Naturespeak A naturalist's view of the world

July 20, 2009

A Symmetrical Swallow

Filed under: Uncategorized — wykes @ 2:16 pm

 

Barn Swallows enjoy a working relationship with people throughout the temperate globe. The two species manage to find each other throughout Europe, Asia, Africa, and here in the Americas.  The unwritten contract specifies that the people build the barns and the birds do the swallowing. They don’t swallow the barns, however, but they do swallow the bugs that fly about ’em. They also nest upon ’em. Although the specifics of this partnership have changed over the eons, as the nature of the man-made structures have changed dramatically, the intimacy of the partnership has not.

Swallows have integrated themselves into our very fiber. At one time it was believed that low flying swallows were a sure indication of impending rain. There is some validity to this because of the influence of low-pressure weather fronts usually associated with rain, but the association is not faultless. Like any bit of folk wisdom, this one only rings as “kinda true”. Last week, for instance,  I confidently predicted that it wouldn’t rain based on the sight of high flying barn swallows. Unfortunately, that same group suddenly dove and started flying  low over the ground just before it started to rain. The rains that followed were biblical.  It appears that the low-flying thing is not really a predictor as much as it is a confirmer of conditions – like the infamous “Indian weather rock” which, if wet, confirms that it is indeed raining. 

The ancients believed that swallows burrowed into the mud every autumn and hibernated through the winter. This also was not true – the birds  migrate away in late summer-but the conclusion was a logical one based on observations of mud-gathering swallows. Barn Swallows, like Cliff Swallows, build thier nests out of clay pellets (see a bird at work here). Their constructions are not nearly as picturesque as the Cliff Swallow creations but are built more on the robinesque cup-shaped plan. The nests, lined with dried grasses and white feathers, ultimately are used to house up to two broods per year. 

Unfortunately, these mud creations – along with the droppings associated with nesting – are about the only reasons human find cause to complain about these creatures. In a give and take world, where the swallow’s “take” pales in comparison to their “give,” such complaints are pretty weak.

Their constant chortling is one of those reassuring country sounds which should definitely be placed in the swallows “give” category, for instance. The  variety of calls produced by a cluster of singing swallows is an auditory treat for even the most cynical of ears.  One reference attempts to categorize these vocalizations into nine different types ranging from twitters & whistles to whines and chirps, but such words fail to capture the essence. The basic Barn Swallow call consists of a chippering “kvit” punctuated by some cracklets, gutteral buzzes, and rattle clicks (Listen to hirundo-barn-swallowswav). How can you not be delighted by such a bubbly expression of life, even if it’s not verbally definable?

Barn Swallows are easy to identify no matter where they are or what they are doing (see here). They are  irridescent blue birds with orange chests, sleek pointed wings, and gracefully forked tails (see below). Oddly enough, the symmetry of that tail is a key beauty point among the swallows themselves. Female birds tend to pick males possessing perfectly symmetrical tails and wings. No one is exactly sure how they do this. After-all, most Barn Swallows look balanced most of the time. But the fact remains that symmetrical birds have greater longgevity than the asymmetric ones. That’s not folk lore, by the way, that’s fact. What happens to those poor asymmetrical” males that are left out in the cold? Apparently they are the ones who fly high during rainstorms and drown their sorrows by diving headfirst into the mud.

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