If you’re not a bird-watcher, you might be surprised to hear that there’s one species of hummingbird — just one — that spends winters in Southwest Idaho.
Anna’s hummingbirds are as mysterious as they are beautiful.
“With iridescent emerald feathers and sparkingly rose-pink throats, they are more like flying jewelry than birds,” according to the description of them in the Cornell Lab of Orthinology’s online catalog “All About Birds.”
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So what the heck are they doing in Idaho during the winter — and has this cold, snowy winter killed them off?
“We don’t have evidence they died off but I do suspect some of them did die,” said Heidi Ware, education and outreach director at the Intermountain Bird Observatory.
The observatory is an academic research and outreach program of Boise State University, with a staff of eight full-time ornithologists. It is located on campus at 2225 W. University Drive.
Last winter, Idaho bird-watchers spotted 55 Anna’s hummingbirds, with most observed in Southwest Idaho and the Panhandle. This winter, 37 of the birds were noted.
Those who feed, watch and monitor the birds in their yards reported that all of the Anna’s disappeared in mid-December. The last reported sighting was Jan. 2.
About two-thirds of the birds disappeared around the same time last year, so it’s unknown whether it’s because of the unusual weather. Last February, some of the birds that left returned — then departed again in March.
This winter comes on the heels of several mild winters. We’ve had five days below zero in January, with the lowest recorded temperature at the Boise Airport dropping to -11. If still here, could these little birds survive that kind of cold?
One bird-watcher who lives in the Garden City area saw an Anna’s hummingbird in his yard in December, when the thermometer at his house read -8.
“With any bird, the reason they leave for the winter is not usually dependent on what temperatures they can survive. It’s all about food,” Ware said. “It’s about the food being there.”
Anna’s hummingbirds love late-blooming salvia. Once these birds find a yard or other locale with a good food source, they tend to stay there. But there was one documented case of a bird flying back and forth between two yards a mile apart, Ware said.
In general, birds try to consume enough food during the day to have enough fat to shiver through the night, Ware said. Hummingbirds go into “torpor,” a state of hibernation that allows them to burn less energy than other birds.
“There’s a lot of evidence that other larger birds aren’t doing so well either in this unusual weather,” Ware said. “We’ve seen a number of reports of freezing finches at feeders, barn owls struggling to survive cold temps, and very cold northern flickers and Western screech owls roosting under eaves to seek warmth.”
The first documented Anna’s sightings in Idaho were in the mid-1970s. The little birds began appearing in increasing numbers in Idaho over the past decade.
“Anna’s breed on the Pacific Coast and come here in the winter,” Ware said.
It’s counterintuitive to researchers that these birds would choose to winter in a location with harsher climate conditions than where they breed.
“I think it’s that they’re really adaptable,” Ware said. “They’re adapting and getting whatever resources they can get.”
They’re a species whose range has expanded significantly over the past century, possibly due to development and habitat changes.
The birds were first documented in Southern California in the early 1900s. Their range expanded to Northern California by the 1950s, and then as far as Oregon and Washington by the 1960s and 1970s.
Ware said research on Anna’s has found that insects are a large percentage of their diets.
But are there enough insects to eat in a winter when we have record snow depth? There are a “surprising number” of insect hatches through the winter, Ware said.
Researchers band Idaho hummingbirds to study breeding and migration patterns. The public is encouraged to participate in summer banding projects. Look for announcements about banding at the Intermountain Bird Observatory’s website.
Feeding in the winter
Providing nectar for hummingbirds can be tricky when temperatures drop below freezing. But there are a couple of ways that the Intermountain Bird Observatory recommends:
▪ A heated bird feeder called Hummers Heated Delight was created by a man in Albany, Ore. There are two sizes of feeder, and costs range from $22.50 to $28.50 (plus $8.50 shipping). They use a 7-watt bulb as a heat source and have been tested down to 1 degree.
▪ Another option is to place the feeder on a heated dog bowl. Be sure to do this only in an area that is cat-free.