Showing papers in "Journal of Ornithology in 2015"

Nest predation research: Recent findings and future perspectives

Abstract: Nest predation is a key source of selection for birds that has attracted increasing attention from ornithologists. The inclusion of new concepts applicable to nest predation that stem from social information, eavesdropping or physiology has expanded our knowledge considerably. Recent methodological advancements now allow focus on all three players within nest predation interactions: adults, offspring and predators. Indeed, the study of nest predation now forms a vital part of avian research in several fields, including animal behaviour, population ecology, evolution and conservation biology. However, within nest predation research there are important aspects that require further development, such as the comparison between ecological and evolutionary antipredator responses, and the role of anthropogenic change. We hope this review of recent findings and the presentation of new research avenues will encourage researchers to study this important and interesting selective pressure, and ultimately will help us to better understand the biology of birds.

Why birds matter: from economic ornithology to ecosystem services

Abstract: Birds are conspicuous in many habitats, occur worldwide, are ecologically diverse, and are better known than other vertebrate groups. Birds devour pests, pollinate flowers, disperse seeds, scavenge carrion, cycle nutrients, and modify the environment in ways that benefit other species. Investigation of these ecosystem functions directly as ecosystem services has grown immensely over the last two decades and the ecological relevance of birds is well established. Birds are also observed, fed, and used as artistic and spiritual inspiration by millions of people around the globe. Yet the economic relevance of birds is not widely appreciated and the economic relevance to human society of birds’ ecological roles is even less understood. Quantifying the services provided by birds is crucial to understand their importance for ecosystems and for the people that benefit from them. In this paper, we briefly review the rise and fall of economic ornithology and call for a new economic ornithology with heightened standards and a holistic focus within the ecosystem services approach. Birds’ ecological roles, and therefore, ecosystem services, are critical to the health of many ecosystems and to human well-being. By understanding and valuing bird services and disservices through careful natural history research, we can better assess the environmental consequences of bird declines and extinctions and communicate these findings to the public and policy makers, thereby increasing public support for the conservation of birds and their habitats.

Seize the night: European Blackbirds (Turdus merula) extend their foraging activity under artificial illumination

Abstract: In the urbanized world, the diurnal cycle of light and darkness has lost its accuracy due to artificial light at night (LAN). Because light is one of the most important zeitgebers for the synchronization of the endogenous clock, this loss of the night has serious implications for health and activity patterns. Although it is a well-known phenomenon that LAN advances the onset of dawn song of passerines, little is known ABOUT whether birds extend their activity into the evening hours and THUS may benefit from exploiting the night light niche. By observing wild urban Blackbirds (Turdus merula) under different LAN intensities, we found birds exposed to high levels of LAN to forage longer in the evening than their conspecifics in the darker areas. This difference was most pronounced during the short days in March, but decreased steeply towards the summer solstice. However, body condition of the Blackbirds did not correlate with the exposure to LAN, indicating that urban birds extending their activity under LAN might not benefit from the prolonged foraging times. Our findings further indicate that male Blackbirds are more sensitive to LAN than females. This study reveals that LAN plays a considerable role in the activity times of urban Blackbirds but, regarding their body condition, other urban factors may be more important than the influence of LAN.

The effects of light pollution on biological rhythms of birds: an integrated, mechanistic perspective

Abstract: Light pollution is considered a threat for biodiversity given the extent to which it can affect a vast number of behavioral and physiological processes in several species. This comes as no surprise as light is a fundamental, environmental cue through which organisms time their daily and seasonal activities, and alterations in the light environment have been found to affect profoundly the synchronization of the circadian clock, the endogenous mechanism that tracks and predicts variation in the external light/dark cycles. In this context, birds have been one of the most studied animal taxa, but our understanding of the effects of light pollution on the biological rhythms of avian species is mostly limited to behavioral responses. In order to understand which proximate mechanisms may be affected by artificial lights, we need an integrated perspective that focuses on light as a physiological signal, and especially on how photic information is perceived, decoded, and transmitted through the whole body. The aim of this review is to summarize the effects of light pollution on physiological and biochemical mechanisms that underlie changes in birds’ behavior, highlighting the current gaps in our knowledge and proposing future research avenues.

Speciation in seabirds: why are there so many species…and why aren’t there more?

Abstract: Speciation—the multiplication of species through the evolution of barriers to reproduction between populations—plays a central role in evolution since it enables two or more populations to adapt and evolve independently. However, mechanisms of speciation are notoriously difficult to study and poorly understood. Seabirds provide useful models to investigate factors that may promote or inhibit speciation because their ecology and evolutionary genetics are relatively well understood. Here I review population genetic studies of seabirds to test the importance of six factors with the potential to disrupt gene flow enough to result in speciation. Over 200 studies, including over 100 species, have been published to date. Most show evidence of restrictions in gene flow. Physical (geographic) barriers to dispersal are clearly important: conspecific populations that are separated by large expanses of land or ice show evidence of restricted gene flow, and sister species often are separated by physical barriers to gene flow. However, many species of seabirds show evidence of restrictions in gene flow in the absence of physical barriers to dispersal. Study results indicate that differences in ocean regimes, nonbreeding distributions, foraging distributions during the breeding season, and breeding phenology also can disrupt gene flow enough to lead to speciation. Of these, physical isolation and differences in ocean regime appear to be the most important. Philopatry alone may be sufficient to result in reproductive isolation, but usually it acts in combination with other barriers to gene flow. The effects of many other potential influences on gene flow need to be investigated more thoroughly, including colony distribution/location, wind, interspecific interactions, environmental stability/variability, variation in phenotypic traits associated with mate choice (morphology, behaviour, vocalisations) and intrinsic (genomic) incompatabilities. Recent advances in genome sequencing, especially if used in combination with ecological tools such as geolocators and new methods for data interpretation, are opening exiting new avenues to test the importance of various behavioural, ecological, demographic and genomic factors in reducing or promoting gene flow and so affecting speciation.

