Perch site selection by reintroduced peregrine falcons Falco peregrinus

As part of a program to recover the peregrine falcon Falco peregrinus in the southeastern U.S. we recorded perching behaviour with the objective of characterizing perches used in the reintroduction area. We used a site-attribute design and logistic regression to compare characteristics between used and non-used perches. Peregrines used pines Pinus spp. exclusively, while pines comprised 78% of available trees. Perches were larger than non-used trees (diameter at breast height in cm (in R SD); 29.2 +/- 15.7 and 23.9 +/- 10.3), in more advanced stages of decay (2.5 +/- 1.5 and 1.5 +/- 1.1 (index)), and usually dominant in crown class (1.5 +/- 0.6 and 1.7 +/- 0.5 (index)). Perches were always on cliff plateaus and tended to be situated in sites with a less even canopy (0.5 +/- 0.3 and 0.7 +/- 0.2 (index)) and fewer deciduous stems (1.8 +/- 3.4 and 2.3 +/- 2.3 (stem density)) than nonused trees. These attributes depict selection of perches that provide unobstructed flight paths, good visibility, and a capacity to detect and respond rapidly to stimuli.