The Baffling Phenomenon of Brood Parasitism

In the 1957 science fiction novel The Midwich Cuckoos, John Wyndham wrote about an English village that mysteriously lost consciousness for a day. Then the people awakened. All the women of childbearing age were pregnant, and as the 61 offspring grew, it was realized that they were aliens. And dangerous.

The word cuckoo in the title is in reference to that family of birds, sixty of which are brood parasites. They lay eggs in the nests of other birds. The unhappily adoptive parents seldom expel the eggs of the intruders, who often kill the rightful nestlings after hatching.

Eurasian (common) cuckoo, Wikimedia Commons / Vedant Raju Kasambe (CC BY-SA 4.0)

Brood parasitism is best known among cuckoos and cowbirds (neither of which is impressive in appearance), but also happens in some fish. When searching these topics, expect to find the non-explanation of "it evolved," even though brood parasitism defies evolutionary concepts.

More puzzling is when obligate brood parasites (such as those birds) must hijack the nests of others because they cannot build nests and raise their own young! Creationists also need to work on providing satisfactory explanations of brood parasitism.

Most people are aware of the effects of parasites. Parasites are organisms that live off their host, sometimes living inside and sometimes outside the body of their host. Some parasites cause disease or substantially weaken their host, while others have minimal effect. What most people are not aware of is that some animals engage in a unique form of parasitism. Known as brood parasitism, it is most commonly seen in birds, though a few insects and fish also employ the strategy. In this form of parasitism, the parasite does not directly parasitize the host. Instead, it lays its eggs in the host’s nest, allowing the host to raise young that are not directly related to them.

Read the rest of this interesting article at "Evolution Doesn’t Explain Cowbirds and Other Brood Parasites."