto unconceivable. Hence we can claim that ornithology has entered the era of big data. In this paper, which is particularly addressed to undergraduate students and starting researchers in the emerging field of movement ecology, I summarise the current state of the art of individual-based tracking methods for birds as well as the most important challenges that, as a personal user, I consider we should address in future. To this end, I first provide a brief overview of individual tracking systems for birds. I then discuss current challenges for tracking birds with remote telemetry, including technological challenges (i.e., tag miniaturisation, incorporation of more bio-logging sensors, better efficiency in data archiving and data processing), as well as scientific challenges (i.e., development of new computational tools, investigation of spatial and temporal autocorrelation of data, improvement in environmental data annotation processes, the need for novel behavioural segmentation algorithms, the change from two to three, and even four, dimensions in the scale of analysis, and the inclusion of animal interactions). I also highlight future prospects of this research field including a set of scientific questions that have been answered by means of telemetry technologies or are expected to be answered in the future. Finally, I discuss some ethical aspects of bird tracking, putting special emphases on getting the most out of data and enhancing a culture of multidisciplinary collaboration among research groups.

Prioritising Research in Steppe Bird Conservation: A Literature Survey 
Manuel B. Morales and Juan Traba

With the aim to identify priorities in conservation-oriented research, this paper reviews the level of scientific attention given to steppe birds in Spain during the last 50 years. We surveyed scientific literature using Thomson Reuters Web of Science and the journal Ardeola, using the English names of 28 species of steppe birds and the word “Spain” as search terms. Every species was assigned a Scientific Attention Index (SAI), based on the number of articles published on each of them. In addition, a vulnerability measure (Vulnerability Score; VS) was calculated for each species on the basis of the trend estimate provided by the Sacre or Noctua monitoring programmes, or according to expert criteria. The sample gathered (432 articles) was a significant and thus representative proportion of WOS and Ardeola contents on the species considered. The most studied species was the red-legged partridge Alectoris rufa, with 83 papers (20.15%); while the least studied was the short-eared owl Asio flammeus (1 paper; 0.24%). The most studied knowledge area was Habitat Selection (92 papers; 22.17%), while the least was Niche/Climate, with nine papers (2.17%). Preferred habitat (grass steppe, shrub steppe or mixed) was not a significant factor in the level of scientific attention given to the different species. However, large-sized species (non-Passerines) were significantly more studied than small-sized ones (Passerines), indicating a research bias for the former group. Finally, no significant relationship was found between SAI and VS, which suggests that research effort has been allocated irrespective of the species' conservation status. These results highlight the scarce scientific attention given to most steppe birds in Spain in spite of their overall high vulnerability, and for most of the knowledge areas considered. On the other hand, they also show the high relative importance of research carried out in Spain, in both the Mediterranean and world contexts. This work underscores the need to focus scientific effort on certain species, especially those that currently show more regressive trends or higher levels of vulnerability, and in most areas of knowledge.

Birds in Ecological Networks: Insights from Bird-Plant Mutualistic Interactions 
Daniel García

Research in ecological networks has developed impressively in recent years. A significant part of this growth has been achieved using networks to represent the complexity of mutualistic interactions between species of birds and plants, such as pollination and seed dispersal. Bird-plant networks are built from matrices whose cells account for the field-sampled magnitudes of interaction (e.g. the number of plant fruits consumed by birds) in bird-plant species pairs. The comparative study of mutualistic networks evidences three general patterns in network structure: they are highly heterogeneous (many species having just a few interactions, but a few species being highly connected), nested (with specialists interacting with subsets of species with which generalists interact) and composed of weak and asymmetric relationships between birds and plants. This type of structure emerges from a set of ecological and evolutionary mechanisms accounting for the probabilistic role of species abundances and the deterministic role of species traits, often constrained by species phylogenies. Although bearing structural generalities, bird-plant networks are variable in space and time at very different scales: from habitat to latitudinal and biogeographical gradients, and from seasonal to inter-annual contrasts. They are also highly sensitive to human impact, being especially affected by habitat loss and fragmentation, defaunation and biological invasions. Further research on bird-plant mutualistic networks should: 1) apply wide conceptual frameworks which integrate the mechanisms of interaction and the responses of species to environmental gradients, 2) enlarge the ecological scale of networks across interaction types and animal groups, and 3) account for the ultimate functional (i.e. demographic) effects of trophic interactions.

Roles of Raptors in a Changing World: From Flagships to Providers of Key Ecosystem Services 
José A. Donázar, Ainara Cortés-Avizanda, Juan A. Fargallo, Antoni Margalida, Marcos Moleón, Zebensui Morales-Reyes, Rubén Moreno-Opo, Juan M. Pérez-García, José A. Sánchez-Zapata, Iñigo Zuberogoitia and David Serrano

