Must-See Idaho Migrations
By land, air and stream, Idaho's critters are on the move.
Animals of the world are in motion again — flying, swimming, running and crawling to their seasonal homes and breeding grounds. Often the first critters that come to mind are the large, four-legged ones we might run into on the road or the trails. But there are also lesser known migrations of the small kind.
The Pahsimeroi and Lemhi rivers are waters that salmon, quite literally, will die for. Each year, these rivers and their tributaries mark the end of a 900-mile journey from the Pacific Ocean for the salmon. When they get to the small streams of central Idaho, they spawn and then die. After hatching and growing, young salmon—called smolts—will begin their own migration to the sea. Many salmon, unfortunately, return the full 900 miles only to be stopped short of their final spawning area by insufficient water or irrigation diversions. The Nature Conservancy works with landowners and partners to remove those barriers.
While salmon can be difficult to see in large rivers, you can carefully watch them as they move up small streams, such as at the Idaho Department of Fish and Game’s Wildlife Management Area along the Pahsimeroi in May, Idaho. A spectacular place to see the salmon is at Dagger Falls, on the Middle Fork of the Salmon River. Around July 4th, the salmon can be seen leaping up the falls—a dramatic sight.
It can be easy to overlook some of Idaho’s smaller migratory sky-dwellers during the flurry of waterfowl and raptor migration in autumn. However, similar to birds, many dragonfly species also fly south for the winter! In August the Green Darner- Idaho’s largest species of dragonfly- travels from Idaho to ponds in the southwest US where individuals lay eggs and then die. The water-dwelling eggs, known as aquatic nymphs, prepare to return to Idaho upon hatching in the Spring. It remains a mystery how these young dragonflies are able to successfully find the path back north, as their parents have long since died off!
Although all 14 species of Idaho’s bats migrate South for the winter, the distance of such migrations vary between species. While the majority of Idaho bats will travel short distances of up to 60 miles in search of winter hibernation grounds, the Silver Haired bats and the Hoary bats fly up to 600 miles to seek warmer weather!* Traveling to California, Arizona or even northern Mexico, these bats migrate one of two reasons: a seasonal lack of food or unsuitable living winter living conditions. When the temperatures rise enough for insects to return in the Spring, the bats make the trip back to Idaho. Migratory bats can be spotted in the night skies in many parts of the state including the Conservancy's Ball Creek Preserve.
*Source: Department of Idaho Fish & Game
Each spring, raptors return from Mexico and Central and South America to nest in the rocky canyons of the Snake River. They find the sagebrush plains that surround these canyons to be the perfect place to spend the summer, due to one of the highest densities of ground squirrels in the world. Golden eagles, prairie falcons, ferruginous hawks, burrowing owls and other species build nests in remote canyons, but they can often be seen out hunting in the mornings and afternoons. Spectacular interactions—golden eagles stealing meals from prairie falcons, red-tailed hawks fighting over territory—can often be observed. A great place to catch the action is the Morley Nelson Snake River Birds of Prey National Conservation Area, located near Kuna. As you watch raptors, keep an eye out for badgers, too, as this area has one of the world’s largest populations of this interesting mammal.
Pronghorns are the only large mammals remaining from the Pleistocene—the time period when woolly mammoths, cheetahs and giant sloths roamed North America. Their migration routes are literally millennia old. One such migration was recently tracked in a study by the Wildlife Conservation Society and Lava Lake Land and Livestock. Each fall, the pronghorns migrate from the low-elevation, sagebrush lava beds of Craters of the Moon National Monument, through private ranches in the Southern Pioneer Mountains, over expansive public lands to the north and into Montana. It’s a migration of 180 miles—one of the longest mammal migrations in North America. In the spring, the pronghorns return to Craters of the Moon, and are very visible in the wide-open sagebrush country.