"No Spring Cleaning"

Brown-headed Cowbird

        I remember... when Spring came at our house, it was time to clean the windows inside and out. My mom would take the inside windows, and I got to go outside and climb the ladder. It seemed like a boring job to a 10 year old who liked to complain. My mom would wash and dry the inside windows all sparkling bright, and then point out the streaks I missed on the outside. We made a good team, and the cleaning got done.
        There is one bird that doesnít worry about Spring cleaning, or any parenting activity; the parasitic Brown-headed Cowbird. Cowbirds make no nest, they lay their eggs in the nests of other bird species, and saddle the host bird with the task of raising their young. Females tend to be "sneaky" when searching for host nests. The female often locates a potential host nest during its construction phase. Then she regularly visits the nest while the host species are absent. The female cowbird lays eggs at dawn; she removes (and occasionally eats) an egg of the host the day before or the day after the parasitic egg is laid. If only one host egg is present, she does not remove it (otherwise the host might abandon its now eggless nest).

        A major adaptation for parasitism is their rapid development. Cowbird eggs usually hatch one day ahead of the hostís eggs. Cowbird nestlings are larger, grow faster than the hostís young, and will push the other babies out of the nest. Their persistent calling (crying) enables them to garner more than their fair share of the food brought to the nest. The Cowbird fledglings do not recognize their foster parents as individuals, and will beg food from all adults of their foster parentsí species. Each female Cowbirdís egg laying cycle appears adapted to take advantage of a continuous supply of host nests for about a two-month period. Even so, only about 3% of the Cowbirds ever reach maturity.

        With all their faults, you canít help but like these clever, non-parenting birds. If you see a flock of Blackbirds, look closely for any brown heads. These look-alikes fool a lot of people. When there are a lot of Cowbirds, you know that their host birds are in trouble, for hosts will hatch few, if any, of their own eggs.

        Brenda Rusnell is the artist for this weekís Brown-headed Cowbird. Itís amazing how many bird species come to Brendaís home. They must know she likes birds. Thank your for your artistic expression of the Cowbird. If you would like to find a bird to get enthused about, come to our Red Cliffs Audubon meetings every 2nd Wednesday of the month. For more information, call Marilyn Davis at 435 673-0996.

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