Trumpeter Swan Numbers Up In Idaho After Birds Learn New Survival Skill

Mar 16, 2015

Even though trumpeter swans have begun eating in fields, Jeff Knetter says he hasn't heard of complaints from farmers because the birds mostly glean in fields after harvest.
Credit Tony Cyphert / Flickr Creative Commons

The population of trumpeter swans that winters in Idaho, Wyoming and Montana was 26 percent larger this year than last year. This continues the dramatic comeback of a species that nearly disappeared from the lower 48 states due to hunting.

Jeff Knetter, the top migratory bird specialist at Idaho’s Fish and Game Department, says in 1968 there were fewer than 900 trumpeter swans in the Yellowstone area. And that was the last place they could be found outside Alaska and Canada.

Now the swans winter in several states, and a recent survey by Wyoming's Game and Fish Department counted 6,775 birds in Idaho, Wyoming and Montana -- what's known as the Rocky Mountain Population. That’s up from 5,368 this time in 2014. As many as 95 percent of this population winters in eastern Idaho.

That population went up 80 percent between 2005 and 2010, and Knetter says warmer winters may have increased the number of swans in Idaho. He says in the last decade trumpeter swans have also made an interesting adaptation.

“Trumpeter swans have started feeding in fields,” Knetter says. “They’re actually using winter wheat fields and they also use potato fields. This seems to be a relatively new, learned behavior. They didn’t really utilize that resource previously. And so we’re also starting to see more birds in areas where we haven’t seen them before.”

Previously Knetter says the swans ate mostly natural aquatic plants. But things like potatoes left behind after harvest are carbohydrate-dense and give the birds extra energy for their migrations.

Knetter says it’s not just swans that have figured out that farms are a great spot for lunch. He says this change in behavior accounts for a huge increase in the number of snow geese and white fronted geese in the Treasure Valley.

Find Adam Cotterell on Twitter @cotterelladam

Copyright 2015 Boise State Public Radio