Monday, June 15, 2009

Bank Swallows

Rob Hardy posted yesterday about bank swallows that have excavated residences at a construction site just east of Target in Northfield, so we went to see them this evening.

I loved this juxtaposition of the swallows' colony of dwellings against the human colony of apartments going up behind it. You can see a swallow zipping by at the top right of this photo. It's even possible to see the white underquarters that make this small brown and white bird so striking (click on any of the photos for a closer view).

In the photo above, if you look closely, you should be able to see three or four swallows flying low in front of the colony. The swallows flick in and out of their holes quickly, making it a matter of pure luck to catch one at the door.

This one, seen through the spotting scope, actually paused briefly, perhaps checking on babies within. Bank swallows get their Latin name, riparia riparia, from the riverbanks in which they frequently nest, but they can adapt to a range of erodable banks and cliffs, including sand and gravel quarries. They breed over most of the northern two-thirds of the United States as well as Europe and Asia.

It was a treat to see such an organized community spring up in such a temporary situation as a construction site. I hope they are not disturbed before their young are fully fledged.

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John T. said...

I wonder if human activity has actually increased habitat and population for bank swallows.
I've been noticing a colony of bank swallows in a sandstone road cut- I'm pretty sure its not dirt. As I drive by I've been wondering how they manage to dig their nesting holes.

Rob Hardy said...

Much better photos than mine! I was put off by the No Trespassing sign! And I agree, the juxtaposition of the swallow nests and the windows of the apartment building going up is wonderful.

Penelope said...

Rob - I didn't see a No Trespassing sign; we were just standing on the public sidewalk. I was very glad your post alerted us to this very interesting sight. It was not something I'd seen before.

John T. - Interesting questions! I don't know. Here are a couple of abstracts of scientific journal articles about the spacing of bank swallow tunnel entrances and the effect of soil penetrability on nesting site selection for bank swallows (also known as sand martins).