Nearly every world has birds in it, if you look. Gulls circle the harbour. Crows sit on the rooftops. A blackbird sings somewhere in the trees, and a heron stands in the pond, doing what herons do, which is nothing, beautifully.
Birding in VR is like birding anywhere else: patience, a notebook, and a willingness to stand in one spot for longer than seems reasonable. The differences are that the weather is always what the creator chose, and that if you wait long enough, the same gull will come round again in exactly forty seconds.