In many socially monogamous animals, females engage in extrapair copulation (EPC), causing some broods to contain both within-pair and extrapair young (EPY). The proportion of all young that are EPY varies across populations and species. Because an EPC that does not result in EPY leaves no forensic trace, this variation in the proportion of EPY reflects both variation in the tendency to engage in EPC and variation in the extrapair fertilization (EPF) process across populations and species. We analyzed data on the distribution of EPY in broods of four passerines (blue tit, great tit, collared flycatcher, and pied flycatcher), with 18,564 genotyped nestlings from 2,346 broods in two to nine populations per species. Our Bayesian modeling approach estimated the underlying probability function of EPC (assumed to be a Poisson function) and conditional binomial EPF probability. We used an information theoretical approach to show that the expected distribution of EPC per female varies across populations but that EPF probabilities vary on the above-species level (tits vs. flycatchers). Hence, for these four passerines, our model suggests that the probability of an EPC mainly is determined by ecological (population-specific) conditions, whereas EPF probabilities reflect processes that are fixed above the species level.

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Wetland bird species have been declining in population size worldwide as climate warming and land-use change affect their suitable habitats. We used species distribution models (SDMs) to predict changes in range dynamics for 64 non-passerine wetland birds breeding in Europe, including range size, position of centroid, and margins. We fitted the SDMs with data collected for the first European Breeding Bird Atlas (EBBA1) and climate and land-use data to predict distributional changes over a century (the 1970s–2070s). The predicted annual changes were then compared to observed annual changes in range size and range centroid over a time period of 30 years using data from the second European Breeding Bird Atlas (EBBA2). Our models successfully predicted ca. 75% of the 64 bird species to contract their breeding range in the future, while the remaining species (mostly southerly breeding species) were predicted to expand their breeding ranges northward. The northern margins of southerly species and southern margins of northerly species, both, predicted to shift northward. Predicted changes in range size and shifts in range centroids were broadly positively associated with the observed changes, although some species deviated markedly from the predictions. The predicted average shift in core distributions was ca. 5 km/year towards the north (5% Northeast, 45% North, and 40% Northwest), compared to a slower observed average shift of ca. 3.9 km/year. Predicted changes in range centroids were generally larger than observed changes, which suggests that bird distribution changes may lag behind environmental changes leading to “climate debt. We suggest that predictions of SDMs should be viewed as qualitative rather than quantitative outcomes, indicating that care should be taken concerning single species. Still, our results highlight the urgent need for management actions such as wetland creation and restoration to improve wetland birds' resilience to the expected environmental changes in the future.

SummaryThe biodiversity and naturalness of forests that cover stream valleys in submontane areas have not been investigated as intensively as riparian forests along large lowland rivers. In this study we compared data on total bird assemblages and on selected indicator species detected in forests along submontane stream valleys (‘Vall’) with those detected in forests covering submontane slopes and tops in the foothills (‘Hill’) of the Western Carpathians, considering also environmental characteristics of the studied locations. The aim of this study was to verify the hypothesis that forests along submontane stream valleys harbour significantly richer and more diverse bird communities and that they are an important habitat for rare and threatened species. We found that the species richness, abundance of birds and bird diversity were almost twice as high in ‘Vall’ than in ‘Hill’ locations and that indicator species mostly or exclusively inhabit ‘Vall’ locations. Moreover, species diversity was highly and positively correlated with higher tree species diversity and a higher amount of large trees and dead wood, but negatively correlated with logging intensity. The results of our study confirmed that forested river valleys in submontane areas play an important role as refugia both for rare and endangered bird species as well as for the whole bird assemblage. This study is the first to present an assessment of this type of habitat for birds in the Western Carpathians. Forests along submontane stream valleys, if protected or unmanaged, could be treated as reference areas for nature and biodiversity conservation.

Extra‐pair paternity is common in many socially monogamous bird species. Increasing evidence suggests that extra‐pair copulations are female‐driven, but benefits for females mating outside social pair‐bonds are still poorly understood. The most influential explanation, “good genes” hypothesis, states that females mated socially with low quality males, engage in extra‐pair copulations to obtain genetic benefits for their progeny. According to this model, enhanced performance of extra‐pair offspring is expected. Here, based on 4‐year study of collared flycatcher Ficedula albicollis, we compared the condition of extra‐pair and within‐pair young. We found no difference in immune response and body size between maternal half‐siblings raised in the same nests. Additionally sex ratio was not biased among extra‐pair nestlings, and paternity was not associated with hatching rank. Our results failed to reveal “good genes” effects in the studied population. These effects might be hard to detect, but other hypotheses should also be studied more thoroughly in the future.