Birds of prey have been, in comparison to other avian groups, an uncommon study model, mainly due to the limitations imposed by their conservative life strategy (low population density and turnover). Nonetheless, they have attracted a strong interest from the point of view of conservation biology because many populations have been close to extinction and because of their recognised role in ecosystems as top predators and scavengers and as flagship species. Today, after more than a century of persecution, and with the exception of some vultures still very much affected by illegal poisoning, many populations of birds of prey have experienced significant recoveries in many regions of Spain and the European Mediterranean. These changes pose new challenges when addressing the conservation of raptors in the coming decades. On this basis, and from a preferentially Mediterranean perspective, we have focused our attention on the need of describing and quantifying the role of these birds as providers of both regulating (rodent pest control and removal of livestock carcasses) and cultural ecosystem services. Moreover, we revisited persisting conflicts with human interests (predation of game species) and call attention to the emergence of new conflicts with a strong social and media component such as the predation on live cattle by vultures. Also, the rampant humanization of the environment determines the need for new solutions to the growing, yet scarcely explored, problem of accidents in new infrastructures such as mortality in wind farms. Finally, we explored in depth the ecological response of birds of prey to large-scale habitat changes such as urbanisation and abandonment of marginal lands that are also expected to increase in the near future. We urgently need more scientific knowledge to provide adequate responses to the challenge of keeping healthy populations of avian predators and scavengers in a rapidly changing world.

Friday, 8 July 2016

Journal of Ornithology; Volume 157, Issue 3, July 2016

Journal of Ornithology

Volume 157, Issue 3, July 2016


Original Articles

No short-term effects of geolocators on flight performance of an aerial insectivorous bird, the Barn Swallow (Hirundo rustica)

Piotr Matyjasiak, Diego Rubolini, Maria Romano, Nicola Saino

Miniaturized light-level geolocators are becoming increasingly popular devices for the study of avian migration. However, the effects of these devices on birds’ flight behaviour, and hence fitness components, are poorly known. We investigated the effect of miniaturized geolocators on flight performance of the Barn Swallow (Hirundo rustica), which may be especially susceptible to geolocator deployment as it is a small (~20 g), aerially insectivorous, long-distance migratory species. We tested whether miniaturized geolocators (~3.5 % of body mass) affected short-term flight performance traits of breeding males by comparing flight manoeuvrability, velocity and acceleration of geolocator-equipped versus control (handled only) birds in flight tunnels. We used a robust experimental design wherein the within-individual change in flight performance was compared between geolocator-equipped birds (after allowing for a period of acclimation) and control birds (that were also tested twice). We found no statistically significant evidence that short-term flight performance traits were affected by geolocator deployment. Here we discuss the implications of our findings for the deployment of geolocators in studies of migratory behaviour of small birds.

Combining stable hydrogen (δ2H) isotopes and geolocation to assign Scaly-sided Mergansers to moult river catchments

Diana Solovyeva, Keith A. Hobson, Natalia Kharitonova, Jason Newton, James W. Fox, Vsevolod Afansyev, Anthony D. Fox


Scaly-sided Mergansers Mergus squamatus breed on freshwater rivers in Far East Russia, Korea, and China, wintering on similar habitat in China and Korea, but information on their post-breeding moulting habitats remains elusive. We combined analysis of stable hydrogen isotope ratios (δ2H) in flight feathers from nesting females equipped with geolocators to test whether we could correctly identify their use of moulting rivers (which show a strong north–south gradient in river water δ2H characteristics) based on feather δ2H values. The results are the first ever to demonstrate a strong positive correlation (r 2 = 0.91) between measured river catchment water δ2H and feather δ2H from birds of known moulting location (from geolocation) in an avian piscivorous species. Furthermore, our δ2H results overwhelmingly supported previous determinations based on feather δ13C and δ15N measurements from the same individuals confirming that most Scaly-sided Mergansers of both sexes moulted on freshwater, although four non-breeding and failed breeding females (out of 21) and one male (out of six) apparently undertook moult migration to brackish and marine waters. The single case where the δ2H results contradicted previous isotopic evidence was likely due to birds eating migratory fish of marine provenance that migrate up freshwater rivers. These results confirm the potential power of feather δ2H to assign piscivorous birds to specific river catchment moult sites and the utility of using multiple stable isotopes to assign birds to moult habitat and location in potentially complex estuarine and brackish situations or where migratory prey may be used by birds in freshwater habitats.

Migration routes and timing in a bird wintering in South Asia, the Common Rosefinch Carpodacus erythrinus

Robert Stach, Cecilia Kullberg, Sven Jakobsson, Kåre Ström, Thord Fransson


Only few bird species from Western Europe migrate eastward to wintering areas in South Asia, and little is known about this migratory flyway. The Common Rosefinch has in the past century expanded its breeding range westward to include Western Europe and migrate along this flyway to wintering sites in South Asia. This is the first study describing the migration routes of Common Rosefinches between Europe and Asia in detail, revealed by light level geolocators. The rosefinches showed loop-migration with more northerly routes in autumn than in spring, possibly in order to shorten the flight over the Central Asian deserts, which are very inhospitable at this time of the year. In spring the deserts are less dry and richer in vegetation, which may have supported the more southerly routes. During autumn migration the birds used several staging sites in Central Asia for prolonged periods. Although the birds passed over mountain regions at this time, which potentially act as barriers to them, the length of the stops seem unrealistically long for only fuel deposition. Instead, this suggests that the birds temporarily suspended migration to take advantage of abundant and predictable food sources in this region. During spring migration the birds made a few longer stops while still in north India or Central Asia, before migrating at fast speeds towards the breeding grounds. The birds covered 4–5000 km with only very short stopovers and thus most of the fuel used on spring migration must have been accumulated in Asia. Our results thus indicate that Central Asia, and north India, are important staging areas for this species in both autumn and spring. During winter, birds used two sites located several hundred kilometres apart, and relocation was probably a response to local food availability.

