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NATURE HAPPENINGS - September 2004

September Sojourn
by Damian Fagan

Light winds from the northeast caress the cliff face below us before they pass southward towards the mountain peaks. Several of us sit near the edge of Bull Canyon - a small slice in the northeast edge of the La Sal Mountains. Better known for the nearby dinosaur tracks, this rim is our vantagepoint to watch the migration of southbound birds of prey.

Sharp-shinned and Cooper’s hawks, both relatives in the Accipiter Family of raptors, seem to be the most common hawks that pass by this site. At times they are difficult to distinguish from each other due to plumage similarities and their close size overlap. The sexes of each species are dimorphic, meaning that females are larger than males. This adds a degree of confusion into the in-flight identification. Whereas a female sharp-shinned hawk is almost as large as a male Cooper’s hawk, their partners form the extreme ends of the scale. The smaller male sharpies seem to rock in flight when buffeted by even the slightest of breezes, while the female Coop flies as steady as a Boeing jet.

In the mix of adults and juveniles it is interesting to note the relatively longer wing and tail feathers on the juveniles. These first-year feathers will hopefully help with the bird’s maneuvering, as they must now hunt on their own. Short on experience, this species may suffer a high mortality percentage during their first winter. Starvation and disease take their toll, as well as illegal shooting.

Joining the accipiters are small falcons formerly known as sparrowhawks and today referred to as American kestrels. Somewhat similar in size, females are distinguished by their barred brick-red backs and tails, while the males have rusty brown backs and bluish wings. At a distance they may be mistaken for a sharp-shinned hawk, but their sickle-shaped wings, which are drawn backwards to a distinct point, readily distinguish them from the sharpies.

During the breeding season, sharpies nest in woodlands while kestrels are birds of open areas, often usurping an abandoned woodpecker’s or screech owl’s home for their own. They take to nest boxes, artificial homes that may be attached to interstate signs or residential trees, where natural structures do not exist. These falcons are not built for zooming through woods or chasing prey down through thickets like the sharp-shins.
Often seen hovering above a grassy field, kestrels search the field below for mice, grasshoppers or even small birds. During migration they stop to hunt, unlike their close relatives the merlins that can consume dragonflies on the run.

Interrupting the quiet migration moments are the raucous ravens and local jays, scrub and Stellar’s, parading between oak groves and their caches. As the birds fly by, sometimes at eye level, it is easy to see their crops bulging with their baggage of nuts. These birds horde acorns for winter consumption, and judging by the constant traffic, perhaps this winter will be a long one.
The members of this bird watch ponder the final location of each raptor that passes our view. Perhaps that kestrel will winter in Arizona, while the Cooper’s hawk may travel as far south as Costa Rica. We catch a peregrine falcon cruising southward, which interrupts our conversation and creates a stir among the birders and birds. The birders get excited because this is the first, and only, large falcon of the day. The flow of jays suddenly ceases as this aerial predator parts the local bird traffic like Moses at the Red Sea.

Peregrine is from the Latin word “peregrinus” which means “wanderer.” True to their description, these birds may end up hundreds of miles from their natal areas or cross vast stretches of ocean and end up overseas. One such bird, banded in the Glen Canyon National Recreation Area, ended up in Japan one winter.

As morning turns to afternoon, the flow of birds decreases to almost zero. Red-tailed hawks and a northern goshawk round out our species list. Several birders head back down the hill, returning to Moab and other obligations. A few of us remain; the drive to leave means we might miss an unusual species or some spectacular display.

This site doesn’t rank high in hawk migration circles. Nothing like the Goshute Mountains, west of Salt Lake City, where a thousand birds might pass the observation station on a good September day. It pales in comparison to the Isthmus of Panama, the umbilical cord between Central and South America. There a million raptors a day might funnel between those two areas. Whereas we might record thirty or forty individuals on a good day here above Bull Canyon, it is the ambiance that draws us. Perched on this rocky rim we have a front row seat to one of the greatest natural phenomenons of the avian world – the September Sojourn.

Red Tail

Northern Goshawk

American Kestrel

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