After attracting a female through spectacular displays of flashing colors and daring flights, the male copulates and moves on. The female is on her own to build a nest, incubate the eggs and feed the young. All of these patterns of parenting are found among humans. There are mothers who give up their babies for adoption though it is usually done through negotiation rather than dumping on the doorstep. Many couples are as willing as Gnatcatchers to raise someone else's child.
Many men move on like hummingbirds leaving young children behind to be raised solely by the mother.
My wife, Lynne, is very fascinated with the fathering instinct of the Emperor Penguin. She loves to tell the story of how these penguins start their family in the beginning of winter in Antartica. They go inland a few miles where the female lays one egg and returns to the sea to feed. Her mate takes over the egg, puts it in a brood patch near his feet and incubates it for two months. He stands there in the dark with thousands of other males through the Antarctic winter.