[HIGHLIGHTS] Bird populations have fallen by 25% in the last 40 years in Europe

Birds in Europe have fallen by 25% in the last 40 years, according to a new study. The authors of the study say the main cause is the use of pesticides.

Climate change is also a factor in the decline of birds in Europe, they say. The study was published in the journal PNAS on Wednesday. It was compiled by the European Commission and the European Council of Learned Animals (ECOAM) The authors say the study is based on data from more than 20,000 birds.