[Bird mortality and monitoring the environment (author's transl)].

Birds are useful parameters in studying toxicological contamination of the environment. Birds can be heard and seen, breeding results and feeding patterns being recorded on a rather extensive scale in the Netherlands. Since 1974, a working party was constituted to study normal and abnormal death of birds. This group consists of members of ornithological and veterinary institutes as well as local field workers, bird revalidation centres and bird preservation and protection groups. In 1979, approximately 2,000 birds were available for post-mortem and bacteriological, virological and toxicological studies. The cases of poisoning were classified into acute and chronic, accidental and crop-protecting effects. In the Laboratory of the Central Veterinary Institute, Poultry Department, the birds suspected of poisoning are screened by a biological-toxicological standard method using Lebistes and Daphnia. Pseudo-poisoning is caused in nature by Pasteurellosis, accidents, etc. Investigations are restricted by predation, the likelihood of finding of dead birds and retention of dead birds of prey for taxidermy. Acute poisoning in the Netherlands is mostly associated with protection of crops, nuisance caused by pigeons and other birds in gardens. Some cases of poisoning are due to quarrels between neighbours and people who poison game-birds out of revenge. Chronic poisoning is caused by metals such as lead pellets from cartridges. Chronic and acute poisoning continue to occur as a result of illegal use of prohibited insecticides.