Study on white-tailed eagles
Lead poisoning most common cause of death
09 May 2018, 04:09 ( 2 Months ago) | updated: 09 May 2018, 10:58 ( 2 Months ago)
Lead poisoning is the most common cause of death of white-tailed eagles, reports a new Finnish study.
White-tailed eagles are poisoned when they ingest lead shot or fragments of lead ammunition remaining in their prey or when scavenging. A significant rate of mortality of these eagles is also caused by collision with power cables, cars, trains, and wind turbines, said a press release issued by the Finnish Food Safety Authority (Evira) on Tuesday.
During the 2000-2014 study, Evira, the Finnish Museum of Natural History and WWF Finland’s White-tailed Eagle Working Group collaborated in examining the causes of death of a total of 123 white-tailed eagles.
“Human-related factors accounted for up to 60 per cent of the causes of death. The most common of these was lead poisoning, in slightly 30 per cent of the cases, followed by various human-related accidents, the culprit in almost one fourth of the dead white-tailed eagles we examined,” said Evira Senior Researcher Marja Isomursu.
Lead poisoning was more common in Åland than in the mainland Finland. In Åland, lead ammunition can still be used in all hunting, but on the mainland lead shot has been prohibited in waterfowl hunting since 1996. Lead poisoning was clearly more common during the cold season, when white-tailed eagles often resort to scavenging.
Lead causes paralysis, anaemia, and typically slow emaciation. Lead is harmful to humans, too, particularly children and foetal development, as it, for instance, affects the central nervous system.
Natural causes of death (40 per cent of the cases) included injuries in sexually mature birds due to territorial fights, various illnesses or starvation. Illegal shooting accounted for about five per cent of the cases studied.
White-tailed eagle’s organs were also analysed for mercury. Mercury concentrations were highest in the oldest age group of mature eagles. However, no actual mercury poisoning was detected, and the levels found were no longer as high as they were in the 1960s.