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Thursday, 21 January 2016

Journal of Ornithology, Volume 157, Issue 1, January 2016

Journal of Ornithology

Volume 157, Issue 1, January 2016

Research Articles

Vocal behaviour of White-eared Ground-sparrows (Melozone leucotis) during the breeding season: repertoires, diel variation, behavioural contexts, and individual distinctiveness
Luis Sandoval, Carolina Méndez, Daniel J. Mennill

There are relatively few quantitative descriptive studies of the vocalisations and vocal behaviour of tropical bird species, in spite of the tropic’s rich avian biodiversity and the extensive variety of vocalisations produced by tropical birds. This lack of information inhibits our understanding of tropical animals, including our ability to perform comparative analyses on vocal behaviours from an evolutionary perspective. In this study, we present the first quantitative description of the vocal repertoire and daily vocal activity of White-eared Ground-sparrows (Melozone leucotis), using focal and autonomous recordings collected during two consecutive breeding seasons in Costa Rica. We classified vocalisations into categories based on their visual appearance on sound spectrograms to create a library of vocalisations for this species. We found that White-eared Ground-sparrows produce three main categories of vocalisations: solo songs, calls, and duets. Solo songs were produced only by males. Each male sang a repertoire of solo song types, which all shared the same general structure with short introductory notes, a frequency-modulated middle section, and a terminal trill. Both sexes produce calls and coordinated vocal duets. We quantified patterns of diel variation in each category of vocalisation, and found that the Ground-sparrows produced all three vocalisations at higher output at dawn (between 0500 and 0600 hours) compared to the rest of the day. This study allowed us to conduct the first comparisons of vocalisations between White-eared Ground-sparrows and North American species in the genus Melozone, and revealed both similarities and differences between the species groups. Our investigation also showed that vocalisations related to communication within pairs and to territory defence (calls and duets) exhibited lower levels of individual distinctiveness than vocalisations related mainly to female attraction (male solo songs). Our observations suggest that each of the three types of vocalisations have multiple functions in White-eared Ground-sparrows, revealing diverse communication functions with a small vocal repertoire in this tropical songbird.

Composition and sequential organization of song repertoires in Cassin’s Vireo (Vireo cassinii) Richard W. Hedley

The rules governing bird song sequences vary considerably across the avian phylogeny, and modifications to these rules represent one of the many ways in which bird song varies interspecifically. Cassin’s Vireo (Vireo cassinii) is one species that shows a highly structured syntax, with clearly non-random patterns of sequential organization in their songs. Here I present a description of Cassin’s Vireo song sequences from the Sierra Nevada Mountains in California and employ network analysis to quantify transition patterns within the songs. Repertoire sizes varied between 44 and 60 phrase types per bird for the 13 birds analyzed here. The repertoire was subdivided into ‘themes’ containing between two and seven phrase types. The birds sang the phrase types in a given theme for a time before eventually introducing a new theme; in this manner the repertoire was revealed relatively slowly over time. Theme composition within a bird’s repertoire did not change within or between singing bouts throughout the season. The tendency to sing in themes was corroborated by network analysis, which revealed small-world structure in the songs. Phrase types were widely shared within the population. I discuss these findings as they compare with the singing styles of other species, both closely and distantly related.

Social foraging European shags: GPS tracking reveals birds from neighbouring colonies have shared foraging grounds Julian C. Evans, Sasha R. X. Dall, Mark Bolton, Ellie Owen

Developments in tracking technologies have enhanced our understanding of the behaviours of many seabird species. However few studies have examined the social aspects of seabird foraging behaviour, despite the effect this might have on the distribution of foraging areas and the differences that might arise between colonies. Here we use bird-borne GPS and behavioural observation to study the social foraging behaviour and habitat use of breeding shags from three breeding colonies in the Isles of Scilly, UK. Thirteen breeding shags from three colonies (six at two colonies and a single bird from another) were tracked between 2010 and 2012 and related to observations of conspecific foraging aggregations (2013–2014). Tracked shags had short foraging ranges (1.74 ± 1.6 km) mostly travelling to shallow waters between the islands and observations revealed that many shags foraged in large social groups that were consistent in time and space. There were also no clear differences in foraging distributions among colonies—birds shared similar foraging grounds. Our finding provides important insight into the use of social information among foraging seabirds and how this may lead to shared foraging areas, as well as space partitioning.

Postcopulatory sexual selection favors fertilization success of restocking hybrid quails over native Common quails (Coturnix coturnix) Ines Sanchez-Donoso, Pablo Antonio Morales-Rodriguez

Postcopulatory sexual selection plays an important role in the reproductive success of males in many species. Differences in fertilization success could affect rates of admixture and genetic introgression between divergent lineages. We investigated sperm precedence in matings in captivity involving Common quails (Coturnix coturnix) and farm quails of hybrid origin (C. coturnix × domestic Japanese quail, C. japonica), the last used in restocking practices to increase hunting bags. These inter-specific matings in natural conditions are claimed to represent an important threat to the conservation of native Common quail populations. Results showed that fertilization success of each male depended on (1) the time it spent with the female, (2) the presence of sperm from a previous male in the female oviduct, (3) the time that the previous partner had been copulating with the female, and, most importantly, (4) the genetic origin of the male (wild or farm). Farm hybrid males showed higher fertilization success than wild Common males, and they required less time with the female to fertilize the same proportion of eggs. The presence of sperm from another male in the female oviduct reduced the percentage of fertilized eggs by a male. However, this reduction was higher for wild males when the precedent mate was a farm male. In summary, the sperm of farm hybrid males may outcompete the sperm of native males and this could be favoring the introgression of domestic Japanese alleles into the Common quail population, thus constituting a severe conservation threat to wild Common quail populations.

Blocking of ultraviolet reflectance on bird eggs reduces nest predation by aerial predators Canchao Yang, Jiajia Wang, Wei Liang

Visual sensitivity in ultraviolet (UV) light is widespread in the animal kingdom and occurs in all major taxonomic groups, including birds, which possess UV-sensitive photoreceptors and thus perceive UV light and use it in food selection, mate choice, offspring care and egg discrimination. However, no studies have been conducted to elucidate whether birds (aerial predators) could detect nests by UV light reflectance of eggs. In the present study, we performed artificial tree nest experiments in which pairs of pigeon eggs were treated with either a UV-blocker or a control substance before being exposed to nest predators in a tropical forest. The results showed that nest predation increased with duration of exposure, and that blocking UV reflectance of eggs could significantly reduce nest predation on tree nests. This provides experimental evidence for nest predation risk being linked to UV reflectance, and implies that aerial nest predators may detect nests by UV reflectance of eggs.

