In the past thirty years, carotenoid‐based animal signals have been an intense focus of research because they can potentially broadcast an honest reflection of individual reproductive potential. Our understanding of the underpinning physiological functions of carotenoid compounds is still emerging, however. Here, we argue that wildlife researchers and managers interested in assessing the impact of

Incubation is an energetically costly parental task of breeding birds. Incubating parents respond to environmental variation and nest‐site features to adjust the balance between the time spent incubating (i.e. nest attentiveness) and foraging to supply their own needs. Non‐natural nesting substrates such as human buildings impose new environmental contexts that may affect time allocation of incubating

The plastic regulation of internal energy reserves is acknowledged as the main adaptive response to winter conditions of resident small birds in northern latitudes, a strategy that may be altered whenever human‐supplemented food is available. We investigated the effects of supplementary feeding on the energy management strategy of two wild passerine species, the Willow Tit Poecile montanus and Blue

Despite declines in numerous migratory bird populations due to global climate and landscape changes, the Pacific Flyway population of Greater White‐fronted Geese Anser albifrons frontalis in North America has flourished over recent decades. However, the demographic foundations of the population increase remain unclear, largely due to sparse data. In this study, we used a Bayesian integrated population

The Mascarene petrel (Pseudobulweria aterrima ) is a critically endangered seabird endemic to Reunion Island, with an extremely small population suffering several threats. Fifteen polymorphic microsatellite loci were isolated from this species to analyse genetic diversity, estimate contemporary effective population size, search for evidence of a population bottleneck and see if results support the

Anthropogenic noise (≤ 3 kHz) can affect key features of birds’ acoustic communication via two different processes: (1) song‐learning, because songbirds need to hear themselves and other birds to crystallize their song, and (2) avoidance of song elements that overlap with anthropogenic noise. In this study we tested whether anthropogenic noise reduces the number of song elements in the repertoire of

The titles reviewed in this section of Ibis are available for reference at the Alexander Library of the Edward Grey Institute of Field Ornithology, Radcliffe Science Library, Parks Road, Oxford, UK. Please write, telephone +44 (0) 1 865 271143 or email sophie.wilcox@bodleian.ox.ac.uk prior to your visit to make an appointment. The aim of the Alexander Library is to build up a comprehensive collection

The pace‐of‐life syndrome hypothesis (POLS) represents an attractive theoretical framework suggesting that physiological and behavioural traits have evolved together with environmental conditions and life‐history strategies. POLS predicts that metabolic differences covary with behavioural variation such that high metabolic rate is associated with risk‐prone behaviour and a faster pace‐of‐life, whereas

Uniparental offspring desertion occurs in a wide variety of avian taxa and usually reflects sexual conflict over parental care. In many species, desertion yields immediate reproductive benefits for deserters if they can re‐mate and breed again during the same nesting season; in such cases desertion may be selectively advantageous even if it significantly reduces the fitness of the current brood. However

Based on monitoring of Bearded Vultures over 24 years in the French Pyrenees, we assessed factors explaining temporal and spatial variations in numbers and breeding performance. The number of territorial pairs increased throughout the study period from 16 in 1994 to 44 in 2017. No significant negative trends in mean productivity (fledglings per territorial pair) were detected with increasing population

Parent birds employ various strategies to protect their offspring against nest predators. Two well‐researched anti‐nest‐predation strategies involve visual concealment of the nest by way of parental camouflage and egg camouflage. By contrast, camouflage of nest structures is relatively under‐researched, particularly in the case of cup‐nests in trees and bushes. We explored how birds camouflage cup‐nests

Tracking tags have been used to map the distributions of a wide variety of avian species, but few studies have examined whether the use of these devices has impacts on the study animals that may bias the spatial data obtained. As Global Positioning System (GPS) tags small enough for deployment on terns (family: Laridae) have only recently become available, until now tracking of this group has been

A major cause of reproductive failure in birds is nest predation. Predation risk depends on predator type, as predators vary in their ecology and sensory modalities (e.g. visual vs. olfactory). Snakes (generally olfactory predators) are a major nest predator for small birds, with predation strongly associated with higher temperatures. We investigated nest survival in a ground‐nesting alpine species

The parental food compensation hypothesis suggests that parents may compensate for the negative effects of parasites on chicks by increased food provisioning. However, this ability differs widely among host species and may also depend on ecological factors such as adverse weather conditions and habitat quality. Although weed management can improve habitat quality, management measures can bring about

Global anthropogenic changes are significantly impacting the ecology and evolution of many species. Among temperate taxa, changes to reproductive phenology as a result of warming springs are apparent. However, how such responses to abiotic change interact with biotic impacts resulting from human management interventions are less clear. Here we examine the response of a range of breeding metrics (laying

