FOOD HABITS AND RESOURCE PARTITIONING IN A GUILD OF NEOTROPICAL SWIFTS

The Coastal Cordillera of Venezuela has a rich avifauna including swifts. The aerial arthropod prey of three species found there, Gray-rumped Swift (Chaetura cinereiventris), Vaux's Swift (Chaetura vauxi), and White-tipped Swift (Aeronautes montivagus), included spiders plus nine orders and 110 families of insects. Diptera and Hymenoptera were the most numerous prey taxa (>60%) taken by all three swifts. Prey size ranged from 0.5-17.9 mm body length, and averaged 2.69 mm for Gray-rumped Swifts, 2.91 mm for Vaux's Swifts, and 5.52 mm for White-tipped Swifts. Niche breadth was similar in Gray-rumped and Vaux's Swifts (2.4 and 3.13), and niche overlap was also high (0.98). Niche breadth was higher in White-tipped Swifts (8.49) and niche overlap was <60 with both Gray-rumped and Vaux's swifts. Observed elevational differences in foraging habitat and altitudinal foraging zones are proposed as resource partitioning mechanisms for this guild of sympatric aerial insectivores.