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took place prior to the 2008 nesting season. Nest fate data (Table 6) demonstrated that active nest trees with no predator guards were extremely vulnerable to predation and had a very low probability of success. Discussion Colony status Survey data demonstrated that, while brood size has remained consistent at Peltier Lake since 2005 (Figure 31D), the ratio of fledglings to chicks detected has increased and overall chick survival (i.e., number of fledglings per nest) has increased significantly. Predator guard performance Initially, the results of this methodology were unsatisfactory. In 2005, widespread nest failures and scratch data, collected during end of season surveys, suggested that the climbing ability of raccoons was underestimated. Given the decreasing proportion of successful climbs per attempt, refinements to the tree guarding techniques appear to have made some difference. This reduction in climbing success was not significant however, which underscores the challenge of colony -wide tree protection. Additionally, scratches on the flashing likely underestimated raccoon climbing success given the forest density, the abundance of climbing routes available, and raccoon Table 6 - Fate of nests in unguarded trees. (A) Over four seasons, all nine unprotected trees (i.e., no predator guards) that were occupied by herons failed to produce fledglings. (B) In contrast, over the same time period, 53.2% (n = 58) of active protected trees produced 136 fledglings Number of nests 1200 1000 800 600 400 200 12 8 c1 0 co c- 120 70 r 500 600 1137 554 625 ri N M cr it lD N 00 cl c C1 c1 c1 c1 cl o Ql 01 cl c, cl c1 Cr) c1 Q1 c1 cl e-i ri .--I r-I e-i ri r1 r-1 r-I Year 696 o Success ■ Abandonment ® Partial success 545 300 300 O 180 0 .--1 N CO cf 0 0 0 0 0 0 0 0 0 0 N N N N N