Birds of Prey Occupy Unique Niches

Filed in Birding, Expert Articles by on November 12, 2013

While driving and spending time outdoors in the Vail Valley, it has become obvious that many hawk-like birds have arrived on the local scene. Watch for these many birds of prey either soaring or perched. These avian raptors include hawks, eagles, falcons, and vultures.

TWG_story_birding14imgIndividual species occupy a specific niche. For instance, an osprey hunts fish, a red-tailed hawk hunts rodents, and a peregrine falcon hunts birds. Visit areas rich in prey, and the predators will be there too. For example, if you know where there’s an area thick with ground squirrels, hang out nearby in your car and watch for a circling red-tailed hawk, a soaring golden eagle, or a cruising prairie falcon.

It is best to approach raptor identification by first establishing which habitat the bird is seen. Is it soaring over pastureland? Is it perched in the forest? Or, is it cruising fast and low over alpine tundra? Then, ask yourself, “what is the bird doing?” Good descriptions include, “a fairly large hawk which was first perched on a fencepost, and then took off, and was coursing low, riding on wind currents low over a shrubland. With wings held in a V-shape, it descended upon a rodent from three feet above.” These observations tell us a lot. Now, add field marks like it was blue gray in color, with a vivid white rump patch, and you’ve got a perfect description of a northern harrier.

Now, contrast the description, “I was sitting on a rock in a thick forest, quietly drinking a cup of coffee at sunrise, when suddenly a small to medium sized hawk darted into the scene. It then sat motionless on a concealed perch in some thick pine branches. It was gray with orange horizontal barring on its chest, prominent banding on its long tail, and a red eye.” This observation perfectly describes on of our forest hawks. Known as accipiters, these fast maneuverable hawks flush and hunt other birds while in hot pursuit through thick forest. Forest hawks include sharp-shinned hawk (small), Cooper’s hawk (medium), and goshawk (large). Identification of accipiters is largely a matter of size. Females are larger than the males in each species, which interestingly accounts for six individual sized hunters best suited to hunt specific sizes of prey. Therefore, a mated pair could exploit a wider niche, than if they were equal in size.

So what raptors are we most likely to see? The most common hawk here is the red-tailed hawk. Red tails are hawks of the open field, often seen circling above while they use their keen eyesight to locate prey, such as mice, ground squirrels, rabbits, or snakes. Red tails are easiest to identify in flight, as they circle on rising hot air thermals. Watch and wait for the sun to provide perfect lighting to make the reddish-orange tail glow.

Another good hawk of the field to keep your eyes peeled for is the Swainson’s hawk. This well-traveled flyer is due back from its winter tip to Argentina; 15,000 miles of global navigation is no problem for this bird-brain. The Swainson’s hawk is easiest to identify while it is perched on a pole, tree, or fence post. It is a slender hawk with a white face, and a cinnamon brown bib. The sit and wait hunting technique of the Swainson’s hawk proves reliable as it descends from its perch and nabs its prey such as mice, rabbits, other small mammals and sometimes insects.

All predators, including birds of prey, are opportunistic. What does this mean? Imagine yourself stranded in the woods, and the only food available is what you could hunt and gather. In this situation you may collect berries on the trailside, noodle a fish from a stream, or throw a stone at a grouse. Being opportunistic means you take advantage of what comes along in your travels.

The American kestrel is a great example of an opportunistic hunter. This small colorful falcon commonly perches on a wire and waits. Like many other raptors, the kestrel’s eyesight is six times more powerful than our own. What does this visually magnified world bring? To the kestrel, it is often a bounty of insects, small birds, lizards, and mice.

Vultures are the epitome of opportunistic hunters. In fact, they exclusively feed on carcasses of already dead animals. They locate the dead bodies by sense of smell, and their featherless heads are perfectly adapted for plunging into a maggot-filled carcass. Road kill, leftovers from the mountain lion’s kill, or the rotting carcass in the rancher’s field, are all fair game for the vulture. Recognize our local turkey vulture by wings that are lifted in a steep V-shape while soaring, and a constant tilting back and forth while in flight. Turkey vultures rely on hot air thermals for efficient flight, so we only see them here in the late spring and summer.

Lastly, always remember the golden eagle, a year-round resident of the valley. The golden is the king of raptors, with a golden head, and dreadfully powerful talons. Weighing ten pounds, with a seven foot wingspan held in a shallow-V while soaring, the golden eagle is capable of breaking the neck of a red fox, scooping up a ground squirrel, or knocking a bighorn lamb from a high cliff. The golden eagle is the largest and most aggressive raptor in North America, and can easily spot prey from a mile away.

As with all bird watching, observing raptors is challenging. Binoculars or a spotting scope bring a magnificent creature up close enough for you to enjoy its complex plumage, the glaring look in its eye, and its graceful motion. When viewing a bird, wait for the prime lighting conditions to occur, in order to get the best information on color. Be patient, and learn about the bird over a period of several minutes of pleasant viewing.

Remember in birding, it is observing the beauty and fascinating behavior of birds that is the best part of the activity. Naming the species may be secondary. Above all, enjoy being outside and immersed in the peacefulness of a scenic landscape, with our friends, the birds.

Tom and Tanya Wiesen are owners of Trailwise Guides; a year-round Vail Valley guide service specializing in hiking, mountain biking, and natural history tours. Daily private tours are available. Contact Trailwise Guides at (970) 827-5363.

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