Studying phenotypic variations along gradients may provide insights into mechanisms that drive species distributions and thus can be useful indicators of environmental change. In mountains, the study of phenotypic variation along elevation gradients is of increasing relevance due to the impacts of climate change. We analysed European ringing data to measure the direction of phenotypic variation along

Pheasants (order Galliformes) are typical ground‐dwelling birds, having a large body size and weak flight abilities. Sympatric pheasants are expected to share narrower niche space and face more extensive interspecific competition. However, little work has been undertaken simultaneously to investigate niche partitioning among sympatric pheasant species across multiple ecological dimensions. We compared

The Asian songbird crisis which is currently unfolding in Southeast Asia has seen multiple bird taxa go extinct in the wild and even more slip into regional or local extinction over the span of only a few years. The hill mynas Gracula spp. are among its main victims, encompassing the Critically Endangered Nias Hill Myna Gracula [religiosa] robusta and other endangered populations across the West Sumatran

The timing and duration of each stage of the life of a long‐distance migrant bird are constrained by time and resources. If the parental roles of males and females differ, the timing of other life stages, such as moult or pre‐migratory fuelling, may also differ between the sexes. Little is known about sexual differences for species with weak sexual dimorphism, but DNA‐sexing enables fresh insights

Patterns of nest attendance in birds result from complex behaviours and influence the success of reproductive events. Incubation behaviours vary based on individual body condition, energy requirements and environmental factors. We assessed nest attendance patterns in Cinnamon Teal Spatula cyanoptera breeding in the San Luis Valley of Colorado in 2016–2017 using trail and video cameras to observe behaviours

Theoretical models on the movement of colonial animals predict that neighbouring colonies may segregate their foraging areas, and many seabird studies have reported the presence of such segregations. However, these studies have often lacked the appropriate null model to test the effect of neighbouring colonies on foraging areas, especially in small colonies or in short‐ranging species. Here, we examined

Tracking studies are often used to inform conservation plans and actions. However, species have frequently only been tracked in one or a few localities, whereas space use can be remarkably flexible, especially in long‐lived species with advanced learning abilities. We assessed variability in space use in the Critically Endangered Hooded Vulture Necrosyrtes monachus by pooling movement data from three

Crossbills (Loxia spp.) provide a classical avian model of ecological specialization on food resources. Previous studies have suggested that morphometric, genetic and vocal diversification among Common Crossbill Loxia curvirostra populations is better explained by ecological distance (use of different conifers) than by geographical distance, indicating that populations have diverged adaptatively. We

Although the effects of shifting fire regimes on bird populations have been recognized as important to ecology and conservation, the consequences of fire for trophic interactions of avian species – and raptors in particular – remain relatively unknown. Here, we found that within national parks with long‐standing (40+ years) fire management programmes, California Spotted Owls Strix occidentalis occidentalis

Epigenetic mechanisms such as DNA methylation may vary in response to environmental stressors and introduce adaptive or maladaptive gene expression within and among wild bird populations. We examined the association between DNA methylation and demographic characteristics of the Louisiana Waterthrush Parkesia motacilla in territories with and without disturbance from shale gas development in a Central

Body mass declines during wing moult in numerous, but not all, populations of Anatidae. We assessed two leading hypotheses for body mass dynamics during wing moult: (1) body mass dynamics are adapted to attain a target body mass at the end of wing moult (restraint hypothesis) vs. (2) body mass dynamics reflect environmental constraint on the nutrient–energy balance during wing moult (constraint hypothesis)

Life‐history theory predicts that parents refer to the resources they hold to determine their breeding strategy. In multi‐brooded species, it is hypothesized that single‐brooded parents produce larger clutches and raise offspring with a brood survival strategy, whereas multi‐brooded parents only do this under good breeding conditions. Under poor conditions, they produce smaller clutches and raise offspring

The simultaneous effects of habitat traits and interspecific interactions determine the occurrence and habitat use of wildlife populations. However, little research has been devoted to examining spatial co‐occurrence among closely related species while considering the effect of habitat variation and imperfect detectability of species in the field. In this study, we focused on migratory and resident

Forest fragmentation represents a threat to several bird species worldwide. Several factors can change across seasons (e.g. bird perception of the landscape, weather conditions, biotic interactions), which can modify the response of bird populations to forest fragmentation. However, most studies have been conducted only during the breeding season. Here we assessed the relationship between forest fragmentation

High mountain areas are subject to strong seasonal fluctuations, and species inhabiting these particular environments show a high degree of habitat specialization to cope with extreme abiotic conditions. Estimates of habitat use are influenced by the spatial and seasonal scales at which they are evaluated, so studies at multiple scales are important in order to explore adaptive responses to seasonal