Spring and fall migration phenology of an Arctic-breeding passerine

Emily A. McKinnon, C. M. Macdonald, H. G. Gilchrist, O. P. Love


Understanding patterns in avian migration phenology and the proximate mechanisms for such patterns is important for assessing behavioural responses of individuals or populations to climate change. Among songbirds, protandry in spring is a common pattern; phenology in fall is less well described. Using tracking data collected from geolocators deployed at a breeding site, and capture data from banding stations, we assessed fall and spring migration phenology of an Arctic-breeding passerine, the Snow Bunting (Plectrophenax nivalis), by sex and age. We measured migration timing, speed, and distance, as well as duration of migration stopovers to test proximate mechanisms for observed sex and age differences in spring and fall migration phenology. During fall migration, hatch-year birds preceded adults, and adult males tended to precede adult females; however, there remained extensive variation by year. Males and females tracked directly arrived at winter sites at approximately the same time. During early spring migration, Snow Buntings exhibited moderate protandry, where after-second-year males preceded all other age-sex classes by ~6 days, on average. Surprisingly, protandry was not apparent at late spring migration or at breeding arrival. Instead, arrival dates by sex and age appeared highly variable between years. The winter site arrival date was predicted by fall migration departure date, total number of stopover days, migration speed, and migration distance. The breeding site arrival date was similarly predicted by spring migration departure date, total stopover days, and migration speed. Our results provide key baseline data for monitoring ongoing changes in migration phenology of this important Arctic-breeding songbird, as climate change effects become more pronounced across temperate and Arctic regions.

Contrasting annual cycles of an intratropical migrant and a tropical resident bird

André C. Guaraldo, Jeffrey F. Kelly, Miguel Â. Marini


Throughout their annual cycle, migrants often adopt different foraging and microhabitat usage strategies. Previous studies treat migrants as niche-trackers/niche-followers, i.e., they track similar niches along their annual cycle, almost exclusively based on food resource availability, which is inferred based on the climate at either the wintering or breeding grounds. An alternative approach is the use of such techniques as stable isotope analyses that allow researchers to more directly infer a migrant’s niche across seasons. While the use of carbon isotopes enables an assessment of microhabitat traits, that of nitrogen isotopes provides information on a bird’s trophic level. In the study reported here, we performed comparative analyses of stable carbon and nitrogen isotope ratios in tissues of the resident Plain-crested Elaenia and the intratropical migrant Lesser Elaenia to evaluate their year-round ecological niches. Our data suggest that both residents and migrants were consistent in their use of similar microhabitats throughout the year, which indicates a niche-tracking behavior on the part of migratory individuals. Migrants often fed at higher trophic levels than residents, but both species exhibited similar trophic level shifts through the year, feeding on higher trophic levels during breeding and on the lowest ones while wintering. The observed patterns could be due to several factors, including differential energetic demand needed for the migratory journey, species-specific nutritional needs during each stage of the year, and/or the use of multiple wintering grounds by migrants.

Survival and dispersal of the Cyprus wheatear Oenanthe cypriaca, an endemic migrant

Marina Xenophontos, Will Cresswell


Many populations of European migrant bird species are declining and this may be driven by survival rates; however, there are few studies that can estimate true survival rates. Cyprus wheatears Oenanthe cypriaca are an endemic migrant that winter in East Africa: populations are probably not declining but are annually variable. We recorded territory occupation and reoccupation in a colour-ringed population of 45–69 pairs over a 4-year period (2010–2013) from April to August to measure apparent survival and determine how it varied with sex, age, breeding productivity and year. We then estimated true survival by correcting apparent survival for dispersal by recording territory shifts and how this also varied by sex, age, breeding productivity and year. Apparent annual survival rate varied significantly by sex, age and year (males 2011, 2012, 2013: 0.70, 0.50, 0.62; females: 0.56, 0.34, 0.47; chicks: 0.35, 0.19, 0.28) but was not affected by the productivity of a territory. An average of 1.1 % of males and 8.2 % of females were lost during breeding, where 5/7 lost females were found depredated during incubation. Adults did not usually change territories between years (87 % were resident and 99 % moved less than four territories between years) regardless of sex, productivity or year; chicks, independent of their sex, moved on average three territories away from their natal territory. After correcting apparent survival for the probability of dispersal, males had the highest true minimum annual survival compared to females which were very similar to chicks (males 2011, 2012, 2013: 0.77, 0.50, 0.65; females: 0.65, 0.35, 0.50; chicks: 0.64, 0.34, 0.49). The results indicate a very high survival rate for a small passerine migrant, although they are probably sufficiently annually variable to profoundly affect annual population dynamics. If females have a lower survival rate, the sex ratio at birth may be female-biased to compensate; alternatively, females may have longer range dispersal than we could measure, particularly if they respond to their mates not returning by moving territories, leading to underestimation of their true survival. A high survival rate may be due to the rarity of sparrowhawks on Cyprus and the wheatears relatively short distance migration.

