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Hadeda Ibis ( Bostrychia hagedash ) have increased in population size and expanded in range in South Africa possibly as a result of increased use of exotic trees for nesting and roosting in urban areas. We investigated the urban nesting and roosting sites of the Hadeda Ibis by measuring tree height and species used by Hadeda Ibis for nesting and roosting in Pietermaritzburg, KwaZulu-Natal, South Africa. We expected Hadeda Ibis nests and roosts to have habitats, like wetlands, to be within 10 km of the roost or nest tree. Hadeda Ibis nest and roost locations were mapped using ArcGIS and available resources (grasslands, wetlands, plantations, other natural water sources) 10 km around each roost and nest tree were determined. Results showed that Hadeda Ibis use exotic trees for nesting and roosting in urban areas more than indigenous trees. This may be because exotic trees are more available in urban environments, particularly those trees that have ornamental value. Hadeda Ibis did not nest and roost closer to expected resources. Although previously associated with wetlands, Hadeda Ibis in urban environments were not close to natural water sources. This can be explained by swimming pools providing accessible drinking water and well watered lawns providing suitable foraging habitat therefore allowing them to roost and nest in this urban habitat.

1. Communal roosting behaviour in birds is hypothesized to reduce the risk of starvation by lowering the energetic expenditure required to survive the night. However, the metabolic benefit gained is likely to depend on various factors, including an individual's position within the roost. 2. The long-tailed tit Aegithalos caudatus L. is a social species that lives in flocks during the non-breeding season, forming linear roosting huddles in which individuals compete to avoid occupying the peripheral positions at either end of the roost. Using observations of 18 temporarily captive flocks of long-tailed tits, we examine the effects of position and other factors on the mass lost during roosting. 3. We found that, on average, long-tailed tits lost about 9% of their body mass overnight, and that individuals occupying the peripheral positions in a roost lost significantly more mass than those occupying inner positions. 4. Overnight mass loss was related to minimum temperature, being greatest at 4 °C and decreasing at higher and lower temperatures. This result suggests that long-tailed tits may use facultative nocturnal hypothermia to reduce energetic costs at low ambient temperature. Mass loss also tended to increase with group size, perhaps because of the greater competition for inner positions in larger flocks, although we have no direct evidence for this. Mass loss was also positively correlated with mass when going to roost, and males lost marginally more mass than females. 5. There was no evidence that individuals strategically adjusted their daily mass when going to roost in relation to their likely roosting position even though outer positions are consistently and therefore predictably occupied by the same individuals on successive nights. 6. We conclude that long-tailed tits mitigate the costs of surviving the night by roosting communally, but the benefits gained vary in relation to position within the roost, explaining previous observations of competitive interactions during roost formation. 7. The benefit derived from communal behaviour is likely to vary among individuals and the degree of conflict over these benefits is likely to depend on both intrinsic and extrinsic factors.

In forests worldwide, tree-cavity supply can limit populations of the 10-40%% of bird and mammal species that require cavities for nesting or roosting. Conservation efforts aimed at cavity-using communities have often focused on woodpeckers because, as cavity excavators, they are presumed to control cavity supply. We show that avian excavators are the primary cavity producers in North America (77%% of nesting cavities), but not elsewhere (26%% in Eurasia and South America; 0%% in Australasia). We studied survivorship of 2805 nest cavities and found similar persistence of cavities created by woodpeckers and those created by decay in Canada, but low persistence of woodpecker-excavated cavities in Poland and Argentina. Outside of North America, the ephemeral nature of many woodpecker cavities may render most cavity-using vertebrates critically dependent on the slow formation of cavities by damage and decay. The future of most cavity-using communities will therefore be highly dependent on changing forest policies to stem the current loss of old trees.

