Swainson's Hawk on the Tuolumne River

I was out for one of my walks today, checking for any bird activity along the Tuolumne River bluffs in Waterford. There were some Magpies and Western Bluebirds here and there, but as I was staring off in the distance, some kind of hawk flew right overhead, so I pulled up the camera to try and get a decent close shot. I didn't, and while I was still fumbling with the camera, a second hawk flew overhead, and I didn't get a shot of it either!

After a few minutes I found them again flying over a cottonwood tree down on the Tuolumne River and I realized they were at a nest. I caught a few very long range shots with which I hoped to identify them, because I could see it was not one of the usual species I've been seeing. The white pattern on the wings was clearly different from a Red-tail or Red-shouldered Hawk.

I cropped and magnified the best one and identified it as a Swainson's Hawk (Buteo swainsoni). That would explain why I haven't seen them around much, as the Swainson's Hawks typically spend their winters in Argentina. They have one of the longest migrations of any raptor, from Argentina to as far north as Alaska and northern Canada. It is apparently an awesome sight to catch the migration, as they travel in flocks hundreds or thousands strong.

In any case, I figured out where the nest was, and took another very long range shot. One of these times I'll try and walk along the river and see if I can see any little ones as season progresses.

I didn't think I had any good pictures of a Swainson's Hawk, but I checked the archives and realized I had in fact caught a pretty clear shot of one over the cow pasture near my house last June, so that became the opening picture in today's post.

Bird of the Day: A Different Canada Goose, the Cackling Kind. Evolution on the Continent

If you've ever been accosted by a Canada Goose at the local park, pictures like these might give you the shivers. If one of them can deliver a nasty bite, just imagine what a few thousand of them can do. But take heart, these scenes are no nightmare. They aren't even Canada Geese. The birds occupying this field in the San Joaquin National Wildlife Refuge west of Modesto are Aleutian Cackling Geese (Branta hutchinsii). It's true, though, that before 2005 they were Canada Geese. Allow me to explain.

The Canada Goose lives in many environments, and in some cases particular flocks broke away and colonized different islands or territories (see yesterday's post for an extreme example). The presence or lack of food sources or differences in the nature of predators favored certain traits (size and behavior, for instance) in the young. The geese who summered on the Aleutian Islands were long recognized as a smaller subspecies of the Canada Goose, but recent DNA analysis has led researchers to consider these birds an entirely different species. And so these birds are not Canada Geese, they are the much smaller Aleutian Cackling Geese, which are genetically distinct from the Canada Goose.

The Cackling Geese winter by the tens of thousands in the wildlife refuge a few miles west of my home. It is a stunning sight to see so many of the birds in one place. From the observation deck on Beckwith Road, one can see and hear thousands of birds taking off and landing, and in general making a racket (cackling, as it were). They have been encouraged to stay here instead of nearby agricultural fields through the planting of corn and other food plants. In April they will pick up and leave, headed north to breed in the Arctic.

The refuge is also home to thousands of lesser Sandhill Cranes. We could just make out a flock of them in the far distance. Snow Geese also winter in the area. There were five of them among the thousands of Cackling Geese yesterday, looking mildly confused. They usually arrive in large numbers in late November or early December.

"George, are you SURE this is the right place? Shouldn't you have asked directions in Oregon?"

As we were standing and watching the flocks there was a tremendous BOOM, and thousands of the geese immediately took flight. A huge dust plume over to the west revealed where the explosion had come from. And why.

It was a huge net. Several dozen of the birds had been trapped and for the next few minutes we could see Fish and Wildlife employees tagging them.

As usual, the picture quality from YouTube sucks (the compression process I suppose), but you can get a sense of the cacophony of sound from the flying geese from the short video below.