Reproductive success and productivity of the Cyprus Wheatear Oenanthe cypriaca, a migratory, island endemic

Marina Xenophontos, Will Cresswell


Population dynamics of annually breeding bird species depend crucially on productivity, and so this variation can help us understand the causes of declines in migrant birds. We investigated variation in annual productivity 2010–2012 in the Cyprus Wheatear Oenanthe cypriaca, a small endemic migrant passerine at the National Forest Park (NFP) of Troodos. Clutch size for first nests was usually five, although 0.40 eggs lower in 2011. Nest survival did not vary with year, nesting attempt, or clutch initiation date, but was significantly higher in the chick (0.96; 0.88–0.98, 95 % CI) versus the egg stage (0.74; 0.62–0.83, 95 % CI). The number of chicks fledged from a successful nest varied with nest type—with first nests and second nests after failure being similar producing ~3–4.5 chicks dependent on year, and with second nests after success producing ~2 chicks, independent of year. There were only weak positive or negative effects of clutch initiation date dependent on year, controlling for nest type, and no effects of male age on productivity. After fledging, chicks had a >95 % chance of surviving the first month, but with a greater probability of one or rarely two chicks per brood dying if fledged later in the season. Renesting rate was significantly different in all years (26, 48, and 78 % renesting): 2010 had a much lower renesting rate after success with very few second broods (29 versus 76 % and 73 % in 2011 and 2012, respectively). Overall productivity per territory did not vary with year with 3.96 ± 0.09 SE chicks alive 1 month after fledging. Cyprus Wheatears showed several unusual breeding parameters including a highly variable renesting probability, high nestling, and very high fledgling survival, resulting in exceptionally high productivity. This may be because renesting is constrained by high mid-summer temperatures and low abundance of chick predators.

Patterns of nest attendance by female Greater Prairie-Chickens (Tympanuchus cupido) in northcentral Kansas

Virginia L. Winder, Mark R. Herse, Lyla M. Hunt, Andrew J. Gregory, Lance B. McNew, Brett K. Sandercock


Nest attendance behavior is a critical component of avian ecology that influences nest survival and population productivity. Birds that provide uniparental care during incubation and brood-rearing must balance the benefit of reproductive success with the costs of physiological needs and predation risk. We used miniature nest cameras to record 5904 h of video footage at 33 nests of Greater Prairie-Chickens (Tympanuchus cupido) during 2010 and 2011 in northcentral Kansas. We quantified the timing and duration of incubation bouts to address alternative hypotheses about physiological requirements and predation risk as drivers of incubation behavior. We also identified nest predators and determined timing of predation events, and tested for effects of nest attendance and monitoring technique on nest survival (video vs. telemetry). Female prairie chickens exhibited high incubation constancy per day (~95 %) and typically took two ~40-min recesses per day: one after sunrise and one before sunset. Mesocarnivores were responsible for 75 % (18 of 24) of nest losses, and most nest predation events occurred during crepuscular or overnight hours. Controlled comparisons provided no evidence that video surveillance attracted predators to nests. Variation in nest attendance had a minimal effect on nest survival compared to height of vegetative cover at the nest site. Timing of recesses did not indicate avoidance of predator activity in our study system. The bimodal pattern of incubation breaks observed in most grouse species is likely driven by physiological requirements of the female rather than predation pressure. Female Greater Prairie-Chickens appear to prioritize their metabolic needs and future reproductive potential over current nest survival.

Comparative breeding ecology, nest survival, and agonistic behaviour between the Barred Warbler and the Red-backed Shrike

Marcin Polak

The majority of studies have demonstrated that the Barred Warbler Sylvia nisoria (BW) and the Red-backed Shrike Lanius collurio (RBS), where they occur sympatrically in central Europe, inhabit similar niches and are not averse to nesting in each other’s vicinity. The present work compares the reproductive parameters, nest survival, and behavioural interactions between these two ecologically similar species. The study was carried out in eastern Poland in two types of habitat: a river valley and farmland. Inter-habitat analysis showed both species to have similar reproductive parameters, although nest survival of the RBS was greater in farmland than in the river valley. Interspecific comparison revealed that the BW built smaller nests, laid fewer and smaller eggs than the RBS, but the production of offspring was similar in both species. In comparison to the other populations from Europe, both the BW and RBS in eastern Poland experienced good breeding parameters, and this is likely to be related to the region's extensive agriculture management and abundant food resources. The main factor reducing breeding success in both species was the plundering of their broods by raptors. Analysis using the MARK program indicated that habitat parameters significantly affected brood survival in the RBS to a relatively constant extent throughout the season. While habitat factors were less decisive in BWs, the fate of this species’ broods was strongly dependent on the phase of the reproductive cycle, and its nests were least likely to survive in the middle of the breeding season. The level of aggression between the BW and RBS was low, as demonstrated by experiments with stuffed models; this was a factor in favour of their nesting in close proximity to one another.

