Methods for determining concealment of arboreal bird nests

摘要: Visual estimates of vegetation concealing bird nests have typically been used to assess the importance nest concealment predators. We developed a new method that more accurately quantifies concealment. During breeding season 2001, we took digital pictures 63 from 3 vantage points (1 m above nest, 1 at level and below nest); imported into Adobe Photoshop (Adobe Systems Incorporated, San Jose, Calif.) determined percent by dividing number pixels total pixels. compared this with visual for each 4 authors another counting squares on transparent grid over photographs. Of 45 paired t-tests, 29% resulted in significant differences between individual observer 2 other methods. In contrast, there were no trials using method. also found inconsistencies among methods evaluation depredated nondepredated nests. suggest improves repeatability estimates, thus providing accurate assessment basis which evaluate management decisions.