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House Sparrows of London (Pbader domesticus) have dropped 71% since 1995, with new research suggesting that bird malaria may be the cause.
Once ubiquitous in the capital, the sudden and unexplained decline of these iconic birds led a team from the ZSL (London Zoological Society), the RSPB, the British Trust for Ornithology (BTO) and the University of Liverpool to investigate parasitic infections. were involved.
The researchers collected data between November 2006 and September 2009 on 11 sites in London. Each site was centered on a single breeding colony and spaced at least four kilometers apart so that birds from different groups did not mix. The team estimated changes in the number of birds by counting mature males and collected tiny blood and stool samples from carefully captured and released sparrows to monitor the rate and severity of infections.
Of the 11 colonies studied, seven were declining. On average, 74% of sparrows carried avian malaria – a strain that affects only birds – but this differed from one group to another, some even reaching 100%. However, it is the intensity of the infection (ie the number of parasites per bird) that varies significantly and is, on average, higher in the declining colonies.
Dr. Daria Dadam, a former researcher at the ZSL Zoology Institute, now the BTO's director, said, "Parasitic infections are known to cause the decline of wildlife elsewhere." Our study indicates that this could occur with house sparrow in London.number of parasites, but only Plasmodium relictum, the parasite responsible for avian malaria, has been badociated with a reduction in the number of birds. "
Professor Andrew Cunningham, Deputy Scientific Director of ZSL, said: "Although we found that almost all sparrows were Plasmodium carriers, there was no badociation between the number of carriers and population growth of local sparrows .. The intensity of infection was however significantly higher among young birds from declining populations with fewer sparrows monitored in surviving groups from year to year . "
The malaria strains identified by the study are widespread and infect several bird species. They are therefore probably from the United Kingdom and have housed sparrows long before their numbers began to drop. The parasite is transmitted by mosquitoes, which transfer it when they bite to feed. It has been suggested that avian malaria will become more prevalent in northern Europe as a result of climate change, as higher temperatures and wetter weather conditions favor mosquito breeding. In addition, more mosquitoes will contribute to the spread of the disease. The researchers think that this could be at the origin of the sudden change.
Dr. Will Peach, Research Manager at RSPB, said: "The populations of house sparrows have declined in many cities in Europe since the 1980s. This new study suggests that avian malaria may be involved in the loss of house sparrows across London.The infection may affect the birds is unknown.Maybe that warmer temperatures increase the number of mosquitoes, or that the parasite has become more virulent. "
ZSL works to protect the health of wildlife and understand how animal diseases spread between people and their habitats. Diseases, such as avian malaria, are an important cause of wildlife decline, a direct threat to a number of endangered species and can also infect domestic animals. Only by understanding the mechanisms of infection and the effects of these diseases can we put in place strategies to mitigate them.
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Notes to editors
Press contacts:
Will Richard, [email protected], +44 (0) 20 7449 6246
Interviews with Dr. Dadam: Paul Stancliffe, [email protected], +44 (0) 7585 440910, +44 (0) 1842 750050
House Sparrows
House Sparrows (Pbader domesticus) are small gray-brown birds from much of Europe and Asia, but are now widely introduced elsewhere. They feed opportunistically and are found in a variety of habitats, often in close contact with humans. House sparrows were once one of the most abundant birds in the UK, but their numbers have dropped considerably. Their current population in the UK is estimated at 5,300,000 breeding pairs.
Avian malaria
Avian malaria is most often caused by a parasite called Plasmodium relictum. Like human malaria, it is transmitted only by mosquitoes, which transmit the parasite to healthy birds when they are feeding. The parasite breeds in red blood cells and other tissues and can be fatal in severe cases. Avian malaria is not a danger for people.
ZSL (Zoological Society of London)
Founded in 1826, ZSL (London Zoological Society) is a scientific, conservation, and international educational charity whose mission is to promote and achieve the global conservation of animals and their habitats. Our mission is achieved through our innovative science, active conservation projects in more than 50 countries, and our two zoos, ZSL London Zoo and ZSL Whipsnade Zoo. For more information, visit http: // www.
BTO
The BTO is the leading charity for bird research in the UK. An increasing number of members and up to 60,000 volunteer bird watchers contribute to the OTB's surveys, collecting information that underpins conservation actions conducted in the United Kingdom. The BTO employs 100 people in its offices in Thetford, Stirling, Bangor (Wales) and Bangor (Northern Ireland), which badyze and disseminate the results of surveys and projects. BTO's work is funded by BTO supporters, government, trusts, industry and conservation organizations. http: // www.
RSPB
The RSPB is the largest charity for nature protection in the UK. It encourages everyone to welcome nature. Together with our partners, we are protecting endangered birds and wildlife so that our cities, our coasts and our countryside can come back to life. We play a leading role in BirdLife International, a global partnership of conservation organizations. rspb.org.uk
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