Journal of Ornithology

Volume 155, Issue 3, July 2014

ISSN: 2193-7192 (Print) 2193-7206 (Online)



In this issue 

Review


Abstract

The term ‘short-stopping’ is increasingly used in ecology to describe spatio-temporal changes in occurrence of migratory species. Spurred by the insight that it has been used in a variety of contexts, we reviewed its use in avian ecology. A literature search yielded 59 papers explicitly treating short-stopping in birds, most of them in peer-reviewed journals. The term was first used in 1967 to describe a northward shift in wintering Canada Geese in North America and has been used with increasing frequency to the present day. Geese dominate the short-stopping literature, which is confined to the northern hemisphere. Short-stopping has been used to describe (1) a shortened autumn migration that results in a wintering distribution closer to breeding areas, (2) a shortened spring migration that results in a breeding distribution closer to wintering areas, and (3) a delay in autumn migration that leads to a perceived reduced abundance in some part of the winter range. We advocate that short-stopping should be used only to describe (1) range shifts that involve shortening of the migratory corridor, and that they are qualified explicitly by season (i.e. breeding/winter) and degree (i.e. full or partial range shift). In other cases of breeding, wintering or entire range shifts where the migratory corridor is elongated or remains the same, we recommend using the term ‘range shift’, qualified by season, geography and orientation (i.e. the direction of the range shift). We also discuss the need for spatially explicit avian count monitoring mechanisms (rather than capture–recapture or hunting bag data) designed specifically to track such changes in distribution in the future.




Abstract

The first molecular and morphological study of the insufficiently known Black-collared Lovebird Agapornis swindernianus of West and Central Africa indicates that this species is the sister taxon of all the remaining Agapornis parrots. The systematic position of the Grey-headed Lovebird A. canus could not be convincingly resolved by the sequence analysis of the cytochrome b gene, but morphological characters support earlier assumptions that this species forms a clade with the Red-faced and the Black-winged Lovebird, A. pullarius and A. taranta. The new phylogeny of Agapornis presented here suggests that the last common ancestor of lovebirds originated on the African continent, and that it was a more arboreal forest-dweller, probably with a preference for small fruit seeds. Thus, a preference to more open woodlands and a change to a more granivorous diet must have evolved after the split of the lineages leading to A. swindernianus and all the remaining lovebird species.


Abstract


Great Spotted and Syrian Woodpeckers (Dendrocopos major and D. syriacus) are known to hybridize in nature; however, the extent of this phenomenon is not known due to difficulties in hybrid detection based on plumage analyses. Here, we tested five markers (one mitochondrial and four nuclear) and a set of six microsatellite loci for the identification of these two Woodpeckers and their hybrids. Sequencing of DNA from 26 individuals of both Woodpeckers from different parts of their ranges: one allopatric (D. major; Norway) and two sympatric (Poland and Bulgaria) showed that both species can be clearly separated based on all sequence markers. The highest number of fixed nucleotide sites were found in the mtDNA control region and intron 5 of the transforming growth factor. Analyses of microsatellite data distinguished the two species, but all loci showed a large number of common alleles and their utility in identifying hybrids is therefore doubtful. According to the DNA sequence analyses, 2 out of 18 specimens within the sympatric range in Poland were identified as possible hybrids, most probably paternal backcrosses. Moreover, both hybrids are from synantropic populations (settled in cities), whereas none of the D. major sampled in forests and in its allopatric range (Norway) showed signs of an intermixed genotype. Further research on hybridization and introgression in woodpeckers is undoubtedly needed and could be useful for understanding ecological and ethological interactions among these species, particularly for D. syriacus, which is relatively rare in Europe.


Abstract


Declining body size has been suggested to be a response of animals to global warming, but analyses of time series have led to contradictory results. One problem is that each trait related to body size may vary in response to factors other than temperature and independently of size. We analyse trends of three morphological traits of a passerine bird species: the Stonechat Saxicola torquata. Wing lengths were increasing and tail length mostly decreasing between 1989 and 2012. Variation in tarsus length showed no consistent trend. Wing length increased with increasing temperature. Concomitant decreasing tail length suggests, however, that increasing wing length cannot be explained by increasing temperatures during the study period. As tarsus length is a surrogate for overall size, we argue that there was no detectable trend in body size. Wing and tail length are related to flight performance, and increasing wing and decreasing tail length could be indicative of selection for more effective flight, related to either longer migration distances or increased predation pressure. The first scenario is unlikely given the strong suggestions of reduced migratory activity in birds as a response to climate change. The density of the Sparrowhawk Accipiter nisus recently increased almost tenfold in the study area, but the hypothesis of changing morphology as a response to increasing predation pressure remains to be tested. Our study suggests, however, that linking fluctuating lengths in single morphological traits to body size change as a response to global warming may be premature when alternative hypotheses are not considered.


