About one percent of the 9,000 plus bird species on this planet does not construct nests and raise their own young. These birds pawn this job off onto birds of other species. They do this by laying their eggs in other birds’ nests, letting them do the incubating and rearing for them.
In North America, the three species of cowbirds are well known for this behavior. Bronzed Cowbirds are found in the southwestern United States and along the Gulf Coast as far east as Louisiana. The Shiny Cowbird is native to the Caribbean area and is currently expanding its range through Florida and along the Gulf Coast as far west as Texas. The Brown-headed Cowbird is found throughout the United States and most of Canada. It is known to parasitize the nests of more than 200 bird species and lay up to 40 eggs per year.
When a cowbird parasitizes a nest, it removes one of the host species’ eggs and replaces it with one of its own eggs. The cowbird egg has a shorter incubation period, which means it will usually hatch before the other eggs do. The cowbird young also grows faster than the host species’ young and will dominate the food brought to the nest. If there is a plentiful supply of food, all the young will survive. If not, only the cowbird young will survive.
Brown-headed Cowbirds are birds of open country, preferring to feed around livestock. In spite of being an open country bird, they will penetrate dense forested areas a short distance to lay their eggs in the nests of birds living there. But woodland birds living deep in the forests far from open areas are safe from the cowbirds. Before the settling of North America, the eastern part of this country was heavily forested, and the Brown-headed Cowbirds were found only on the Great Plains where they followed buffalo herds around and were not very common.
Most species of birds that occurred with the cowbirds on the Great Plains were used to the cowbirds parasitizing their nests and were not easily fooled by a strange egg showing up in the nest. They would usually respond by either abandoning the nest, removing the cowbird’s egg, or building a new nest layer over the top of the cowbird egg. Enough birds were fooled to keep a small population of cowbirds surviving.
With the settling of eastern North America, the vast forests were opened up and fragmented for farming and livestock. This allowed the cowbird to invade the area, where it quickly adapted to feeding around livestock in place of buffalo. The eastern forest birds in this area were not used to the cowbird’s nest parasitism and were easily fooled by them, resulting in a population explosion for the cowbirds and a decrease in the host species populations. Only the birds that lived deep in the few large, unfragmented-forested areas left were safe from the cowbirds. Most of the eastern host species are slowly adapting to the cowbirds, but a few species are not and are threatened or endangered because of habitat loss and cowbird brood parasitism.
Just as the only birds that are safe from the cowbird’s attack are the ones living deep in the forests out of their reach, so the only people who are safe from Satan’s attacks are those who dwell in the arms of Jesus. “Dangers and perils surround us; and we are only safe when we feel our weakness and cling with the grasp of faith to our mighty Deliverer.” Testimonies, vol. 3, 473. “Our only safety is in keeping fast hold of Jesus. Never are we to lose sight of Him.” Selected Messages, Book 2, 59.
David Arbour writes from his home in DeQueen, Arkansas. He may be contacted by e-mail at: landmarks@stepstolife.org.