no
the cowbird
Yes, there is a species of bird called a cowbird.
Bluebird, blackbird, ovenbird, cowbird, bower bird, hummingbird. Kingbird, mockingbird, tropicbird, catbird, frigatebird.
The most well-known bird to do this is the Cuckoo.
Yes, the cowbird is a brood parasite that lays its eggs in the nests of other bird species. The host birds unknowingly raise the cowbird chicks as their own, often at the expense of their own offspring.
Brown-headed Cowbird
cow birds lay there eggs in other bird's nests.
The brown-headed cowbird is a small blackbird native to North America. It is known for laying its eggs in the nests of other bird species, a behavior called brood parasitism. The young cowbirds are raised by the host parents, often at the expense of their own offspring.
In this interaction, the cowbird has deposited its eggs in the sparrow's nest, leading the sparrow to unknowingly raise the cowbird chick along with its own. This is an example of brood parasitism, where the parasitic bird relies on others to raise its young. It can negatively impact the host species by diverting resources away from their own offspring.
NO ... birds do not give milk. They lay eggs and, the babies are hatched ready to eat a regular bird diet.
It's not symbiotic, it's parasitic. The cowbird lays it's eggs in the nest of other birds expecting them to hatch and feed it. In some cases when the host bird rejects the egg the cowbird has been known to return to the nest and ransack it in what scientists call Mafia behavior.
Here's a picture of a male Brown-headed Cowbird http://upload.wikimedia.org/wikipedia/commons/8/84/Malecowbird.jpg