Journal of Avian Biology最新文献

Biologgers enable real-time collection of detailed behavioural and physiological data from wide-ranging animals, including seabirds inhabiting remote regions. However, the number of studies using tracking devices has not been matched by research exploring the behavioural and fitness costs of deployment, and the effects on data reliability. We assessed how GPS loggers, video loggers, and time depth recorders (TDRs) affect the behaviour, physiology, and reproductive performance of European shags Gulosus aristotelis breeding on Sklinna, Norway. The loggers varied in mass, attachment location and deployment duration, allowing comparison of their relative effects. Birds without loggers served as controls to assess logger-related changes in adult body mass, chick growth, reproductive success, and survival. Birds with longer-term tail-mounted GPS loggers and leg-mounted TDRs showed altered foraging behaviour, including shorter trips and dives, compared to birds with tail-mounted GPS and TDRs of the same weight, instrumented for only two days. A mean loss in body mass was experienced by adult birds regardless of the logger type used, while chick growth rate dropped to 20% of that observed in control nests when video, TDR and GPS loggers (~ 4% of body mass) were deployed together. Logger attachments did not impact reproductive success, and overall logger birds showed higher survival than controls. However, female survival was lower than that of males among birds fitted with video and long-term GPS loggers. Our results demonstrate the importance of measuring behavioural and physiological effects that can scale over time. The advances in our understanding of animal ecology and behaviour generated by biologging have been impressive, but there is a need to consider the impacts on animal welfare and data quality. Consistent reporting of logger deployment details is essential to assess biologging impacts across species and refine protocols that account for device weight, drag and attachment location.

The long-distance migrations of thousands of bird species and their billions of individuals are feats of astounding physiological specialization and plasticity. Whereas numerous organ systems require modification to achieve successful fueling and navigation capabilities, given their overarching importance for movement and contribution to body mass, skeletal muscles are subject to exceptional performance optimization and anatomical plasticity. To express the appropriate changes throughout the complicated life history of migration, while remaining in synchrony with the environment, skeletal muscles must receive preparatory signals and express transcriptional and biochemical modifications required for full expression of the migratory phenotype. In all likelihood, these muscles must also temporally signal their state and needs to other organ systems. By considering other well-studied avian skeletal muscle systems, this review explores how endocrine signaling likely impacts skeletal muscles involved in migration and, conversely, how those muscles might relay their condition elsewhere throughout the bird's body. Systems biology offers exceptional modeling for capturing this complex biology.

Wild, C., Brandl, R., Decker, O., Hochrein, S., Ingrosso, A., Mallick, S., Mitesser, O., Rothacher, J., Thorn, S., Müller, J. (2025). Nest mass in forest tits (Paridae) increases with elevation and decreasing body mass, promoting reproductive success. Journal of Avian Biology, 2025: e03407. https://doi.org/10.1002/jav.03407

In the above article, the family name Paridae was erroneously omitted from the title. The article also included an incorrect Supporting Information file.

The original article has now been updated to correct these items.

We apologize for the errors.

To understand the distribution of avian biodiversity, it is crucial to understand the interspecific interactions present in avian communities. The ‘natural removal experiment', which explores patterns consistent with competition by comparing a species' habitat relationships in sympatry and allopatry with those of a potential competitor, has held promise, but has thus far had limited general replicability. We offer an adaptation of this method applicable to many study systems and over broad geographic scales, without requiring a prioriknowledge of an interaction. We use this method to ask whether the distribution of the chestnut-backed chickadee Poecile rufescens(CBCH) is consistent with competition with the black-capped chickadee Poecile atricapillus(BCCH) in urban areas in the Pacific Northwest. Using data from eBird, we compared relationships of CBCH relative abundance to urban- and forest-related variables in different local urban centres and across region-wide areas of allopatry and sympatry with the BCCH. As predicted under competition, we found that in allopatry, the CBCH adopted habitat relationships similar to the BCCH, inhabiting less forested, more urban habitats, both in local urban centres and at the region-wide scale. When examining the potential consequences of absence or ubiquity of BCCH across the region, we found when model predictions were made as if BCCH were ubiquitous, CBCH abundance was lower in urban areas, and that when predictions were made as if BCCH were absent CBCH abundance increased, consistent with competitive release. These lines of evidence suggest that the distribution of CBCH is consistent with that expected under competition with the BCCH in urban areas. As the BCCH expands its range further into the Pacific Northwest, our assessment foreshadows the eventual replacement of CBCH from urbanized areas. Expanding beyond this case study, we discuss considerations in the application of this method to offer researchers a broadly applicable tool to study species interactions.

