03/11/2002 Council Minutes - Laserfiche WebLink

Home Search

COUNCIL MINUTES MARCH 11, 2002 heron's critical nesting period, April 1 to mid to late June, in 1997, 1998, 1999, 2000 and only once in 2001, he believed there was some other reason. He presented the City Council with a summary chart of the lake's history. Mr. Lindner noted one food source of the herons in the British Columbia rookery is black bullheads, which is similar to the Lake Peltier rookery. He believed this food source is decreasing with the introduction of game fish, which are eating black bullhead eggs and young (comprised to be the highest species, 60 percent, of fish in Lake Peltier, based on a 1997 Department of Natural Resources survey) in Lake Peltier and Centerville Lake. Herons and egrets have begun to search in larger areas for food. Additionally, herons have been noted to feed from dusk to midnight, and again in the early morning. He felt that this could explain why Custer did not see herons feeding at Trout Air. Mr. Lindner noted bald eagles had been removed from the endangered/threatened species list in 1999. From a 1998 survey, bald eagles have increased eight fold sinc- 1972. He and his neighbor have noted the presence of a number of eagles that live on, and arou ltier Lake. Additionally, his neighbor, Dick Hansen, made the following observations of ea: eron activity in his front yaid: "Often, eagles frequently land on my large cottonwood tree . shore. When they fly in, my resident heron departs from my dock only to return when t g as left." Mr. Lindner indicated the Great Blue Heron article frew Peltier Island Heron Rookery Task Force packet referenced predatory behavior by bald eagles On sday, March 7, 2002, he discovered at the University of Minnesota library numerous art biting a past history of heron rookeries being ransacked, food stolen, herons attacked, n mature herons taken from their nests, and herons killed and used by the eagles for food. ee-year study stated what happened in a Coquitlam Rookery in New England, whe f bald eagles nested near the colony, nearly identical to the Peltier Lake colony. He ted, 'a pair of bald eagles nested in the center of the Coquitlam colony and apparently cauplete abandonment, even though some eggs were laid...In the Pener Harbour colony.speared to be using the heronry as a free lunch counter. Several times durinhat s _ eagles were seen to take young birds from nests, and occasional predation on adult c The heronry remained unoccupied, but occasional disturbance by the eagles cause " e a• ult herons to leave the colony for much longer periods than would usually be the case. This 1 permitted predation by ravens. Ravens took eggs and young birds. They would knock nestlings to the ground where they would eat the entrails...In the Crescent colony, it was abandoned after egg laying, perhaps because of nearby nesting eagles, and the herons did not return in subsequent years. Crows apparently destroyed the abandoned eggs..." Mr. Lindner noted another independent study by Donald Norman in 1989 documents eagle incursions where "The eagle ripped apart and consumed at least two chicks approximate three weeks old...in addition to our observations, we received reports of eagle -heron interactions by local residents for seven of the eight colonies studied. Residents near the Powell River colony repeatedly observed adult eagles carrying heron chicks towards the eagle's nest. No young fledged from the Powell River colony, even though eight of eleven nests observed weekly were known to contain chicks. This suggests that eagle predation is more widespread than our two documented cases. Eagles can also cause adult herons to leave nests, leaving eggs and small young vulnerable to chilling and predation by corvids. Eagles may be an important factor affecting heron productivity." Mr. Lindner believed 11