Effect of nestbox type on the breeding performance of two secondary hole-nesting passerines

Javier Bueno-Enciso, Esperanza S. Ferrer, Rafael Barrientos, Juan José Sanz

The use of nestboxes to study secondary cavity nesting avian species has greatly improved the knowledge related to many fields of environmental sciences. The aim of this study has been to compare the breeding performance of Great Tits (Parus major) and Blue Tits (Cyanistes caeruleus) in two types of nestboxes that differ with regard to their shape and thermal properties. Both nestbox types were placed in the same area to avoid confounding factors. There were significant differences between the extreme values of temperature and relative humidity obtained for the two nestbox types, and this was also the case in their daily patterns. Secondary hole-nesting birds appear to prefer breeding in woodcrete nestboxes. Nest predation was, however, significantly greater in woodcrete nestboxes. The nest height was significantly higher in woodcrete nestboxes, as was the danger distance between the nest cup and the entrance hole, which could account for the fact that Great Tits prefer this type of nestbox. The laying date was earlier in woodcrete boxes, but nestbox type did not influence clutch size. However, the eggs of both species were significantly smaller in woodcrete boxes. Breeding success was worse in woodcrete nestboxes. Nestbox type also affected the incubation pattern in both species, and attentiveness was significantly diminished in woodcrete nestboxes. This study reinforces the idea that the type of nestbox used in avian studies is not a trivial issue and may have strong biological effects on avian populations. It is important to take this into account when nestboxes are used as management measures for bird conservation.

Breeding biology of Magellanic Penguins (Spheniscus magellanicus) at the Beagle Channel: interannual variation and its relationship with foraging behaviour

Gabriela Scioscia, Andrea Raya Rey, Adrián Schiavini

Interannual variation in seabird foraging or reproductive behaviour may reflect fluctuations in marine resources. In this study, we evaluated different foraging and breeding parameters of Magellanic Penguins (Spheniscus magellanicus) from Martillo Island in the Beagle Channel, and the relationships between these parameters at different stages within the season (incubation, early and late chick-rearing) over three consecutive breeding seasons (2006–2007, 2007–2008 and 2008–2009). In 2007, we observed greater adult foraging effort (longer foraging trip duration and vertical travel distance, VTD) and lower chick feeding frequency, together with a slower growth rate and later fledging date of chicks, which we suggest was linked to lower food availability near the colony that year. The increased foraging effort appeared to be compensated by enhanced feeding activity (e.g., number of wiggles per dive). However, this increase did not coincide with a larger amount of food load brought to colony, which may have been due to a change in the type or size of prey consumed by the penguins. Magellanic Penguins from Martillo Island showed great plasticity in foraging behaviour, as evidenced by changes in consumed prey type or increased foraging effort and feeding activity when the consumption of their main prey item, Sprattus fuegensis, seemed to decrease. Moreover, during this particular breeding season, although the growth rate of chicks was lower, the breeding success remained constant throughout the study period, suggesting that the penguins managed to compensate for the apparent decrease in Fuegian sprat.

Variable decline of Alpine Rock Ptarmigan (Lagopus muta helvetica) in Switzerland between regions and sites

Roman Furrer, Michael Schaub, Andreas Bossert, Res Isler, Hannes Jenny, Tobias Jonas, Christian Marti, Lukas Jenni

Alpine species adapted to mountain climate are particularly vulnerable to environmental changes and have recently come under multiple environmental pressures, such as climate change associated with habitat loss (e.g. upward shift of the treeline) and unfavourable weather, as well as increasing human recreation activities. A prime example is the Alpine Rock Ptarmigan (Lagopus muta helvetica), a subspecies restricted to the Alps. We analysed counts of territorial males from 40 sites in the Swiss Alps since 1995 with state-space models including various environmental variables. Over the 18 study years, population growth rate (as deduced from territorial males) was negative overall (−13 %), but varied greatly between different regions of the Swiss Alps (from −50 to +6 %) and between sites, with some declining drastically and others doing well. Overall and within regions, growth rates showed little evidence for synchrony between local study sites. We did not find an overall factor which explained variation in population growth rates, except for a curvilinear effect of July temperature. It thus seems that various factors act locally to different degrees, such as upward shift of the treeline, unfavourable weather, and perhaps local increase in winter and/or summer tourism and unsustainable hunting. Together with a predicted shrinkage of the distribution area in the future due to global warming, the observed decrease of this isolated subspecies is of conservation concern. A better understanding of the different causes of decline and possibly different management strategies will be essential for the conservation of Alpine Rock Ptarmigan in Switzerland.

No short-term effects of climate change on the breeding of Rock Ptarmigan in the French Alps and Pyrenees

