Idaho’s winter may be harsh for humans, but some bird species appreciate what it has to offer and take up residence in the Gem State by choice.
It does warrant the question, though: why do migratory birds choose a cold, windy and often snowy winter setting like Idaho instead of a warm “paradise” like Mexico or California?
Heidi Ware, education and outreach director for the Intermountain Bird Observatory (IBO) in Boise, said that good weather is nice, but not the main factor in migration.
“We think of birds as moving south for the winter because it’s warmer in southern areas,” she said. “But really it’s all about food availability.”
Take, for instance, the rough-legged hawk: according to the Cornell Lab of Ornithology, these hawks breed in the summertime in the arctic tundras of Northern Canada and Alaska. It hunts among the open fields for small rodents like voles.
“Coming to Idaho is great for them,” Ware said. “We have small rodents like voles in ag fields. And there’s not as much snow as in the tundra and the daylight is much longer than the tundra for hunting. Plus, if you think about it, migrating south is riskier and it takes more energy.”
Before long migrations, birds typically have to store up on fat-filled food sources. Along the way the birds have to conserve enough energy not to fall out of the sky while also being alert for predators, and nocturnal migrants have to adapt to the new sleep cycle necessary to fly at night.
So why not stop somewhere closer if possible?
In Idaho, the biggest group of winter arrivals are waterfowl. Some of them stick around all year long, like mallards, gadwalls and Canada geese. But others, like ring-necked ducks, tundra swans and trumpeter swans, only come around in the wintertime.
Sarah Harris, a biologist at the College of Southern Idaho and a leader of the Prairie Falcon Audubon Society, said that if you want to see an overload of these waterfowl, go to the Hagerman Wildlife Management Area (WMA).
“Pretty soon here, the Hagerman Valley, especially the Hagerman WMA, is going to be a place for thousands and thousands of waterfowl,” she said. “Ducks, geese, swans, egrets, herons, all of the above.”
One of the most recognizable migratory guests of the Magic Valley is the bald eagle, the national bird. Bald eagles inhabit Southern Idaho in the mainly because of the availability of food in ponds, lakes and rivers. It’s not just what’s in the bodies of water, but also what’s on them: waterfowl.
Ware said that there are usually multiple roosts in Hagerman where the bald eagles nest, and in her hometown of Boise she often sees a big jump in the winter.
“In Boise, we might have one or two pairs in the summer that actually nest, but you could go out and on a good day see about 16 or so,” she said.
Other birds of prey swoop in for the winter too, including sharp-shinned hawks and rough-legged hawks.
There are some pretty strange visitors as well, including one tiny bird that has become a winter resident in recent years: Anna’s hummingbird.
This habitation almost defies the normal logic of a rule of thumb in biological thermodynamics: the larger the bird, the more insulated it is, and therefore the more likely it is to survive in cold conditions.
However, Anna’s hummingbird, no larger than four inches on average and about the weight of a nickel, has begun to take up residence in the cold and windy lands of Western and Southern Idaho.
“IBO is trying to figure that out,” Ware said. “But we know the Anna’s have more insects in their diets that other hummingbird species, so that is potentially a big factor.”
So where’s the best place to find a wide range of birds that have taken up winter residence in the area?
“Generally, where I like to bird is anywhere where there’s open water,” Ware said. “Hagerman has a lot of open water. Any reservoir like American Falls or Magic Reservoir is a great spot to check. But also driving around roads with ag fields to see all the winter migrants that arrive.”
Harris said the fields around Eden and Hazelton and river canyons are good local places to scout for birds of prey.
“Any place that’s got a lot of structural diversity — grasses, bushes, trees, and a little bit of water — is going to have lots of birds,” she said.
Harris said the Audubon Society also helps with Christmas bird counts in the winter at various areas throughout Magic Valley, which provides an opportunity to see unique bird species while also contributing to a citizen science initiative. The first two happen in Twin Falls and Hagerman on December 16th and 17th, respectively, scouring a 7.5 mile radius from each town’s respective post office.
For rare bird updates, Ware and Harris say eBird is a great way to get alerts. eBird is a citizen-sourced bird sighting database that allows researchers and naturalists, as well as amateur birdwatchers, to track bird sightings and distributions.
“I do think that eBird is the absolute best,” Harris said. “Every time we meet, we talk about encouraging to those that are reluctant to use eBird to do so because it’s the best tool.”
They both also recommend the Idaho Birding Facebook page, which they admit has been more of a site that photographers have used to post pictures, but it also lets the public learn about events and rare birds in the area.
And Harris says even if you can’t travel far, you can attract some of the migrants from the luxury of your house.
“Keep your feeders full and you’ll get some of the local winter residents,” she said.