May232007

Warblers! Warblers! Warblers!

The New World warblers or wood-warblers are a group of small often colorful passerines restricted to the North, Central, and South America. They are not related to the Old World warblers (Sylviidae) or the Australian warblers. Most are arboreal, but some, like the Ovenbird and the two waterthrushes, are more terrestrial. Most members of this family are insectivores. It is likely that this group originated in northern Central America, which retains the greatest diversity and numbers of species. From there, they spread north during the interglacial periods, mainly as migrants, returning to the ancestral region in winter. Two genera, Myioborus and Basileuterus seem to have colonized South America early, perhaps before the two continents were linked, and provide most of the resident warbler species of that region. Many migratory species, particularly those breeding further north, have distinctive male plumage at least in the breeding season, since males need to reclaim territory and advertise for mates each year. This tendency is particularly marked in the large genus Dendroica. In contrast, resident tropical species, which pair for life, show little if any sexual dimorphism. Enjoy the photos!