Claude Novoa, Guillelme Astruc, Jean-François Desmet, Aurélien Besnard

In the last decades, the effects of climate warming have been particularly marked in high mountain areas. High-altitude species adapted to cold temperatures are consensually held to be particularly vulnerable to climate warming. Among these species at risk, alpine birds like the Rock Ptarmigan (Lagopus muta) are expected to exhibit a strong negative response, particularly at the southern margins of their ranges in the northern hemisphere. In this study, conducted from 1998 to 2011, we investigated whether variations in the local climate affected the breeding biology of Rock Ptarmigan in the French Alps and Pyrenees. The median hatching date did not significantly advance in either massif, suggesting that Rock Ptarmigan did not breed earlier during this period. The date of snowmelt and spring temperatures influenced the onset of breeding but not consistently in both sites. In the Alps, the median hatching date was significantly correlated with the date of snowmelt, but this correlation was less clear in the Pyrenees. Unlike woodland grouse which inhabit lower elevations, the onset of breeding in Rock Ptarmigan may be related to both date of snowmelt and spring temperatures. Reproductive success varied greatly over the years and among sites. On average, the number of young per adult in the Pyrenean population was greater than that recorded in the two populations in the Alps. A significant positive trend of reproductive success over the period of 2000–2009 was detected in the Pyrenees but not in the Alps. The model that best explained annual variation in reproductive success included the additive effects of site, date of total snowmelt and rainfall after hatching. The estimates from this model showed that for all sites, reproductive success was much lower when snowmelt was late, and rainfall after hatching was high. We did not detect any altitudinal changes in locations of either breeding females or nests, suggesting that the breeding habitat of the species has not shifted upward from 1998 to 2011. To conclude, although the Rock Ptarmigan is generally considered a potential sentinel species for indicating temperature-induced changes in alpine avifauna, our study did not show a short-term effect of climate change on the breeding biology of the southern populations of this species.

Effects of habitat and land use on breeding season density of male Asian Houbara Chlamydotis macqueenii

M. A. Koshkin, R. J. Burnside, N. J. Collar, J. L. Guilherme, D. A. Showler, P. M. Dolman

Landscape-scale habitat and land use influences on Asian Houbara Chlamydotis macqueenii (IUCN Vulnerable) remain unstudied, while estimating numbers of this cryptic, low-density, over-hunted species is challenging. In spring 2013, male houbara were recorded at 231 point counts, conducted twice, across a gradient of sheep density and shrub assemblages within 14,300 km2 of the Kyzylkum Desert, Uzbekistan. Four sets of models related male abundance to: (1) vegetation structure (shrub height and substrate); (2) shrub assemblage; (3) shrub species composition (multidimensional scaling); (4) remote-sensed derived land cover (GLOBCOVER, 4 variables). Each set also incorporated measures of landscape rugosity and sheep density. For each set, multi-model inference was applied to generalised linear mixed models of visit-specific counts that included important detectability covariates and point ID as random effects. Vegetation structure received strongest support, followed by shrub species composition and shrub assemblage, with weakest support for the GLOBCOVER model set. Male houbara numbers were greater with lower mean shrub height, more gravel and flatter surfaces, but were unaffected by sheep density. Male density (mean 0.14 km−2) estimated by distance analysis differed substantially among shrub assemblages, being highest in vegetation dominated by Salsola rigida, high in areas of S. arbuscula and Astragalus, respectively, lower in Artemisia and lowest in Calligonum. The study area was estimated to hold 1824 males (CI 1645–2030). The spatial distribution of relative male houbara abundance, predicted from vegetation structure models, had the strongest correspondence with observed numbers in both model calibration and the subsequent year’s data. We found no effect of pastoralism on male distribution, but potential effects on nesting females are unknown. Density differences among shrub communities suggest extrapolation to estimate country- or range-wide population size must take into account vegetation composition.

Stress response varies with plumage colour and local habitat in feral pigeons

Hélène Corbel, Ariane Legros, Claudy Haussy, Lisa Jacquin, Julien Gasparini, Battle Karimi, Adrien Frantz

Bird populations exposed to different extrinsic conditions often differ in the responsiveness of the hypothalamo–pituitary–adrenal (HPA) axis and thus in corticosterone response that individuals mount when facing stressful events. However, the contribution of genetic variation to among-individual variability in HPA axis responsiveness across different environmental conditions is poorly understood. Melanin-based coloured types provide reliable phenotypic markers of alternative genotypes underlying stress coping styles. Large variations in melanin-based colouration are heritable in feral pigeons. We tested whether melanin-based colouration is associated with variation in corticosterone stress response in feral pigeons. To this end, we examined how corticosterone response varies both within and between differently coloured individuals across different environmental conditions. Differently coloured individuals produced different stress-induced corticosterone levels in relation to their environmental conditions: dark pigeons exhibited a higher corticosterone when originating from rural habitats, while this was not observed in pale pigeons. This suggests that among-population variation in stress response is higher in dark pigeons, this variation possibly reflecting adjustment and/or (epi)genetic adaptation to environmental conditions. In addition, corticosterone response increased with the degree of melanin-based colouration in pigeons originating from rural habitats but not in pigeons originating from more urbanized populations, resulting in the coexistence of alternative stress responses in some populations, but not in others. Our results suggest that species with melanin-based variation in differently urbanized populations along rural–urban gradients are potentially good candidate systems for studying stress coping styles under alternative selective regimes.

