Grenada first week

In the front of the yard, we had a Carib Mockingbird nest. Momma build a beautiful nest in the bush right next to where Crapzilla is parked. We were careful to disturb her as little as possible, but not even Crapzilla could disrupt her from caring for her babies.

Unfortunately, her nest experienced a difficulty of an entirely different kind. This blog has thus far not covered my love of nature and birds, and I regret that this subject initially comes up in a dreadful light. The nest above was parasitized by a cowbird. Shiny cowbirds, like the brown headed cowbird many in the US are more familiar with, are exclusive nest parasites (or "brood parasites"), meaning that they never build their own nests. They lay eggs in the nests of other birds, for an entirely different species to raise. (There are great evolutionary advantages to this system: for example, brown headed cowbirds are thought to be one of the most sophisticated vocalists of the bird world.) So, utilizing the services of another isn't so bad, but cowbird babies hatch much more quickly than most other passerines, and are significantly larger. Within one day of hatching, a cowbird can eject, and thus kill, any other eggs or hatchlings in the nest. If the cowbird baby doesn't outright remove others immediately, the baby will often outcompete all other birds in the nest until the cohabitants perish for lack of food. In some cases, most or all of the native nestlings will survive; oftentimes the outcome is dependent upon the particular species being parasitized. I have observed parasitism in the past, but only in the context of an ornithology study, where I was prohibited from interfering. (Brown headed cowbirds, by their means of reproduction, have nearly eliminated the solitary vireo from existence in Colorado.) Since we would be leaving Grenada in a week, it wasn't an option to raise the cowbird myself. I struggled with what to do or not do, consulting anyone who would listen. If I were to interfere on behalf of the three mockingbird babies, I couldn't just remove the cowbird egg, as it would open the nest to further cowbird parasitism (another female, or the same one, would then be likely to discover the "available" nest and lay another egg inside. They generally will not lay in a nest that has already been parasitized.) So, in an effort to potentially save three birds, I acted to eliminate, i.e. murder, one. I placed the egg in the refrigerator for 36 hours, which is likely, although not certain, to slow the development of a fertilized egg to the point where it would cease to live. In a pathetic attempt to lessen the vitriol of readers at my potential act of murder, I will take care to note that I have spent innumerable hours over fourteen years as a wildlife rehabilitator in Colorado, rehabilitating birds and raising baby birds, regardless of species (including cowbirds.) I would also note that similar interference on any scale whatsoever in this area would seem impossible, as the local population cannot tell a Grenada Dove from a Common Dove...let alone identify different species by the appearance of an egg.

To see a video of a brown-headed cowbird ejecting a live nesting from its nest, check out the following: http://www.facstaff.bucknell.edu/ddearbor/cowbird_ejects.html. I utilized this video in a talk at the University of Colorado years ago with Don Dearborn's permission; here you can go to the source.

To hear a superb audio story about human "morality" (an excerpt of which was recently played on This American Life, www.thislife.org) check out Radio Lab at: www.wnyc.org/shows/radiolab/episodes/2006/04/28.