Effects of cadmium on parental behaviour in free-living willow ptarmigan hens

Earlier studies have shown that elevated levels of Cd may negatively affect the behaviour of birds and mammals. However, these experiments were carried out under controlled laboratory conditions, and results from free-living populations have not been available. By using osmotic minipumps implanted subcutaneously in free-living willow ptarmigan hens, the effects of Cd contamination on parental behaviour were studied. When CdCl2 (83.2 mg Cd/l) was administered, an increase in the Cd content in the liver and kidneys was achieved that was comparable to normal field levels. After hatching, the hens were followed by radio telemetry and parental behaviour was recorded when the broods were flushed. Chick survival up to 8-9 days was recorded. Cd-contaminated hens showed less distraction display and flew longer when flushed compared with control hens, although not significantly so. The Cd-contaminated hens had significantly lower chick survival than control hens.