Migrating sparrows tracked to Alaska Colored areas show the breeding ground of four sparrow in the PRBO tracking study. Credit: Point Reyes Bird Observatory PETALUMA, Calif., April 11 (UPI) -- New tracking technology has been used for the first time to follow sparrows on their migration from California to Alaska, researchers say. Using tiny tracking tags to track a bird's location, biologists from the Point Reyes Bird Observatory in Petaluma, Calif., have unlocked the mystery of where golden-crowned sparrows, which spend winters in California, go to breed in the spring. The observatory's scientists attached small tags that record day length to sparrows wintering in and near Point Reyes National Seashore before they headed north on spring migration. When the birds returned the following fall, four tagged birds were safely recaptured, the tags were removed, and the data downloaded to a computer, a release issued by the observatory Tuesday said. Each bird, which weighs just slightly more than an ounce, migrated from 1,600 to 2,400 miles one-way to their breeding grounds. Their individual breeding locations spanned about 750 miles along the coast of Alaska, researchers said. "This study is helping to unravel the mystery of bird migration and answer the age-old question of where birds go, which helps protect habitat along their entire migratory journey," lead author Nat Seavy said. The breeding locations for the four birds included areas of Katmai National Park, Wrangell-St. Elias National Park and the Chugach National Forest. "Until now, all we knew was that these birds bred far to the north and undertook one of the longest migrations of all songbirds that winter in central California," observatory researcher Diana Humple said. We're very excited to finally pinpoint exactly where some of our golden-crowned sparrows breed.