What is the whistle all about? A study on whistle songs, related male characteristics, and female song preferences in common nightingales Conny Bartsch, Henrike Hultsch, Constance Scharff, Silke Kipper

In many passerine species certain song structures have evolved to convey information to conspecific males or females. For example, in the common nightingale Luscinia megarhynchos, the ‘whistle part’ is a striking acoustic feature of some song types. Whistle songs have been suspected to be particularly well suited to attract females and/or to be important during female choice, but this has never been tested directly. In this study, we used a two-pronged approach for addressing the function of whistle songs in intersexual communication. First, we analysed relationships between whistle song features and male characteristics reflecting overall male quality. We found that the number of whistle songs produced and acoustic consistency of single whistle elements predicted male body measures, i.e., males who sang more whistle songs were heavier and larger, and produced whistle elements with higher consistency. Second, we conducted playback experiments with females either with or without whistle songs. Females responded more strongly to whistle songs by moving and vocalizing more during the whistle playback. We conclude that whistle songs might play an important role in nightingale mating, as they evoke high arousal in females, and different whistle song features may signal different aspects of male quality to females.

The effectiveness of endozoochory in three avian seed predators Grzegorz Orłowski, Joanna Czarnecka, Artur

The role of granivorous birds as agents of seed dispersal has been little explored and is poorly understood. We assessed the ability of three species of birds from a Central European agricultural landscape to disperse seeds of dry-fruited plants. We hypothesised that Grey Partridge Perdix perdix is a better seed disperser than either of two species of buntings—Yellowhammer Emberiza citrinella and Reed Bunting Emberiza schoeniclus—in terms of the number of intact seeds recovered from their droppings. Partridge droppings contained the highest number of intact seeds. Surprisingly, however, the number of intact seeds per 1 g of droppings was the highest in Reed Bunting, smaller in Grey Partridge and the smallest in Yellowhammer. Our findings suggest that the passage of intact seeds of dry-fruited plants through the digestive tract of seed-eating birds is most likely an effect of limited digestion, resulting from the intake of a large volume of seeds, a small part of which remains undigested. This effect could be magnified by the inclusion in the diet of some items of different digestibility (invertebrates or leaves). We suggest that non-standard dispersal of seeds with no adaptations to endozoochory by birds is a far more frequent and as yet under-appreciated phenomenon, which has potential ecological implications for the colonisation of new habitats/islands by plants. The ultimate elucidation of this process is extremely difficult and would require large sets of faeces to be examined.

Breeding persistence of Slavonian Grebe (Podiceps auritus) at long-term monitoring sites: predictors of a steep decline at the northern European range limit J. Stien, K. B. Strann, J. U. Jepsen, V. Frivoll, R. A. Ims

The Slavonian Grebe (Podiceps auritus) has its European northern range limit in northern Norway, and is a species of national conservation concern due to its small population size and unknown population trend. Long-term monitoring at the range limit suggests breeding site use is in decline. We used annual occupancy data from 104 breeding lakes monitored since 1991 in northern Norway to investigate correlates of change in occupancy. Persistence was 100 % until 1999, but thereafter decreased to 25 % (26 lakes with breeding pairs). A particularly steep decrease occurred between 2010 and 2012. Persistence increased with the number of pairs present in each lake in the initial monitoring year of 1991. The number of grebe pairs also decreased in the lakes that had continuous breeding persistence over the entire 22-year monitoring period, suggesting that a large-scale factor caused the population decline. Over the last year of the monitoring series, lake altitude was negatively related to the probability of persistence, indicative that locally harsh climate played some role in breeding distribution. The temporal pattern of persistence was not related to mean winter temperature at the breeding sites; however, the decrease between 2010 and 2011 coincided with a late ice melt in 2010. Monitoring that includes a larger area of the species’ range is required to conclude whether the observed decline can indicate an overall decline in population size, or range fluctuations at the edge of the species’ range. However, investigating the processes that determine population range borders can give insights into important limiting factors pertinent to the conservation of species in the long term.

Late Miocene buttonquails (Charadriiformes, Turnicidae) from the temperate zone of Eurasia Nikita V. Zelenkov, Natalia V. Volkova, Leonid V. Gorobets

Abstract The evolutionary history of the extant buttonquails (family Turnicidae) is poorly known. The Oligocene stem representatives of the family differ significantly morphologically from the extant members of Turnicidae and presumably had different ecology and lifestyle. Until now, the only pre-Pleistocene record of the crown-group buttonquails was a find in the Pliocene of South Africa—within the modern distribution range of the group. Here we describe remains of the modern-type Turnicidae from the late Miocene of Hungary, Southern Ukraine, and Northern Kazakhstan. These finds show that Turnicidae, which nowadays are restricted to the subtropical and tropical regions, had much wider geographical distribution in the late Miocene. This range expansion might have been related to the wide spread of the open and arid landscapes during the late Miocene. Importantly, all remains described herein are morphologically similar to the living genus Ortyxelos, which has been considered primitive and now inhabits arid landscapes in Africa. The genus Ortyxelos is thus likely yet another (along with ostrich and some mammals) taxon which now inhabits sub-Saharan Africa, but once had a much wider distribution across Eurasia.

High winter site fidelity in a long-distance migrant: implications for wintering ecology and survival estimates Emma Blackburn, Will Cresswell

The decision for a migratory animal to be site faithful in its non-breeding season has profound implications for migratory connectivity, resilience to winter habitat loss and population dynamics through carry-over effects on future breeding success and fitness. Knowledge of the temporal and spatial scale of site fidelity and dispersal is also central to accurate survival estimates. We established the observed spatial and temporal scale of site fidelity and the ability to detect small-scale dispersal within and between years for a wintering long-distance Palearctic migrant, the Whinchat Saxicola rubetra, by comparing predicted and observed detection rates within the study site. Across 2 years, 54 % of birds returned to the study site and all returning birds reoccupied the territories they used in the previous winter. Observed dispersal was very low despite the high probability of detecting any local dispersal, suggesting that return rates are indicative of true between-winter survival rates for this population. In any winter, 50 % of returning individuals had a previously occupied but now empty territory that was less than one territory-span away from the centre of their current territory; high site fidelity was therefore very unlikely to be because of limited territory availability. Over-winter residency time (defined by departure month) differed significantly across sites and with age, but did not determine the probability of whether a bird returned in the following year. This suggests the use of more than one wintering site for some individuals, rather than reduced over-winter survival. This study is one of the first to comprehensively document site fidelity at the territory scale in a Palearctic system, although less comprehensive studies or anecdotal evidence suggests that high winter site fidelity may be relatively common. Here we provide evidence for the serial residency hypothesis, where selection acts for individual migrants to have generalist habitat requirements, allowing them to survive in and remain site faithful to even relatively low-quality, but sufficient and familiar sites. Lower dispersal and higher site fidelity compared to that during breeding suggest that annual survival estimates are more accurate when measured on the wintering grounds. This study supports previous findings that wintering conditions do not limit Whinchat populations.