Excretion patterns of coccidian oocysts and nematode eggs during the reproductive season in Northern Bald Ibis (Geronticus eremita)

Didone Frigerio, Lara Cibulski, Sonja C. Ludwig, Irene Campderrich, Kurt Kotrschal, Claudia A. F. Wascher

Individual reproductive success largely depends on the ability to optimize behaviour, immune function and the physiological stress response. We have investigated correlations between behaviour, faecal steroid metabolites, immune parameters, parasite excretion patterns and reproductive output in a critically endangered avian species, the Northern Bald Ibis (Geronticus eremita). In particular, we related haematocrit, heterophil/lymphocyte ratio, excreted immune-reactive corticosterone metabolites and social behaviour with parasite excretion and two individual fitness parameters, namely, number of eggs laid and number of fledglings. We found that the frequency of excretion of parasites’ oocysts and eggs tended to increase with ambient temperature. Paired individuals excreted significantly more samples containing nematode eggs than unpaired ones. The excretion of nematode eggs was also significantly more frequent in females than in males. Individuals with a high proportion of droppings containing coccidian oocysts were more often preened by their partners than individuals with lower excretion rates. We observed that the more eggs an individual incubated and the fewer offspring fledged, the higher the rates of excreted samples containing coccidian oocysts. Our results confirm that social behaviour, physiology and parasite burden are linked in a complex and context-dependent manner. They also contribute background information supporting future conservation programmes dealing with this critically endangered species.

Seasonal and daily patterns of nocturnal singing in the Field Sparrow (Spizella pusilla)

Antonio Celis-Murillo, Kirk W. Stodola, Brian Pappadopoli, Jessica M. Burton, Michael P. Ward

Nocturnal singing in diurnal birds is poorly described in the literature and is not well understood. Most research has been limited to the documentation of the behavior, with little information regarding the patterns and function of nocturnal song. We used autonomous acoustic recording units and automated detection and classification algorithms to examine the seasonal and nocturnal patterns of song in the Field Sparrow, Spizella pusilla, a diurnal songbird. We used a generalized linear mixed model to investigate the patterns in the probability of recording each of the two song types described for the species (simple and complex) at night from 7938 10-min recordings from 14 different individuals singing in six different grassland patches. We fit different models investigating the influence of date within the season and time period during the night, and compared models using the Bayesian information criterion. Male Field Sparrows sang both simple and complex songs during the early stages of territory settlement and mate acquisition. However, as the breeding season progressed, we detected fewer instances of simple song, while the occurrence of complex song increased, reaching its peak during the height of reproductive activity. The seasonal pattern of simple and complex songs suggests that they may have a similar function at night and during the day, with simple songs used for inter-sexual interactions and complex songs used for intrasexual functions. Consequently, the role and function of nocturnal song may be more important for reproductive activities than previously assumed.

Genetic and morphological sex identification methods reveal a male-biased sex ratio in the Ivory Gull Pagophila eburnea

Glenn Yannic, Thomas Broquet, Hallvard Strøm, Adrian Aebischer, Christophe Dufresnes, Maria V. Gavrilo, H. Grant Gilchrist, Mark L. Mallory, R. I. Guy Morrison, Brigitte Sabard, Roberto Sermier, Olivier Gilg

Sex identification of birds is relevant to studies of evolutionary biology and ecology and is often a central issue for the management and conservation of populations. The Ivory Gull Pagophila eburnea (Phipps, 1774) is a rare high-Arctic species whose main habitat is sea ice throughout the year. This species is currently listed Near Threatened by the IUCN, because populations have drastically declined in part of the species distribution in the recent past. Here we tested molecular sexing methods with different types of samples. Molecular sexing appeared to be very efficient with DNA extracted from muscle, blood, and buccal swabs, both for adults and young chicks. We also performed morphological analyses to characterize sexual size dimorphism in Ivory Gulls sampled in three distinct regions: Greenland, Svalbard, and Russia. Males were larger than females for all morphometric measurements, with little overlap between sexes. Discriminant analysis based on six morphometric variables correctly classified ~95 % of the individuals, even when using two variables only, i.e., gonys height and skull length. Therefore, both molecular and biometric methods are useful for sexing Ivory Gulls. Interestingly, our results indicate a male-biased sex ratio across all Ivory Gull populations studied, including two samples of offspring (67.8 % males).

Sexual size dimorphism and discriminant functions for predicting the sex of Atlantic Puffins (Fratercula arctica)

Alexander L. Bond, Rebecca A. Standen, Antony W. Diamond, Keith A. Hobson

Assortative mating is an important aspect of mate choice, especially in species where both sexes express ornamentation. Such ornaments could function as signals of individual quality and could result in individuals mating with partners of similar quality. We tested for assortative mating by measuring 63 pairs of Atlantic Puffins (Fratercula arctica) at two Canadian colonies (Gull Island, Witless Bay, Newfoundland and Labrador; and Machias Seal Island, New Brunswick), and constructed a function to predict the sex of puffins from Witless Bay. Male and female puffins have similar plumage, and both sexes have fleshy rosettes at the base of their bill, which are supposedly ornaments. We also examined changes in measurements over time in 5–30-year-old puffins recaptured at Machias Seal Island. Our discriminant function correctly predicted the sex of 88 % of puffins from Witless Bay. Overall, males were larger than females in all measurements, but within pairs, some females were larger in 4–27 % of individual measurements. We found no evidence of positive assortative mating or of assortative mating by rosette size, and rosette area did not increase with age. The importance of puffins’ rosettes as indicators of quality requires further investigation.

