Vireo (genus) - Voice and Breeding

Voice and Breeding

Males of most species are persistent singers. Songs are usually rather simple, ranging from monotonous, in some species of the Caribbean littoral and islands, to elaborate and pleasant to human ears in the Chocó Vireo. Calls often include "scolding chatters and mews".

The species whose nests are known all build a cup-shaped nest that hangs from branches. Its outer layer is made of coarse leaf and bark strips or of moss, depending on the species; in either case the material is bound with spider silk and ornamented with spider egg cases. The lining is made of fine grass stems neatly circling the cup. In most species both sexes work on the nest, but the female adds the lining. In the Red-eyed, Black-whiskered, Yucatan, and Philadelphia Vireos the male does not help, instead singing and accompanying the female while she builds the nest. The female does most of the incubation, spelled by the male except in the Red-eyed Vireo complex.

The eggs are whitish; all but the Black-capped and Dwarf Vireos have sparse, fine brown or red-brown spots at the wide end. Tropical species lay two, while temperate-zone species lay four or five. Incubation lasts 11 to 13 days, and the young fledge after the same amount of time. Both sexes feed the nestlings arthropods, and each fledgeling is fed by one parent or the other (not both) for as long as 20 days.