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.
Going with the flow? Costs and benefits of river flow variability to riverine birds
New research by the University of Birmingham and the BTO used data from the Waterways Breeding Bird Survey and the National River Flow Archive to show how the occurrence of river birds, including Dipper, Kingfisher and Great Crested Grebe, is influenced by the magnitude and timing as well as variation (i.e. extreme events) in river flow. River systems are vulnerable to climate change, with decreases in summer flows and increases in winter flows forecast. This research helps suggest how bird communities might respond to a climate change-induced shift in river flows and highlights which species will be at risk if the predicted increase in the intensity of floods and droughts comes about.
Plenty of fish in the sea? Seabird breeding shows impact of commercial fisheries in the North Sea
New research led by the BTO shows that the UK’s internationally important seabird populations are being affected by fishing activities in the North Sea. Levels of seabird breeding failure were higher in years when a greater proportion of the North Sea’s sandeels, important prey for seabirds, was commercially fished. The results demonstrate that seabird breeding can show how these key species are responding to environmental pressures before such changes become evident at the population level. Detecting such impacts as early as possible is a priority, as the management of the marine environment is changing, with expansion of offshore developments, the introduction of marine protected areas, and modification of fishing discards policy.
Moving with the times? Why the timing of bird migration is advancing when individuals are not
The BTO is involved in new research showing that young birds are the trend-setters when it comes to migration. It had generally been believed that the flexibility of individuals to respond to warmer springs lies behind the phenomenon of advancing migration. In this paper, focusing on the changing arrival dates of Black-tailed Godwits in Iceland, the authors show that individual, colour-ringed birds are not changing their schedules over time. Instead, it is the earlier spring migration of birds hatched in more recent years that lies behind the observed pattern of advancing arrival for the species.