Abstract


We used stable isotope tracers in the growing primary feathers of Eurasian Spoonbill chicks (Platalea leucorodia leucorodia) to study seasonal variation in their diet on one of the Frisian islands, Schiermonnikoog, The Netherlands. Using growing individual primaries as natural samplers over time, samples were taken along the length of primary feathers to estimate both within- and between-individual variation in diet. Absolute isotopic ratios of feather material ranged from −26.2 to −14.7 ‰ for carbon (δ13C) and from 13.0 to 18.7 ‰ for nitrogen (δ15N). The variation in δ13C values suggests the use of a variety of feeding habitats, ranging from freshwater to marine. Across the breeding season, there was a shift from predominantly freshwater prey early on to a more marine diet later in the season. Surprisingly, this shift did not occur within the growth trajectory of early born chicks which instead showed the opposite, but it did occur within individual chicks born later in the season. Stable isotope Bayesian mixing-model (SIAR) outcomes demonstrated that the freshwater/brackish prey had the highest isotopic contribution “(51 %; 95 % confidence interval 39–63 %) to the diet early in the breeding season, whereas marine prey contributed most (78 %; 66–89 %) to the diet later. That chicks fed with either freshwater or marine food items had similar body condition indices suggests that the eating of marine prey did not come at a major cost for growing Spoonbill chicks.


Abstract


It has been shown that songbird migrants can use several compass cues for orientation (e.g. sun position at sunset and possibly sunrise and related polarised light cues, stars and the geomagnetic field); therefore, the obtained information is redundant. This suggests that compasses of migratory birds must have certain hierarchical relationships and be calibrated. Currently, it is not known how avian compass calibration is accomplished. We report the results of our experiments with Garden Warblers Sylvia borin, long-distance songbird migrants. We tested the birds in two experimental conditions: in a local magnetic field with access to a starry sky (Control group) and in a vertical magnetic field that does not provide magnetic compass information with access to stars (Clear sky experimental group) or without it (Overcast experimental group), and analysed locomotor activity and orientation in all three groups. For the Garden Warblers from the control and experimental groups, we revealed two periods of activity separated by a quiescent period: twilight and nocturnal periods. The average direction for both periods of activity showed no significant difference in the control group. Birds from the experimental group were disoriented in both periods. Birds from the clear sky and overcast groups were also disoriented. These data suggest that long-distance songbird migrants, particularly the Garden Warbler, need information from the geomagnetic field, but not from the stars, at sunset and during twilight in order to choose the correct migratory direction. The nocturnal period of migratory activity probably represents actual migratory flight, while the nature of the twilight period remains unknown. The results of the present work and data from prior cue-conflict experiments on other species suggest that the twilight period may correspond to compass calibration activity.


Abstract

Extreme storm events encountered during any stage of the annual cycle can result in increased mortality and influence population dynamics. Storms during the reproductive season, when birds are tied to fixed nesting locations, can be particularly problematic. Given predicted changes in the frequency and intensity of storms in a changing climate, studies examining the impacts of storms on reproductive success in model systems are important. Island-nesting seabirds may be particularly vulnerable to changes in storm frequency and intensity. Here, we report on the effects of an extreme storm in June 2012 on Herring Gull (Larus argentatus) reproduction on an island in the Gulf of Maine, USA. More than 22 % of monitored nests were lost in this single event leading to a seasonal shift in the optimal nesting locations for birds in our population. Nests closer to water and nests located at low elevations were disproportionately affected by the unusual weather, reversing trends in optimal nesting sites recorded in previous seasons. Spatiotemporal shifts in optimal nesting locations, therefore, may be one result of climate-induced changes in storm frequency and intensity. Although some birds with nests destroyed in the storm attempted to renest, these attempts experienced low success, and overall reproductive success in the storm-affected season was lower than in the previous three nesting seasons.


Abstract


It is not clear at present if variation in testosterone (T) levels is associated with variation in plumage signal expression in female birds. In Iberian populations of Pied Flycatchers Ficedula hypoleuca, some females exhibit a distinctive white forehead patch similar to that found in males. Both sexes also exhibit conspicuous white patches on wings that vary greatly in size. Males show markedly larger wing patches. These patches are exhibited in social interactions. We have aimed at detecting if naturally occurring variation in T circulation is linked to the expression of forehead patch presence and folded wing white patch area in female Pied Flycatchers. There was marked variation in female plumage patches and in T levels. The area of the wing white patch but not the presence of a forehead patch in females was associated with higher circulating T levels during the incubation phase when controlling for female age and hatching success. Older females, and females suffering a reduced hatching success, also presented lower levels of T. Our study indicates that a female plumage trait that is equivalent to a sexually selected trait in males may signal T levels. Females, like males, may use plumage traits to signal their T-mediated aggressive disposition.


