Egg Fraud

The gooseberry bushes, planted decades ago by my parents, have become badly overgrown with grass and weedy shrubs. A couple of days ago I made a mental note to bring out my pruning sheers and tidy up the mess. But just as I eyed a honeysuckle plant that would be on the hit list, I noticed that it held a dainty little nest, containing two delicate eggs. It belonged to a pair of Yellowthroat warblers. She flew off the nest and then scolded me from a nearby branch. Trimming will have to wait until the nesting season is over.

 A female Yellowthroat warbler waits for me to leave before returning to her nest.

Her tidy little nest held two dainty and speckled eggs.

A male Yellowthroat warbler challenges his reflection in my window.

This afternoon I noticed that the Yellowthroat nest now has four eggs. But something is not quite right about the clutch. One egg is noticably bigger than the others and patterned a little differently. It belongs to a Brown-headed cowbird. Bad news for the Yellowthroats! The illegitimate cowbird egg means almost certain death for the warbler young.

Three Yellowthroat warbler eggs and one Brown-headed Cowbird egg.

Brown-headed Cowbirds lay their eggs in the nests of over 200 bird species, sneaking in at daybreak and quickly depositing an egg as well as throwing out an egg belonging to the host. Red-winged blackbirds are capable of raising both their own young as well as that of the cowbird, but this is seldom the case of the smaller host birds.

Each female cowbird is capable of laying dozens of eggs per season. She never builds a nest or cares for her young. No Mother's Day cards for her!