Return to the Malay Archipelago: the biogeography of Sundaic rainforest birds

Abstract: During the last 15–20 years, phylogenetic, phylogeographic, paleontological, geological, and habitat modeling studies have improved our knowledge of Sundaic biogeography dramatically. In light of these advances, we review (or postulate) where Sundaic rainforest birds came from, the causes of their endemism, and the influence of Pleistocene climatic perturbations on their diversification. We suggest that four scenarios make up a coherent, plausible explanation of patterns of extant diversity. First, relictual lineages, which represent hangovers from the warm, wet Eocene, survived the hard climatic times of the colder, drier Oligocene and Pliocene in the mountains and adjacent lowlands of eastern Borneo, where rainforest has existed continuously for the last 20–30 million years. Second, most modern SE Asian genera developed during the Miocene. Third, the rainforest of Sundaland and its avifauna were largely isolated from the rest of SE Asia during the late Miocene and Pliocene by seasonal habitats in southern Indochina and ocean boundaries elsewhere, increasing regional endemism. Finally, the advent of global glaciation in the Pleistocene introduced a different diversification dynamic to Sundaland. Early glacial events caused sufficient drying in central Sundaland to fragment rainforest and its avifauna into refugia in eastern and western Sundaland and to allow dry-habitat taxa to reach Java from Indochina. More recent glacial events resulted in sufficient perhumid habitat in central Sundaland to reconnect previously vicariated rainforest populations, creating the lowland and elevational parapatry we see today. This Pleistocene dynamic was probably not simply one period of separation and one period of connection, but rather a complex interplay of isolation and colonization, influenced by highly variable population sizes, changing levels of gene flow, and behavioral idiosyncrasies of the species involved. Throughout all of these events, Borneo played a seminal role in rainforest bird evolution by providing the habitat necessary for diversification and the long-term survival of taxa.

Resource requirements of parrots: nest site selectivity and dietary plasticity of Psittaciformes

Abstract: Parrots (Order Psittaciformes) are secondary cavity-nesters that depend on existing cavities for nest sites, and consume plant resources of fruits, seeds, and flowers that are highly variable, but little is known of resource selectivity by parrots, or how they deal with variable environments. We reviewed published studies of nest-cavity use by parrots, and those evaluating parrot diet and their relationship with food resources. Most studies have been conducted within the last 20 years and these present data on resource use for only one-third of parrot species worldwide. However, basic information on resource requirements is lacking for the vast majority of Psittaciformes, particularly for species from the Asian region. Nesting studies have found that parrots use nest cavities in large trees, high above the ground, with large nest chambers, of 0.5–1 m deep, and entrance diameters related to body size of the parrot species. A few studies demonstrate that parrots select nest sites based on cavity characteristics, which may influence nest success, but a complete evaluation of adaptive nest site selection by Psittaciformes is lacking. Parrots have varied diets and may employ a combination of strategies of diet switching, habitat shifts, and movements to track food resources. This plasticity in diet and foraging strategy may influence the extent to which parrots can respond to anthropogenic pressures of global change. Parrots may also play an important functional role in forest ecosystems, yet little is currently known of plant–animal interactions of parrots, or the impact of parrot populations on forest dynamics. Based on our review of the literature, we suggest that to meet their resource requirements, parrots employ resource selection strategies of hierarchical nest site selection to increase the likelihood of nest success, and plasticity in diet and foraging strategy to track variable food resources. Future studies need to evaluate resource selection and the consequences of this for fitness in order to assess the potential impacts of global change on parrot populations, and to identify characteristics which make species vulnerable to human pressures.

Developmental stress: evidence for positive phenotypic and fitness effects in birds

Abstract: The developmental environment has strong and pervasive effects on animal phenotype. Exposure to stress during development (in the form of elevated glucocorticoid hormones or food restriction) is one environmental cue that can have strong formative effects on morphology, physiology, and behavior. Although many of the effects of developmental stress appear negative, there is increasing evidence for an adaptive role of developmental stress in shaping animal phenotype. Here, we take a three-pronged approach to review studies that have uncovered positive effects of developmental stress on phenotype in birds. We focus on studies that: (1) examine phenotypic effects likely to increase fitness in offspring, (2) directly identify increased fitness in offspring, or (3) provide evidence of fitness benefits to the mother, at a cost to the offspring. Throughout, we focus on studies that evaluate the environment when assessing the ‘costs/benefits’ of phenotype alterations and examine the effects of developmental stress across life-history stages. Finally, we consider the two common methods used to simulate developmental stress: food restriction and direct hormone manipulation. Although these methods are often considered to elicit equivalent responses, there has been very little discussion of this in the literature. To this end, we review the main methods used to implement developmental stress in experimental studies and discuss how they may simulate different environmental conditions. In light of our conclusions, we propose possible avenues for future research, stressing the need for a greater focus on direct fitness metrics, longitudinal studies, and experiments in free-living animals.

