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

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

Using the BirdTree.org website to obtain robust phylogenies for avian comparative studies: A primer

Comparative studies of trait evolution require accounting for the shared evolutionary history. This is done by including phylogenetic hypotheses into statistical analyses of species’ traits, for which birds often serve as excellent models. The online publication of the most complete molecular phylogeny of extant bird species (www.birdtree.org, BirdTree hereafter) now allows evolutionary biologists to rapidly obtain sets of equally plausible phylogenetic trees for any set of species to be incorporated as a phylogenetic hypothesis in comparative analyses. We discuss methods to use BirdTree tree sets for comparative studies, either by building a consensus tree that can be incorporated into standard comparative analyses, or by using tree sets to account for the effect of phylogenetic uncertainty. Methods accounting for phylogenetic uncertainty should be preferred whenever possible because they should provide more reliable parameter estimates and realistic confidence intervals around them. Based on a real comparative dataset, we ran simulations to investigate the effect of variation in the size of the random tree sets downloaded from BirdTree on the variability of parameter estimates from a bivariate relationship between mass-specific productivity and body mass. Irrespective of the method of analysis, using at least 1,000 trees allows obtaining parameter estimates with very small (< 0.15%) coefficients of variation. We argue that BirdTree, due to the ease of use and the major advantages over previous ‘traditional’ methods to obtain phylogenetic hypotheses of bird species (e.g. supertrees or manual coding of published phylogenies), will become the standard reference in avian comparative studies for years to comePeer reviewe

population trends of wintering waterbirds in lombardy between 2002 and 2013

Birds are among the most important biological components of wetlands. They play a key role in their ecology and are an important cultural resource for the public, in part because some species can be legally hunted. The conservation of waterbirds is especially important in terms of land use planning, in light of their ecological, cultural, and economic value. Here we summarize the results of wintering waterbirds censuses carried out in Lombardy between 2002 and 2013, using the standardized International Waterbird Census methodology. Our goals were to identify priority sites for waterbirds; estimate population sizes; define demographic trends; and provide a technical framework for making administrative and legislative decisions on the management and conservation of wetlands and their bird species. Lombardy hosts substantial numbers of wintering waterbirds, and many of its wetlands qualify as areas of conservation interest under Ramsar Convention criteria, as they host &gt;1% of the Italian population of one or more species. Trends for the 20 species of highest conservation or hunting interest showed stable or increasing populations in most cases, with the exception of Black-necked Grebe, Common Pochard, and Eurasian Coot, which instead decreased in 2002-2013. The favourable population trends for most species suggest that the ecological status of Lombardy's wetlands is essentially stable, but it could be improved by simple measures to improve the natural value of the shorelines and bottoms of major lakes and flooded gravel pits. Hunting was one of the main factors affecting the distribution and abundance of wintering waterbirds, which concentrate in protected areas - over 50% of all birds, rising to over 70% for species of conservation interest concentrate there, despite the fact that protected areas only account for 43% of sites surveyed. Overall, protected areas hosted bird densities that were almost seven times higher than those managed primarily for hunting, while mixed-use areas hosted intermediate densities of birds. The presence of protected and unprotected areas within the same wetland mitigates the effects of hunting on bird populations and species diversity, and may help maintain adequate conditions for their conservation

Maternal effects mediated by egg quality in the Yellow-legged Gull Larus michahellis in relation to laying order and embryo sex

<p>Abstract</p> <p>Background</p> <p>Maternal effects mediated by egg size and quality may profoundly affect offspring development and performance, and mothers may adjust egg traits according to environmental or social influences. In avian species, context-dependency of maternal effects may result in variation in egg composition, as well as in differential patterns of covariation among selected egg components, according to, for example, position in the laying sequence or offspring sex. We investigated variation in major classes of egg yolk components (carotenoids, vitamins and steroid hormones) in relation to egg size, position in the laying sequence and embryo sex in clutches of the Yellow-legged Gull (<it>Larus michahellis</it>). We also investigated their covariation, to highlight mutual adjustments, maternal constraints or trade-offs in egg allocation.</p> <p>Results</p> <p>Laying sequence-specific patterns of allocation emerged: concentration of carotenoids and vitamin E decreased, while concentrations of androgens increased. Vitamin A, estradiol and corticosterone did not show any change. There was no evidence of sex-specific allocation or covariation of yolk components. Concentrations of carotenoids and vitamins were positively correlated. Egg mass decreased along the laying sequence, and this decrease was negatively correlated with the mean concentrations of carotenoids in clutches, suggesting that nutritionally constrained females lay low quality clutches in terms of carotenoid content. Finally, clutches with smaller decline in antioxidants between first- and last-laid eggs had a larger increase in yolk corticosterone, suggesting that a smaller antioxidant depletion along the laying sequence may entail a cost for laying females in terms of increased stress levels.</p> <p>Conclusions</p> <p>Since some of the analyzed yolk components (e.g. testosterone and lutein) are known to exert sex-specific phenotypic effects on the progeny in this species, the lack of sex-specific egg allocation by mothers may either result from trade-offs between contrasting effects of different egg components on male and female offspring, or indicate that sex-specific traits are controlled primarily by mechanisms of sexual differentiation, including endogenous hormone production or metabolism of exogenous antioxidants, during embryonic development.</p