Eberhart-Hertel, L., Williams, E. M., McGilvary-Howard, A., Howard, T., Habraken, T., O'Donnell, C. F. J., Küpper, C. and Kempenaers, B. (2025). Evaluating the effects of tracking devices on survival, breeding success, behavior, and condition of a small, partially migratory shorebird. Journal of Avian Biology, 2025: e03490. https://doi.org/10.1002/jav.03490

In the above article, the author affiliations were listed incorrectly. The correct version is as follows:

Luke Eberhart-Hertel^1,2, Emma M. Williams³, Ailsa McGilvary-Howard⁴, Ted Howard⁴, Tony Habraken⁵, Colin F. J. O'Donnell³, Clemens Küpper² and Bart Kempenaers¹

¹Department of Ornithology, Max Planck Institute for Biological Intelligence, Seewiesen, Germany

²Research Group for Behavioural Genetics and Evolutionary Ecology, Max Planck Institute for Biological Intelligence, Seewiesen, Germany

³Fauna Science Team, Department of Conservation Christchurch Office, Christchurch, New Zealand

⁴Kaikōura Banded Dotterel Project, Kaikōura, New Zealand

⁵Port Waikato Banded Dotterel Project, Port Waikato, New Zealand

The original article has also been updated to reflect these changes.

We apologize for the error.

Many birds schedule their activity to a specific phase of the diel (24-h) light–dark cycle. Two notable exceptions are the nocturnal migration of many otherwise diurnal songbirds and the diverse activity patterns of birds during the continuous light above the Polar Circles during summer. Assumptions about the phase relationship between migratory activity and the diel cycle can be incorrect, and the diel activity of Arctic migratory birds during the year is largely unknown. We used the snow bunting Plectrophenax nivalis to investigate whether breeding songbirds above the northern Polar (Arctic) Circle have 24-h activity rhythms with distinct active and inactive phases across the annual cycle, and whether their migration aligns with a specific phase of their activity rhythm. We found that male snow buntings maintain a robust 24-h activity rhythm with distinct active and inactive phases across most of the annual cycle, including during polar summer, but the robust 24-h periodicity attenuated during vernal migration. Birds scheduled long and short flights across their diel activity rhythm. However, shorter flights most often began during the active phase, and the longest flights most often began during the transition between the active and inactive phase of the diel activity rhythm. This indicates that snow buntings can flexibly schedule their flights across their prominent diel activity rhythm, although their longest flights during migration typically overlapped with their normal inactive phase, probably corresponding to nighttime. Several open questions, however, remain about the generality of our results for other songbirds, such as: what is the phase relationship between the diel activity rhythm and flight to the diel light–dark cycle, and how do historical accounts of diel migration phase align with empirical activity data for other species?

The increasing presence and activities of people in both urban environments and non-urban areas result in the exposure of many wild animal populations to persistent human disturbance. As a response, individuals in disturbed populations often become tolerant towards humans, which can have significant ecological and societal consequences, for example by affecting ecosystem services and human–wildlife conflicts. Although several mechanisms have been proposed to explain the emergence and spread of disturbance tolerance, their biological bases are rarely investigated in natural populations. In this study, we investigated behavioural tolerance in great tits Parus major along urbanization gradients of two cities representing different levels of human disturbance. Specifically, we studied whether variation in disturbance tolerance is related to epigenetic variation in the DRD4 gene that is often linked to behavioural plasticity. We did not detect differences in DNA methylation at 23 CpG sites between wild great tit populations breeding in differently urbanized areas. However, variation in methylation at some CpG sites was associated with two proxies of tolerance, return latency and the vigilance behaviour of parent birds measured after standardized disturbance. These findings suggest that epigenetic variation may be involved in the processes generating behavioural tolerance to human disturbance. These results have implications for understanding the mechanisms by which animal populations can respond to disturbances in human-dominated environments.

