Wednesday, February 23, 2011

February 21 - Winter Songbird Monitoring

As we inch closer to spring, early breeding birds are busy singing and establishing territories, while later breeding birds have been concentrating in areas of food. Black-capped Chickadees and Marsh Wrens have become more territorial over the last week, with males actively patrolling territories and chasing away other males. American Robins, Song Sparrows, Bewick's and Pacific Wrens have all been heard singing more frequently than before. Grasses and other herbaceous plants along the paths have been greening up and providing food for Golden-crowned and Song Sparrows. The bud's on the willows along the west side of the woodlot have been increasing in size and insects have been congregating in this area as well. Yellow-rumped Warblers, kinglets, and chickadees have all been spending more time in this area presumably to take advantage of increased food availability here.

We managed to catch our second Myrtle Warbler in as many days of monitoring, this bird was a second-year male. The usual mix of both kinglets, chickadees, Spotted Towhees, Fox and Song Sparrows were present, the only 'different' birds were a Pacific Wren recaptured that was originally banded in November and a bright looking American Robin. Other birds of note are the same birds that have been seen all winter, including several Virginia Rails and the American Bittern.

It has been interesting comparing the variation in Fox Sparrows that have been caught at IIBO this winter, with most from the Sooty Fox Sparrow group, but several from the Red Fox Sparrow group as well. We managed to catch two this time that had characteristics of Red Fox Sparrows, such as white tipping to their greater and median coverts and a very rufous colour, but they did not have well defined reddish streaking on their backs. These are likely hybrids between the two groups, possibly from north-central BC, although without genetic testing we will never know. Compare the following photos of the two birds with a more typical Sooty Fox Sparrow.

Nearby at the Vancouver International Airport, a program has been started this winter to capture, tag, and relocate raptors to try and reduce the number of airline strikes, benefiting both raptors and travelers. To get to Iona Island you must pass by the airport and so it is worthwhile to check any Red-tailed or Rough-legged Hawks that you see for patagial (wing) tags. These tags will have a letter and a number to individually identify a bird. The bird below with tag C7 is a Harlan's Hawk (a subspecies of Red-tailed Hawk) that was banded in late January and relocated, but it has subsequently returned to the airport.

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