A striking case of deceptive woodpecker colouration: the threatened Helmeted Woodpecker Dryocopus galeatus belongs in the genus Celeus Martjan Lammertink, Cecilia Kopuchian, Hanja B. Brandl

The Helmeted Woodpecker Dryocopus galeatus is a threatened species of the Atlantic Forest in southeastern South America. It has traditionally been placed in the genus Dryocopus, but it shows similarities in plumage and structure with woodpeckers in the genus Celeus. We sequenced mitochondrial and nuclear DNA that was sampled from live captured Helmeted Woodpeckers. We found that the Helmeted Woodpecker has a phylogenetic position embedded within the genus Celeus, and recommend its taxonomic treatment as Celeus galeatus. The Helmeted Woodpecker belongs to a clade within Celeus that includes Kaempfer’s Woodpecker C. obrieni, Rufous-headed Woodpecker C. spectabilis, and Cream-coloured Woodpecker C. flavus. It has the southernmost distribution range of the woodpeckers in this clade. The Helmeted Woodpecker is sympatric throughout its range with Lineated Woodpecker Dryocopus lineatus and Robust Woodpecker Campephilus robustus and these species from three different genera show a remarkable convergence in plumage colours and patterns. With the inclusion of Helmeted Woodpecker in Celeus, this genus has four out of 15 species on the International Union for Conservation of Nature (IUCN) red list, a higher proportion of red listed species than in the woodpecker family overall.

Searching for a breeding population of Swinhoe’s Storm-petrel at Selvagem Grande, NE Atlantic, with a molecular characterization of occurring birds and relationships within the Hydrobatinae Mónica C. Silva, Rafael Matias, Vânia Ferreira, Paulo Catre

Long-distance dispersal plays a critical role in population dynamics, particularly in species that occupy fragmented habitats, but it is seldom detected and investigated. The pelagic seabird Swinhoe’s Storm-petrel, Oceanodroma monorhis, breeds exclusively in the NW Pacific. Individuals have been regularly observed in the Atlantic Ocean since the 1980s, but breeding has never been confirmed. In this study, we searched for evidence of breeding of Swinhoe’s Storm-petrels on Selvagem Grande Island, NE Atlantic, between 2007 and 2013. During this period, six individuals were captured, sexed and characterized molecularly for two mitochondrial loci, cytochrome oxydase I and the control region, to confirm species identity, survey genetic diversity and estimate evolutionary relationships within the Hydrobatinae. These individuals were confirmed to be Swinhoe’s Storm-petrels, and all except one are females. Phylogenetic analyses suggest sister relationship with Matsudaira’s Storm-petrel and dismiss misidentifications with other dark rump species. Patterns of genetic variation suggest that dispersal occurred likely by more than a single female. Despite the record of a pair duetting in a burrow, breeding could not be confirmed. Swinhoe’s Storm-petrels are regularly occurring at Selvagem Grande, but capture/recapture patterns suggest that a possible breeding population is small and likely not self-sustaining. In seabirds, long-distance dispersal events may facilitate colonization of new habitats created in the context of predicted climate change impacts on the marine ecosystems.

Body reserves in intra-African migrants Chima Josiah Nwaogu, Will Cresswell

Avian migration has been shown to be a life history strategy for surviving environmental resource variability, but it requires increased body reserves for long distance flight. Fat reserves make excellent energy stores for barrier crossing, whereas proteins generate less energy for the same mass of fat but provide water during breakdown, which may become especially useful when birds become water stressed. Intra-African migrants are probably unlikely to have to cross barriers equivalent to the Sahara and the Mediterranean sea and so may have different patterns of mass reserves reflecting the utility of metabolizing fat versus protein in hot, tropical environments. We examined differences in proportions of body mass gain, pectoral muscle score, and fat score between intra-African migrants, Palearctic migrants, and resident African species. We tested whether intra-African migrants show a distinct seasonal peak in mass gain corresponding to expected peak migration period in a manner similar to Palearctic migrants, but maintain larger muscle tissues, because Palearctic migrants are more constrained by a need to heavily up-regulate fat in addition to fat-free reserves before migration due to the energy requirements of crossing the barrier of the Sahara. We found that intra-African migrants had a peak seasonal mass gain similar to Palearctics whereas African residents did not, and that Palearctics increased fat reserves with pectoral muscle reserves, so that they had much higher fat scores for any given level of pectoral muscle compared to intra-African migrants or resident species. Our results suggest that barrier crossing leads to a distinct increase in fat reserves rather than migration per se, and suggests that intra-African migrants are more similar in their reserve management to African residents. Mass gain devoid of visible fat accumulation in intra-African migrants may, therefore, suggest absence of barriers during migration.

Response of reed warbler and sedge warbler to acoustic playback in relation to age, sex, and body condition Katarzyna Wojczulanis-Jakubas, Jakub Wietrzykowski

Acoustic playback has been shown to substantially increase the number of birds trapped. However, other effects of playback have rarely been investigated; the few studies that have been published strongly suggest that when playback is applied some groups of birds may be captured more easily than others, leading to biased results. In this study, we evaluated the experimental effect of acoustic playback (by comparing days when playback was used and was not used) at a stop-over site in central Europe during the post breeding period and the autumn migration. We examined the influence of playback on numbers of birds captured, i.e., two reedbed passerines—the reed warbler Acrocephalus scirpaceus (RW) and the sedge warbler A. schoenobaenus (SW)—with respect to their age, sex and body condition. We found that playback increased the number of birds captured 2.5 times in RW and 3.6 in SW. We did not find evidence for a differentiated response to the acoustic stimuli between adults and immatures. The sex ratio in RW was not affected by acoustic playback, but we did record significant male-bias in SW. The body condition of lured and non-lured birds was similar in both species. The sex bias revealed in one species but not in the other, clearly shows that great caution should be exercised when using playback to attract various species.

