A Day at Wings Over Willcox

17 January 2008

My toes numb from the cold, my fingers stiff and barely able to focus my new binoculars, when it became light enough to see, I discovered that I had it relatively good. The object of our study and the reason roughly two dozen of us were out on the Willcox Playa on such a cold morning, sandhill cranes, were pulling their feet out of a sheet of ice.

Standing four feet tall and weighing over seven pounds on average, the Sandhill Crane (Grus canadensis) cannot simply take to the air to escape a predator. Once aloft, it flies with a slow-beating grace, but leaving the ground involves a few hops and flaps to get started. Accordingly, it nests in water, which provides a buffer against coyotes, mountain lions, and bobcats, all of which would undoubtedly find it a tasty meal. One wouldn't think to find water birds in southern Arizona, but both the Sonoran and Chihuahuan deserts support a few pools, and the birds have found them. "Crane Lake", a low and perennially wet area of the usually dry endorheic Willcox Playa, is one such pool. A school bus, rented by the organizers of the annual Wings over Willcox festival, took roughly two dozen of us and a few guides from the Audubon Society there in the half-hour before sunup, to set up tripods with cameras and spotting scopes and see the cranes at their nests before they flew off to forage waste grain in the farm fields of Kansas Settlement.

We could hear the cranes before seeing them, an incessant chatter from the adults punctuated by the occasional juvenile peep. As the night's darkness began to lift, first a few cranes took off, forming wishbone-shaped flocks like Canada geese silhouetted by the orange pre-sunrise light, then filling out to stretch in lines and clusters across the sky. Over the course of an half-hour the departing flocks thinned out, leaving only a few stragglers still warming their legs and feet. We returned to the bus to observe feeding, driving out to the farm roads and using the vehicle as a blind.

While the Willcox area's sandhill cranes nest in dense concentrations, feeding is much more dispersed; the thousands nesting at the plaza split up into flocks of twenty to a hundred birds and walk the fields in search of sorghum, corn, chiles, and pinto beans. Southern Arizona has nearly the greatest bird biodiversity in the world--four hundred species can be found in the San Pedro Valley alone--but irrigated agriculture in the Sulphur Springs Valley is what caused the Sandhill Crane to come to Willcox Playa and the nearby Whitewater Draw in such large numbers. With agriculture comes predators, too. Raptors--red-tailed hawks, mostly, but also ferruginous hawks, Cooper's hawks, and harriers--can be found on nearly every center-pivot sprinkler in the early morning; golden and bald eagles, both known to take the occasional crane in flight, are a rarer sight. A loggerhead shrike, a passerine predator known for impaling its prey on thorns or barbed wire, perched very near to the bus, giving us plenty of opportunity to take photos but little to observe its peculiar behavior. This enhanced predator population comes at a price, however; prey species are seen in decreased abundance and every effort to re-introduce the extirpated thick-billed parrot (Rhynchopsitta pachyrhyncha) to Arizona has been thwarted by overpredation.

After a quick lunch and a trip to photograph the ghost town of Dos Cabezas, on which I also spotted a juvenile Cooper's hawk and came upon a large flock of cranes out feeding, I was off on my second tour, the "Half-day Hawk Stalk". Led by an expert birder, we toured the area west and north of Willcox in a van in search of raptors, getting out every so often to watch.

The highlight of the afternoon was seeing a ferruginous hawk (Buteo regalis) out hunting, circling a field and occasionally coming very low to the ground near a single spot, intent on catching an unseen meal. We also saw a few Northern harrier (Circus cyaneus) and plenty of red-tail hawks. Toward the end too much time was spent riding in the van, to the point of boredom; the tour leader wanted to be sure that we saw a merlin (Falco columbarius), a small, seasonal visitor to the area. Near the end of the tour we did spot one, on a telephone pole near a farmhouse, an anti-climactic contrast to the active harriers and ferruginous hawk. But what we did learn is that the birds know where the prey is; each was spotted near a food source, the merlin near a farmhouse tree favored by passerines.

All in all, my day at Wings over Willcox was well spent, seeing more of the local wildlife than I would if I went out by myself, meeting fellow nature enthusiasts, and learning from experts about local bird behavior, including the effect of irrigated farming on area populations. The 17th Annual Wings over Willcox festival will take place from 13-20 January 2010. Tickets for weekend tours are still available; visit the event website for more information.