Mark Palas posed a comment that suggested cowbird control might be considered more seriously than it has, because of how man's activities exacerbate their negative effect on host species. A classic case of how this approach has been successful has been in the management of the endangered Kirtland's warbler in Michigan. Because of this warbler's tiny population and the access cowbirds have to their habitat, cowbird parasitism itself was deemed serious enough by experts that it could have reduced the warbler's population below a sustainable level and could have resulted in its extinction.
In general, however, there is little evidence that cowbirds present such a risk to most other species. Brood parasitism is their natural *modus operandi*.and evolved as an adaptation to their nomadic existence. There is nothing inherently insidious about this. And, even though we may make it easier for cowbirds by fragmenting forest habitats, there are many areas now where forests are returning and making life more difficult for the cowbirds. I believe we should acknowledge their place in the system and even marvel at the cleverness of this adaptation. But, at the same time, we also need to watch Breeding Bird Survey and atlas results carefully for declines in the populations of potential host species, to be certain that we are not caught by surprise by the next Kirtland's warbler calamity. Marshall Howe ---- Join or Leave mou-net: http://lists.umn.edu/cgi-bin/wa?SUBED1=mou-net Archives: http://lists.umn.edu/archives/mou-net.html
