the mourning warbler , oporornis philadelphia , is a small songbird of the new world warbler family .
these 13 cm long birds have yellow underparts , olive-green upperparts and pink legs .
adult males have a grey hood and a black patch on the throat and breast .
females and immatures are grey-brown on the head with an incomplete eye-ring .
their breeding habitat is thickets and semi-open areas with dense shrubs across canada east of the rockies and the northeastern united states .
the nest is an open cup placed on the ground in a well-concealed location under thick shrubs or other vegetation .
these birds migrate to central america and northern south america .
they forage low in vegetation , sometimes catching insects in flight .
these birds mainly eat insects , also some plant material in winter .
the song of this bird is a bright repetitive warble .
the call is a sharp chip .
the "mourning" in this bird's name refers to the male's hood , thought to resemble a mourning veil .