Carotenoid profile and vitamins in the combs of the red grouse (Lagopus lagopus scoticus): implications for the honesty of a sexual signal L. Pérez-Rodríguez, E. García- de Blas, J. Martínez-Padilla

The carotenoid-based ornaments displayed by many birds often play key roles in social and sexual signalling, revealing information about individual quality. However, the proximate regulation of the honesty of sexual traits remains controversial. Understanding the mechanisms of coloured trait production and maintenance requires an accurate description of their chemical composition and of the physiological pathways involved in pigment production and deposition in the ornaments. Carotenoid-based colouration has been extensively studied in birds, but such information is often lacking for coloured integuments other than feathers, such as fleshy carotenoid-based ornaments. Here we report the carotenoid composition of the combs of the red grouse (Lagopus lagopus scoticus), a sexual trait that honestly reveals individual quality. In the present study, we also investigated blood carotenoid content, as well as associations between carotenoids, retinol and tocopherol (the active forms of vitamin A and E, respectively) within the ornament. We found that comb pigmentation was primarily the result of two red ketocarotenoids (astaxanthin and papilioerythrinone), which are synthesised from their dietary precursors (zeaxanthin and lutein) directly at the comb integument. These red ketocarotenoids are largely deposited esterified with fatty acids. Astaxanthin concentration in the comb was found to negatively correlate with retinol levels but positively correlate with tocopherol levels. Considering evidence from this and other studied species, we suggest that carotenoid esterification is a characteristic of coloured fleshy integuments, probably affecting pigment stability and colouration in living tissues, with subsequent effects on their signalling role and maintenance costs. We found little evidence that the honesty of this signal would result from a direct connection with vitamin A metabolism, as recently proposed. Rather, honest signalling via comb colouration appears more related to potential allocation trade-offs of some specific dietary precursors or to the capacity of individuals to manage the redox reactions interfering with carotenoid metabolism.

Strong cascading effect of weather conditions on prey availability and annual breeding performance in European bee-eaters Merops apiaster Susanne Arbeiter, Martin Schulze, Peter Tamm, Steffen Hahn

Aerial insectivorous birds depend highly on favourable weather conditions for successful foraging because flight activity of insects is constrained by daily weather. Thus, the variation in weather conditions during reproduction, mediated by prey limitations, should be mirrored in annual reproduction performance, and finally in annual breeding success. We analysed the effect of local weather conditions on the availability of airborne insects and on the variation in brood size and nestling condition of European bee-eaters Merops apiaster at the northern edge of their range where years with adverse weather frequently occur. The availability of large flying insects, the common prey of bee-eaters, increased with air temperatures and duration of daily sunshine. As predicted, local weather conditions affected reproductive performance with annual breeding success (mean 3.7 nestlings per breeding pair, range 1.7–4.9 nestlings) being up to 32 % higher in extraordinary dry and hot summers. Additionally, a nestling's body condition (residual mass) was also affected by sunshine duration during their growth period and internally was co-affected by the number of siblings and the individual rank within the sibling hierarchy. Thus, a prolonged duration of daily sunshine causes a cascade from higher insect flight activity, and, thus, higher food availability for chick-rearing bee-eaters, which finally translates into better chick body conditions and higher annual breeding success. Consequently reproduction and population development of European bee-eaters might be especially susceptible to regional changes in weather and climatic conditions.

Sit-and-wait for large prey: foraging strategy and prey choice of White-tailed Eagles Mirjam Nadjafzadeh, Heribert Hofer, Oliver Krone

Little is known about foraging strategy and prey choice in large raptor species and how they might change with age and season. Here, we present results about time allocation, foraging pattern and diet selection of adult territorial White-tailed Eagles Haliaeetus albicilla from northeastern Germany. To assess age-related differences, we also observed foraging behaviour in roaming juveniles. Eagles allocated most of their diurnal time to perching. Since perch-hunting was more efficient than flight-hunting, “sit-and-wait” for prey seems to be a low-cost, highly profitable foraging mode in eagles. A linear mixed model revealed that season significantly affected eagle foraging patterns. Success in prey capture decreased and duration of foraging flights increased considerably in winter. Eagle strike success varied significantly between different territories and increased with increasing habitat quality. Adults foraged more efficiently than juveniles, presumably because of their superior spatial knowledge and hunting skills. A use–availability design for prey selectivity indices judged by log-likelihood chi-square statistics indicated that eagles make choices, within both their primary prey fish and alternative prey waterfowl, consistent with predictions of optimality models. When prey was abundant, eagles preferred large over small fish and slow over agile waterfowl species. Thus, prey choice by eagles reflected a complex function of absolute availability, size and anti-predator behaviour of their prey. Our study demonstrates that large raptors such as White-tailed Eagles are generally energy maximisers and pursue a “sit-and-wait” hunting mode to capture profitable prey, and can modify their foraging strategy to cope with variations in weather conditions and food availability.

The reproductive biology of the Syrian Woodpecker Dendrocopos syriacus in a newly colonized area of south-eastern Poland Jerzy Michalczuk, Monika Michalczuk

In 2003–2006, 73 Syrian Woodpecker nests were studied in a 305-km2 area of the agricultural landscape in SE Poland. The median egg-laying date was found to be 12 May and the median fledging date was 20 June (the earliest laying date was April 24 and the latest fledging date was July 25). Females laid from two to seven eggs (median 5.0 eggs, n = 56). An average of 4.4 young hatched per nest (SD = 1.18, median 5, maximum 6, n = 41) after 9–13 days of incubation (median 10 days, n = 37). Two to six nestlings left successful nests (median 4, n = 37) after 24–30 days (median 27, n = 36), with a mean of 2.8 (SD = 2.24, median 3, n = 56) young fledging per nest. The main reason for the loss of young observed in 31 % of the Syrian Woodpecker broods was nest parasitism by starlings. These results suggest that the process and dynamics of the range expansion of the Syrian Woodpecker are influenced by a higher reproductive output of Syrian Woodpeckers at the extremities of its range as compared to that of the rest of the Syrian Woodpecker population.

