Winter raptors

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Ferruginous Hawk, courtesy U.S. Fish and Wildlife Service Digital Library

Published Dec. 4, 2016, in the Wyoming Tribune Eagle, “Winter raptor marvels, mysteries show up in southeast Wyoming.”

By Barb Gorges

Mark and I drove over to join the Laramie Audubon Society on their mid-November raptor field trip on the Laramie Plains.

It was a beautiful day that makes you forget all the previous white-knuckle drives over the pass. However, what’s good weather for driving isn’t always good for finding raptors.

Trip leader Tim Banks checked his intended route the day before and found nary a hawk, falcon, owl or eagle. So instead, we drove across the Laramie Plains on a route his chapter frequently takes for general birding.

The reason for our first stop was a mystery, but then the broken branch stub of a lone cottonwood across the road became a great horned owl. However, a rough-legged hawk and a northern harrier were too distant to enjoy.

Finally, at Hutton Lake, out of the birdless sky, the wind picked up and kicked out a golden eagle, two bald eagles, and a ferruginous hawk.

Three weeks before, on a Cheyenne Audubon field trip at Curt Gowdy, we saw two bald eagles in the canyon. Another day at the park, Mark spotted three checking out his stringer of fish.

Bald eagles are marvelous looking, but I also marvel at their history, from endangered species to birds seen three times in three weeks.

Bald eagles were first federally protected in 1940. Later they were classified as endangered. Banning the pesticide DDT and educating people not to shoot them allowed their numbers to increase. In 1995 they were reclassified as merely threatened. They were completely delisted in 2007, though they are still protected by the Bald and Golden Eagle Protection Act.

While bald eagles do breed in Wyoming, there are more here in the winter, migrating from farther north. Fish are their favorite food (carrion is second choice) so looking for them around reservoirs and Wyoming’s larger rivers is good strategy, especially if there are big cottonwoods for them to roost in.

We all recognize the adult bald eagle, dark brown with white head and white tail, but until they are about 4 or 5 years old, they are dark with splotchy white markings like those of young golden eagles.

Golden eagles never came quite as close to extinction as bald eagles, but they were targeted by stock growers. In 1971, one man confessed to killing many of the 700 found shot or poisoned near Casper.

Golden eagles live in Wyoming’s grasslands and shrublands year-round. They might choose to nest on cliffs. And they prefer eating rabbits, ground squirrels, prairie dogs and the occasional new lamb if the rancher isn’t watching.

If you see a massive raptor flying in Wyoming in the winter, it is probably an eagle. Balds and goldens have wingspans about 80 inches long.

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Rough-legged Hawk, courtesy U.S. Fish and Wildlife Service Digital Library

But if it is a smaller dark bird, wingspan only 50-plus inches, with a neater black and white pattern under the wing, it might be a rough-legged hawk.

Every winter they come down from their Arctic breeding grounds, sometimes right into Cheyenne, wherever there’s a power pole perch, open land, and mice, voles or shrews. It’s a break from eating lemmings all summer.

They were also shot at, but like all migratory birds, they are now protected by the Migratory Bird Treaty Act.

For me, the most fascinating raptor we saw on the Laramie Plains is less common: a ferruginous hawk. Its name refers to the color of rusted iron because its top side is a reddish brown. Its belly is a creamy white, slightly spotted, compared to the streaky rough-legged’s. Both have feathers all the way down their legs.

However, some sources say the ferruginous shouldn’t have been in Wyoming in November. They are almost all supposed to migrate south in October and return in March.

Some field guides show the Colorado and Wyoming border as the north boundary of their winter range. I think that winter range boundary at the state line may have more to do with the greater number of birders in Colorado in the past who could distinguish between ferruginous and rough-legged. But there are now a dozen Laramie Plains and Cheyenne-area eBird records for ferruginous from November through February within the past three years.

Guess I can no longer assume in winter any large dark hawk that isn’t a red-tailed hawk is a rough-legged. It might be a ferruginous.

Meanwhile, we can all brush up on our hawk identification skills at www.AllAboutBirds.org or download the free Merlin Bird ID app for help. It will make winter more interesting.