Abstract


Artificial nests are a commonly used management technique to increase the breeding population and/or productivity of birds with nest site limited populations. We compared nest survival of saker falcons breeding in artificial nests erected in a flat steppe landscape with those breeding in natural nests on rocks and cliffs in adjacent hills of central Mongolia. We found no significant difference in daily nest survival during the egg and nestling stages of the breeding cycle. Nest survival varied across years and was higher at artificial than natural nest sites, primarily because of higher survival rates during the egg stage at artificial nests. However, fledgling productivity was not significantly different although artificial nests produced an average of 3.2 fledglings compared to 2.3 at natural nest sites. We found no significant differences in offspring sex ratios and fledgling mass at artificial and natural nest sites. Provision of artificial nests can increase the range, size and productivity of saker falcon breeding populations, a globally endangered species subject to high mortality and trapping for falconry. This management technique can be used for incentive-driven conservation initiatives, whereby sustainable harvest quotas can be generated from demographic models based on parameters derived from a managed and monitored population breeding in artificial nests.


Abstract


The realized distribution of animals is often delimited by climatic factors which define, next to the specific habitat and food availability, their species-specific potential distribution. We studied the environmental limitations affecting the realized breeding and wintering distributions of the Citril Finch (Carduelis citrinella), one of the few endemic bird species of European mountain ranges. To assess the environmental limits that shape the seasonal distribution, we used species distribution models (SDMs) derived from macroclimate in combination with land cover information. Our data suggest a high congruence between the potential modelled breeding distribution of the Citril Finch and the currently known breeding sites, indicating a high level of niche filling. The unusual absence in several suitable breeding habitats at the eastern and northern range limit (Eastern Alps, Carpathians, Bavarian Forest, Harz Mountains, Fichtelgebirge, Krkonoše Mountains) is likely linked to a combination of both missing resources and restricted physiological migration capacities from the available wintering grounds. Since the accomplished migratory distances hardly exceed more than 500 km, it seems likely that the distance to the main wintering areas is too large for exceeding eastern and northern range limits. We discuss the differences in SDM outcomes when including distal predictor variables instead of using proximal predictors alone, and highlight the importance of considering a seasonal niche duality to gain more insights into complex range effects in species with seasonal ranges.


Abstract


Microbial infection is one of the main factors reducing survival in the first stages of life in oviparous species, and recent studies have shown that the avian eggshell harbors an important variety of microorganisms that can rapidly multiply and penetrate the shell, leading to a decrease in hatchability. Here, we report the results of an experiment in which we examined how incubation and maternal preen oil affect the growth of avian eggshell microbes, using the Mallard (Anas platyrhynchos) as a model species. We compared the bacterial and fungal loads on the shell of non-incubated eggs and eggs incubated by females having free or blocked access to their preen gland. An increase of eggshell bacterial loads was observed in all conditions, but bacterial growth was higher on the shell of incubated eggs than on non-incubated eggs. We did not find any significant difference in eggshell bacterial growth for eggs incubated by females with free or blocked access to their preen gland. In addition, fungal growth during our experiment was not affected by incubation or the mother’s preen oil. Our findings are in contrast with those of previous studies which showed that incubation limited or had no effect on eggshell bacterial growth. Differences in environmental conditions and/or species ecology may explain the difference between the results of our experiment and those of previous studies. Our study provides the first data on the effect of maternal preen oil on eggshell microorganisms, showing that preen oil does not limit eggshell microbial growth.


Abstract


A multitude of anthropogenic factors are threatening bird populations but their roles as drivers of population changes are generally poorly understood. Several duck species, for instance, have unfavorable conservation status at the Pan-European level but in most cases we do not know why the species have been declining, nor do we know actual drivers of their population dynamics. We studied population dynamics of the Garganey (Anas querquedula), a quarry species with unfavorable conservation status at the Pan-European level. As a trans-Saharan migrant, Garganey is potentially highly vulnerable to climate change impacts. We used long-term (1989–2012) data of breeding numbers from a study area in central Finland and assessed the relative importance of three climatic variables (representing conditions in wintering areas and during spring migration) and local hunting pressure in explaining the interannual variation in breeding numbers. Population size of Garganey showed a decreasing trend over the study period but also considerable interannual variation. Spring temperature in southern Finland was the most important factor in explaining interannual variation in breeding numbers. Rainfall in the wintering areas was also of importance, whereas the NAO (North Atlantic Oscillation) and local hunting pressure appeared not to be important. Our results suggest that weather conditions during spring migration largely drive interannual variation in Garganey breeding numbers at the NW edge of the species’ range. However, positive effects of warm springs may be counteracted by negative effects of drought in the wintering areas.