Environmental, ecological and mechanistic drivers of avian seasonal metabolic flexibility in response to cold winters

Abstract: Small birds inhabiting regions with cold winter climates show seasonally flexible metabolic phenotypes, with the winter phenotype characterized by increments of summit metabolic rate (Msum) and cold tolerance. In the study reported here, we focused on variations in Msum as a metric of metabolic performance because it is positively correlated with cold tolerance in birds and positively related to overwinter survival in small mammals, although the latter has yet to be demonstrated in birds. Temperature appears to be a prominent driver of seasonal metabolic phenotypes in birds, as evidenced by the correlation between inter- and intra-seasonal variation in Msum and temperature variation, by recent temperature variables serving as better predictors of Msum variation than long-term climate variables, and by the induction of Msum variation by experimental cold exposure. In contrast, photoperiod and social status do not appear to be prominent drivers of metabolic flexibility in birds studied to date. Because skeletal muscle is the primary thermogenic tissue in birds, studies of the mechanistic underpinnings of metabolic flexibility have focused on skeletal muscles, particularly flight muscles. At the level of the skeletal muscle, two potential mechanisms exist for increasing thermogenic capacity, namely, muscle hypertrophy and elevated cellular metabolic intensity. Correlative studies suggest consistent winter increments in flight muscle size, with a potential regulatory role for the muscle growth inhibitor myostatin. Recent experimental studies in small birds, including modification of flight costs, cold acclimation, and exercise training, also suggest that muscle size is an important driver of metabolic flexibility in birds. Therefore, the focus of our study was on the seasonal regulation of muscle size and its contribution to metabolic flexibility. Future studies should address fitness consequences of Msum variation, the relative roles of muscle hypertrophy, and other factors (e.g., oxygen and substrate transport, cellular metabolic intensity) promoting Msum variation, as well as the molecular mechanisms underlying seasonal phenotypes.

Avian genomics: fledging into the wild!

Abstract: Next generation sequencing (NGS) technologies provide great resources to study bird evolution and avian functional genomics. They also allow for the identification of suitable high-resolution markers for detailed analyses of the phylogeography of a species or the connectivity of migrating birds between breeding and wintering populations. This review discusses the application of DNA markers for the study of systematics and phylogeny, but also population genetics and phylogeography. Emphasis in this review is on the new methodology of NGS and its use to study avian genomics. The recent publication of the first phylogenomic tree of birds based on genome data of 48 bird taxa from 34 orders is presented in more detail.

Protecting stopover habitat for migratory shorebirds in East Asia

Abstract: Many migratory species depend on staging sites at which they refuel while on migration, and effective protection of such habitats is crucial to their conservation. Here we investigate the extent to which protected areas cover and ameliorate loss of tidal flats in East Asia, the key staging habitat for threatened and declining shorebirds migrating through the East Asian–Australasian Flyway. We discover rapid losses of the tidal flat ecosystem both inside (−0.42 % year−1) and outside (−0.89 % year−1) protected areas. In China, tidal flats are well represented within protected areas (22.9 % of current tidal flats occur within protected areas), but habitat loss continued despite protection (−0.55 % year−1 inside, −0.97 % year−1 outside). By contrast, in South Korea, where 12.1 % of remaining tidal flat is in protected areas, the rate of habitat loss outside protected areas was the highest in our study region (−1.83 % year−1), yet inside protected areas there was tidal flat aggradation (+1.13 % year−1), indicating either that protected area placement is biased away from vulnerable habitats, or protected areas are highly effective in South Korea. Tidal flats across our study area were lost most rapidly in internationally important sites for migratory shorebirds (−1.66 % year−1), suggesting that transformative land use change of coastal areas is occurring disproportionately in regions that are important for migratory birds. We urge (1) improved management of existing protected areas in East Asia, particularly in China, (2) targeted designation of new protected areas in sites crucial for supporting migratory birds and (3) integrated decision-making that simultaneously plans for coastal development and coastal conservation.

Morphological and behavioural adaptations to feed on nectar: how feeding ecology determines the diversity and composition of hummingbird assemblages

Abstract: Hummingbirds are the most specialised nectarivorous birds and show close ecological relationships to their food plants. Their small body size, bright colors, and unique behaviour have fascinated generations of naturalists. In this review, we investigate the morphological and behavioural adaptations of hummingbirds to feed on nectar and arthropods, and explore their diffuse co-evolution with their food plant species. Further, a list of plant genera including species mainly pollinated by hummingbirds is presented. Summarising the existing knowledge on hummingbird feeding ecology, we find that much of the variability in morphology and behaviour of hummingbirds is determined by their unique feeding mode and the constraints set by their food plants. Based on the existing literature, we developed a hierarchical system explaining how different environmental factors have shaped the current richness of hummingbirds, and their morphological and behavioural diversity. We propose that climatic stability within and between seasons and days determines the constancy of food availability, which in turn is the most important factor for species richness in hummingbird assemblages. However, the assemblage composition of hummingbirds is also influenced by phylogenetic factors, especially under harsh environmental conditions. Unsurprisingly, the highest morphological and behavioural diversity is observed in the most species-rich assemblages. This diversity may have at least partly evolved to reduce inter- and intraspecific competition. Independently of which morphological character we consider, the 360 different hummingbird species have evolved a large morphological variability to adapt to their individual feeding niches.

