Malaria is killing Britain's sparrows and owls as mosquitoes invade

Sparrows, chaffinches, owls and nightingales in the British Isles are being killed off by an upsurge in malaria.

Experts say at least 30 species of British birds are affected and growing numbers are dying. They believe the tropical disease is on the rise because the mosquitoes that spread it have benefited from this country’s warmer and wetter climate.

Thirty per cent of UK house sparrows are infected with malaria – compared with barely 10 per cent in 1990.

Songbirds such as greenfinches (right) have been hit particularly badly, with
many householders finding dead or dying birds beneath their bird feeders. As with avian malaria, a warmer climate is enabling these diseases to spread, as their agents (such as ticks) are no longer being killed off by prolonged winter cold.

Malaria is not the only problem facing Britain's bird life. Salmonella, avian tuberculosis and the respiratory disease trichomonosis have also wreaked havoc amongst British birds,
especially those that congregate in gardens for the free food provided, passing their germs around.

Two thirds of the country’s 38,000 tawny owls (left) are hit. In 1996, just one in 40 had the disease. The great tit has seen its infection rate soar fivefold to 15 per cent.

All three species are non-migratory and must have been infected with avian malaria in the UK, through mosquito bites.

The disease, which is brought into the country by infected migratory
birds, cannot spread to humans. Grahame Madge, of the Royal Society for the Protection of Birds, said: ‘Malaria is circulating at low levels in the UK.

‘It is not always fatal as many birds have resistance to it, but if we get new strains and new types of mosquitoes it poses an increasing hazard to an already declining population.

‘Climate change is bringing warmer weather conditions that are likely to favor the colonization of some insects to our shores that cannot
survive at the moment, and that could bring an upsurge in disease.’

Since 1970, sparrow populations (left) have declined by 67 per cent, and nightingales by 90 per cent, for a variety of reasons, including other diseases, predators and threats to their habitats.

Ben Sheldon, professor of ornithology at Oxford University, said:
‘Malaria is a significant cause of mortality, but how it is transmitted is not straightforward. It is quite hard to predict.’

The avian malaria epidemic was identified in a study published in May by Laszlo Garamszegi, an expert with the Spanish government.

In the largest analysis carried out so far he examined malaria infection rates from more than 3,000 species around the world, dating back over 70 years.

He found that an increase in global temperatures of 1c was
accompanied by a two- to three-fold increase in the average prevalence of malaria in birds. He said there had been big increases in the past 20 years. (At left: cuckoo)

Perhaps the biggest issue with these diseases is that they are hitting birds when they already have so many problems to
contend with. Habitat loss, both at home and abroad, is affecting migrants such as the cuckoo and nightingale, while our farmland species continue to suffer as a result of agricultural policies. At such a tricky time, avian malaria may turn out to be the proverbial straw that breaks the camel's back. (Right: chaffinch)


Daily Mail,"Malaria is killing off our sparrows and owls as mosquitoes invade", accessed August 15, 2011

The Guardian, "Is avian malaria a disaster for British birds?", accessed August 15, 2011


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