|Female Brown-headed Cowbird|
They lay their eggs in the nests of other birds. The birds whose nest is used by the cowbird is tricked into raising the young cowbirds.
The Brown-headed Cowbird has over 220 hosts. The other cowbird species have fewer known hosts, but all the species are generalists when it comes to choosing a host. This means that the eggs may look very different from the hosts' eggs.
Mafia-type behaviour[change | change source]
It seems that Brown-headed Cowbirds periodically check on their eggs and young after they have deposited them. Removal of the parasitic egg may trigger a retaliatory reaction termed 'mafia behaviour'. Cowbirds may penalise hosts which remove the cowbird egg: they often destroy the eggs or nestlings of those hosts.
- "Central to the persistence of mafia-type behavior in brood parasites and acceptance in hosts is the fact that hosts produce significantly more offspring by accepting parasitism rather than ejecting parasitic eggs".
References[change | change source]
- Mermoz, Myriam E. and Francisco Oralis, Juan 2004. Phylogenetic analysis of life-history adaptations in parasitic cowbirds. Behavioral Ecology 15 109-119 
- Jeffrey P. Hoover; Scott K. Robinson (2007). "Retaliatory mafia behavior by a parasitic cowbird favors host acceptance of parasitic eggs" (PDF). Proceedings of the National Academy of Sciences. Retrieved 26 August 2009.
- Friedmann, Herbert; LLoyd E. Kiff and Stephen I. Rothstein (1977). "A further contribution to knowledge of the host relations of the parasitic cowbirds" (PDF). The Smithsonian. Smithsonian Institution Press. Retrieved 26 August 2009.