Re: Warbling Vireo and brown-headed cowbird chick, Mammoth

Observers: Donna Willey
Verification: MONO
Remote Name:
Date: 07/31/2007
Time: 12:23 AM -0400


Connie thank you for your reply. I am afraid though that I said nothing incorrect. According to various articles several of which cite Widmann (1907)the establishment of brood parasitism, how it began, its origins in the North American cowbird M.ater probably began more than several centuries ago. A date was not given because they do not know the exact date but I will quote directly from the article for you. "We know that fossil remains of horses, not much unlike ours, are found abundantly in the deposits of the most recent geological age in many parts of America from Alaska to Patagonia. It was probably at that period that the Cowbird acquired the habit of accompanying the grazing herds, which were wandering continually in search of good pasture, water and shelter, in their seasonal migrations and movements to escape their enemies. As the pastoral habit of the bird became stronger, it gave rise to the parasitic habit, simply because, in following the roving animals, the bird often strayed from home too far to reach its nest in time for the deposition of the egg, and being hard pressed, had to look about for another bird's nest wherein to lay the egg... by a combination of favorable circumstances this new way of reproduction proved successful, and the parasitic offspring became more and more numerous. In the course of time the art of building nests was lost, the desire to incubate entirely gone, paternal and conjugal affection deadened, and parasitism had become a fixed habit" (Widmann, 1907 as cited in Brown-headed Cowbird, 2007). The Brown-headed cowbird (Molothrus ater)is derived from a species which originated in South America. It is supposed to have entered North America via Mexico and to have extended its range eastward and westward, moving to the coasts as the forests disappeared (Brown-headed Cowbird, 2007). Its former name is buffalo-bird, bison-bird and yes, it did follow the big herds of bison that did roam at the very least several centuries ago across the plains. This bird has probably been following the herds of large herbivores, including horses for centuries. The buffalo, we know have been in North America since glacial times and without looking this up, I believe it is approximately 12,000 years ago. I do not believe you can fault anything I said in my original post. No one knows exactly when Molothrus ater entered North America nor does anyone know exactly when it moved from nest building to parasitism. All we have are our theories, and perhaps the fossil record. I invite you to spend some time and research Molothrus ater. My statement that brood parasitism in the brown-headed cowbird has been on-going for centuries is probably not far off the mark. Actually it is probably a conservative estimate. At any rate, it is my estimate after having read several articles one of which I cite below. Best, Donna Willey Reference Brown-headed Cowbird, 2007. Retrieved from internet on July 30, 2007 from, P.S. Thanks for the compliment on my photos; I work at it.