Density‐dependence effects acting on fecundity can be explained by two competing hypotheses. The individual adjustment hypothesis (IAH) states that, as population density increases, interference among individuals negatively affects their breeding performance. The second hypothesis, the habitat heterogeneity hypothesis (HHH), proposes that, as more individuals occupy the space available, lower quality

Ground‐nesting species are vulnerable to a wide range of predators and often experience very high levels of nest predation. Strategies to reduce nest vulnerability can include concealing nests in vegetation and/or nesting in locations in which nests and eggs are camouflaged and less easy for predators to locate. These strategies could have important implications for the distribution of ground‐nesting

The titles reviewed in this section of Ibis are available for reference at the Alexander Library of the Edward Grey Institute of Field Ornithology, Radcliffe Science Library, Parks Road, Oxford, UK. Please write, telephone +44 (0) 1 865 271143 or email sophie.wilcox@bodleian.ox.ac.uk prior to your visit to make an appointment. The aim of the Alexander Library is to build up a comprehensive collection

Mark Rehfisch was one of the first ecologists to realize that the impacts of climate change on wintering waders and wildfowl in the UK would tend to move birds eastwards rather than northwards. He recognized that the isotherms in winter lie north–south as opposed to east–west, as occurs in the summer. A series of papers (Rehfisch et al. 2004a, Austin & Rehfisch 2005, Maclean et al. 2008) confirmed

With the death of Colin Pennycuick on 9 December 2019 at the age of 86 years, the ornithological community has lost a doyen of avian biology whose passion for flying informed his pioneering research into avian flight for over five decades. His innovative studies, which famously include developing the use of wind tunnels for studying flight performance, led to him to describing key principles underlying

Determining the links between breeding populations and the pressures, threats and conditions they experience presents a challenge for the conservation of migratory birds which can use multiple sites separated by hundreds to thousands of kilometres. Furthermore, migratory connectivity – the connections made by migrating individuals between networks of breeding and non‐breeding sites – has important

Local weather can influence the growth and development of young birds either indirectly, by modifying prey availability, or directly, by affecting energetic trade‐offs. Such effects can have lasting implications for life history traits, but the nature of these effets may vary with the developmental stage of the birds, and over timescales from days to weeks. We examined the interactive effects of temperature

This report covers the period October 2019 to January 2020. The 50th Report appeared in Ibis 162: 263–268.

We compared the shape and eggshell thickness of Great Auk Pinguinus impennis  eggs with those of its closest relatives, the Razorbill Alca torda , Common Guillemot Uria aalge and Brünnich's Guillemot Uria lomvia , in order to gain additional insights into the breeding biology of the extinct Great Auk. The egg of the Great Auk was most similar in shape to that of Brünnich's Guillemot. The absolute thickness

Distraction displays are conspicuous behaviours functioning to distract a predator's attention away from the displayer's nest or young, thereby reducing the chance of offspring being discovered and predated. Distraction is one of the riskier parental care tactics, as its success derives from the displaying parent becoming the focus of a predator's attention. Such displays are prominent in birds, primarily

All birds sleep and many do so in a specific location, the roost. Thus, every day each individual needs to decide when to go to (enter) and leave the roosting place. This determines the timing of activity, a trait shaped by both natural and sexual selection. Despite its importance in a variety of contexts, including foraging, predation, mating success and parental care, variation in the timing of activity

The ability to rotate the fourth toe to accompany the first toe in opposition of the second and third toes is well known for the Osprey Pandion haliaetus , as an adaptation to have a stronger grip in catching and carry fish. The presence of a similar ability in the Grey‐headed Fish Eagle Haliaeetus ichthyaetus and Lesser Fish Eagle Haliaeetus humilis , not shared with other piscivorous eagles, has

Empirical studies often support the notion that testosterone inhibits paternal behaviour in animals, although most studies have focused on high, as opposed to low, levels of paternal care. We studied the relationship between plasma testosterone levels and incubation in male Japanese Barn Swallows Hirundo rustica gutturalis , in which some males participate in incubation. Contrary to our prediction

We focus on reconstructing a spatiotemporal scenario of diversification of a widespread South American species, the Pectoral Sparrow Arremon taciturnus (Aves: Passerellidae). This species is widely distributed in both the humid and the dry forests of South America and therefore provides an interesting model for understanding the connection between different biomes of South America. We examined nucleotide

Lead contamination is a global problem affecting a large number of bird species around the world. Among the different avian guilds, vultures and facultative scavengers are particularly threatened by this toxic metal. However, little information is available about differences in exposure to this metal for sympatric vulture species that share food resources. We compared blood lead concentrations of two

