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; infection with any one of over 2,500 types (known as serovars) can cause particular problems for infants, those with compromised immune systems and the elderly. One of the most commonly isolated serovars, known as Salmonella Typhimurium, has been isolated from both people and bird species (including Greenfinch, Chaffinch and House Sparrow). Salmonella Typhimurium itself occurs in a number of forms, known as phage types, and some of the phage types found in wild birds have also been found in humans. What is unclear, however, is the extent to which wild birds might act as reservoirs for Salmonellosis in humans. New research, involving the BTO and led by the Institute of Zoology, aims to address this through a study that is especially relevant given the growing popularity of garden bird feeding, bringing people in ever closer contact with wild birds. This work characterised and compared phage types isolated from humans and garden birds suffering from Salmonellosis, and also examined the timing and geographical occurrence of infection across these two groups. Results showed that the phage types matched in a high proportion of cases, and that there was a similar spatial and temporal pattern to the infections, supporting existing evidence that garden birds can act as a reservoir for Salmonellosis in humans. The incidence of infection was low, however. 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. If you find a sick or injured bird, please report it to through Garden Wildlife Health, a joint project between the Institute of Zoology, BTO, Froglife and RSPB. Don’t forget to check dead birds to see if they are ringed, details of which can be submitted via the Ringing Scheme pages.

Although House Sparrows are conspicuous birds and can still be found cheeping away in many areas, their numbers have fallen sharply in recent years, leading to their inclusion on the Birds of Conservation Concern Red List. Declines are greater in urban than in rural areas, and in eastern and south-eastern Britain than in other parts of the country (where the population is stable or increasing). A new study by the BTO has used data collected by volunteers participating in Garden Birdwatch (GBW), the Nest Record Scheme (NRS) and the Breeding Bird Survey (BBS) to investigate possible reasons underpinning these trends. The research focussed on measures of breeding performance. In keeping with population 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. The number of breeding attempts per year and post-fledging survival did not differ between regions, so are not thought to contribute to the differences in population trends. The results suggest that the processes driving regional differences in House Sparrow productivity are likely to be complex and operating over a large-scale (e.g. climatic processes), but interacting with local factors (e.g. habitat changes). The absence of productivity differences between rural and urban areas suggests other factors contribute to the varying population trends in these habitats, for instance differences in food availability affecting adult survival. This work 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.