Swallows a colorful sight for bird watchers

Posted April 25, 2009, at 1:13 a.m.

Generally, whenever I go home to visit family in New Jersey, I am rewarded with some great bird sightings. This time proved to be the case as well.

There are some relatively healthy parks within short driving distance from my Mother’s house — Lenape Park is one of them. Comprised of 450 acres of wetlands, meadows, and forests, a portion of it contains a paved walking trail overlooking prime bird habitat. As well, local citizens had erected bluebird and tree swallow houses in an overgrown meadow bordering both the wetland and the walkway—and it was just my luck that the swallows, at least, had just arrived from their wintering grounds in the southern United States and Central America.

I developed a routine every morning: I’d go get a cup of coffee and head to Lenape Park to watch “my” swallows. I loved their graceful, acrobatic aerial maneuvers as they pursued insects on the wing, and it was interesting to see their territorial and courtship behaviors up close. One particular pattern was obvious: a tree swallow would cruise at mid-height over the nest box area with an exaggerated, shallow fluttering motion, with wings held in a downward-pointing “U” shape. This is called “flutter-flight,” and is done by the male in response to the presence of a female, as described in Volume One of the “Stokes Nature Guides: A Guide to Bird Behavior.”

What I also love about tree swallows is their plumage—simple but elegant. The metallic blue on their upperbodies—glinting spectacularly whenever the sun hits them just right—contrasts vividly with their clean white underbodies. This, together with their effortless flight and endless twittering calls raining down from the sky, make them noticeable to even the most unconcerned joggers or other passersby in the park.

They certainly occupied almost all of my attention, which is why I immediately noticed an individual bird that didn’t fit in with the crowd.

This swallow’s back was chocolate-brown in color, instead of metallic blue. It also didn’t have the characteristic demarcation between upper-and-underbody plumages; instead, its whole head, face, and throat and upper chest were a tannish-brown. As well, the remainder of its chest and belly lacked the pristine white seen on a tree swallow. I realized what I was seeing was a northern rough-winged swallow.

This swallow is so named because of the particular composition of one of its primary flight feathers. The primary feathers are those that grow at the end of the wing, farthest from the body.

According to the “Birds of North America,” species account, early naturalists, with the bird in-hand, noted “a file-like roughness when the finger is drawn along the edge of the quill from base toward tip,” of a primary feather of a male swallow. The sound of air passing through this feather’s modified structure may produce sound during territorial or courtships displays, according to the BNA.

Northern rough-winged swallows breed throughout most of the contiguous United States and also in Central America. They winter in Central America and certain portions of the southern U.S.

These swallows nest in burrows, as do bank swallows, but also in cavities of human-made structures. They usually lay a clutch of between 4 and 7 eggs between mid-May to mid-June, which hatch a little more than two weeks later. Fledging occurs up to twenty days after that.

An interesting observation in the BNA regarding parental care of fledglings piqued my interest. Adults have been seen to follow fledglings as they make their first flights, occasionally forcing the young to land in apparent attempts to prevent notice and capture by a predator.

I wonder if the northern rough-winged swallow I saw that day would be successful at producing young this year. The tree swallows in the area would not tolerate it near their nest boxes, it seemed; I observed a few skirmishes between the two swallows in the air directly above the nest boxes.

Hopefully, it will find an abandoned kingfisher nest hole or cavity-filled rock wall, attract a mate, and raise young.

bdnsports@bangordailynews.net

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