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Sunday, April 21, 2013

For the Birds: The Swallows are coming… The Swallows are coming…

Barn Swallow by Kelly Sagen


The Swallows are coming… The Swallows are coming…
By Christine Southwick

Locally, some of the swallows have already completed their trip from Central or South America. Swallows migrate depending solely on insects, and since cold weather reduces the number of flying insects, the northward migration may be slower some years than others. Swallows catch insects during the day, and therefore migrate during day-light, whereas most other songbirds migrate at night.

Tree Swallow by Scott Ramos

In the Shoreline/greater Seattle area/Lake Forest Park area, we have Tree Swallows, Barn Swallows, Violet-Green Swallows, Northern Rough-winged Swallows, Cliff Swallows, and Bank Swallows. Tree Swallows arrive first, in early April; Bank Swallows usually arrive in May. The other species arrive sometime between these two species.  Even though the six species can often be found flying /resting together, they each have their own feeding niche—either by being selective as to preferred insects, or by height from ground.

Barn Swallows are the easiest to recognize—they are the only local species with a long forked tail.

Cliff Swallow in nest by Max Warner

Look for swallows flying low over bodies of water (Lake Ballinger/Twin Ponds/ Ronald Bog/Green Lake), rivers, creeks, or marshy areas, with their short wide bills open above the water, catching their flying-insect-meals using amazingly agile aerial techniques. These aerial insectivores spend more time on the wing than any other songbirds in the world. Another place to look for them is resting on telephone wires near boggy/marshy areas—often more than one species can be found resting on the same wires.

Some local species, like the Barn Swallows, and Cliff Swallows, have evolved to nesting on man-made structures. Other species may use nest boxes.  Most male swallows spend some time helping incubate the 3-4 eggs. Monogamous, most swallow species return to the same breeding area each year, and may use the same site, if their last effort was successful. This is called “site fidelity”. First-year breeders usually choose a nesting site near where they were born.

Barn Swallow nestling opening up for next meal by Joe Sweeney

Last year, because we had such a long rainy spring with few insects, there were a number of failed nests due to starvation of adults and nestlings. 
Loss of habitat, including habitat-trees called snags, and the wide-spread use of pesticides has decreased many swallow species.

These aerial acrobats are a joy to watch, and by snatching up to an insect per minute, are veritable vacuum cleaners of the skies. They munch on mosquitoes, gnats, flying ants, termites, and other aggravating-to-human insects.


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