Out here, in the open desert west of the Tucson Mountains, Red Tails, Harris Hawks, and Kestrels are a more obvious presence than Cooper's Hawks. But the Cooper's stealthy way of hunting from a hidden perch may have something to do with that. For years we knew that a big female Cooper's was using our neighbors' big mesquite tree as her daytime roost. Nearly every morning she makes one fast swoop at the doves and quail that enjoy a one-time feeding in our backyard (just a handful of seeds tossed on the ground). This usually results in a lot of fluttering, squaking and aggravation, and even our dogs join in the melee.
We rarely witness a catch. But we find telltale piles of feathers, mainly of doves, but once even the wings and tail of a screech owl. Over the last months, the big female and her mate must have been raising a clutch of young ones in another neighbor's big old pine tree.
During that time she was less visible. But lately got into some territorial disputes with the local group of Harris Hawks that was trying to take over her mesquite tree, so she's probably back to her old habit of spending the day in its cool, green canopy.. Several fledglings must be on their own, and they are becoming a menace.
|The young Cooper's in pursuit of the Gila Woodpecker (Photo-montage!)|
|Change of the guard at the Saguaro nest of a Gila pair (photo Dave March)|
For years we had some established adult Gila Woodpeckers that frequented our hummingbird feeders. Individuals had their own special techniques to get to the sugar water, so we got to know them well.
One male used to tip the feeder with his weight, causing messy drips under the feeder, another one used his long tongue to reach in, one female employed a very distinctive tremolo to induce sugar water to flow from the seams of the feeder. For years, a pair spent its resting time right in front of my studio window and brought their young ones to my feeder as soon as they could fly.
In the eighties, my friend Erik Kretschmar and his ethology professor Eberhard Curio raised a number of the smallest European Accipiter species - the Sperber (Accipiter nisu) to investigate how prey preferences were formed, as the prey base of the species includes many different animals from insects to birds to small mammals, but most individual birds are more specialized. I short, they found that the first hunting experiences of a youngster are quite determining for its further career as a hunter. Success in grabbing a tasty mouse during early trials may make a particular hawk a rodent specialist, while clashing into a nasty thorn bush in pursuit of a lizard may sour that kind of prey for this particular bird. I do not remember how specific that imprinting process was. It cannot be too narrow or it would limit the food supply for the bird too much, but it may keep partners (or for a while siblings) who share a territory from competing too much for resources.
When I watch Gila Woodpeckers, our most common Picidae, and I notice the very distinct flight pattern, choice of perch, pose while sitting, their noisy calls, and I can imagine that a hunter may consider them as a prey group as distinct as 'small rodent', 'small bird', 'lizard', 'snake' etc. and specialize on them.
|Young Cooper's after an unsuccessful swoop (photo Glenn Seplak)|
Luckily, Gila Woodpeckers are not always helpless victims. During the breeding season I saw heroic parents take on our top predator, the Great Horned Owl, who came to close to the saguaro hole with its chicks. The Owl did not stay long.