Nocturnal roosting sites are integral to bird habitats, with their use and selection by birds serving as indicators of behavioral adaptations to environmental pressures. Black‐necked Cranes (Grus nigricollis), which typically roost in shallow water, have exhibited an unexpected “terrestrialization” of nocturnal roosting sites within their eastern wintering population of southwest China. Despite this phenomenon being documented since the late 20th century, research on terrestrial nocturnal roosting behavior remains limited, hindered by technological challenges. To address this knowledge gap, we combined GPS‐GSM tracking data from 14 individuals monitored between 2015 and 2022 in northeastern Yunnan and western Guizhou with remote sensing imagery to systematically analyze their nocturnal roosting patterns. Our results indicated that area of water body, the location of foraging grounds, and individual behaviors influenced the proportion of terrestrial nocturnal roosting in Black‐necked Cranes. On land, Black‐necked Cranes preferred to roost on highlands (headwaters, uphill terraces, mountain tops, and local ridges) and avoided valleys (canyons, shallow valleys, and U‐shaped valleys). Notably, nocturnal terrestrial roosting sites were associated with increased nocturnal mobility compared to shallow water (11.6% vs. 0.8%). These findings suggest that terrestrial roosting behavior may reflect adaptive trade‐offs under habitat pressure. We recommend that regional conservation strategies should prioritize the following: (1) Protect existing large wetlands, (2) Connect and restore fragmented small wetlands, (3) Strengthen nighttime monitoring of the Black‐necked Crane, and (4) Strictly manage free‐ranging dogs to minimize anthropogenic disturbance on terrestrially roosting cranes. The choice of roosting sites is crucial for organisms. Our results indicate that the Black‐necked Crane's terrestrial roosting behavior may reflect adaptive trade‐offs under habitat pressure.

Phenology is a key feature in the description of species niches to capture seasonality in resource use and climate requirements. Species distribution models (SDMs) are widespread tools to evaluate a species’ potential distribution and identify its large-scale habitat preferences. Despite its chief importance, data phenology is often neglected in SDM development. Non-migratory bats of temperate regions are good model species to test the effect of data seasonality on SDM outputs because of their different roosting preferences between hibernation and reproduction. We hypothesized that (1) the output of SDMs developed for six non-migratory European bat species will differ between hibernation and reproduction; (2) models built from datasets encompassing both ecological stages will perform better than seasonal models. We employed a dataset of 470 independent occurrences of bat hibernacula and 400 independent records of nursery roosts of selected species and for each species we developed separate winter, summer and mixed (i.e. generated from both winter and summer occurrences) models. Seasonal and mixed potential ranges differed from each other and the direction of this difference was species-specific. Mixed models outperformed seasonal models in representing species niches. Our work highlights the importance of considering data seasonality in the development of SDMs for bats as well as many other organisms, including non-migratory species, otherwise the analysis will lead to significant biases whose consequences for conservation planning and landscape management may be detrimental.

Nipah virus is a bat-borne paramyxovirus that produces yearly outbreaks of fatal encephalitis in Bangladesh. Understanding the ecological conditions that lead to spillover from bats to humans can assist in designing effective interventions. To investigate the current and historical processes that drive Nipah spillover in Bangladesh, we analyzed the relationship among spillover events and climatic conditions, the spatial distribution and size of Pteropus medius roosts, and patterns of land-use change in Bangladesh over the last 300 years. We found that 53% of annual variation in winter spillovers is explained by winter temperature, which may affect bat behavior, physiology, and human risk behaviors. We infer from changes in forest cover that a progressive shift in bat roosting behavior occurred over hundreds of years, producing the current system where a majority of P. medius populations are small (median of 150 bats), occupy roost sites for 10 years or more, live in areas of high human population density, and opportunistically feed on cultivated food resources—conditions that promote viral spillover. Without interventions, continuing anthropogenic pressure on bat populations similar to what has occurred in Bangladesh could result in more regular spillovers of other bat viruses, including Hendra and Ebola viruses.

