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2005 Nesting Season <br />During the 2005 field season, Peltier Island was the only colony monitored. Predator <br />deterrents (metal flashing) had been installed on trees within the colony in response to <br />observed raccoon predation in 2004. Efforts were made to increase the sample size by <br />modifying the pattern of camera placement. An additional goal for video surveillance was to <br />assess the performance of metal flashing as a <br />deterrent to mammalian predators in a tree nesting <br />heron colony. Unfortunately, the number of <br />returning herons in 2005 fell approximately 80% <br />below the 2004 population resulting in only about 30 <br />active nests. The greatly reduced colony size placed <br />major limitations on appropriate camera placement. <br />Furthermore, a plan to experimentally manipulate the <br />predator deterrents was abandoned in the interest of <br />protecting as many nests as possible. <br />Figure 12: <br />A juvenile Great Blue Heron forages in the north <br />eastern section of Peltier Lake. This is one of four <br />chicks known to have fledged from the Peltier <br />Island colony during the 2005 nesting season. <br />The Peltier Island colony did experience substantial chick loss during the 2005 <br />season. Predation by raccoons, American Crows (Corvus brachyrhynchos), and Great <br />Horned Owls is thought to have occurred. Two thunderstorms may have accounted for the <br />loss of two chicks. Sibling aggression was confirmed to have accounted for the loss of a <br />large, nearly fledged chick. And finally, mortality due to uncertain causes was also <br />documented. Despite the large number of failed nests, a total of four chicks, from three nests <br />situated in two trees are known to have fledged. These chicks were observed foraging along <br />the shoreline of Peltier Lake during the month of July (Figure 12). This marks the first <br />documented recruitment from the Peltier Island colony since 2003 or possibly 2000. <br />11 <br />