Abstract


Male birds sing to find a mate or to defend a territory. Their songs are known to be highly species-specific, but males may additionally show high levels of song individuality. Differences in song features have been shown to code for male quality and/or motivational states. Quantifying differences and similarities in the singing of males may broaden the general understanding of avian song and pairing systems. Here, we investigated the song of an Eastern German population of Reed Buntings (Emberiza schoeniclus), a species with a medium-sized song repertoire and extraordinary high extra-pair young rates (up to 55 %). Using a computed template-recognition algorithm, we analysed songs of 11 males focussing on individual variation in song composition and use. To determine the degree of song sharing among males, we compared two different measurements of song similarity (DICE coefficient and coefficient of compositional similarity; CCS). We found that males sing highly individual with respect to most analysed parameters. On average, males shared 62 % of their syllable type repertoire with at least one other male. However, taking song use into account, the overall degree of song sharing was low to moderate for both similarity measures, and average DICE values were higher than the CCS values. Additionally, we found that the closer the male territories were to each other, the higher the proportion of song sharing tended to be. We discuss the implications of our findings for the function of song in the Reed Bunting.


Abstract


Eggshell pattern scoring, a method to quantify the degree of surface maculation, can potentially be a quick, inexpensive and reliable method to obtain information on eggshell appearance and spot patterns. The key pigment responsible for red-brownish hues, protoporphyrin IX, is often localized as spots, either on the surface or in distinct layers within the eggshell. Heritable pigment spotting has been linked to factors such as breeding performance and eggshell strength. In this study, we investigated whether pigment scoring of eggshell patterns is repeatable within and between observers, by testing observers under standardised conditions, using the eggshells of two commonly studied passerines, Great Tits (Parus major) and Blue Tits (Cyanistes caeruleus). We found that repeatability of eggshell scores was poor, both within and between observers for both the species. We, therefore, encourage future studies to use alternative methods for quantifying spot patterns, such as digital image analysis, a technique which has already been used extensively.


Abstract


Geese often forage on mid-winter foods that fail to satisfy daily energy needs, but they may do so to acquire other nutrients, such as nitrogen. We tested this hypothesis by evaluating nitrogen budgets, namely the balance of nitrogen income against expenditure, of wintering Lesser White-fronted Geese Anser erythropus feeding at two sites within East Dongting Lake, China, where they could and could not balance daily energy budgets. Geese could balance nitrogen budgets in energy-rich habitats but were less able to do so in habitats where they failed to balance energy budgets. This study presents the first full nitrogen budget for a wintering goose species, and suggests that, rather than acting as a source of nitrogen, use of energy-poor but undisturbed habitats may represent a refuge from human disturbance at other habitats.


Abstract


Sex allocation in cooperative breeding species may be influenced by the return in fitness that parents receive when producing offspring of each sex, especially if helping behavior is sex-specific. Factors such as the presence of helpers assisting the breeding pair, resource availability, and timing of breeding may also influence brood sex ratio. In this study, we evaluated brood sex allocation in a neotropical cooperative breeding, the White-banded Tanager Neothraupis fasciata, which shows a slightly higher numbers of males, the helping sex, in the adult population. We tested brood sex allocation in relation to the presence of helpers in the groups, nest initiation date, and territory quality. At the population level, we found strictly equal numbers of offspring of both sexes. At the individual level, there was no effect of the ecological, environmental, and temporal variables we tested in the sex allocation of tanagers’ offspring. We suggest that brood sex allocation is unlikely to occur in the study species, and that high levels of nest predation may inhibit the development of sex allocation strategies in neotropical open nesting species, such as White-banded Tanager.