Global patterns of seasonal acclimatization in avian resting metabolic rates

Abstract: The adjustment of resting metabolic rates represents an important component of avian seasonal acclimatization, with recent studies revealing substantial differences between summer and winter in birds from a wide range of latitudes. We compared seasonal variation in basal metabolic rate (BMR) and summit metabolism (M sum) between temperate and tropical/subtropical latitudes, and examined correlations with latitude and temperature. The direction and magnitude of seasonal adjustments in BMR are broadly related to temperature and latitude, but are significantly more variable among tropical and subtropical species compared to those inhabiting temperate zones. Winter adjustments in BMR among subtropical species, when expressed relative to summer values, range from decreases of approximately 35 % to increases of more than 60 %, whereas the majority of temperate-zone species show increases in BMR during winter. Relatively few seasonal M sum data exist for tropical/subtropical species, but those that are available involve responses ranging from winter decreases to increases of similar magnitude to those characteristic of many temperate-zone species. Recent studies also highlight the substantial variation in seasonal adjustments that may occur within species, and reiterate the need for further investigations of the relative roles of environmental variables such as temperature and food availability as determinants of seasonal metabolic variation.

Heritability of telomere length in the Zebra Finch

Abstract: Telomere length predicts survival in birds, and many stressors that presumably reduce fitness have also been linked to telomere length. The response to selection of telomere length will be largely determined by the heritability of this trait; however, little is known about the genetic component of telomere length variation in animals other than humans. Moreover, published heritability estimates of telomere length are based on telomere measurements with techniques that do not distinguish between terminal telomeres, which are susceptible to age and stress, and the interstitial telomeric repeats, which are relatively inert. Heritability estimates that combine interstitial and terminal telomeres are difficult to interpret in species such as birds, where interstitial telomeres are often numerous. We estimated the heritability of terminal telomere length in a captive Zebra Finch population of cross-fostered (half-)siblings using data obtained with an electrophoresis technique that excludes the interstitial repeats from the measurements. We used both a Bayesian quantitative genetic ‘animal’ model and a frequentist sibling regression approach to estimate heritability. With the animal model, we estimated a high heritability of telomere length (h2 = 0.99, 95 % credible interval = 0.87–1), but had insufficient statistical power to separate parental and permanent environment effects. The frequentist approach yielded similar heritability estimates, although with large confidence intervals. We used general linear mixed models to disentangle variance components of telomere length. The relative contributions of the individual, mother and father to telomere length variation were statistically indistinguishable at 23–31 %. Chicks were cross-fostered 4-days after hatching, and no effect of rearing nest was found, indicating that any undetected environmental effects exerted their influence prior to, or soon after, hatching. Thus, we conclude that telomere length resemblance between relatives is high and proportional to their relatedness, but we cannot conclusively distinguish between genetic and other forms of inheritance.

Artificial lights and seabirds: is light pollution a threat for the threatened Balearic petrels?

Abstract: Petrels are among the most threatened group of birds. On top of facing predation by introduced mammals and incidental bycatch, these seabirds have to deal with an emerging threat, light pollution, which is increasing globally. Fledglings are disoriented and attracted to artificial lights in their maiden night flights from their nests to the sea. Once grounded, they are exposed to multiple threats leading to high mortality. We report on numbers of three petrel species (Balearic shearwater Puffinus mauretanicus, Scopoli’s shearwater Calonectris diomedea, and European storm-petrel Hydrobates pelagicus) rescued on the Balearic Islands, Mediterranean Sea, in the period 1999–2013. We assessed the proportion of grounded fledglings in the population and colonies impact based on radiance levels measured from a nocturnal satellite image. We also calculated the radius of light pollution impact. At least 304 fledgling birds were found stranded due to attraction to artificial lights, fatally affecting 8.5 % of them. The proportion of grounded fledglings ranged between 0.13 and 0.56 % of the fledglings produced annually. The body mass of Balearic and Scopoli’s shearwater fledglings decreased with rescue date. Light-induced mortality increased during the fledging period for Scopoli’s shearwaters. Birds were rescued at a mean distance of 4833 m from the nearest colony, and between 30 and 47 % of colonies were exposed to light-polluted areas. Although impact seems to be low for all species, urban development and, consequently, the increase in light pollution in the proximity of the colonies should be taken into account to reduce as much as possible this emerging source of mortality.

