Monday, March 5, 2012

Tree swallow sightings trigger flights of imagination

Sherry Boas

The first time I saw the lakeside property where we now live, a flock of swallows was flying overhead.  The acrobatic birds – there must have been at least two dozen of them - took turns skimming over the water’s still surface before soaring upward, circling about then swooping down for another go-around.  I remember standing on the shore mesmerized by what looked like poetry in motion.  I felt privy to a private show.

I fell in love that day with a land and lake rich with potential.  Both held promise of many more performances to come.  The encounter with the swallows fed my imagination.  Because of them, I envisioned a future of wildlife encounters, a host of nature’s bounties.    

The deal was clinched.  Twenty years have passed since that day and I haven’t been disappointed.  Each time swallows reappear, I flashback to that magical first impression of our property. 

It happened again today.

Tree swallows (Tachycineta bicolor) are seasonal visitors to Florida, venturing south in autumn to enjoy the warm winter climate before returning north in springtime to breed.  Not only are these small, forked-tailed songbirds agile fliers, they are also highly social animals.  They feed, roost and fly – up to 25 mph - in large groups called flights, performing their aerial dances en masse.  If you catch sight of a flight of swallows, you will see dozens of white undersides flash in sharp contrast to their iridescent blue-green upperparts. 

Consummate bug eaters, tree swallows, with their lithe, streamlined bodies, are adept at capturing insects on the wing.  Gnats, mosquitoes, mayflies, ants, beetles, spiders and grasshoppers are among the many bugs caught in their short, pointy bills.  While insects make up about 80 percent of their diet, tree swallows also eat some berries and seeds.  They are especially fond of the berries found on wax myrtle and bayberry bushes and will often feed on those berries on rainy days when the weather is not suitable for flying.

I don’t see tree swallows often and that’s one reason I find each sighting so special.  Another reason is the gracefulness of these birds in flight, especially over water.  Tree swallows travel with such ease of motion.  Simply watching them feels enlightening. 

I’ve often wondered what motivates swallows to intersperse their aerial displays with brief touchdowns upon the water’s still surface.  Are they after food?  A drink of water?  Are they taking a bath or simply having fun?  As it turns out, it could be any of those reasons.

Food and Water – Although they are experts at catching airborne insects, tree swallows occasionally seek out water-bound prey like water boatmen (hemiptera) and midges, miniscule bugs that live on a lake’s surface.  When the birds swoop down, their wide-open mouths act like scoops, skimming up insects as well as water to drink.

Bathing – A tree swallow’s bath is a two-in-one operation.  It’s a bath as the bird brushes the water with outstretched wings.  It’s a shower, as it shakes water off while regaining altitude.  Tree swallows also take advantage of rainfall to preen feathers and do a bit of personal grooming.

Just for Fun – It’s impossible to know what goes on in any animal’s mind, but it’s hard to imagine how these aerial artists could not derive some pleasure from their aquatic touchdowns.  Such fun it must be to fly as they do.  Watching a flock on the wing over water is the perfect combination of beauty with grace, utilitarian action with the sublime.

For most of Florida’s seasonal birds, March signals migration time.  Tree swallows will soon be gathering in large flocks – sometimes numbering in the thousands – for the long flight north.  They will return to homes throughout North America to find nesting sites in open spaces near marshes or water where they’ll mate and produce young.  The nests they build in either tree cavities or in manmade nesting boxes are soft cuplike structures lined with feathers and made out of whatever materials are close by – usually grasses, twigs and pine needles.

Although Floridians will miss the reproductive period of the tree swallow life cycle, we can take solace in anticipating their springtime return.  I know I’m grateful for whatever encounters I have with these avian beauties.  I consider each visit a gift as well as a reminder that 20 years ago my husband I made the right choice in selecting a place to call home.

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