Patchy habitats expose woodland birds to winter weather
Projected climate change impacts on the populations and distributions of species pose a challenge for conservationists. In response scientists and policy makers have proposed a number of management strategies to enable species to persist in a changing climate. However there is limited evidence to support these management interventions, making it difficult for conservationists to decide on the most appropriate action to take for different circumstances.
New BTO-led research has supported the prediction that habitat attributes (woodland patch isolation and area of woodland at the site and at the wider landscape scale) may influence the ability of some woodland bird species to withstand weather-mediated population declines. Results suggest that these effects were most apparent among generalist species, such as Bullfinch and Robin. However several specialist species, like Nuthatch and Willow Tit, were also more likely to increase following population decline where there was more woodland at the site and in the wider landscape. While management is unlikely to provide a universal benefit to all woodland species, landscape-scale conservation initiatives that maximize woodland patch size and minimize patch isolation may improve the resilience of some woodland bird populations to climate change.
Climate change disrupts natural relationships between species
Change is altering species’ distributions and populations but it is unclear how these impacts occur. New research led by the BTO reviewed almost 150 published studies to show that the main impacts of climate change occur through altered interactions between species within an ecosystem, rather than direct responses to climate. Each species shares an ecosystem with other species, some of which it might eat, and others that might eat or compete with it. This study found it was changes to the populations or activity of these other species that were responsible for many of the impacts observed. For example, upland birds such as the Golden Plover are affected by increasing summer temperatures, which cause problems for their Cranefly prey.
Much conservation action is concerned with managing species’ populations, so the conservation tools to reduce the impacts of climate change are already available and vulnerable species can be helped to adapt. Degraded peatland habitats in the UK uplands could be restored, for example, boosting Cranefly populations, and increasing their resilience to climate change. This study highlights the need to consider the complex ecological relationships between species when assessing the impacts of climate change at a global scale.
Is moorland management for birds feasible without control of predation?
Reseach by the BTO, ADAS UK and the former Scottish Coal has examined the effectiveness of moorland management in south-west Scotland. British moorland can support important populations of breeding waders, gamebirds and birds of prey. Moorland and associated habitats are a result of management, in particular for sheep grazing and sport shooting of Red Grouse, but also prescriptions to maintain, restore or enhance particular components. While a suite of such prescriptions have been taken up quite widely, an ongoing decline of moorland birds is amongst the more marked results of the 2007-11 Bird Atlas.
Annual surveys of vegetation and birds over 10 years showed that the breeding bird community did not increase in response to the management prescriptions adopted. Only two species increased relative to the general trend for moorland and one of them was Carrion Crow, a species that was being actively removed as part of predation control measures. Most species showed no change or actually declined. This work highlights the difficulties in establishing effective management regimes for the benefit of moorland birds. It also underlines a need to develop an improved understanding of the factors that shape moorland bird communities more widely. Raising the question as to whether moorland bird conservation can be effective where they remain vulnerable to predation, it will contribute towards the wider debate on the future of British uplands.
Understanding disease reservoirs in wild birds
Salmonellosis is an infection brought about by the bacterium Salmonella enterica and is a commonly diagnosed cause of mortality among garden birds. The disease can also affect humans but the extent to which wild birds might act as reservoirs for Salmonellosis in humans in unclear. New research involving the BTO showed that the Salmonella phage types found in garden birds and humans matched in a high proportion of cases, and that there was a similar spatial and temporal pattern to the infections. This supports existing evidence that garden birds can act as a reservoir for Salmonellosis in humans. Further research is needed to identify how Salmonella might transmit from birds to humans; it could occur through handling sick or injured birds, or from washing bird feeders in kitchen sinks. There are other possible ways too, such as contact with contaminated soil when gardening. This study therefore highlights how important it is to be aware of the potential for disease transmission between birds and humans, and the need for good hygiene, especially for people like ringers, who frequently handle wild birds.
Citizen scientists help uncover mysteries behind House Sparrow population declines
Although House Sparrow numbers have fallen sharply in recent years, declines are greater in urban than in rural areas, and in eastern and south-eastern Britain than in other parts of the country. A new study by the BTO has used volunteer-collected data from Garden Birdwatch (GBW), the Nest Record Scheme (NRS) and the Breeding Bird Survey (BBS) to investigate possible reasons underpinning these trends.
GBW data showed that annual productivity was highest in Wales and lowest in the east of England, but that there was no difference between rural and urban areas. The regional difference in GBW productivity was mirrored by NRS data, which revealed that House Sparrow clutch and brood sizes were significantly lower in the east of Britain than in the west. This study demonstrates the importance of large-scale datasets collected by citizen science projects in understanding drivers of population change, which is vital for implementing effective conservation measures.