BLUE RIVER -- Hotter, drier summers are having an impact on some of the migrating songbirds that come to Oregon and Washington to breed each spring.

Oregon Public Broadcasting reports that because of rising temperatures, the areas where hermit warblers can live and find food are shrinking by up to 4 percent each year.

Now researchers with Oregon State University are developing an experiment to track the tiny songbirds through the Pacific Northwest.

OSU researchers have already found that warbler populations declined in areas with young forests but in some cases increased in old growth forests despite the warming climate.

Researchers Hankyu Kim and Adam Hadley are conducting a new experiment to determine why the warblers are doing better in old growth areas.

-- The Associated Press