Naturespeak A naturalist's view of the world

September 6, 2009

Goatsucker on High

Filed under: Uncategorized — wykes @ 12:18 pm

Nighthawks are part of a group of insect eating birds known as Goatsuckers. This less than flattering name originated from an archaic farmer belief that these fowl were to blame when their dairy goats inexplicably went dry. They were believed to sneak into the barns at night and suckle milk from the goats.  This belief, of course, had no basis in fact other than the observation that nighthawks were twilight creatures frequently seen hovering over farm-lots and that they happened to have very large mouths. Those mouths, however, are exclusively meant for scooping insects out of the air and not for draining earthly udders. 

Except for a few conspiracy-believing back-hills farmers who wear tinfoil helmets, no one suscribes to the goat-sucking theory anymore. Unfortunately, the name remains as the name of the order to which Nighthawks belong.  Common Nighthawks, the species native to our neck of the woods (see illustration here) are familiar summer residents. We’ll forget the fact that they are in a specific group of goatsuckers called the Nightjars – a equally confusing name – and, even though they are called Nighthawks, are not hawks. All this is fascinating, but my primary intention here is to put semantics aside and call attention to the fall migration of these birds.

Nighthawks begin their southern trek in mid-August and continue their flight into early-mid September. They have to go all the way to South America and cannot afford to tally until the temperatures drop and the leaves change color. Now is the time to look skyward to see large groups of of these slender winged birds overhead. Late afternoon and early evening is the best time to do this. Over the last few days I’ve seen about 35 birds, massed into separate groups of  10-20 birds, glide past the open window of sky framed by the walnuts in my backyard.

During this migration and during their standard year, nighthawks fly in the evening and roost during the day. Typically they rest out in the open on gravelly ground or leafless branches where their cryptic coloration keeps them well concealed.  I was fortunate to see one roosting the other day (see above).  Actually I was told specifically where this bird would be found and found it exactly where it was supposed to be. 

As you can see, the bird was “at one” with the branch upon which it was perched. It is difficult to see, due to my poor photo skills and its excellent camouflage abilities, but the bird is facing left with its large eyes partially closed. The white-speckled gray wing coverts are dropped down to blend in with the dead branch (see detail below).

This bird had instinctively chosen  to assume its position in the manner of all “crepuscular caprimulgids”. It perched parallel to the branch rather than perpendicular to it.  Studies have been conducted on this roosting behavior and several other common features have emerged – it’s almost as if this bird read the literature about it (no doubt using a nightlight)! They tend to roost in dead trees which are taller than the surrounding trees and they face in a direction away from the trunk.  If the chance offers itself, the birds will also face east.

This one adhered to all the nighthawk doctrines, but was facing in more of a westerly/southerly direction. This sucker was probably anticipating the direction of its evening flight towards Brazil and dreaming of nice long daytime siestas in the southern hemisphere.

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