Early evolution of the biological bird: perspectives from new fossil discoveries in China

Abstract: New discoveries of fossil birds belonging to the Jehol Biota uncovered from Lower Cretaceous lacustrine deposits in northeastern China continue to greatly enrich our understanding of the first major avian radiation. The exceptional preservation of some fossils provides a rare chance to discuss many biological issues that are usually impossible to address in paleontological studies, such as: the ossification pattern of the sternum in the extinct group Enantiornithes, which is unlike that of modern birds and all other archosaurs; the discovery of preserved crop, gizzard, and intestinal contents in several clades which suggest that a near-modern digestive tract including specialized crop morphologies evolved early during avian evolution; and the rare preservation of ovarian follicles which support hypotheses that the right ovary was lost in Aves due to the limitations of powered flight. Together, these data allow a partial reconstruction of the biology of Aves very close to its origin. While no skeletal or integumentary features are recognized to define Aves, we identify two possible soft tissue features that may biologically define Aves relative to other amniotes: the presence of a crop and the loss of the right ovary.

Habitat management varying in space and time: the effects of grazing and fire management on marshland birds

Abstract: Freshwater wetlands and marshes with extensive reed beds are important hotspots of biological diversity, but in the absence of proper management, they are subject to biotic homogenisation. We assessed the impact of spatiotemporally variable management by cattle grazing (for 4 years) and late-summer burning (1 or 3 years before the study) on both songbirds and non-passerines in a previously homogeneous reed bed. We surveyed birds using a combination of line transects and point counts in a quasi-experimental design comprising six treatment levels. Management increased both the diversity of marsh habitats and the diversity of bird species. The species richness and abundance of non-passerines (ducks and geese, wading birds, gulls and terns, rails, coots and grebes) was higher in recently burned than in unburned or old-burned patches. Species richness of farmland songbirds was higher in grazed than in non-grazed patches, and the richness and abundance of reed songbirds was higher in unburned, old-burned, and grazed patches than in recently burned patches. Total Shannon diversity and evenness of birds was lowest in areas with the most intensive treatment (patches grazed and twice-burned), whereas Simpson diversity was highest in these areas. Non-managed patches had fewer species and individuals of all groups except reed songbirds. The proportion of old reed was low in recently burned and grazed patches, and was similarly high in all other treatment areas. No other property of reed stands was influenced by management, and both the allocation and the effect of management were independent of water level. Spatiotemporally variable management by cattle grazing and late-summer burning may thus simultaneously benefit several groups of birds. The effect of burning alone disappeared in 3 years, even in the presence of grazing; thus it must be repeated every 2–3 years. We conclude that both management actions are necessary to establish and maintain highly diverse habitats for marshland bird communities.

Long after the event, or four things we (should) know about bird invasions

Abstract: The most significant single event in the study of alien bird invasions occurred in 1981, with the publication of John L. Long’s seminal book “ Introduced birds of the world” (full title: Introduced birds of the world: The worldwide history, distribution and influence of birds introduced to new environments”; David & Charles Ltd., Newton Abbot, UK). The significance of this book derives not just from its content, but also from its timing, coincident with the 1982 Scientific Committee on Problems of the Environment (SCOPE) programme on the ecology of biological invasions. It was not long before studies started to appear that exploited the data in Long’s book to address the questions posed by SCOPE regarding alien invasions. As a result, we arguably have a more complete understanding of the invasion process for birds than for any other taxon. Nevertheless, there are still some key issues in the study of bird invasions where understanding is not all it should be. The aim of this review is to highlight four of these issues by arguing that (1) we do not know half so much about bird invasions as we think; (2) propagule pressure promotes invasions; (3) colonization pressure matters; (4) there is no evidence that escape from parasites promotes alien (bird) invasions. We expect some of the views expressed to be controversial, and others less so, but either way we hope this paper will stimulate others to provide better evidence for—or against—our propositions.

Tropical countryside riparian corridors provide critical habitat and connectivity for seed-dispersing forest birds in a fragmented landscape

Abstract: We conducted extensive mist netting and radio tracking of common frugivorous, seed-dispersing, and tropical forest-dwelling blue-crowned manakins (Lepidothrix coronata; BCMA) and white-ruffed manakins (Corapipo altera; WRMA) to study their habitat use, movements, breeding success, and seed dispersal potential in the fragmented landscape of southern Costa Rica. We obtained 1354 GPS locations from 20 BCMAs and 4040 GPS locations from 54 WRMAs we tracked. These birds were dependent on forest remnants and rarely moved through open habitats. This was more likely for WRMAs, which were slightly more tolerant of forest fragmentation. BCMAs preferred the local Las Cruces Forest Reserve and riparian corridors to smaller (<10 ha) and more isolated forest fragments. Radio tracking showed that both species used small forest fragments less than expected based on the birds’ sites of capture. In general, age ratios were immature-biased and sex ratios were female-biased, especially in riparian corridors, which enabled movements across the highly deforested landscape. Average daily nest survival rate was 92.2 % for BCMA nests and 97.1 % for WRMA nests. Both species used riparian corridors 3–5 times more than expected based on land cover, utilizing these corridors for food, water, breeding, and for moving across a highly deforested landscape. Although most movements of both species were 100 m or less, some birds moved more than 600 m between observations, sometimes in only 15 min. These manakins are abundant in the forest understory and are capable of dispersing seeds more than 600 m, helping the regeneration of native vegetation. Tropical countryside riparian corridors provide critical habitat and connectivity for these common seed-dispersing forest understory birds in a fragmented landscape.

