Migratory Birds Make Mistakes In Direction, But Not Distance

Migratory birds make mistakes in terms of direction, but not distance. These are...

  Migratory birds make mistakes in terms of direction, but not distance. These are the findings of a team of ornithologists and ecologists from the University of Marburg, the Ornithological Society in Bavaria and the Helmholtz Centre for Environmental Research (UFZ), writing in the Journal of Ornithology. The scientists assessed several thousand reports of Asian birds from the leaf-warbler and thrush families that had strayed to Europe. They discovered that the distance between the breeding grounds in northern Siberia and the wintering sites in southern Asia was often similar to the distance between the breeding grounds and Europe. The more similar the distances and the more numerous a particular species, the higher the probability of this species of bird straying to Europe.The birds’ body size is not a factor. For a long time, people suspected that the vagrants had been blown off course by the weather. The new findings, however, support the hypothesis that the vagrant birds end up in the wrong wintering areas as a result of an error in their migratory programme.Since many questions still remain unanswered regarding the spread of the bird flu virus H5N1, there is increasing interest in research into bird migration. Experts believe, however, that it is unlikely that the virus is spread via migratory birds and suspect that it is spread through the international trade in poultry products. In any case, vagrants pose the lowest risk.