Partitioning of Foraging Habitat by Three Kingfishers (Alcedinidae: Cerylinae) along the South Llano River, Texas, USA

Abstract

Current northward expansion of Ringed Kingfisher (Megaceryle torquata) and Green Kingfisher (Chloroceryle americana) into central Texas places them in aquatic systems with the temperate Belted Kingfisher (Megaceryle alcyon). Recent contact among the three species provides an opportunity to assess resource partitioning. A 23.5 km stretch of the South Llano River near Junction, Texas, USA was surveyed to determine seasonal abundance and compare foraging perch characteristics among the species. Data were collected on 7 foraging perch characteristics for 250 kingfisher observations across 26 surveys. Mean encounter rate for Green, Belted, and Ringed kingfishers per river kilometer was 0.48, 0.22, and 0.09, respectively. Green Kingfishers were present year-round, while the Belted and Ringed kingfishers were absent or rare from mid-spring to mid-summer. Characteristics of foraging perches were similar among the species with the exception of perch height, with Green Kingfisher having lower perches (142.3 cm ± 126.6 SD) than both Belted (550.8 cm ± 449.4 SD) and Ringed kingfishers (551.1 cm ± 422.7 SD). Mean perch heights of Green Kingfishers averaged higher during surveys when Belted Kingfishers were absent (210.5 cm ± 191.0 SD, n = 36) compared to surveys when Belted Kingfishers were present (124.0 cm ± 89.1 SD, n = 129).