Intensity of haemosporidian infection of parids positively correlates with proximity to water bodies, but negatively with host survival

Abstract: In birds, haemosporidian parasites have been found to have direct pathogenic effects on the host with important consequences for their fitness. However, less is known about distribution patterns of parasite vectors, which may significantly affect parasite prevalence, infection intensity and, thus, pathogenicity in hosts. Here, we tested for relationships between infection intensity, survival, predation and distance from water bodies of mixed-species tit flocks. We found that the prevalence of Haemoproteus and Plasmodium infections decreased with increasing distance from forest lakes and bogs outside the bird breeding season. Haemoproteus and Plasmodium parasites were found to be associated with a low survival rate of willow tits (Poecile montanus) in the vicinity of water bodies, while crested tits (Lophophanes cristatus) were affected only by Haemoproteus. Crested tits, a dominant species of parid social groups, had a lower parasite prevalence and they survived better than the subordinate willow tit. This can be explained by the crested tits foraging higher in the pine canopy as parasite vectors supposedly cannot reach hosts in the upper canopy as equally as in lower parts of the canopy. We show that individuals staying in flocks further from the forest water bodies and spending more time foraging in the upper parts of the canopy have higher chances of survival into the next breeding season. This suggests that different forest and canopy areas may differ in terms of parasite risk and associated mortality. Finally, we found that the infection status of parids increases the probability of predation by the pygmy owl (Glaucidium passerinum). We conclude that distance from water bodies and foraging location in the forest canopy may affect the intensity of parasite infection with fitness consequences in wintering parids.

Natural nest-sites of Great Tits ( Parus major ) in a primeval temperate forest (Białowieża National Park, Poland)

Abstract: Knowledge of the breeding ecology of the Great Tit Parus major is vast, but almost exclusively concerns birds using nest-boxes. Information on birds nesting in natural conditions is scant. Here, we present the results of the first thorough study on natural nest-sites of the Great Tit. The data, including descriptions of nest-cavity location and dimensions, were collected during 39 breeding seasons in the primeval forest of Bialowieza National Park (BNP), Poland. With an excess of available tree-cavities providing a diverse choice of nesting options, Great Tits nested mainly in non-excavated, very deep and spacious cavities with elongated, narrow openings, placed at intermediate heights in living tree trunks. Different sets of tree species were used in different habitats. The pattern of nest-site utilisation by Great Tits in BNP overlapped with that recorded in other areas, but showed niche separation from other non-excavating hole-breeders in BNP. This indicates that Great Tits have core nest-site preferences, which have probably evolved in response to selective forces such as, e.g., risk of predation, flooding, sufficient nest illumination and/or efficient air ventilation.

GPS tracking of Red Kites (Milvus milvus) reveals fledgling number is negatively correlated with home range size

Abstract: To date, reliable studies on the spatial area use and home range size of the Red Kite (Milvus milvus) during the breeding season are lacking. Between 2007 and 2014, 43 adult individuals were fitted with GPS transmitters in Germany. The home range sizes of 27 males, which successfully reared 47 broods, ranged between 4.8 and 507.1 km2 based on the 95 % kernel utilization distribution. The median during the nestling and post-fledging dependent periods was 63.6 km2. The home ranges of 12 females, with a total of 21 successful broods, ranged between 1.1 and 307.3 km2. Within a single breeding season, there were considerable differences among home range sizes. There was also considerable variation in the home range size of adults during the course of a season. Across years, the median home range size of all males ranged between 21 and 186 km2, depending on prey availability. For individual males at the same nest site, the home range size varied up to a factor of 28 across years. Kites with very large home ranges had only one fledgling, which indicates that resources were scarce. Individuals with more nestlings had intermediate-sized to small home ranges. The relationship between the number of fledged young and home range size was modelled using a cumulative logit model. Fifty-six, 37, and 26 % of male kite fixes were beyond a 1, 1.5, and 2 km radius around the nest, respectively. Birds with very small or very large home ranges differed considerably from these average figures. Adults sometimes travel very long distances to visit distant grasslands during and shortly after mowing (up to more than 34 km) from the nest, due to the increased likelihood of prey availability at these sites. In conclusion, home rage size serves as a useful indicator of Red Kite habitat quality, which may provide key conservation information at the wider ecosystem level.

