A room with a view

Cliff Swallows look down on the world from their mud-construction apartment complexes.

Cliff Swallows peer out and look down on the world from their mud apartment complexes.

These are the famous Swallows of San Juan Capistrano that return faithfully to nest on the walls of the Mission each year within a day or two of March 19.  They spend most of the fall and winter in western South America, especially the grasslands of Argentina, but then spread out to breed over almost all of North America, including northern British Columbia and Alaska.

Their gourd-shaped nests are constructed entirely from mud and saliva of the many Cliff Swallows in the colony.  This happened to be a small colony, but Cliff Swallows are a very gregarious species, so there might be as many as 3000 nests in a particularly insect-rich environment.

There was a lot of activity at this colony with birds flying in and out of the nest holes.  Sometimes it got a little chaotic, with individuals in adjacent nests almost colliding on their entry or exit.

cliff swallows

cliff swallows

They are handsome birds with their russet colored cheeks and throats, white foreheads, and blue-black heads and backs.  They might be mistaken for Barn Swallows, but have squared-off rather than forked tails, and pale breast and belly feathers rather than russet colored.

cliff swallow

Like Barn Swallows, Cliff Swallows construct their mud nests under overhangs, like the eaves of buildings, bridges, or overpasses on roadways.  Flying in and out of their nests can put them directly in the path of moving vehicles, and has been a significant source of mortality for these birds.  However, ScienceNow reported that wings of Cliff Swallows that successfully nested near roadways were significantly shorter than those of birds killed on the roads.  Shorter wings might increase the energy cost of flight, but it would improve aerial mobility, allowing birds to avoid collisions. This species, at least, seems to be successfully adapting to human selective forces.

2 thoughts on “A room with a view

  1. These nests remind me of city living in Washington DC, where space is at a premium and traffic is really heavy. Pedestrians in DC run the same kind of risks of running into each other or being hit by bicyclists or distracted drivers. Fortunately, things are a bit better in the suburbs, where I live. I am utterly fascinated by the nests and am amazed that all it takes to build them is mud and saliva. How much saliva can a swallow produce, after all? You answered the question that I was going to ask about their resemblance to Barn Swallows. I really like the action shots!

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