Habitat management for Red–backed Shrike, Lanius collurio, conservation in farmland systems

The Province of Verbano Cusio Ossola, North-Eastern Piedmont, carried out a LIFE-Nature project during the period 2003-2007. The project focused on a Natura 2000 site, located along the middle course of river Toce. One of the interventions was directed at the conservation of the breeding population of Lanius collurio through dedicated management of lowland hay meadows (with maintenance of unmown portions) and shrublands (with increasing habitat openness in overgrown shrublands). Those interventions resulted an increase in the local breeding population of the species from 9 to 25 pairs in 5 years

Disentangling the taxonomic status and phylogeographic structure of Marmora\u2019s (Curruca sarda) and Balearic Warbler (Curruca balearica): a genetic multi-marker approach

Marmora\u2019s Warbler (Curruca sarda) and Balearic Warbler (C. balearica) are allopatric sibling species and were recently split mostly based on morphological and ethological characteristics. Here we provide the first phylogenetic and phylogeographic analyses of this species complex to support the taxonomic status of C. sarda and C. balearica in light of integrative taxonomy. We sampled the two taxa in most of their breeding ranges and we sequenced three mitochondrial and one nuclear gene region. All C. balearica individuals had private haplotypes for the four markers and formed monophyletic clades. Genetic distances between the two taxa were comparable with those found between other species belonging to the Curruca genus. Furthermore, most of the genetic variance was expressed at the interspecific level, rather than between different populations within taxa or between individuals within populations. Our results strongly support the current taxonomic status of these two warblers as distinct species

Analysis of Movement Recursions to Detect Reproductive Events and Estimate Their Fate in Central Place Foragers

Background Recursive movement patterns have been used to detect behavioral structure within individual movement trajectories in the context of foraging ecology, home-ranging behavior, and predator avoidance. Some animals exhibit movement recursions to locations that are tied to reproductive functions, including nests and dens; while existing literature recognizes that, no method is currently available to explicitly target different types of revisited locations. Moreover, the temporal persistence of recursive movements to a breeding location can carry information regarding the fate of breeding attempts, but it has never been used as a metric to quantify recursive movement patterns. Here, we introduce a method to locate breeding attempts and estimate their fate from GPS-tracking data of central place foragers. We tested the performance of our method in three bird species differing in breeding ecology (wood stork (Mycteria americana), lesser kestrel (Falco naumanni), Mediterranean gull (Ichthyaetus melanocephalus)) and implemented it in the R package ‘nestR’. Methods We identified breeding sites based on the analysis of recursive movements within individual tracks. Using trajectories with known breeding attempts, we estimated a set of species-specific criteria for the identification of nest sites, which we further validated using non-reproductive individuals as controls. We then estimated individual nest survival as a binary measure of reproductive fate (success, corresponding to fledging of at least one chick, or failure) from nest-site revisitation histories during breeding attempts, using a Bayesian hierarchical modeling approach that accounted for temporally variable revisitation patterns, probability of visit detection, and missing data. Results Across the three species, positive predictive value of the nest-site detection algorithm varied between 87 and 100% and sensitivity between 88 and 92%, and we correctly estimated the fate of 86–100% breeding attempts. Conclusions By providing a method to formally distinguish among revisited locations that serve different ecological functions and introducing a probabilistic framework to quantify temporal persistence of movement recursions, we demonstrated how the analysis of recursive movement patterns can be applied to estimate reproduction in central place foragers. Beyond avian species, the principles of our method can be applied to other central place foraging breeders such as denning mammals. Our method estimates a component of individual fitness from movement data and will help bridge the gap between movement behavior, environmental factors, and their fitness consequences

Home, dirty home: effect of old nest material on nest-site selection and breeding performance in a cavity-nesting raptor

The quality of a breeding site may have major fitness consequences. A fundamental step to understanding the process of nest-site selection is the identification of the information individuals use to choose high-quality nest sites. For secondary cavity-nesting bird species that do not add nest lining material, organic remains (faeces, pellets) accumulated inside nest cavities during previous breeding events may be a cue for high-quality nest-sites, as they contain information about past successful breeding and may improve thermal insulation of eggs during incubation. However, cavities in which breeding was successful might also contain more nest-dwelling ectoparasites than unoccupied cavities, offering an incentive for prospective parents to avoid them. We exposed breeding cavity-nesting lesser kestrels (Falco naumanni) to nestbox dyads consisting of a dirty (with a thick layer of organic substrate) and a clean nestbox (without organic material). Dirty nestboxes were strongly preferred, being occupied earlier and more frequently than clean ones. Hatching success in dirty nestboxes was significantly higher than in clean ones, suggesting a positive effect of organic nest material on incubation efficiency, while nestbox dirtiness did not significantly affect clutch and brood size. Nestlings from dirty nestboxes had significantly higher ectoparasite load than those from clean nestboxes soon after egg hatching, but this difference was not evident a few days later. Nest substrate did not significantly affect nestling growth. We concluded that nest substrate is a key driver of nest-site choice in lesser kestrels, although the adaptive value of such a strong preference appears elusive and may be context-dependent