Wednesday, December 31, 2014

Eurasian Tree Sparrow

Yesterday, Gerald Hoekstra and I drove to a bird feeder south of Hastings in nearby Dakota County, Minnesota. For the last few days, an Eurasian Tree Sparrow was reported from that location. Gerry and I spent over an hour trying to spy the bird among a plethora of House Sparrows at the feeder. We finally noted its chestnut crown (not gray like the House Sparrow’s) and black ear patches. After seeing it a few times, we also recognized the Eurasian Tree Sparrow by the bird's slightly smaller size and paler overall coloration.
The weather—a frigid -5 degrees F., with wind chill warnings posted—did not help finding the bird or taking decent photographs. We had permission by the landowners to watch from the road, but not to enter their property. This was decent of them, but did not allow us an opportunity for closeups. Also not helpful were a flock of Blue Jays that bullied the sparrows from the feeders. These photos are our best effort, the top one by me, and the bottom two digiscoped by Gerry, who very kindly gave me permission to post them here. (The last photo is of the bird in flight, bounding from the feeders to either the ground or to a nearby bush.)
Eurasian Tree Sparrows were introduced to North America from Germany in April 1870. They were released in an effort to "enhance the native North American avidfauna" in Lafayette Park, in St. Louis, Missouri. This initial introduction may have been augmented by subsequent releases. The sparrows rapidly became established in St. Louis, but House Sparrows outcompeted them in the countryside. Eurasian Tree Sparrows slowly spread into Illinois and Iowa—the main breeding range now encompasses about 250 kms from north to south.

This expansion more or less follows the Mississippi River. The species prefers wooded city parks and woodlots. A quick look at eBird illustrates their range and various extralimital sightings. Birds have been sighted around the northern midwest, and as far afield as British Columbia, Oregon, and the East Coast. Ornithologist do not know if these distant sightings are of escaped cage birds, sparrows arriving by ship from Europe or Asia, or individuals originating from their expected range in North America.

The source for most of the information and the quote in this post is Barlow and Leckie (2000). Not included in their account in The Birds of North America is a specimen from Huron, South Dakota, of an Eurasian Tree Sparrow collected on 19 April 2005 by a Purple Martin enthusiast clearing his bird houses of House Sparrows.

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