A report has found that more than 52 million wild birds are being killed lawfully by hunters in Europe each year.
The study provides data on 82 species of wild bird which may be legally hunted.
The research paper, which has been compiled by staff from the Committee Against Bird Slaughter (CABS) is a follow-up to a report which was first conducted back in 2005.
It makes official hunting statistics from 24 EU member states plus Switzerland and Norway available publicly for the first time.
The authors point out that despite a long-term decrease in the gross number of killings compared with older data, the bag figures for certain migratory species, such as Common Pochard, Northern Lapwing, Turtle Dove and Skylark, remain high in proportion to their declining populations Europe.
Against a backdrop of declining populations of many affected species, hunting pressures are undermining conservation efforts undertaken for these species in other countries.
"The hunting of birds with rapidly declining populations is not sustainable and therefore is a clear breach of the European Birds Directive", CABS Conservation Officer Geraldine Attard, who is one of the authors of the study, concluded.
The report is published this week in the journal British Birds.