Towheeblog

At the scenic Burns Sewer Ponds last week, we were the only visible mammals, but birds galore—ducks, gulls, Caspian Terns, cormorants, Eared Grebes, Snow Geese, Spotted Sandpipers…and feeding Black Terns.
Their buoyant flight, their needle-pointed wings, their silvery shine at the right or wrong angle, their swerves and curves and verve, ups, downs and arounds, their intense silence, their skimming the pond surface turning a circle at speed, bounce in every ounce, their passing us within a few yards.  Never has a stance along a sewer pond berm been more mesmerizing.
The setting:

The actors in action:

It is almost the same body length as an American Robin.  That’s just under 10 inches.  Yet the tern’s wingspan is 7 inches greater (two feet), more than 40% advantage. The tern is also lighter than a robin as much of the tern length is its talented tail.  A rail that enables its aerial acrobatics and seeming weightlessness in air.  Black Tern: 24 inch wingspan well over 200% of 9.75 inch body length.  The high ratio of wingspan to body length intrigued me.  I found only common, “ordinary” American species with an even greater ratio—it is my beloved Common Nighthawk, also found at Malheur (read Edge of Awe to learn more).  Nighthawk: 24 inch wingspan, 9.5 inch body length.  Higher ratio by a fraction.  The swifts, naturally, have even higher wing to body ratios, but they live in the air, sometimes not landing for months at a stretch, eating, sleeping, molting in flight.

The Black Tern and American Kestrel have much the same length proportions, but the kestrel is a muscular bird, weighing nearly double the tern though not quite as long.  Kestrel’s must sometimes eat prey that resists.  These terns swallow many flying insects—gone in one gulp.  They also take small aquatic prey. The Black Tern breeds in inland North America, in loose colonies.  They range from Colorado to northern Canada.  In warm months juvenile birds may stay along the Pacific Coast.  In Eurasia Black Terns are found inland at the same lattitudes.  Both populations winter in sub-tropical climates.

My next Field Station sponsored birding trip: June 2-7. There are some seats on the van still open. Best trip for Bobolink and Eastern Kingbird (not here in early May) and Common Nighthawk. Call 541-493-2629 for details.
September trip is 7-12, includes trip to summit of Steens Mountain and a visit to the snow-tortured aspens with horizontal trunks.