A stem falconid bird from the Lower Eocene of Antarctica and the early southern radiation of the falcons

Marcos Cenizo, Jorge I. Noriega, Marcelo A. Reguero

Antarctoboenus carlinii nov. gen. nov. sp. is a large-sized falconiform bird from the La Meseta Formation (Lower Eocene) at Seymour (Marambio) Island, West Antarctica. The holotypical tarsometatarsus was originally assigned to Falconidae and its affinities to Polyborinae were pointed out. Detailed osteological and comparative analyses of the Antarctic specimen allowed recognition of the new taxon as a member of stem group Falconidae, i.e. it is supposed to belong to the early radiation of the falconiform lineage. Antarctoboenus carlinii is distinguished from members of crown group Falconidae by having a very shallow sulcus extensorius, a large foramen vasculare distale, an undistinguishable tendinal attachment for the m. adductor digiti II, and short trochlea metatarsi II, among its main diagnostic characters. Purported phylogenetic relationships between A. carlinii and Polyborinae are based on plesiomorphic characters retained in the tarsometatarsus of the latter clade. Our conclusions reinforce the hypothesis about the Neotropical or Austral origin of Falconidae supported by previous molecular phylogenies.

Year-round spatiotemporal distribution of the enigmatic Semi-collared Flycatcher Ficedula semitorquata

Martins Briedis, Johan Träff, Steffen Hahn, Mihaela Ilieva, Miroslav Král, Strahil Peev, Peter Adamík

We examined migration routes and non-breeding sites of a poorly studied long-distance migrant, the Semi-collared Flycatcher Ficedula semitorquata, by tracking adult birds with geolocators from an eastern European breeding population across two subsequent years. All 11 birds migrated in a clockwise loop fashion where autumn migration routes lay east from the spring migration routes. Non-breeding sites were located in Eastern-Central Africa, i.e. Uganda, Tanzania, Burundi, Rwanda, and east DR Congo, where birds spent on average 128 days. Non-breeding sites of two birds were located outside of the currently estimated species’ non-breeding range.

Migration routes of Eurasian Curlews (Numenius arquata) resting in the eastern Wadden Sea based on GPS telemetry

Philipp Schwemmer, Leonie Enners, Stefan Garthe

The Wadden Sea is an important resting site on the East Atlantic Flyway for Eurasian Curlews (Numenius arquata). However, there is currently little information regarding the connectivity between breeding, staging, and over-wintering sites. We equipped four Curlews with GPS-data loggers and recorded their migration patterns during 2014–2015. Curlews left the Wadden Sea during April and migrated to their breeding grounds in (north-) eastern Russia within 2–4 days. All individuals remained in the breeding area for 51–53 days, and then returned to the same place in the Wadden Sea where they had been caught, indicating high site fidelity.

Female and male Blue Tits (Cyanistes caeruleus) sing in response to experimental predator exposition

Katharina Mahr, Carlo L. Seifert, Herbert Hoi

Female song is recognized to serve a similar function as male song and underlies sexual selection processes; yet certain patterns of the expression of female singing behaviour are not in line with traditional explanations known from male songbirds. In particular, in northern hemisphere songbirds, female singing behaviour is regarded to occur only rarely, and; therefore, studies investigating it are sparse. Within the framework of an experimental study on nest defence behaviour, we observed female singing in a common European passerine, namely, the Blue Tit (Cyanistes caeruleus). Females expressed singing behaviour when a dummy of a Sparrow Hawk was exposed to the nest, raising the idea that song might be multifunctional in this species.

Phylogenetic position of the Wallcreeper Tichodroma muraria

Min Zhao, Per Alström, Urban Olsson, Yanhua Qu, Fumin Lei

The Wallcreeper Tichodroma muraria is usually placed in a monotypic family or subfamily within the superfamily Certhioidea, with assumed close relationships to Certhia (treecreepers), Sitta (nuthatches) and Salpornis (spotted creepers). Previous studies have suggested that Tichodroma is most closely related to Sitta, alternatively to Salpornis. We analysed the relationships of Tichodroma using two mitochondrial and five nuclear loci. The tree based on concatenated sequences strongly supported a sister relationship between Tichodroma and Sitta, as well as between Salpornis and Certhia. However, species tree analysis (MP-EST) was unable to resolve these relationships, and although the concatenation tree remains the best hypothesis, more data are needed to corroborate this.

No genetic structure in a mixed flock of migratory and non-migratory Mallards

Robert H. S. Kraus, Jordi Figuerola, Katharina Klug

Mallards do not show genetic differentiation into migratory populations across typical flyways. It is also known that some Mallard populations are non-migratory. The aim of this study was to test if genetic structure exists between migratory and non-migratory Mallards in an area where they occur sympatrically, in Doñana, Spain. After quality filtering we analysed 350 single nucleotide polymorphism markers (SNPs) from 104 migratory and non-migratory Mallards. No genetic structure was evident from our data. We conclude that the lack of large-scale genetic structure of the global Mallard population remains valid when specifically testing potential differentiation between migratory and non-migratory Mallards.

“Shortest-distance” method is more accurate than conventional method in estimating flight initiation distances for close, perched birds

Kent B. Livezey, Daniel T. Blumstein

The conventional method to determine avian flight initiation distance (the distance at which birds exposed to an approaching human activity initiate escape behavior) overestimates this distance for perched birds because it uses the distance between the bird and the ground at the person’s feet rather than the distance between the bird and the part of the person’s body closest to the bird. Here, we introduce an alternative “shortest-distance” method that more accurately estimates flight initiation distance, especially for close, perched birds.