Ok, really, just Jay. He’ll scream his name at you when you’re running past, anyway. I am, of course, talking about Blue Jays. They’ve been on my mind the past couple of days for two reasons. The first one is that over the weekend, I watched a Northern Mockingbird do a great imitation of a Blue Jay song. Not the “jay!” call, but the whistled, flutey song. It was quite impressive. This morning, I heard and saw one in the bushes along Little Sugar Creek.
Since I’ve moved back here, I haven’t seen as many Jays as I remember from when I was growing up. I had heard that their populations had been impacted by the spread of West Nile Virus, back in 2002 and 2003. I hadn’t seen any of the analysis of that statement, though, so this morning I went looking. I have to apologize, but the article I found (while very interesting) isn’t free-access, so you only get to see the abstract (unless you’ve got a good library nearby), but I’ll give you the gist of it all.
LaDeau, S.L., A.M. Kilpatrick and P.P. Marra. 2007. West Nile virus emergence and large-scale declines of North American bird populations. Nature 447 (7145): 710-713.
This article shows that populations of several species were highly affected by the spread of West Nile. American Crows, Blue Jays, Tufted Titmouse, American Robin, Chickadees and Eastern Bluebird populations all went through large population declines during that period. As these are birds that often do well with increasing suburban development, the decline in populations really was not likely due to other causes.
Given that West Nile was such a strong factor in population declines, the follow-up question relates to the current population trends for those birds. It’s actually quite interesting AND the researchers don’t have any definitive answers (though I’ll dig around for articles that build from this one). First of all, American Crows were among the hardest hit, declining by 45% in some places. Crows, Jays and Titmice were highly impacted. Now, that was all 8 years ago, at this point. Well, as of 2006-2007 when they compiled these data, some of the bird populations had begun to recover. American Crows were having a hard time recovering and Blue Jays populations were recovering in some populations but not others. That’s the weird thing- in some of the areas from which they have data, Blue Jay populations in 2005 seemed to be approaching pre-virus status and in other places, they were still low. Charlotte wasn’t a site in their study, but it does make me curious about where we sit in that data set (and why there is such variability).
More to come on this one…
Birding Without Binoculars 