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The children’s story of Horton Hatches The Egg, by Dr. Seuss, tells the story of an elephant who is tricked into sitting on an egg, while its mother Mayzie, takes a vacation in Palm Beach.
In real life, like Mayzie, who didn’t want the responsibility of raising her young, there is a phenomenon called Avian brood parasitism, where certain species of birds lay their eggs in the nests of others, which relieves them from the challenge of parenting their young. In the Americas, the species of cowbirds and striped cuckoos are examples of parasitic birds. In fact, cowbirds are not fussy, including more than 250 different hosts nests to choose from.
There are two main types of Avian brood parasites. Facultative brood parasites will often build their own nests and on occasion, will lay eggs in the nests of others. Obligate brood parasites have evolved to never make their own nests, and rely on other birds to raise their young.
Adding to the mix, some parasitism is intra-specific where the parent places its eggs in the nest of the same species. Of the 200 species of birds that use this strategy, more than one-third are waterfowl. Inter-specific parasitism like the cowbirds, is when the parent lays the eggs in the nest of other species. In some situations, the parent seems to choose specific types of nests.
The host species have several ways of reacting to the invasion of their nest.
- Chase off the invader.
- Recognize the different egg and remove it from the nest.
- If not noticing the difference, they incubate as usual.
To discover more:
Brood Parasitism in Birds
The Ecology of Avian Brood Parasitism
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