Evolutionary history of passerine birds (Aves: Passeriformes) from the Qinghai–Tibetan plateau: from a pre-Quarternary perspective to an integrative biodiversity assessment

Abstract: As one of the most prominent topographical features on Earth, the Qinghai–Tibetan plateau (QTP) underwent a long and complex history of the QTP uplift from the collision of the Indian and the Eurasian plates to the present. At its southern and southeastern margins, it is flanked by the most significant hotspots of organismic diversity of the northern hemisphere (including birds), the Sino-Himalayan mountain forests. In contrast, the central plateau region itself harbours species-poor communities but also a good number of endemics that presumably evolved from rather ancient (pre-Pleistocene) phylogenetic lineage splits. We discuss the evolutionary history of QTP passerines from a twofold perspective including examples from our own research. First, we provide an overview of those alpine QTP endemics that represent late Miocene and Pliocene lineage splits, i.e. early colonisations to the central alpine QTP region. As an example, true rosefinches (genus Carpodacus) presumably evolved from a forested eastern QTP centre of origin and colonised the (semi-)open plateau habitats several times independently. Second, we discuss younger speciation events corresponding to phylogeographic east–west divides along the southern QTP margin. A multidisciplinary approach combining genetic, bioacoustic and morphological markers shed new light on the phylogenetic relationships of Pnoepyga wren babblers and on the intraspecific subdivision of the Buff-barred Warbler (Phylloscopus pulcher).

Mechanisms of antimicrobial defense in avian eggs

Abstract: One of the greatest threats to the survival of avian eggs is the risk of infection by microbes; as such, a large number of parental defense mechanisms have evolved in response to the decreased fitness imposed by microbial infection. The existing literature on this topic has focused largely on the mechanisms of microbial invasion through eggshells and the identification of molecules with antimicrobial properties in eggs of commercial species. However, little is still known about antimicrobial mechanisms in wild birds or how they vary with environmental pressures. This review concentrates on recent findings that shed new light on the role of parental behaviors (including incubation and placement of vegetation with antifungal activity in the nest) and the physical properties of eggshells (including nanometer-scale spheres that prevent microbial attachment) that protect eggs from contamination in high-risk environments. In addition to presenting a summary of current information, we identify evident gaps in knowledge and highlight research avenues for the future.

Flexibility in foraging strategies of Brown Skuas in response to local and seasonal dietary constraints

Abstract: The Brown Skua Stercorarius antarcticus lonnbergi is an opportunistic species that displays a high degree of flexibility in foraging tactics. We deployed glo- bal positioning system (GPS) and immersion (activity) loggers on breeding Brown Skuas of known sex, body size and condition at Admiralty Bay, King George Island with the aim to examine the impacts of spatial and seasonal fluctuations in prey availability on movement and foraging behavior. We also investigated whether reversed sexual size dimorphism (females larger than males) in this species leads to differences between sexes in foraging behavior and whether this or other factors contribute to variation in breeding success. Analysis of the GPS data highlighted the high degree of plasticity in foraging behavior among individuals. Although most Brown Skuas were flexible in their feeding tactics, this was not enough to ensure a suc- cessful breeding season, as few pairs fledged chicks. Dur- ing early chick rearing, Brown Skuas spent most of their time on land, feeding almost exclusively on penguin chicks. By late chick rearing, when the availability of penguins had diminished, Brown Skuas supplemented the food obtained on land by traveling to the ocean. All for- aging trips to sea occurred during daylight, mostly during the early morning. Despite marked sexual size dimorphism, we failed to find any difference in foraging tactics between males and females. Furthermore, although laying date affected the number of chicks hatched (earlier pairs were more successful), no relationship was found between breeding success and male or female body size, condition or degree of dimorphism within pairs.

Fire management, climate change and their interacting effects on birds in complex Mediterranean landscapes: dynamic distribution modelling of an early-successional species—the near-threatened Dartford Warbler (Sylvia undata)

Abstract: The current challenge in a context of major environmental changes is to anticipate the responses of species to future landscape and climate scenarios. In the Mediterranean basin, climate change is one the most powerful driving forces of fire dynamics, with fire frequency and impact having markedly increased in recent years. Species distribution modelling plays a fundamental role in this challenge, but better integration of available ecological knowledge is needed to adequately guide conservation efforts. Here, we quantified changes in habitat suitability of an early-succession bird in Catalonia, the Dartford Warbler (Sylvia undata), which is globally evaluated as Near Threatened in the IUCN Red List. We assessed potential changes in species distributions between 2000 and 2050 under different fire management and climate change scenarios, and described landscape dynamics using a spatially-explicit fire-succession model that simulates fire impacts in the landscape and post-fire regeneration (MEDFIRE model). Dartford Warbler occurrence data were acquired at two different spatial scales from: (1) the Atlas of European Breeding Birds (EBCC) and (2) the Catalan Breeding Bird Atlas (CBBA). Habitat suitability was modelled using five widely-used modelling techniques in an ensemble forecasting framework. Our results indicated considerable habitat suitability losses (ranging between 47 and 57 % in baseline scenarios), which were modulated to a large extent by fire regime changes derived from fire management policies and climate changes. Such result highlighted the need for taking the spatial interaction between climate changes, fire-mediated landscape dynamics and fire management policies into account for coherently anticipating habitat suitability changes of early-succession bird species. We conclude that fire management programs need to be integrated into conservation plans to effectively preserve sparsely forested and early succession habitats and their associated species in the face of global environmental change.

Individual variation in workload during parental care: can we detect a physiological signature of quality or cost of reproduction?