Experimental field studies have demonstrated negative fitness consequences of Hen Flea Ceratophyllus gallinae infestations for bird hosts, yet it is currently unclear whether these negative effects are a direct consequence of flea‐induced blood loss or a result of flea‐borne pathogen transmission. Here we used a 16S rRNA gene sequencing approach to characterize the bacterial microbiota community of

The increasing use of, and visits to, isolated territories by people (especially tourists) enables the investigation of how biodiversity reacts to evolutionarily novel pressures. We explored the behavioural reaction of a breeding seabird species, the Brown Noddy Anous stolidus , to our repeated visits at two study sites in the Chesterfield Islands, a newly classified reserve in the Coral Sea Natural

The development and miniaturization of GPS tracking devices has enabled a better understanding of migration phenology, but it can be challenging to identify where and when migration starts and ends, and researchers rely on multiple methods to infer it. Here, we use GPS tracks of 18 trans‐Saharan migrant White Storks Ciconia ciconia to determine how the choice of method influences the estimation of

Dozens of studies have documented that brood parasites are well adapted to a brood parasitic lifestyle but not all parasitism events are successful. Co‐evolution between brood parasites and their hosts is a dynamic process so it is reasonable to expect that a female brood parasite may commit errors during egg deposition by laying her eggs outside the laying period of the host, with consequent impacts

Autonomous recording units (ARUs) provide a non‐invasive and efficient method for acoustic detection of elusive species across large temporal and spatial scales. However, species with indistinct vocalization structures can be a considerable challenge for automated signal recognizers. We investigated the performance of ARUs and signal recognizers in identifying the broadband, short‐syllable, pulsed

Gut microbial communities play critical roles in the biological functions of their host, such as mediating nutrient absorption, digesting food components the host cannot, and offering protection against enteric pathogens. Extensive research on gut microbial communities has been conducted on mammals, including humans and rodents, but much less work has been done in birds. Furthermore, much of the research

Social cohesion and prey location in seabirds are largely enabled through visual and olfactory signals, but these behavioural aspects could potentially also be enhanced through acoustic transfer of information. Should this be the case, calling behaviour could be influenced by different social–ecological stimuli. African Penguins Spheniscus demersus were equipped with animal‐borne video recorders to

Intermittently incubating birds alternate between sessions of egg warming and recesses for foraging during the day, but stay on the nest continuously at night. Hence, energy costs of nocturnal incubation (which increase during longer and colder nights) cannot be replenished until the next day. Night conditions might therefore be expected to affect morning incubation behaviour the day after. We tested

This study addresses for the first time the movement patterns of the globally near‐threatened Bearded Vulture Gypaetus barbatus in its most important stronghold, the high‐altitude mountain ranges of Asia. Tracked individuals (n  = 8) in the Annapurna Himalayan range (Nepal) foraged over a vast range of 60 715.9 km2 and our results indicated age‐class differences in the use of space. Territorial adults

Long‐distance migrants are particularly susceptible to climate change because of their multi‐stage life‐cycle, but understanding how climatic conditions at each of these stages influence population dynamics remains a key challenge. Here, we use long‐term data from a UK population of Sand Martins Riparia riparia , a declining Afro‐Palaearctic migrant, to investigate how weather on the wintering grounds

Assessing and modelling abundance from animal count data is a very common task in ecology and management. Detection is arguably never perfect, but modern hierarchical models can incorporate detection probability and yield abundance estimates that are corrected for imperfect detection. Two variants of these models rely on counts of unmarked individuals, or territories (binomial N ‐mixture models, or

Altricial birds show enormous intraspecific diversity in their provisioning strategies, in terms of both the provisioning rate and the amount of food delivered per feeding bout. Extra‐pair copulations (EPCs), which result in either extra‐pair paternity (EPP) or maternity (EPM), provide an opportunity to demonstrate why provisioning strategies vary among individuals. Because EPP‐cuckolded males and

Passerine wing‐feather moult has been studied historically in terms of its intensity, duration, timing and extent. However, little is known about variation of wing‐moult phenotypes (i.e. the identity of moulted wing feathers in a given individual) within species, among moult episodes and in relation to passerine phylogeny. Here we studied 5373 wing‐moult cards from 285 Holarctic and 155 Neotropical

Carotenoids are essential antioxidant micronutrients. Oviparous species acquire carotenoids from their food and deposit them in the egg yolk, where they support embryonic development. The total carotenoid concentration in the egg yolk is typically measured analytically, which requires time, equipment and expertise, and can limit the sample available for other measurements, at least in species laying

Domestic species are excellent examples of the great adaptive potential of animal species under strong selective pressure. Among them, domestic pigeons (Columba livia var domestica ) represent one of the first domesticated bird species. Artificial selection through centuries, together with the multipurpose use of this species, has led to an extraordinary phenotypic diversity among breeds. Here, the