31 March 2009

Red Crossbills Move In - From the Treetops or the North?

This winter has been a great one for seeing crossbills in Utah, and around the United States. There was a big influx of White-winged Crossbills from the north, presumably in response to a failing spruce crop this year. But just recently, the Red Crossbills (like the one above) have shown up in big numbers down to the seed feeders. What is most surprising to me is how synchronous this arrival seemed. Around Cache County and even further south around Salt Lake City, people started reporting Red Crossbills at their feeders last weekend. Within days they were at the feeders of everyone I know who keeps a feeder. What caused this big change at the feeders? Did the local cone crop suddenly run out? Has a second big influx of crossbills, this time Red Crossbills, pushed down from the north? My guess is that it is both happening at the same time. One thing I've noticed is that at the same time Red Crossbills started showing up at feeders, I started hearing different call notes from them.

Red Crossbills have as many as nine subspecies around the continent that some people think should be considered full species. Each subspecies specializes on a different kind of conifer, has a different-sounding call note, and has a different shape to the bill that is adapted for the conifer on which they feed. Our local population has a very liquid "kip" or "quip" call that is relatively soft. In the last week, I've also heard a very dry, sharply-upturned "whit" or "swit" call from a crossbill type that is normally found feeding on Douglas-firs in the Pacific Northwest. I've also recently heard another call type that I cannot identify, but it has the same upslurred "quip" as our locals but calls more loudly and harshly, with less time between notes. So, although our cone crop may be getting low, I think we also have some new Red Crossbill visitors in town.

22 March 2009

Brewer's Duck

I found a very interesting duck in Logan today, a "Brewer's Duck". The famous ornithologist John James Audubon described this species in 1840 on the basis of a specimen he collected in Louisiana. He mentioned that he had been unable to procure a second specimen, and that he thought this species was probably closely related to both Mallards and Gadwall. He was more right than he knew. We now know that this "species" is in fact not a species at all: it is a hybrid between a Mallard and a Gadwall.

I wasn't able to photograph the bird I saw, unfortunately. I got distant looks at it through my spotting scope, but as I moved closer to take some photos, it flew away to the south and out of sight. But, a very similar bird was found by Carl Ingwell and Jeff Bilsky less than an hour's drive from here on the Great Salt Lake exactly one week ago. (Photos of that bird are here. Edit - removed broken link; those photos are gone.) Could this be the same bird? We will probably never know, but I think it's likely given how relatively close the other sighting was in both time and space. I'll keep looking for the bird in the hopes that I can get a photograph, which might help us determine whether it's the same bird.

This hybrid combination is rare, as are all hybrid combinations. It's the rarity of hybrids that keep species discrete from one another. However, ducks are famous (or notorious) for the amount of hybridization between species, relative to other taxa. For example, see this blog post for a series of beautiful duck hybrids, including the Brewer's Duck. My favorites are the Mallard x Red-crested Pochard, and the Mallard x Wood Duck. Keep an eye out for unexpected hybrid combinations at a pond near you. You never know what beautiful combinations might turn up!