Population abundance and trends of Saltmarsh (Ammodramus caudacutus) and Nelson’s (A. nelsoni) Sparrows: influence of sea levels and precipitation W. Gregory Shriver, Kathleen M. O’Brien, Mark J. Ducey

Evidence of biological responses to climate change continues to grow. Long-term monitoring programs are critical in documenting these changes as well as identifying the primary stressors that may influence a species’ ability to adapt to changing climate. Eastern North American salt marshes support the greatest number of endemic salt marsh vertebrates globally, two of which are sympatric from southern Maine to northern Massachusetts, USA. Saltmarsh Sparrows (Ammodramus caudacutus), listed ‘vulnerable’ by the International Union for Conservation of Nature (IUCN), have a restricted global breeding range that occurs in salt marshes from Maine to Virginia, USA. Nelson’s Sparrows (Ammodramus nelsoni) breed in salt marshes from Massachusetts north to the Canadian Maritime Provinces and west to the prairie pothole regions of central Canada. These taxa hybridize in sympatry which may affect how these taxa respond to changing habitat quality and availability caused by climate change. We present the first estimates of the effects of sea level rise, breeding season precipitation, and salt marsh patch size on the abundance and population trends for three groups: (1) Saltmarsh Sparrows, (2) Nelson’s Sparrows, and (3) all Sharp-tailed Sparrows [the combined population of both species including hybrids]. We used 14 years of population monitoring data (2000–2013) from nine saltmarshes within the Rachel Carson National Wildlife Refuge, Maine, USA. We detected a declining trend for Saltmarsh Sparrow (i.e., significant decline, but not significantly more than 5 % per year), stable trends for Nelson’s Sparrows and for all Sharp-tailed Sparrows (i.e., no significant increase or decrease over the time period). Abundances for the three sparrow groups varied among years and marsh units. Drier years with relatively low mean sea levels had the greatest abundances. Breeding season precipitation negatively influenced population trends for Saltmarsh and Nelson’s Sparrows and mean sea level had a negative effect on Saltmarsh Sparrow population trends. Our results indicate that Saltmarsh Sparrow, the species most specialized to salt marshes, has declined which may be indicative of broader, regional patterns. The negative relationships of mean sea level and precipitation with Saltmarsh Sparrow population trends suggest that the negative effects of increasing nest flooding may be having demographic-level effects on this local population. Analyses of other salt marsh bird long-term monitoring programs are warranted to determine if this pattern is consistent in other portions of the Saltmarsh Sparrow range.

Plasma metabolites correlate with weekly body mass changes in migrating black-tailed Godwits Limosa limosa feeding on different diets Noelia Albano, Francisco Santiago-Quesada, Auxiliadora Villegas

The study of variations in plasma metabolite profiles has emerged as a useful physiological tool to assess fuel deposition rates from a single blood sample. Diet may be a key factor in the study of refueling patterns in long-distance migratory birds, but the potential confounding effect of diet on the conclusions drawn from plasma metabolites has rarely been considered. Here, we assessed whether plasma metabolite levels correlate with the weekly increase in body mass of migrating Black-tailed Godwits Limosa limosa, a medium–large shorebird, feeding on two natural diets (insectivorous vs. granivorous) during the refueling period. We found that glycerol and triglycerides successfully explained the weekly natural change in body mass of Black-tailed Godwits. Although the diet type contributed to the change in body mass, all interactions between plasma metabolites and diet treatment were non-significant. Our results support the use of plasma metabolite profiling to predict body mass changes on a long-term (weekly) scale in medium–large birds.

The flight feather moult pattern of the bearded vulture (Gypaetus barbatus)
Iñigo Zuberogoitia, Juan Antonio Gil, José Enrique Martínez

Moult is an extremely time-consuming and energy-demanding task for large birds. In addition, there is a trade-off between the time devoted to moulting and that invested in other activities such as breeding and/or territory exploration. Moreover, it takes a long time to grow a long feather in large birds, and large birds that need to fly while moulting cannot tolerate large gaps in the wing, but only one or two simultaneously growing feathers. As a consequence, large birds take several years to complete a full moult cycle, and they resume the moult process during suboptimal conditions. A clear example of this pattern is the Bearded Vulture (Gypaetus barbatus), which needs 2–3 years for changing all flight feathers. Here we describe the sequence, extent, and timing of moult of 124 Bearded Vultures in detail for the first time. We found that extent and timing of flight feather moult was different between age classes. Subadults (from 3rd to 5th calendar year) started moult, on average, in early March, whereas adults only started moult, on average, in late April, possibly due to breeding requirements. Second calendar year individuals delayed onset of moult until the middle of May. In general, the moult lasted until November, and although adults started to moult later than subadults, they moulted more feathers. Subadults needed 3 years for moulting all flight feathers, whereas adults normally completed it in 2 years.

A siblicidal origin for avian brood parasitism?
Andrew Goldklank Fulmer, Mark E. Hauber

We present a model for the evolution of host selection by avian brood parasites from the ecological context of siblicidal brood reduction tactics. Our analysis concentrates on the fitness costs and benefits that permit the evolution of brood parasitism as an adaptive strategy from a state of obligate parental care already featuring siblicide. Limited resources delivered by provisioning parents may incite siblicidal behaviour in offspring, directed towards nestmates regardless of kinship. The extent of siblicidal behaviour (in frequency of occurrence and number of nestmates killed) can extend to the eradication of all nestmates, as has been observed in some raptors and in seabirds. For parents of siblicidal offspring, laying each egg parasitically may maximize offspring survival by eliminating competition between related but siblicidal nest mates. To permit the evolution of conspecific (intraspecific) brood parasitism, costs of siblicide by the offspring of parasitic parents must exceed costs paid by the parasitic parents when losing related conspecifics (host offspring) in a host nest. To permit the evolution of obligate interspecific brood parasitism, costs to fitness from siblicidal offspring or nest reduction of related hosts must exceed costs of heterospecific parental care. Understanding the kin structure between parasites and hosts in conspecific parasitism, and measuring the costs paid by parasitic young due to mismatched incubation, provisioning, and social behaviours by heterospecific foster parents, should provide novel insights into the opportunities and constraints of the evolution of avian brood parasitism.

Philopatry in a changing world: response of pink-footed geese Anser brachyrhynchus to the loss of a key autumn staging area due to restoration of Filsø Lake, Denmark
Kevin Kuhlmann Clausen, Jesper Madsen

Site fidelity is a strong and widespread feature of many waterfowl species, but little is known about the response of philopatric birds to changing environmental conditions at their preferred staging sites. In this study we analyse the response of pink-footed geese Anser brachyrhynchus to the sudden loss of a major autumn staging area along their migration corridor, Filsø in Denmark, which followed the re-establishment of a former lake on open arable land serving as foraging site to tens of thousands of geese. Comparisons of goose usage before and after the restoration event revealed that (1) approximately 80 % of pink-footed geese abandoned this staging area and (2) formerly site-faithful geese moved to other staging areas along the Danish west coast rather than moving further south to the Netherlands. Despite these significant changes in site use, the subsequent spring body condition of birds formerly philopatric to the Filsø area was unaffected, suggesting that geese quickly moved to other areas and responded well to the sudden decline in available food at their formerly preferred staging site. These findings indicate that, at least for pink-footed geese, the cognitive plasticity necessary to alter site use allows a swift response to rapidly changing environmental conditions. This may partly be due to the agricultural habitat use of this species, leaving them plenty of alternatives in the modern Danish landscape.

