Wednesday, February 20, 2013

Bald Eagle Surveys- Winter Foraging

Last Sunday, January 27th, the North Cascades Basecamp lead another successful wintering bald eagle survey in the valley. After spotting our first eagle, a 1st year juvenile, within minutes of meeting at the Barn in Winthrop, we took off. This winter, there seems to be fewer eagles in the Winthrop to Mazama area than last year. This is likely due to a small to minimal run of steelhead migrating back to the hatchery this winter, which differs from last January/February.  It also could be the result of a minimal deer mortality, since the deer have easy access to food this year; With hard winter years, there are more deer mortalities and therefore increased food resources for these scavengers. Another theory is that deeper snow in the Winthrop area during the winter pushes the eagles down-valley, looking for more food and foraging opportunities.    Regardless, we took off south to find eagles.
A 2-year juvenile perched shows off its beautiful mottling. 
We began to spot bald eagles along the East Country Road near Twisp where the cows are calving, leaving the fields littered with placentas, a nutritious meal for a bald eagle.  There was also an unidentified carcass (most likely a deer) in the field, which also attracted attention from eagles, ravens, and crows. In total, we saw 17 bald eagles at this site. Several were perched in cottonwoods around the field’s perimeter, while others feasted on the carcass. There was a nice array of juveniles at the field. The group got great views of 1st, 2nd, and 3rd year olds, allowing us to see the progression in plumage, beak, and eye color.
An adult bald eagle watches over a carcass.
If you look close you can see the
blood on it's face! 
As we continued south along East 20 and 153, we saw 7 more eagles perched in trees near the river. We finally pulled over and discovered one of the night roosts the eagles are using this winter. From 4:45PM – 5:10PM we saw 22 birds fly in to the area to spend the night. We saw 12 of these eagles (6 adults and 6 juveniles) fly to into a portion of the night roost right off the road. As they perched, they noisily communicated with each other. We also saw 8 eagles head up a valley about 200 meters further south. These eagles were most likely headed to a different night roost, although we lost sight of them behind a hill, and do not know where exactly they ended up. We are excited to find out in upcoming surveys!

Want to join us next time? We are heading out again on February 10th and 24th,1-5:30pm; cost is $20/person.  Email, or call (509)996-2334 for more information.

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