Swainson's Hawk nestlings and more

Finally, I have edited my photos of the Swainson's Hawks and other birds I photographed in the San Luis Valley last week. During my trip last week to the San Luis Valley, I GPS’ed 22 Swainson’s Hawk nests (though 7 nests were on my Breeding Bird Survey route, the rest were along routes that I took while driving around the Vallay and not systematically surveyed).

I was able to observe nestlings on 5 of the nests, usually finding two nestlings (varied in age from quite young to very large and ready to fledge). The results confirmed my belief that the San Luis Valley hosts a very high density of Swainson’s Hawks and specifically for nesting Swainson’s.

I found a lot of variability of disturbance sensitivity by these hawks. Some were quite sensitive and flushed off the nest when I stopped my car (also documented in a report on this species by the Northern Prairie Wildlife Research Center as well as data that some birds will abandon their nests when disturbed). It was clear that getting out of the car was more disturbing as one bird flushed off the nest and flew overhead vocalizing its displeasure when I stepped out of my car at one my BBS stops to do my surveying, not realizing there was a nest nearby until the parent created a fuss. Though the temps were moderate, eggs and young birds need shading from the sun so I moved away quickly so the parent would return to the nest before harm was done. It was often best to stay at least a hundred feet away to avoid stressing the adults. If birders visit the area, please park a distance from the nest sites and stay in your car—I got great views and photos (better because I could steady my camera on the window) from my car. Since the trees where the nests are located are often near the road it is necessary to either pull up away from the nest or drive to next place to turn vehicle around so you can drive back and stop a distance before the nest.

This long-distance Neotropical migrant has a very long migration from its wintering grounds in the grasslands of Argentina (where significant pesticide poisonings have occurred) to western prairies in the US and Canada, distances of up to 6,000 miles.

I got some good photos (with 12X Panasonic digital camera, not digiscoped) of Swainson’s including several on nests and some nestlings as well as other birds in the San Luis Valley. They can be seen at http://www.flickr.com/photos/smoss/ . The photos can be enlarged for better viewing by just double clicking right on the photo.

SeEtta