Ultraviolet lights do not deter songbirds at feeders
Michael W. Habberfield, Colleen Cassady St. Clair

Collision with glass windows is a leading anthropogenic cause of direct mortality for avian species and much attention has been given to developing methods to reduce the incidence of bird collisions. Little empirical research exists, however, examining the mechanisms by which birds might be deterred from human structures. We tested the efficacy of ultraviolet (UV) lights for preventing window strikes in an urban environment by measuring their deterrence effect at bird feeders at eight residential sites. We used remote cameras to count feeder visits over one winter in response to rotating treatments comprising a pulsating UV light, a light-reflecting compact disc, an unlit UV light as a novel object, and a control with no object. Using generalized linear mixed models, we showed that feeder visit rates were influenced by wind speed, site, and site–treatment interactions. The unlit novel object treatment yielded a visitation rate significantly higher than the control (p = 0.01). The UV and passive reflecting treatments slightly increased visitation above the control (p = 0.06 and p = 0.378, respectively). This suggests that novel objects may serve as an attractant in a foraging context and that this effect is stronger than any deterrence effect of UV light. The site–treatment interaction indicated that each of the four treatments produced the highest visitation rate for at least one of the sites. Rather than offer a biological explanation for this interaction, we speculate that it resulted from a spurious effect of temporal and spatial variation in bird activity that interacted with our randomized block design. Although we found no evidence that UV lights would deter urban songbirds from anthropogenic structures, their potential to attract attention may reduce the likelihood that birds fail to see and then collide with windows.

Satellite tracking of Ross’s Gull Rhodostethia rosea in the Arctic Ocean
Olivier Gilg, Alexandre Andreev, Adrian Aebischer

Ross’s Gull is one of the most emblematic Arctic birds and least known seabirds in the world; post-breeding movements and the use of sea-ice habitats have been long debated, but described only from scattered observations. We tracked two adults, a male and female, breeding in the Kolyma Delta, Russia, using the lightest (<5 g) satellite transmitters currently available: the transmitters provided data for 44 and 132 days for the female and male, respectively. After departing from the breeding area and reaching the nearby Laptev Sea at the beginning of July, both birds moved NW, and the male staged until the end of September in an area of scattered sea-ice (concentration 50–100 %), NE of Severnaya Zemlya archipelago, between 80 and 85° N. By mid-October, most likely escaping the polar night, this bird reached the coast of NW Alaska, and a few days later it arrived in the coastal wetlands of North Chukotka, where it remained until the transmitter stopped in early November.

No detectable effects of lightweight geolocators on a Palaearctic-African long-distance migrant
Rien E. van Wijk, Guillaume Souchay, Susanne Jenni-Eiermann

Tracking devices are used in a broad range of species for a broad range of questions, but their potential effects on study species are debated. Outcomes of earlier studies on effects are equivocal: some studies find negative effects on behaviour and life history traits, while others do not. Contrasting results might be due to low sample sizes, temporal scale (no repetition of the study over multiple years) and a limited range of response variables considered. We investigated effects of geolocators on a range of response variables: body condition, physiological states, reproductive performance and, ultimately, annual apparent survival for a medium-sized Palaearctic-African long-distance migrant, the Eurasian Hoopoe Upupa epops, for the combined study period (2009–2014) and for individual years. We investigated response variables 1 year after deployment of the geolocator and found no differences in body condition, physiological states and several components of reproductive performance between individuals with and without geolocators when data were combined. Also, apparent annual survival did not differ between geolocator and control birds. We did, however, find effects in some years possibly related to environmental stochasticity or chance events due to lower sample sizes. We argue that results of studies on the effects of tracking devices should be interpreted and generalized with great caution and suggest that future studies on the effects of tracking devices are conducted over multiple years. Future studies should also apply capture–recapture models to estimate survival, rather than focus solely on return rates.

Moult migration in Bullock’s orioles (Icterus bullockii) confirmed by geolocators and stable isotope analysis
Andrew G. Pillar, Peter P. Marra, Nancy J. Flood

In contrast to the majority of migratory songbirds in North America, which moult on or near their breeding grounds, the Bullock’s oriole (Icterus bullockii) is reported to stop during fall migration to moult en route to the wintering grounds. These birds seem to take advantage of food resources during the Mexican monsoon season in the Southwestern USA and Northwestern Mexico. We studied a population of Bullock’s orioles at the northern limit of their breeding range in Kamloops, British Columbia, Canada, using a combination of light-level geolocators and stable hydrogen isotope analysis. We found evidence that supports the existence of moult migration in this species, with geolocators indicating that all birds appeared to stay in the Mexican monsoon region for moult in an extended stopover period during fall migration. Feathers were isotopically enriched with deuterium compared to predicted breeding isotope values and were significantly more negative than winter-grown claws, confirming that moult occurred somewhere between the breeding and wintering grounds. Stable isotope data were consistent with complete prebasic stopover moult in adults and complete contour feather and variable tail feather moult in first-year orioles. Our results confirm that this northern population of Bullock’s orioles employs a moult migration strategy and highlight the usefulness of combining geolocator and stable isotope studies.

Testing an attachment method for solar-powered tracking devices on a long-distance migrating shorebird
Ying-Chi Chan, Maarten Brugge, T. Lee Tibbitts, Anne Designa

Small solar-powered satellite transmitters and GPS data loggers enable continuous, multi-year, and global tracking of birds. What is lacking, however, are reliable methods to attach these tracking devices to small migratory birds so that (1) flight performance is not impacted and (2) tags are retained during periods of substantial mass change associated with long-distance migration. We developed a full-body harness to attach tags to Red Knots (Calidris canutus), a medium-sized shorebird (average mass 124 g) that undertakes long-distance migrations. First, we deployed dummy tags on captive birds and monitored them over a complete migratory fattening cycle (February–July 2013) during which time they gained and lost 31–110 g and underwent a pre-alternate moult of body feathers. Using each individual’s previous year fattening and moult data in captivity as controls, we compared individual mass and moult differences between years between the tagged and reference groups, and concluded that the attachment did not impact mass and moult cycles. However, some birds shed feathers under the tags and under the polyester harness line commonly used in avian harnesses. Feather shedding was alleviated by switching to smoothed-bottom tags and monofilament harness lines. To field-trial this design, we deployed 5-g satellite transmitters on ten Red Knots released on 3 October 2013 in the Dutch Wadden Sea. Bird movements and tag performance appeared normal. However, nine tags stopped transmitting 11–170 days post-release which was earlier than expected. We attribute this to bird mortality rather than failure of the attachments or transmitters and suggest that the extra weight and drag caused by the tag and its feather-blocking shield increased the chance of depredation by the locally common Peregrine Falcons (Falco peregrinus). Our results demonstrate that species- and place-specific contexts can strongly determine tagging success. While captive trials are an important first step in developing an attachment method, field trials are essential to fully assess attachment designs.

