Summary1. Climate change is reported to have caused widespread changes to species' populations and ecological communities. Warming has been associated with population declines in longdistance migrants and habitat specialists, and increases in southerly distributed species. However, the specific climatic drivers behind these changes remain undescribed. 2. We analysed annual fluctuations in the abundance of 59 breeding bird species in England over 45 years to test the effect of monthly temperature and precipitation means upon population trends. 3. Strong positive correlations between population growth and both winter and breeding season temperature were identified for resident and short-distance migrants. Lagged correlations between population growth and summer temperature and precipitation identified for the first time a widespread negative impact of hot, dry summer weather. Resident populations appeared to increase following wet autumns. Populations of long-distance migrants were negatively affected by May temperature, consistent with a potential negative effect of phenological mismatch upon breeding success. There was evidence for some nonlinear relationships between monthly weather variables and population growth. 4. Habitat specialists and cold-associated species showed consistently more negative effects of higher temperatures than habitat generalists and southerly distributed species associated with warm temperatures. Results suggest that previously reported changes in community composition represent the accumulated effects of spring and summer warming. 5. Long-term population trends were more significantly correlated with species' sensitivity to temperature than precipitation, suggesting that warming has had a greater impact on population trends than changes in precipitation. Months where there had been the greatest warming were the most influential drivers of long-term change. There was also evidence that species with the greatest sensitivity to extremes of precipitation have tended to decline. 6. Our results provide novel insights about the impact of climate change on bird communities. Significant lagged effects highlight the potential for altered species' interactions to drive observed climate change impacts, although some community changes may have been driven by more immediate responses to warming. In England, resident and short-distance migrant populations have increased in response to climate change, but potentially at the expense of long-distance migrants, habitat specialists and cold-associated species.
Threats to biodiversity resulting from habitat destruction and deterioration have been documented for many species, whilst climate change is regarded as increasingly impacting upon species' distribution and abundance. However, few studies have disentangled the relative importance of these two drivers in causing recent population declines. We quantify the relative importance of both processes by modelling annual variation in population growth of 18 farmland bird species in the UK as a function of measures of land-use intensity and weather. Modelled together, both had similar explanatory power in accounting for annual fluctuations in population growth. When these models were used to retrodict population trends for each species as a function of annual variation in land-use intensity and weather combined, and separately, retrodictions incorporating land-use intensity were more closely linked to observed population trends than retrodictions based only on weather, and closely matched the UK farmland bird index from 1970 onwards. Despite more stable land-use intensity in recent years, climate change (inferred from weather trends) has not overtaken land-use intensity as the dominant driver of bird populations.
Summary 1.Over the last century, the loss of around half of the world's wetlands, principally through drainage and conversion to agriculture, has been one of the main drivers of declines in breeding waders. Across Europe, nature reserves have been effective conservation islands for breeding waders, but management of the wider countryside is needed for more wide-scale population recovery. This is likely to require the restoration of wet features, but in a manner which is compatible with farming operations. 2.Here we explore the extent to which three types of wet feature influence the distribution of breeding lapwings Vanellus vanellus and their chicks on grassland. Footdrains are shallow channels used historically for drainage, but which can also be created and managed for water retention and cause little disruption to farming activities. Footdrain floods are areas where water overtops footdrains. Isolated pools are unmanaged areas of surface water resulting from rainfall or high water tables. 3. We selected 70 fields on nine sites which spanned the range of wet feature type and cover in early April. By May, only around 10% of the water within isolated pools remained, whereas 30-40% water was maintained in footdrains into June. 4. Fields with high footdrain flood densities attracted significantly higher densities of nesting lapwing and nests were more likely to be within 50 m of footdrain floods. Later in the season, footdrains were the primary remaining water source, and chick field use increased significantly with footdrain density. Chicks were also more likely to forage nearer footdrain floods in areas of wet mud created by receding water levels. 5. Synthesis and applications. Areas of shallow, small-scale flooding are of critical importance for breeding waders. Management tools such as footdrains, coupled with appropriate hydrological management, provide a means of retaining water throughout the breeding season. Installation of these features is relatively simple, but maintaining sufficient water levels within the system is critical, especially in the face of increasingly unpredictable water supplies associated with climate change. Such management tools offer a solution that may be both effective at improving breeding wader populations and practicable for commercial grazing marsh management.
Summary1. The widespread drainage of wetlands and grazing marshes has been one of the main drivers of severe reductions in the number and range of breeding waders across Europe. Wader chicks require wet, invertebrate-rich foraging habitats and most agricultural land is now too dry to support sustainable breeding populations. Recent efforts to re-create wet grasslands and improve wader breeding success have focussed on reinstating wet features, in order to provide foraging habitats for chicks. The success of wet feature installation will therefore depend on whether they provide sufficient invertebrate prey for chicks throughout the pre-fledging period. 2. Techniques for re-creating lowland wet grasslands from arable and pastoral farmland are becoming increasingly well-established, and support from agri-environment initiatives is now available for wet feature installation on grasslands. Here we explore the effect of wet feature provision on invertebrate abundance and the growth rates and body condition of northern lapwing Vanellus vanellus chicks, on grazing marshes in eastern England. 3. Wet features supported more than double the biomass of surface-active invertebrates and a greater abundance of aerial invertebrates than the vegetated grazing marsh. Chick foraging rates were also two to three times higher in wet features than in the grazing marsh, as was the estimated biomass intake per food item. 4. At the start of the breeding season, chick condition was unrelated to wet feature provision but late in the season, when water levels were low, chick body condition was significantly higher in fields with footdrain densities of more than 150 m ha )1 . Chick condition declined with increasing rainfall, and low growth rates and longer pre-fledging periods in 2007 are likely to have resulted from unusually intense and prolonged summer rainfall. 5. Synthesis and applications. The installation of wet features on grasslands provides valuable foraging locations for chicks, particularly later in the season when these features are likely to be the main source of water available. Predicted changes to the seasonality of precipitation at temperate latitudes means that provision of wet features is likely to be increasingly important for maintaining breeding wader populations.
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