Nest predation and semicolonial breeding in Linnets Carduelis cannabina

Abstract

Capsule Nest predation in Linnets in Denmark was caused mainly by Hooded Crows Corvus corone cornix and Magpies Pica pica with no experimental evidence of antipredator aggression. Aims To investigate the influence of nest clumping on the risk of nest predation in Linnets, a species that often breeds semi-colonially. Methods The predation rates on clumped and randomly distributed nests were compared by the use of artificial nest experiments. Additionally, the behaviour of Linnets towards a potential nest predator was studied by presenting a mounted Magpie near the nest of breeding Linnets. Results The artificial nest experiments showed that semi-colonial breeding was not likely to increase the risk of nest predation, and an experiment with the mounted Magpie showed that Linnets did not exhibit anti-predator aggression. Conclusion Semi-colonial breeding, resulting in increased local nest density, did not appear to influence the risk of nest predation in Linnets. We suggest that semi-colonial breeding in Linnets is a means of pooling information on food sources.