The bi-directional effects of stress on the gut microbiota and the microbiota's mediation of the stress response are an important facet of the brain–gut axis. Stressors can alter hormones present in the body, particularly circulating glucocorticoids, which in turn can affect the composition and diversity of the gut microbiota. Likewise, bacterial community members have been linked to improved or worsened responses to stress. In this study, we manipulated common myna birds in two ways – through sleep deprivation and by increasing glucocorticoids – to determine how their gut microbiota changed in composition and diversity. We also determined whether the gut community was correlated with activity level, a metric for stress response, or with measured faecal glucocorticoid level, and whether birds exhibiting the highest apparent stress response shared any bacterial community members. We found that alpha diversity in the gut significantly decreased after both sleep deprivation and corticosterone ingestion. We also found significant shifts in beta diversity following both treatments, though with substantial variation in the progression of the bacterial community among individuals. Despite these significant shifts in the gut, we found only a marginally significant correlation between gut community and activity level, and between gut community and faecal corticosterone levels. This work provides new evidence for the longitudinal effect of stress on the gut microbiota and identifies bacterial genera that were significantly elevated or depressed following exposure to stressors.

Animals breed at times of the year that ensure offspring production and growth during favorable periods. DNA methylation is one mechanism by which expression of genes necessary for reproduction may be regulated, enabling expression only at appropriate times. Much work on seasonal breeding in vertebrates has focused on the neuroendocrine system, however oviparous vertebrates, including birds, also rely on the liver for production of yolk precursors, such as vitellogenin (VTG) that will provide the nutrients necessary for development in ovo. We hypothesized that changes in DNA methylation in the promoter for VTG2 in the liver may be one mechanism ensuring appropriately timed seasonal breeding. DNA methyltransferases (DNMTs) facilitate de novo (DNMT3a) and maintenance (DNMT1) of DNA methylation. We observed that liver expression of VTG2 was lower in birds sampled during the pre-breeding compared with the early-breeding period, and also observed changes in liver expression of DNMT1 and DNMT3a between these two periods. Contrary to our predictions, we observed an increase in methylation from pre- to early-breeding at one of three CpG sites in the promoter of the VTG2 gene, with no differences at the other two CpG sites. Finally, we asked if patterns of DNA methylation of VTG2 in liver were similar in the blood. Although we observed strong correlations between blood and liver in two sites that did not change between pre- and early-breeding, there was only a trend for a significant association between blood and liver DNA methylation at the site that displayed an increase in liver DNA methylation between sampling periods. Together, these findings suggest that changes in DNA methylation in an important tissue outside of the reproductive endocrine axis (liver) may play a critical role in appropriate timing of seasonal clutch initiation, though it is unclear if these epigenetic changes are all reflected in blood.

The loss of top predators has been shown to lead to drastic changes in community structure. An important part of this is the shift in behaviour of other species. The understanding of such changes is scarce because recordings of behavioural reactions towards lost species are rarely done. This is important for predators experiencing predation pressure themselves, known as intraguild predation. Re-colonizations offer the unique possibility to fill this knowledge gap. However, only a few studies tested experimentally how subordinate predators change their behaviour towards differently sized top predators. Birds adjust the level of nest defence in response to perceived threats. Therefore, we expected birds of prey in intraguild predation systems to show an appropriate level of nest defence against the predator they are faced with, with the highest level shown against the largest predator. We tested this by placing models of eagle owls Bubo bubo and goshawks Accipiter gentilis close to nests of common buzzards Buteo buteo and measured the reaction. Overall, aggression by common buzzards towards eagle owls was greater than towards goshawks, but effect sizes were small and had relatively large confidence intervals. We therefore conclude that the largest predator and the second-largest predator provoke similarly high nest defences. This shows that in ecological communities the largest predator and smaller predators may not belong to different categories from the viewpoint of intraguild prey. Different top predators might be perceived as comparable threats.