Another species that often falls victim to Cowbird parasitism, a Orchard Oriole.

Spring and summer are wonderful times in South Dakota. After a long winter, the weather in the spring and summer is usually fantastic, the landscape comes alive after months of dormancy, and birds return in force.  Come June and July, my yard starts to come alive with the young of the birds that breed in the area.  Unfortunately, it’s also a time where, without fail, I’ll look out into my yard at some point and see a parent of some species feeding a cowbird young.  I don’t know if they’re more prone to cowbird parasitism, but it seems most years I see an adult Chipping Sparrow trying to feed a giant cowbird fledgling that’s easily twice its size.

Human beings definitely are guilty of anthropomorphizing wild animals, treating them as if they have human emotions and feeling sympathy as you would for a human being in a similar situation.  When I see a tiny Chipping Sparrow trying to feed a big, hungry cowbird fledgling, I immediately feel sorry for the Chipping Sparrow, knowing that its nesting success for its own fledglings has likely suffered at the hands of this giant interloper.  I often know where birds are nesting in my yard.  Chipping Sparrows often use my two spruce trees or this thick juniper to build their tiny nests.  In the spring I can often look directly into their nests, and therein lies the ethical dilemma.  What do you do when you see a giant cowbird egg amidst the smaller host bird eggs?

As a scientist, you of course know that cowbirds too are part of the natural environment, and what you’re witnessing is a natural occurrence.  Cowbirds are a native species, and other birds have always had to deal with cowbird parasitism.  On the other hand, there’s also no doubt that cowbirds are more common in many parts of their range compared to historical averages, thanks to human activity.  Cowbirds have always preferred open habitats, but habitat fragmentation and creation of more “edge” habitat has resulted in increased cowbird access to many species that rarely had to deal with it before.

All true!  Cowbirds HAVE benefited from man’s alteration of the landscape!  And that’s the justification I guess I tell myself when I peer into a bird nest, see a cowbird egg, and…pick it out and destroy it.  Yes, I know I’m anthropomorphizing the situation.  Yes, I know it’s a natural occurrence, cowbirds are a native species, and they have a right to survive just as the Chipping Sparrow does.  But in my own mind, it doesn’t seem “right” when I see that cowbird fledgling following around the little Chipping Sparrow fledgling, demanding food.

And thus, I do destroy cowbird eggs when I see them in a nest in my yard.  It’s one of those things I’m conflicted about though, as even though I almost always do it when I see a cowbird egg, I also feel kind of guilty after the act is done.