Thanks, Jane, for the references. I found the sites: Carl Strang's June 2009 entry and Stanford group essay on Cowbirds. I'm a little skeptical about Strang's statement on instinctual behavior - it may be true but it sounds more like a belief not based on any science. (Just a quibble on my part - if he'd said the juvenile cowbirds 'appear' to seek out other cowbirds, based on his observations, I wouldn't have been annoyed - but ascribing the behavior to 'instinct' is a jump too far). A very interesting fact in the Stanford essay is that only about 3 percent of cowbird eggs actually result in adults! That's major mortality. The cowbird female just keeps laying eggs and eggs and eggs ... "An average female lays about 80 eggs, 40 per year for two years. About 3 percent of those 80 eggs end up as adults -- an average of 2.4 adults per female. Clearly, such numbers more than compensate for the excessive loss of eggs and young in the nests of inappropriate hosts." I wonder how the current situation differs from the earlier situation when the cowbirds evolved to follow the bison herds and couldn't hang around to set up a proper nest without dropping behind and struggling to find food for themselves and the young. That behavior probably was dependent on the migration patterns of the bison, but nowadays the cowbirds have the luxury of being able to stay in the same area as their young, even if they don't get involved in the raising of them. As far as which came first, the parasitic behavior or the adaptation to it, I would think that the ability to lay so many eggs and the rapid maturation of the young would come early. There's an interesting entry in the Birds of North America Online site (subscription only) saying that "Most fledgling losses occurred 1 or 2 d after leaving nest". There are a lot of unknowns here, but it's an interesting topic for study. I'm glad I don't have to do the research myself, it would drive me crazy trying to pull together all of the variables. Claire

i had about 5 or 6 pairs of Bullocks orioles show up in late april thru mid may. they hung around the feeders for a week or two filling up on fruit and nectar. they all left to mate and nest and hopefully fledge a lot of little ones. so far one mother has brought 2 little one to the feeders and got them started eating and drinking. should over next week or two have a bunch more if they were successful. last year there were 12 babys i counted.

i have the Bullocks orioles here, There are three pairs of them that had nests nearby this spring. I watch them thru a window on the back yard, The feeders are about 10 feet away. If i don't move or make any noise they are ok but the least movement they are gone. Now i have about eleven fledglings big enough to fly well and they are feeding from daylight till dark and have not learned to be skitish yet. I go thru 2 quarts of sugar water a day and 2 cups of orange juice and several pieces each of watermelon and cantalope and cherry ect. They have already learned to fight with each other over which gets to drink first.

Cool shot! We have had alot of Orioles up on the deck too, have seen 8 juvies at one time and we had at least two adult females and two adult males. Donna