03/01/2010 Council Packet - Laserfiche WebLink

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upon anthropogenic noise mitigation but did not prevent subsequent colony abandonment or population decline at Peltier Lake. These initial attempts to protect the colony yielded little information useful for determining the cause(s) of abandonment and provided no constructive insights to guide further colony management. Considering its precarious status, a rapid and fairly aggressive intervention was deemed necessary to stem the further decline and possible loss of the Peltier Lake colony. prior management of wader colonies has almost exclusively focused on habitat management However, because these two strategies had previously proven ineffective at Peltier Lake, an alternative plan for predator management was proposed. Two primary approaches for predator management were available: (1) predator exclusion and (2) predator removal. Predator exclusion as a means of wader nest colony management has been rarely used and remains largely untested. Predator removal via trapping and removal of furbearers is problematic for several reasons. Trapping is not an effective means of population control in raccoons (Ratnaswamy et al. 1997, Rosatte 2000, Frey et al. 2003) and Prange et al. (2003) found that whatever small gains were achieved via trapping were quickly lost in the absence of control efforts. This suggests that trapping and removal needs to be an ongoing effort, yet, trapping is not an economically viable management tool (Chesness et al. 1968). From a public relations standpoint, trapping is controversial (Gentile 1987, Andelt et al. 1999); and the possibility of non - target captures, particularly of pets also adds to the challenges associated with predator removal. The Peltier Lake colony resides on public land and pet owners, though not permitted (Anoka County Parks Ordinance #2000 -1), regularly exercised their dogs off -leash on the island (A Von Duyke, pers. observ.). If a pet was injured or killed in a trap, the potential for a strong negative reaction from the community would be high. However, if raccoon densities on the island were low, and if only a few were responsible for most of the predation, and if non - target captures (pets) could be prevented, then trapping could make a difference. Theoretically, through reducing the overall local population of furbearers, some if not all of the raccoons that had presumably become conditioned to exploit heron nests could also be removed. Given the challenges associated with trapping and removal of mesopredators, this predator management option was not utilized for the 2005 season. Predator guards appeared to be the best option. Predator exclusion had no negative connotations and was safe for pets. And if correctly installed, predator guards should operate independently of mesopredator density and with less labor. During the winter of 2004 -05, all trees with intact nests were wrapped at breast height with sheet metal (aluminum roof flashing).