Songbird Migration at Camas National Wildlife Refuge

Post Register May 20, 2013

 From 20,000 feet, the shelterbelts and tree rows at Camas National Wildlife Refuge look like tiny specks, insignificant in the surrounding landscape.

To migrating songbirds, though, these same trees are islands of hope in a vast sea of agriculture and high desert.

Thousands of migrating birds home in on this haven as they seek shelter and a chance to refuel and gain a little weight on their trek north.

Because of this concentrated and limited habitat, Camas has long been known by serious birders as the best place to go for a chance to see species otherwise uncommon in eastern Idaho.  A survey conducted in the spring of 2007 identified 65 species, but just about any species can show up there. According to the report, a few of the more unusual species spotted in 2007 included: Wood thrush, Virginia's warbler, magnolia warbler, black-and-white warbler, ovenbird, brown thrasher, northern Parula, Harris's sparrow and golden-crowned Sparrow.

The story of one immature female Wilson's warbler illustrates the importance of Camas and nearby Mud and Market Lake wildlife management areas to migration. She was captured at Camas during her fall migration on Aug. 27, 2006. However, that wasn't the first time she had been captured. Three weeks earlier, and 2000 miles to the north, Alaskan researchers in Denali National Park had placed a tiny band on her ankle.

Her stay at Camas was short, but this warbler was able to gather energy to continue her journey. In two days, she rested and feasted on abundant insects found in the tree rows. She increased her body weight by seven percent, enough to carry her through the next leg of her migration.

Once the waterfowl and the shorebirds have moved on, there is a tendency to think that bird migration is over. The Camas report indicates, however, that mid-May through the first week in June is actually the peak of spring migration for many songbirds attracted to Camas. Honing it down even further, this last week of May will likely see the pinnacle of the spring migration.

Migration is repeated in the fall, with the majority of migrating songbirds passing through between early August and late September. The data is less strong here, but indicates the last week of August and the third week in September may be peak times.

Many songbirds only weigh a few grams, yet must migrate hundreds or even thousands of miles between breeding and wintering areas and must have places to refuel and rest. Although the tree rows and shelterbelts at Camas may seem tiny, even inconsequential in this vast eastern Idaho landscape, as stopover habitats they are essential for migrating songbirds and play a role in songbird conservation on a regional and even continental scale. Stopover habitats are like oases in the desert: they are small, but sustain life when nothing else can. It is crucial that we maintain them and even add to them whenever possible. 

Birds like this yellow warbler depend on stopover habitats like the tree rows at Camas NWR to get them all the way home.