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Thursday, May 15, 2014

Mouthfuls of mud

Eric and I watched a couple of Barn Swallows (Hirundo rustica) gathering mud in a parking lot in Bodega Bay this morning. 

I've always been fascinated by this behavior, in part because it's hard to imagine having a mouthful of mud.

Barn Swallows use mud to build their nests.  Here's a picture of a male with both mud and grass (below).  He flew in with the grass and then started gathering mud.  Note his rust-colored forehead and underparts, and elongate tail feathers.  (The females typically have paler foreheads and underparts, and shorter tails.)

Although it's a little hard to tell, this may be a female that flew in and landed behind the male (see next image). Look for the more cream-colored underparts.

Here are a few quick trivia questions about Barn Swallow nest-building.  The answers are below the next image.

- How many trips per hour do Barn Swallows make while gathering materials for their nests?

- How many mud pellets make up one Barn Swallow nest?


Barn Swallows average about 30 trips/hour while gathering nest materials.  It's a busy time!

A Barn Swallow nest may contain between 750-1400 individual mud pellets.  Now that's a lot of mouthfuls of mud!

[Facts above from the Birds of North America account by Brown and Brown (1999).]

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