On Tuesday May 3, I spotted a blue jay-size bird in a large tree overhanging the path near Catch the Wind. It was backlit, no color visible. I could tell by the way the bird moved that it was anything but a bluejay. It was motionless except for slow movements of its head. It methodically moved its head up and down, left to right, and from side to side. It was inspecting the leaves and branches for prey, caterpillars. This, along with its silhouette told me it was a cuckoo, but which one.
There are two cuckoo species in this part of North America, the yellow-billed and black-billed cuckoos. Both are skulkers and both are large caterpillar specialists. The yellow-billed variety is more common. When the bird flew to another tree I caught a flash of red-brown in the wings. When it landed on a stout branch it showed a mostly yellow bill. Yellow-billed cuckoo!
Cuckoos on this side of the Atlantic do not behave as their European counterparts, the common cuckoo. Common cuckoos are nest parasites who lay their eggs in the nests of other birds leaving the feeding and care of their offspring to the bird whose nest the eggs were laid. We have other species here in North America who fill that niche quite nicely.
On Saturday April 30, as I climbed the stairs in front of the Butterfly House, I spotted a handful of blackbirds at the top of the stairs, brown-headed cowbirds. This is our nest parasite. Female brown-headed cowbirds lay their eggs in the nests of other species. Some 220 species have been used by these freeloading blackbirds. Brown-headed cowbirds evolved out on the wide open prairies with the American bison. Traveling along with the herds presumably led to their evolution of foregoing the nest building process (too time consuming), instead laying eggs in less transient bird species nests.
Contrary to what one may think, cowbirds have spread across the land since the near demise of the bison. This expansion was due mostly to our (people) clearing of forest land for farming and other uses, opening up a whole new set of bird species for the cowbird to enlist as foster parents.
On the same day, April 30, while standing near the fence at the red wolf enclosure I noticed a Carolina chickadee nervously perched on a viburnum branch. The bird had something in its bill, an insect. It was on its way to its nest and didn’t want prying eyes to see where that nest was, whether those prying eyes were mine, a hawk’s, or those of a cowbird.
I backed off. The bird flew off to perch on the top rung of the wolf fence. Satisfied all was secure, It then flew to the top of one of the curved fence posts that make up the fence and disappeared. Its nest was in the fence post, the only fence post without a cap on it.
There’s much to be cautious about when you’re a small bird raising a family. Danger is everywhere, whether predators, snake, bird, human, or parasite like the cowbirds. It pays to keep a sharp eye out for those who may be eyeing you.