06/26/2002 Env Bd Packet - Laserfiche WebLink

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W h.en hundreds of great blue herons vanished from Anoka County, local residents rushed to respond From a vantage point across from Lake Peltier, Art Hawkins bas observed great blue herons for the past three years. On the cover. A great blue heron wades near the island on Lake Peltier. 9 Abandoned Nests: Why Are Great Blue Herons Disappearing from the Northern Metro? by Jennifer Amie Each year around St. Patrick's Day, the great blue herons return to the Rice Crer' chain of lakes, where they have nested since 1945.Their rookery on Lake Peltier island, on the border between Lino Lakes and Centerville in Anoka County, is home to some 200 of the large, majestic birds. he island's maple basswood forest provides the tall trees necessary to support the herons' nests, built from shaggy snarls of twigs and nestled in branches as high as 60 feet off the ground. In spring, the herons work to repair their nests, flying across the lake to gather sticks from nearby fields. In late March or early April, the female birds begin to lay their eggs, which they will tend over the following months. Typically, the herons remain in or around the colony through- out the summer as they raise their young. In mid- September or early October, they begin their southward migration. In March 2000, retired U.S. Fish and Wildlife Service biologist Art Hawkins was preparing for his second season observing the Lake Peltier herons on behalf of the Minnesota Department of Natural Resources (DNR). He set up his spotting scope in a farmer's field across from the lake, watching the birds fly back and forth across the water to fetch twigs and hunt for food. By May, the colony was well- established in what appeared to be a typi- cal nesting season. Then suddenly, in early June, the rookery went silent. Jeff Perry, a natural resources specialist for Anoka County Parks, was among the first to investigate. "We went out to the island in June 2000 and the rookery was quiet. There weren't any noises. It was a forest without any life in it," he recalls. The adult herons had vanished. On the ground beneath their nests, Perry found eggshells that appeared to have hatched, along with the bodies of juvenile birds that had died of starvation. "Everybody was shocked," Perry says. "Quite honestly, we were baffled." What would cause an entire colony of birds to abandon their eggs and hatch - lings? "Whatever it was, it was a massive disturbance," says Hawkins. "Birds are notoriously faithful to their nests during the late stages of incubation or with young to feed, conditions that prevailed when the mass desertion took place."