Abstract: How hard do birds work during parental care, chick rearing, or provisioning of their nestlings? And if birds do work hard, can we detect a physiological signature of individual variation in workload ability (perhaps related to ‘quality’) or costs associated with high workload? Here, we provide a broad conceptual perspective on these questions. Life-history theory predicts (or requires) that (1) parental care is hard work, (2) individuals that invest more in parental care benefit in terms of rearing more, larger, fitter offspring, but that (3) increased investment in parental care comes at a cost: decreased future fecundity and/or survival. However, we start by highlighting studies that are inconsistent with this conventional view, e.g., (1) females often do not pay a survival cost of increased workload (though males do), (2) some (high quality?) individuals appear to maximise numerous life-history traits, and (3) workload during parental care often does not predict productivity. We suggest that an “exercise physiology” perspective on parental care might be informative, but highlight the fact that existing models of exercise often involve conditions very different from that free-living animals experience while foraging (e.g., using forced exercise) and are often divorced from the critical relationship in free-living animals between exercise and acquisition of resources. We briefly review studies looking at physiological effects of workload during parental care in free-living birds, but again highlight our surprising lack of knowledge in this area especially where experimental manipulation of workload is coupled with comprehensive, physiological analysis. Finally, we make three recommendations for how can we advance the study of physiology of parental care in chick-rearing birds: (1) experimental manipulation of workload, (2) obtaining better measures of workload, for large numbers of known-individuals, and (3) better assessment of physiology of individual quality, and identification of specific metrics of workload-induced ‘wear and tear’.

Low nest survival of a breeding shorebird in Bohai Bay, China

Abstract: Nest survival plays an important role in avian demography because of its influence on both individual fitness and population growth. It is also known to vary within species due to local factors such as climate, predation, substrate, and disturbance, among others. Therefore, an understanding of the relative influence of local factors on nest survival is of critical importance for the formulation of appropriate avian conservation and management policies/programs. Over the past 50 years the Yellow Sea has lost almost 65 % of its original intertidal habitats due to land reclamation and development. There has also been a concomitant and rapid decline in the populations of Kentish plover (Charadrius alexandrinus) in East Asia, but the proximate causes of this decline are poorly understood. To gain a better understanding of this conservation issue, we investigated Kentish plover nest survival in Bohai Bay, China, using Program MARK to model the daily survival rate (DSR) of 417 nests. We found that in terms of nest survival, that for the Kentish plover populations in Bohai Bay [0.925 ± 0.004 (±95 % confidence interval)] is the lowest reported worldwide for this species. The most common cause of nest failure was related to anthropogenic disturbance. We determined that nests occupying salt crystallization habitat had the highest hatching success and that initiation date, nest age, and nest density had quadratic effects on DSR. If low nest survival persists for consecutive years, fecundity will unlikely compensate for adult mortality, resulting in dramatic population declines of plovers in Bohai Bay. We therefore recommend that the Local Authority managers responsible for local environmental management act accordingly to create protected alternative nesting habitat for plovers in this region.

Tree-cavity availability and selection by a large-bodied secondary cavity-nester: the Military Macaw

Abstract: Large-bodied secondary cavity-nesters are constrained to use cavities of sufficient size to permit access, while also selecting characteristics to reduce predation. However, no information exists on nest-site availability for large-bodied secondary cavity-nesters in tropical forests. We located 12 tree-cavity nests of the threatened Military Macaw (Ara militaris) in tropical dry semi-deciduous forest in Jalisco, Mexico. For each nest, we determined cavity characteristics, and compared the structure of nest-trees with nearest-neighbor trees. We also established four 100 × 50 m transects in each of deciduous, semi-deciduous, and oak forest to determine tree-cavity availability over 6 ha. Military Macaw nest-sites occurred most frequently in cavities of live Enterolobium cyclocarpum trees. Nest-trees had significantly larger diameter and ramification height than the four nearest-neighbor trees, indicating that macaws selected tall emergent trees as nest-sites. Cavities used as nest-sites by Military Macaws were also in significantly larger trees, at a greater height, and had larger entrance diameter and depth than all accessible cavities. Height above the ground was the main criteria predicting nest-cavity selection, possibly to reduce predation risk. There was also a negative correlation of nest-cavity height with depth, suggesting a trade-off in which Military Macaws may select a nest-cavity high above the ground regardless of depth, but when using lower cavities these tend to be deeper. We found a low density of cavities with characteristics suitable for nesting, and these were concentrated in semi-deciduous forest. Our results demonstrate that the Military Macaw exhibits species-specific selection of nest-cavities, with a low density of cavities suitable for large-bodied secondary cavity-nesters in tropical forests.

From neurons to nests: nest-building behaviour as a model in behavioural and comparative neuroscience.

Abstract: Despite centuries of observing the nest building of most extant bird species, we know surprisingly little about how birds build nests and, specifically, how the avian brain controls nest building. Here, we argue that nest building in birds may be a useful model behaviour in which to study how the brain controls behaviour. Specifically, we argue that nest building as a behavioural model provides a unique opportunity to study not only the mechanisms through which the brain controls behaviour within individuals of a single species but also how evolution may have shaped the brain to produce interspecific variation in nest-building behaviour. In this review, we outline the questions in both behavioural and comparative neuroscience that nest building could be used to address, summarize recent findings regarding the neurobiology of nest building in lab-reared zebra finches and across species building different nest structures, and suggest some future directions for the neurobiology of nest building.