Seminar by Prof. Gordon Orians: 'Four and ninety blackbirds'
|Date:||Friday, 26 October 2012|
|Speaker:||Gordon Orians, Professor Emeritus of Biology, University of Washington, Seattle|
The American blackbirds, Family Icteridae, a clade of nearly one hundred species that range from Alaska to Tierra del Fuego, includes species that collectively display most of the types of social organization found among passerines. There are territorial and colonial species; monogamous, polygynous, and promiscuous species; and brood parasites. They inhabit nearly all vegetation types. There are strong correlations between breeding habitat and social organization, and between social organization and degree of sexual dimorphism. A similar array of social systems is found among members of the Family Ploceidae but the correlation between social organization and environment is not the same. The differences may reflect the importance of the foraging method used by most icterids (gaping), the greater dominance of forest environments in the New World, and the abundance of arboreal bromeliads in Neotropical forests.