Cowbird

[Sarah]

The cow blackbird (Molothrus ater), an American starling. Likethe European cuckoo, it builds no nest, but lays its eggs in thenests of other birds; -- so called because frequently associated withcattle.

[Sarah]

A single woman looking for a man to help raise her kid.

Much like how a cowbird lays the egg in the nest of another bird, and those birds will raise the cowbird.

[Jessica]

Someone who constantly [mooches] from other people, even when [he/she] has [money] of their own.