Predation on Mexican free-tailed bats by Peregrine Falcons and Red-tailed Hawks

Ya Fu Lee, Yen Min Kuo

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Abstract

We observed Red-tailed Hawks (Buteo jamaicensis) and Peregrine Falcons (Falco peregrinus) hunting Mexican free-tailed bats (Tadarida brasiliensis) during their evening emergence and dawn return at Frio Cave, Uvalde County, Texas in the summer of 1997. Predation by Red-tailed Hawks occurred primarily in the evening (89.5%), and predation by Peregrine Falcons was mostly at dawn (90.5%). In the evening, hawks appeared when large numbers of bats emerged and they attacked at distances >50 m and heights <50 m above the cave. Termination of hunting by hawks in the evening coincided with sunset. In contrast, peregrines hunted for a longer period at dawn when bats returned both in high and low numbers, mostly <100 m of the cave but at various heights. Both species made higher proportions of flights passing by bats without attacking them at dawn (88.9% Red-tailed Hawk and 26.5% Peregrine Falcon) than in the evening (16.4% Red-tailed Hawk and 0% Peregrine Falcon). Hawks had a higher attack rate and capture rate in the evening than at dawn and, in the evening, hawks had a higher capture success than peregrines. At dawn, however, peregrines showed a lower proportion of pass-by flights, a higher attack rate and capture rate, and caught a higher mean number of bats than hawks. Botli species were more successful in catching bats after juvenile bats became volant and began foraging. In total, these raptors took 237 bats (96 Red-tailed Hawk and 141 Peregrine Falcon). We estimated the total number of bats taken between mid-April to mid-October to be about 2153 bats which would have accounted for <0.02% of the total colony.

Original languageEnglish
Pages (from-to)115-123
Number of pages9
JournalJournal of Raptor Research
Volume35
Issue number2
Publication statusPublished - 2001 Dec 1

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All Science Journal Classification (ASJC) codes

  • Animal Science and Zoology

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