Abstract


Parasite species are usually specialists utilising specific host species, but parasite assemblages may differ substantially even between populations of the same species and show seasonal and annual fluctuations. Host characteristics such as individual age and sex may also affect parasite species composition and abundance. Here, we report the occurrence of malaria parasites in the Blue Tit (Cyanistes caeruleus) inhabiting Gotland (Sweden) across 5 years. Using PCR-based techniques, we found eight cytochrome b lineages belonging to genus Plasmodium (pTURUD1, pBT7, pSGS1, pSW2, pGRW11) and Haemoproteus (hPARUS1, hPHSIB1, hWW2) with the overall prevalence of 65 %. The Plasmodium infections predominated (prevalence of 49.5 %), whereas Haemoproteus infection rate was much lower (prevalence of 16.5 %). We showed significant differences in infection status between study years and age classes when all parasite lineages were analysed together or the two most common lineages were analysed separately. Overall, older birds showed higher prevalence. A significant interaction between year and genus effect significantly explained variation in infection intensity. This interaction stems from a significant yearly variation of the infection intensity with Plasmodium, while such an effect is not present for Haemoproteus infections. More importantly, the intensity of infection with Haemoproteus was significantly higher than with Plasmodium in 3 out of the 4 study years with data.


Abstract


The Pipridae comprise 52 species of manakins with a wide variety of courtship behaviours, ranging from solitary display, to traditional leks, to cooperative display. Long-tailed Manakins (Chiroxiphia linearis) exhibit an exploded lek-breeding system wherein two unrelated males cooperate to perform complex courtship displays for females. Our objectives in this study were to fully characterize the courtship display of Long-tailed Manakins, to evaluate the sequence and stereotypy of the display, and to investigate specific predictors of copulation success. Whereas the display of Long-tailed Manakins has traditionally been divided into two major parts, the hopping display and the butterfly display, we identified and characterized 16 individual display elements within these larger components of the display. We also determined that some aspects of the display are highly structured and stereotypical in performance, such that certain elements of the display are highly likely to be preceded or followed by particular elements. Nevertheless, other aspects of the display were much more flexible in terms of element sequence. We also found that the length and rate of performance of individual display elements were highly variable across displays. We therefore evaluated whether individual elements of the display could predict courtship success. Our results show that a number of highly correlated elements, namely upright postures, bounces, angel flights, and bows, can predict whether a display ends in copulation with a female. This research enhances our understanding of male display behaviour and female choice in Long-tailed Manakins, and may shed some light on the evolution of complex courtship displays in birds.


Abstract


Billions of seasonally migrating birds and insects use two principal modes of flight, i.e., flapping and soaring–gliding. Flight mode is known to have strong effects on energy expenditure and speed of migration, yet its influence on the migratory track has rarely been investigated. Using radio telemetry, we studied the effects of crosswind on European Bee-eaters (Merops apiaster) during their spring migration with respect to different flight modes. Flapping, soaring–gliding, and mixed flight in which the birds flapped during gliding were distinguished by radio signals while the birds were flying en route over southern Israel. The regional atmospheric modeling system was applied in high spatial (1 km × 1 km) and temporal (5 min) resolution to estimate winds encountered aloft. We analyzed data from 11 birds that flew over a total distance of 810 km and found that lateral drift due to side wind did not differ among birds engaged in different flight modes. Overall, there was almost no effect of crosswind speed on bird lateral speed, as the regression slope was 0.31 (indicting mild lateral drift) and the regression’s R 2 was 0.01. Therefore, we conclude that migrating bee-eaters compensated for crosswind during their spring migration and that this response was not dependent on bird flight mode.


Abstract


A comprehensive phylogeny of the nuthatches, genus Sitta, is proposed based on 21 of the 24–28 species recognized in the genus and three genes, two mitochondrial (cytochrome b and cytochrome oxidase subunit I) and one nuclear (RAG1). This phylogeny is well resolved and reveals several major clades within nuthatches. Przevalski’s Nuthatch Sitta przewalskii is sister to all other nuthatches, without any close relatives in our sampling. The larger species S. carolinensis and S. magna, despite their disjunct distributions, are sister taxa at the base of the tree. The next clade comprises the europaea group, which is sister to the two rock nuthatches (S. tephronota and S. neumayer), and to the Beautiful Nuthatch Sitta formosa of southeast Asia, although with less support. All these species use plastering to reduce the entrance of their hole or to build their nest with mud on rocks, but their ecologies are not as specialized as those of the rock nuthatches. The Asian small species (represented by S. azurea, S. frontalis and S. oenochlamys) form a well-supported clade. We confirm a single origin for the canadensis group that also includes the Yunnan nuthatch Sitta yunnanensis. Both are sister group to the two sibling species of North America (S. pygmaea and S. pusilla); all these species dig their own nest in trunks and are closely associated with coniferous forest. A biogeographical analysis supports the hypothesis of Asia being the center of diversification for nuthatches, with several independent dispersal events to North America.