Importance of a Low Talus in Location of Bank Swallow (Riparia riparia) Colonies

Abstract

After several years of disuse, bank slumping in a large (395.6 m circumference), roughly circular sand pit had raised the talus to a depth of 2.0 m, reaching to within 0.5 to 0.7 m of the overlying sod. No bank swallows (Riparia riparia) were nesting in this sand pit. Two truckloads of this readily-scooped talus were removed in 1995, creating separate stretches (each about 11 m) in which a shallow new talus (<0.5 m) left 2.0 m to 2.2 m of exposed, vertical bank. In the spring of 1996, bank swallows established colonies in each of these newly exposed stretches and nowhere else. A “roulette wheel” probability model is presented from which the probability that these low talus stretches were selected as colony sites by chance is 0.001.