The structure and organization of song in Southern House Wrens (Troglodytes aedon chilensis)
Ednei B. dos Santos, Paulo E. Llambías, Drew Rendall

Studies of birdsong across very broad geographic scales, such as between the north temperate zone and the tropics, provide special opportunities to understand the role of variable ecologies, life histories and mating pressures on song structure and organization. The problem is typically studied through comparative, cross-species analyses because few species have such broad distributions to encompass both regions. The House Wren is an important exception, having the widest distribution of any native songbird in the Americas, from Canada to Tierra del Fuego. Across this range, they manifest considerable variation in life history, mating systems and migration, but there is no systematic research on corresponding song variation. Here we provide a first detailed characterization of song structure and organization for Southern House Wrens (Troglodytes aedon chilensis) in western Argentina and provide preliminary comparisons to Northern House Wrens. Songs of Southern House Wrens contained two distinct sections: an introduction of broadband noisy, or harmonic, notes followed by a louder terminal section of tonal, frequency-modulated syllables with a mean of seven syllables and three syllable types per song. The syllable repertoire was large (28), mostly shared and used to construct very large song repertoires (up to 170 song types with no evidence of a ceiling), but much smaller repertoires of commonly produced song types (24). Males tended to repeat song types many times before switching (eventual variety) but, at times, sang with immediate variety. Compared to Northern House Wrens, there were differences in the detailed form of some notes and syllables as well as in the relative emphasis of the softer introduction versus louder terminal section of songs. In broader patterns of song construction, organization, delivery, and the size of syllable and song repertoires, the two populations were very similar. These patterns are discussed in light of differences in life history, mating and migration between them.

Maternal influence on eggshell maculation: implications for cryptic camouflaged eggs
Camille Duval, Phillip Cassey, P. George Lovell, Ivan Mikšík

Egg camouflage may explain the adaptive significance of avian eggshell pigmentation in ground-nesting species. Eggshell maculation (spots) is predominantly due to protoporphyrin, but both biliverdin (antioxidant) and protoporphyrin (pro-oxidant) may be present in spotted eggshells. Because of their role in oxidative stress, the deposition of eggshell pigments might be condition-dependent. However, because of the fitness benefits of eggshell coloration, cryptic eggshell appearance should be strongly conserved in ground-nesting species regardless of female condition and eggshell pigment concentrations. We investigated whether Japanese quails (Coturnix coturnix japonica) maintained eggshell maculation under food restriction. We quantified eggshell maculation (i.e., percentage of spot coverage) using digital photography, and both protoporphyrin and biliverdin concentrations of eggs laid by females either on a food-restricted or an ad libitum diet. Females on a high quality diet, which are known to decrease the deposition of eggshell protoporphyrin, decreased eggshell maculation compared with food-restricted females that maintained it. For the first time, we propose an experimental study which suggests that eggshell maculation depends on female body condition and that manipulating eggshell maculation may be the strategy used by females to potentially optimize egg camouflage.

Settlement, habitat preference, reproduction, and genetic diversity in recovering the white-tailed eagle Haliaeetus albicilla population Rimgaudas Treinys, Deivis Dementavičius, Saulius Rumbutis

The recovering population of white-tailed eagles Haliaeetus albicilla was studied in Lithuania, Central Europe. In the present study, we focused on (1) clarifying which theoretical distribution model better fits and describes the observed pattern of eagle settlement, (2) examining habitat preference at the level of nesting territory and its relationship with reproduction, (3) ascertaining the genetic diversity profile of the population using D-loop mtDNA. Between 1985 and 2011, the white-tailed eagle population recovered from 0 to 120 pairs and by the end of the period occupied a range of 34,000 km2. As indicated by a mean annual breeding success of 0.67, productivity 1.15, and brood size 1.73, the population reproduced well. The pattern of habitat settlement during the period of population expansion was not random as high-quality habitats were occupied first. Supporting the ideal free distribution model, reproduction was similar across nesting territories in three different habitat types, as well as between territories established in different years. The eagles preferred aquatic habitats, but these preferences were not adaptive in terms of breeding performance. Increased brood failures in later years possibly indicated the growing effect of density-dependent regulation. In total, six different haplotypes were identified in the sample of 45 individual birds. Haplotype diversity was 0.711. Phylogenetically, the Lithuanian population is most closely related to the populations of Sweden, Poland, and Germany, while similarity with Lapland, Kola, and Estonian populations was evident too. These findings indicate possible source populations directly or indirectly participating in the process of recovery of the formerly extinct Lithuanian population. Haplotypes distribution across the three habitat types in Lithuania was uneven.

Low genetic differentiation between Greenlandic and Siberian Sanderling populations implies a different phylogeographic history than found in Red Knots
Jesse R. Conklin, Jeroen Reneerkens, Yvonne I. Verkuil

The Greenlandic and west-central Siberian breeding populations of Sanderlings Calidris alba are separated by ca. 2000 km during the breeding season, but mix in Europe to some extent during migration. However, the number of Siberian Sanderlings that spend the non-breeding season along the East Atlantic Flyway (extending from western Europe to South Africa), if any, is unknown. Although both populations are considered part of the nominate subspecies C. a. alba based on morphology, population structure in Sanderlings has yet to be described with molecular methods. We examined genetic differentiation at the mtDNA control region (CR) and seven microsatellite loci between Greenland- and Siberia-breeding Sanderlings in order to: (1) develop a diagnostic tool for assessing the breeding origin of Sanderlings along the East Atlantic Flyway, and (2) provide a comparison with the co-distributed and ecologically similar Red Knot, in which CR differentiation of geographically analogous populations (C. canutus islandica and C. c. canutus) has indicated isolation of lineages near the time of the last glacial maximum. By contrast, we found only weak differentiation between the Sanderling breeding populations at the CR, and no differentiation at microsatellite loci. These results suggest that the assignment of breeding origin of Sanderlings on Afro-European flyways will not be possible with simple and inexpensive genetic methods, and imply that Sanderlings and Red Knots have very different post-glacial phylogeographic histories.

