Some alder flycatchers settle in interior Alaska, and here they caught the attention of Anna-Marie Benson, who once worked for the Alaska Bird Observatory in Fairbanks.
While studying songbird migration to earn her master's degree at the University of Alaska Fairbanks, Benson searched through Fairbanks weather records to find the latest recorded low of 32 degrees Fahrenheit in the spring, and the first freeze of autumn.
The dates June 13th and August 3rd represent a potential frost-free summer of just 51 days, which would be the worst-case scenario if you happened to be a songbird with lots to accomplish on your visit north.
Most songbirds arrive in Fairbanks before June 13th and leave after August 3rd, but Benson
found the alder flycatcher was an exception, staying in the Interior within that narrow window of the shortest possible summer.
said the alder flycatcher might time its arrival to coincide with the hatching of a large flying insect that would justify a commute across half the planet.
"With the distance they're flying, they've got to be spent when they get here," she
"They've got to be eating some big fat juicy insect, maybe a wasp, that's not available at other times."
Whatever the alder flycatcher is finding to eat, it¹s eating a lot of them.
A bird that establishes a territory, attracts a mate, breeds, makes a nest, lays eggs, and raises young in less than two months doesn¹t take any days off.
is impressed with all the migrant songbirds, which take great risks to breed in Alaska.
Migrant birds that spend their summers at lower latitudes devote specific times to replacing damaged feathers, fattening up, and taking off for the flight home.
Some of the birds Benson studied in Alaska perform each of the energy-sapping tasks at the same time.
The alder flycatcher skips the process of replacing worn flight feathers in Alaska, a gamble that allows it to spend less than two months here before returning 7,000 miles to South America.
Why do any of these tiny birds risk so much to head north each year?
said Alaska and other northern places offer lots of territory, plenty of food, and few nest-robbing predators when compared to the tropics and South America.