[Tweeters] Where are the Varied Thrushes?
wallydavis3 at gmail.com
Mon Jan 2 08:10:19 PST 2017
After reading so many tweets about the Varied thrush, it occurred to me that the numbers have been going down steadily at my feeder. I used to have fairly large flocks show up in the spring and, probably, breed on my property. In the last 15 years the size of the flock has been declining so that, in 2016, I only saw a few. Here’s from Cornell Labs:
Varied Thrushes are fairly common, but populations declined by almost 3% per year between 1966 and 2014, resulting in a cumulative decline of 76%, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 20 million with 82% spending some part of the year in the U.S., 32% in Canada, and 3% wintering in Mexico. The species rates an 11 out of 20 on the Continental Concern Score. Varied Thrush is a U.S.-Canada Stewardship species, and the 2014 State of the Birds Report <http://www.stateofthebirds.org/2014/?__hstc=75100365.4a3341b3f141ce57ee67efed90914571.1454354448614.1483329252602.1483373034008.11&__hssc=75100365.1.1483373034008&__hsfp=2642973505> lists it as a Common Bird in Steep Decline. Because Varied Thrush live in mature and old-growth forests containing very large trees, logging and forest fragmentation can cause habitat loss that reduces their numbers. These birds don’t tend to live in forest patches smaller than about 40 acres. Around human habitation, Varied Thrushes have proven very vulnerable to window strikes as well as predation by domestic and feral cats and collisions with cars. Varied Thrushes may benefit from reserves that have been established to protect the Northern Spotted Owl.
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