SCHIESS: Common loons migrate through eastern Idaho
A quick stop by the Island Park dam to check for migrating birds on my way to Henrys Lake revealed 17 mature and young Common loons fishing off the boat dock. Visiting Henrys Lake later in the day, I counted another 18.
“I guess the loon migration is in full swing,” I muttered under my breath to no one but myself.
I love to watch loons, as they can be very entertaining, even swimming up to you with a crayfish in their dagger-like bill to show you how successful they have been. It’s kind of like a fisherman holding an 18-inch fish at arm’s length and claiming it is 26 inches long.
Most of these migrating loons have come from Alaska and northern Canada where they nested and are heading for northern Mexico to harass the fish and other water dwellers there.
Loons are very specialized birds and because of some of these specializations, residency and nesting are difficult in most southeastern Idaho waters. There are four species of loons may migrate through Idaho, but the Common loon is the only one that nests near the Upper Snake River Valley. Indian Lake on the Idaho/Wyoming border in Fremont County is the only lake outside of Yellowstone Park where nesting is consistent in our area.
Loons cannot use small bodies of water at all as their body is built for diving and swimming. With their large feet located near the back of their body, it makes it difficult for them to walk on land. They also cannot take off from terra firma. On water it will take them from 60 feet to a quarter of a mile to get airborne. Many times after a meal of fish they are unable to fly because of their weight.
Loons are known in Europe as the Great Northern Diver. This name fits this beautiful bird perfectly. Common loons can dive over 200 feet deep and can stay underwater for a full two minutes. Once underwater, their bodies undergoes a 90 percent metabolic reduction as muscles store large amounts of oxygen, their heart rate slows and oxygen is supplied only to the essential tissues and organs. I have timed dives that lasted over two minutes.
Before a dive, a loon will usually swim some distance with its head under water trying to locate fish. Its red eyes may help with locating prey as it is believed their eyes allow loons to see deeper than 15 feet where most light is filtered out by the water.
You might think that getting from their northern nesting areas to southern wintering areas would be a hard process. But once airborne, these birds that weigh about the same as an eagle but have only half an eagle’s wing surface, can cruise at 75 miles per hour. With a wing beat of 260 to 270 beats per minute, they have been clocked at 108 miles per hour.
With more than 100 that usually migrate each fall stopping at Henrys Lake and Island Park, only rarely have I seen them on ponds around Rexburg. But each spring they can be found stopping by ponds and Ririe Reservoir as they migrate north to their nesting grounds. This week I found an immature one at the Sand Creek ponds and hope an adult showed it where to spend a sunny winter before it gets frozen in the ice.
Hopefully they will stick around for another week or two for me to observe them, but if not; I will be waiting for them come April.