Hierarchical habitat selection by Eurasian Pygmy Owls Glaucidium passerinum in old-growth forests of the southern French Prealps
Luc Barbaro, Sébastien Blache, Gilles Trochard, Cindie Arlaud

Maintaining or restoring old-growth stand structures in mountain forests, including deadwood and snags provided by natural disturbances, is considered critical for the conservation of secondary cavity-nesting birds. Under current climate warming, old-growth mountain forests might become increasingly important for boreo-alpine species living in the southern part of their ranges. Here, we focused on hierarchical habitat selection by Eurasian Pygmy Owls Glaucidium passerinum in mixed mountain forests at their low latitude range limit in the southern French Prealps. We quantified Pygmy Owl habitat use at complementary hierarchical levels, from the local population to individual home ranges, by combining systematic playback counts and radio-telemetry. Mean home range sizes for breeding adult males covered 0.67 km2, ranging between 0.46 and 0.98 km2. We found evidence for Pygmy Owl habitat selection being a consistently hierarchical process, with (1) fir-dominated forests selected as the main habitat at the population level; (2) old-growth fir-dominated forest stands including edges with grassland gaps and karstic eroded areas selected at the home range level; and (3) amount of surrounding dead or decaying spruces increasing the occurrence probability of owl nesting cavities. Conserving Pygmy Owls at their low latitude range limit therefore requires the maintenance of old-growth mixed forests dominated by firs that provide these critical habitat features within a complex and heterogeneous landscape mosaic.

Breeding success of the Great Tit Parus major in relation to attributes of natural nest cavities in a primeval forest
Marta Maziarz, Tomasz Wesołowski, Grzegorz Hebda, Marta Cholewa

An overlap in attributes of nest cavities used by Great Tit Parus major across Eurasia suggests similar nest site preferences within the geographical range, although the drivers of these preferences are unclear. To determine whether preferred cavities provide conditions enhancing successful reproduction, we investigated the breeding performance of Great Tits in relation to tree cavity characteristics using data collected during 2008–2011 in primeval conditions (Białowieża National Park, Poland). Here, tree cavities are diverse and superabundant but nesting birds are at risk from a variety of predators. According to expectations, nest losses were high (60 % of Great Tit nests failed), mostly due to predation (69 % of nest failures). The risk of nest failure varied with nest cavity attributes. Compared to successful nests, failures were situated higher above the ground and placed closer to the cavity entrance. Very deep cavities with narrow entrances and strong livings walls provided effective protection against larger predators (e.g., martens, woodpeckers), unable to enter the cavity or pull out the contents. Yet, such holes were no barrier for the smallest predators (e.g., Forest Dormouse Dryomys nitedula), which were able to enter any Great Tit nest cavity and destroyed most of the nests. Avoiding small predators would give a selective advantage to the birds, but this seems hardly possible to achieve. We conclude that tree cavities preferred by the tits show a combination of properties which are a compromise for avoiding predation (the strongest selective pressure) and providing the minimum requirements (sufficient nest illumination, microclimate, protection against nest soaking) for development and growth of young.

Ferruginous Hawks Buteo regalis alter parental behaviours in response to approaching storms Chelsey M. Laux, Cameron J. Nordell, Ryan J. Fisher, Janet W. Ng

Heavy and frequent rain, low temperatures, and strong winds may decrease adult foraging time, cause thermoregulatory stress on nestlings, and lead to nest damage or destruction, all of which can negatively affect breeding success. However, certain parental behaviours can mitigate these potentially negative effects of inclement weather. We examined how parents could mitigate these negative weather effects by adjusting three behaviours—nest attendance, prey deliveries, and nest maintenance—before, during, and after storms at 11 nests of the at-risk Ferruginous Hawk (Buteo regalis) in Canada. Female adults spent an increasing amount of time on the nest as wind speed increased. Similar numbers of prey were delivered before and after storms, suggesting that Ferruginous Hawks do not compensate for lost foraging time. They appeared to demonstrate an ability to detect approaching storms, possibly by responding to falling barometric pressure cues, and may have mitigated the risk of nest damage by increasing their nest maintenance behaviours. Our study is among the first to observe storm preparation behaviour, and indicates that some raptorial birds have the ability to alter nesting behaviour in response to approaching inclement weather.

Northern Goshawk (Accipiter gentilis) may improve Black Grouse breeding success
Risto Tornberg, Seppo Rytkönen, Panu Välimäki, Jari Valkama

Around the nests of many birds of prey the pressure of nest predators is decreased. This attracts other bird species to breed near nests of those birds of prey in order to benefit from protection conferred. This study examines the possible protective effect of the Northern Goshawk (Accipiter gentilis) on two of its main prey species, the Black Grouse (Tetrao tetrix) and the Capercaillie (Tetrao urogallus). If the Goshawk reduces the number of corvids robbing grouse nests, there should be a larger proportion of grouse females with broods near Goshawk nests during late summer. We compared the proportion of grouse females with the broods observed in wildlife-triangle counts, which were performed along a 12-km-long equilateral triangle in relation to distance from a successful Goshawk nest. Where Goshawks had nested inside a triangle, the proportion of Black Grouse females with a brood was 20 % higher than in situations where a Goshawk had nested 2–3 km away from the center of the triangle. On the other hand, the number of adult Black Grouse rose as the distance from the Goshawk nest increased, but this pattern did not hold with chick abundance. No distance effect was found for Capercaillie. This study thus provided indirect evidence based on quantitative data that Goshawks may create a protective effect for one of its main prey.

New locality for the endangered Blackthroat Calliope obscura
Per Alström, Min Zhao, Peng He, Fumin Lei

This study provides new distributional and morphological data for one of the world’s most poorly known species, the Blackthroat Calliope obscura, which, until recently, was only known from fewer than ten museum specimens and a few field observations. Three previously mis-labelled male specimens collected during the breeding season at a presumed breeding site slightly further to the northwest of the formerly known range were recently found.

Longitudinal studies confirm faster telomere erosion in short-lived bird species
Joanna Sudyka, Aneta Arct, Szymon Drobniak, Lars Gustafsson

Evidence is accumulating that telomeres become shorter with advancing age and possibly explain some of the observed variation in longevity. Cross-sectional analyses have shown that species with shorter lifespans lose more telomeric repeats with age than species with longer lifespans. Using existing data from longitudinal studies performed on several bird species, we confirmed a negative relationship between the rate of telomere shortening and maximum longevity.

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