Climate change and the long-term northward shift in the African wintering range of the barn swallow Hirundo rustica

A review of the relative merits of conserving, using, or draining papyrus swamps

Disentangling the effects of fertilisers and pesticides on winter stubble use by farmland birds

Rarity, life history and scaling of the dynamics in time and space of British birds

1. Many patterns in macroecology are closely related to the total abundance of a species in aregion. Here we show that interspecific differences in the pattern of population fluctuations ofBritish bird species can be predicted from knowledge of their overall abundance and some basiclife-history characteristics.2. We identify a rarity syndrome that arises through an increased stochastic influence on populationfluctuations with decreasing population size, mainly resulting from an inverse density-dependenteffect of demographic stochasticity. This syndrome involves an increase in the annual changesin population size with increasing rarity in the United Kingdom.3. The relationship between the magnitude of temporal variation and local mean population sizediffers between species dependent on their life history, i.e. species with larger clutch size and lowersurvival tended to have larger annual changes in population size than low-reproducing long-livedspecies.4. The probability of local disappearance from a study plot depended on the population size andwas hence closely related to the overall abundance of the species in UK. For a given populationsize, this probability was also related to species-specific life-history characteristics, being higher inspecies with larger clutch sizes and smaller survival rates.5. Rareness results in a spatial decoupling of the temporal variation in population size.6. These patterns show that once a species has become rare, e.g. due to human activities, key populationdynamical characteristics will change because of density-dependent stochastic effects, whichin turn are dependent on species-specific life-history characteristics.

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Identification of putative wintering areas and ecological determinants of population dynamics of Common House-Martin Delichon urbicum and Common Swift Apus apus breeding in Northern Italy

To identify the causes of population decline in migratory birds, researchers must determine the relative influence of environmental changes on population dynamics while the birds are on breeding grounds, wintering grounds, and en route between the two. This is problematic when the wintering areas of specific populations are unknown. Here, we first identified the putative wintering areas of Common House-Martin (Delichon urbicum) and Common Swift (Apus apus) populations breeding in northern Italy as those areas, within the wintering ranges of these species, where the winter Normalized Difference Vegetation Index (NDVI), which may affect winter survival, best predicted annual variation in population indices observed in the breeding grounds in 1992–2009. In these analyses, we controlled for the potentially confounding effects of rainfall in the breeding grounds during the previous year, which may affect reproductive success; the North Atlantic Oscillation Index (NAO), which may account for climatic conditions faced by birds during migration; and the linear and squared term of year, which account for nonlinear population trends. The areas thus identified ranged from Guinea to Nigeria for the Common House-Martin, and were located in southern Ghana for the Common Swift. We then regressed annual population indices on mean NDVI values in the putative wintering areas and on the other variables, and used Bayesian model averaging (BMA) and hierarchical partitioning (HP) of variance to assess their relative contribution to population dynamics. We re-ran all the analyses using NDVI values at different spatial scales, and consistently found that our population of Common House-Martin was primarily affected by spring rainfall (43%–47.7% explained variance) and NDVI (24%–26.9%), while the Common Swift population was primarily affected by the NDVI (22.7%–34.8%). Although these results must be further validated, currently they are the only hypotheses about the wintering grounds of the Italian populations of these species, as no Common House-Martin and Common Swift ringed in Italy have been recovered in their wintering ranges.