This study investigates the spatial behaviour and social dynamics of immature carrion crows ( Corvus corone ) caught in Paris, with the objective of discussing the efficiency of current culling strategies used to mitigate crop damage. Using GPS tracking data from 80 first-year crows of four different cohorts, we characterized seasonal variations in movement, roosting behaviour, and fission-fusion spatial dynamics. Results show that young crows remain closely associated with their natal sites until March of the year following hatching, after which they disperse to urban, peri-urban and rural areas, particularly in April and May, with peak daily movement distances averaging 2.7 km. This period coincides with the sowing of sensitive crops such as maize and sunflower, during which culling campaigns are often conducted. Furthermore, we document fission-fusion dynamics, with fluid group associations centred around predictable anthropogenic food sources and communal roosts, certainly facilitating repeated interactions and social learning. These findings suggest that current culling practices, largely targeting transient juveniles, are unlikely to achieve long-term reductions in population size or crop damage. Instead, the study highlights the importance of addressing particularly anthropogenic food availability as a potentially more effective and ethical strategy for managing urban, peri-urban and even rural crow populations.

Dougherty discusses the impact of artificial light at night (ALAN) on the roosting behavior of chimney swifts, a small aerial insectivore. The researchers hypothesized that higher levels of ALAN would cause delayed entry into roosting sites for chimney swifts. To test this hypothesis, the researchers used a sky quality meter, video cameras, and trap cameras purchased with a grant. The findings of the experiment shed light on the causes of chimney swift population decline and the broader effects of ALAN on roosting behaviors in wildlife populations. The project allowed the researcher to develop hypotheses, design and conduct experiments, and interpret results. It also strengthened their scientific communication skills.

Aim: Seasonal migration by animals is an extensively studied, global phenomenon. Yet, we still lack a general understanding whether migrants track their niche between summer and winter ranges (following fixed environmental conditions throughout the year) and which mechanisms influence this behaviour. Here, we assessed the degree of seasonal niche tracking in Holarctic long-distance migratory birds (n = 717; excluding very rare species) and evaluate the influence of biogeographic (regional and range characteristics) and ecological (trophic) factors on tracking. Location: Global. Taxon: Birds. Methods: We calculated seasonal niche overlap by means of ordination, and estimated the degree of niche tracking using similarity tests. Niche tracking was evaluated for two different environmental predictor sets: climate and vegetation productivity (reflecting resource selection) versus climate and land cover (reflecting habitat choice). Multivariate phylogenetic regression was used to evaluate effects of biogeographic and ecological traits on niche tracking. Results: We found significant niche tracking in 65–95% of species with a higher proportion of species significantly tracking climate and land cover compared to climate and vegetation productivity. Traits explained 12–18% of the variance in niche tracking with strong regional differences, a negative effect of migration distance and positive effects of range size on niche tracking. The effects of niche breadth and trophic traits were less pronounced and varied between environmental predictor sets. Main conclusions: Our results indicate that at coarse spatial resolution, long-distance migratory species tend to track their niche and select largely similar environments through seasons. Stronger niche tracking of land cover could reflect conservatism in habitat selection across seasons, for example for foraging and roosting. This conservatism towards land cover should be considered when making predictions to future environments. A better understanding of the factors that constrain seasonal range limits will be critical for predicting how migration patterns could respond to future environmental changes.

Chimney swifts (Chaetura pelagica) are highly manoeuvrable birds notable for roosting overnight in chimneys, in groups of hundreds or thousands of birds, before and during their autumn migration. At dusk, birds gather in large numbers from surrounding areas near a roost site. The whole flock then employs an orderly, but dynamic, circling approach pattern before rapidly entering a small aperture en masse. We recorded the three-dimensional trajectories of ≈1 800 individual birds during a 30 min period encompassing flock formation, circling, and landing, and used these trajectories to test several hypotheses relating to flock or group behaviour. Specifically, we investigated whether the swifts use local interaction rules based on topological distance (e.g. the n nearest neighbours, regardless of their distance) rather than physical distance (e.g. neighbours within x m, regardless of number) to guide interactions, whether the chimney entry zone is more or less cooperative than the surrounding flock, and whether the characteristic subgroup size is constant or varies with flock density. We found that the swift flock is structured around local rules based on physical distance, that subgroup size increases with density, and that there exist regions of the flock that are less cooperative than others, in particular the chimney entry zone.