Covariation in population trends and demography reveals targets for conservation action

Wildlife conservation policies directed at common and widespread, but declining, species are difficult to design and implement effectively, as multiple environmental changes are likely to contribute to population declines. Conservation actions ultimately aim to influence demographic rates, but targeting actions towards feasible improvements in these is challenging in widespread species with ranges that encompass a wide range of environmental conditions. Across Europe, sharp declines in the abundance of migratory landbirds have driven international calls for action, but actions that could feasibly contribute to population recovery have yet to be identified. Targeted actions to improve conditions on poor-quality sites could be an effective approach, but only if local conditions consistently influence local demography and hence population trends. Using long-term measures of abundance and demography of breeding birds at survey sites across Europe, we show that co-occurring species with differing migration behaviours have similar directions of local population trends and magnitudes of productivity, but not survival rates. Targeted actions to boost local productivity within Europe, alongside large-scale (non-targeted) environmental protection across non-breeding ranges, could therefore help address the urgent need to halt migrant landbird declines. Such demographic routes to recovery are likely to be increasingly needed to address global wildlife declines.Peer reviewe

Data from: Wintering bird communities are tracking climate change faster than breeding communities

1. Global climate change is driving species’ distributions towards the poles and mountain tops during both non-breeding and breeding seasons, leading to changes in the composition of natural communities. However, the degree of season differences in climate-driven community shifts has not been thoroughly investigated at large spatial scales. 2. We compared the rates of change in the community composition during both winter (non-breeding season) and summer (breeding) and their relation to temperature changes. 3. Based on continental-scale data from Europe and North America, we examined changes in bird community composition using the community temperature index (CTI) approach and compared the changes with observed regional temperature changes during 1980–2016. 4. CTI increased faster in winter than in summer. This seasonal discrepancy is probably because individuals are less site-faithful in winter, and can more readily shift their wintering sites in response to weather in comparison to the breeding season. Regional long-term changes in community composition were positively associated with regional temperature changes during both seasons, but the pattern was only significant during summer due to high annual variability in winter communities. Annual changes in community composition were positively associated with the annual temperature changes during both seasons. 5. Our results were broadly consistent across continents, suggesting some climate-driven restructuring in both European and North American avian communities. Because community composition has changed much faster during the winter than during the breeding season, it is important to increase our knowledge about climate-driven impacts during the less-studied non-breeding season.,The data has been collected using breeding and winter bird surveys and the detailed methodologies are given in the Supplements of the article. The community temperatures are calculated using methodology of Devictor et al. 2008. Devictor, V., Julliard, R., Couvet, D. & Jiguet, F. (2008) Birds are tracking climate warming, but not fast enough. Proceedings of the Royal Society B, 275, 2743–2748. https://doi.org/10.1098/rspb.2008.0878,The dataset includes two files, one for annual changes and one for long term changes in community temperature index of birds and related temperature values. The annual data includes annual (fyear) estimates (fit), the standard error of the change (se) and 95% confidence intervals (lower, upper) of community temperature indices (CTI) in 57 regions (Country) in North America (Continent) and Europe for breeding and winter seasons (Season). Annual change in CTI (dCTI) and temperature (dTemp) as well as CTI of previous year of regions are also given. The long-term data includes long-term change (annual slope, dCTI) and the standard error of the change (CTI_se) in community temperature index (CTI) in 57 regions (Region) in North America (Continent) and Europe for breeding and winter seasons (Season). Raw mean CTI value (mCTI_raw) and centred CTI (mCTI), coordinates (Lat, Lon), long-term change in temperature (Temp) and its standard error (TempSE), predicted CTI changes (CTITempPred), mean raw temperature (mTemp_raw) and centred mean temperature (mTempSt) of regions are also given. In addition two R scripts to analyses the data (CTI_Annual_Analyses_20200817.R and CTI_Longterm_Analyses_20201130.R) are included.

Population responses of bird populations to climate change on two continents vary with species’ ecological traits but not with direction of change in climate suitability

Climate change is a major global threat to biodiversity with widespread impacts on ecological communities. Evidence for beneficial impacts on populations is perceived to be stronger and more plentiful than that for negative impacts, but few studies have investigated this apparent disparity, or how ecological factors affect population responses to climatic change. We examined the strength of the relationship between species-specific regional population changes and climate suitability trends (CST), using 30-year datasets of population change for 525 breeding bird species in Europe and the USA. These data indicate a consistent positive relationship between population trend and CST across the two continents. Importantly, we found no evidence that this positive relationship differs between species expected to be negatively and positively impacted across the entire taxonomic group, suggesting that climate change is causing equally strong, quantifiable population increases and declines. Species’ responses to changing climatic suitability varied with ecological traits, however, particularly breeding habitat preference and body mass. Species associated with inland wetlands responded most strongly and consistently to recent climatic change. In Europe, smaller species also appeared to respond more strongly, while the relationship with body mass was less clear-cut for North American birds. Overall, our results identify the role of certain traits in modulating responses to climate change and emphasise the importance of long-term data on abundance for detecting large-scale species’ responses to environmental changes