Invasion, Identity Theft, and Murder in North America

Thursday, May 4, 2017

I've never heard of a cowbird. 

And I've never heard of a brood parasite. 

Get ready to learn about a dastardly little bird. 

 

These birds are common in the plains of North America but they can be found in other places as well. They tend to travel around with large herds of cattle, eating insects that the cows stir up. Because the cattle cover large portions of land and are constantly on the move, cowbirds don't build nests. So what do they do when it's time to lay their eggs?

The female watches the nests of other birds. When the nesting female flies away, the cowbird swoops in and lays an egg in the "host" nest. Now she may lay several eggs but many times she will only lay one at a time in several host nests. 

 

I watched a video on the Internet where a mama cowbird laid an egg in a nest with two existing host eggs. When she was finished she grabbed one of the host eggs and threw it out of the nest. Then she flew away. When the unsuspecting mom returned to the nest, she snuggled down to roost on her precious babies, none the wiser. 

There was another nest cam which showed a cowbird fly away after laying her egg. When the "real" mom came back, she sensed what had happened. So she snatched up the parasitic egg, broke it with her beak, and flew it away. 

I've also learned that once the invading cowbird hatches, it wants to be the one and only baby. So with all the strength and leverage it can muster, it pushes other eggs out of the nest. 

 

Isn't that sad! And selfish! And down-right mean. But poor "mama" has no idea what has happened so she proceeds to nurture her dear solitary survivor -- even when there is absolutely no family resemblance. 

 

And the unlikely relationship between a host mama and a brood parasitic cuckoo is even more stark than that of the cowbird. 

 

So how is a brood parasite born with such strong instincts? When it grows up how does it know to forsake its "foster parents" and hang out with others of its own kind? And how does it know to repeat the sinister cycle of invasion, murder, and espionage? 

Lord, your world is so fascinating! Genesis merely mentions your creation of the birds of the air. Yet their complexity is so great that we have spent thousands of years trying to figure out their behavior and still don't quite understand it. Your imagination is beyond comprehension! We are in awe!