Friday, November 7, 2008

Wildlife at the Yolo Bypass

Today, my dog, Truman, and I took a late afternoon walk at the Yolo Bypass in Yolo County. This is the area where overflow from the Sacramento River is directed so the City of Sacramento doesn't get flooded during winter storms. Part of the Bypass is a State Fish and Game reserve, while other parts are farmed with rice. It was a nice clear, warm day, that made it an enjoyable walk for Mister T.

Even though the Yolo Bypass is located within a few miles of the City of Sacramento, an intensely urbanized area inhabited by a couple of million people, a wide variety and abundance of native wildlife calls it home. You can routinely see Swainson's hawks (Buteo swainsoni), red tailed hawks (Buteo jamaicensis), white-tailed hawks (Elanus leucurus), white faced ibis (Plegadis chihi), and a rare golden eagle (Aquila chrysaetos). During the winter there are literally thousands of ducks, and an occasional flock of tundra swans (Cygnus olor). I have seen large flocks of sandhill cranes (Grus canadensis) flying over the Bypass, as well.

Trials, tracks and scat from river otter (Lutra canadensis) are common at the Yolo Bypass, though I have never been lucky enough to see one here. Beaver (Castor canadensis) are common too. Even though it is widespread and common in the west, I was surprised to see a young black-tailed deer (Odocoileus hemionus) hanging out in one of the groves of willow and cottonwoods a few summers ago.

Today, we saw three individuals of the cabbage butterfly (Pieris rapae), three alfalfa sulphur butterflies (Colias eurytheme), two variegated meadowhawk dragonflies (Sympetrum corruptum), and one large male green darner dragonfly (Anax junius). I thought it was late for these insects, but I checked my field notes and the last day that I saw the first three species last year was November 4, except for the green darner which was last seen on October 28. The first freeze of the year kills these animals off until next spring or summer. Interestingly, my field notes reminded me that I saw a single fresh male cabbage butterfly in flight during the middle of winter on December 11, 2007!

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