Echolocation and feeding behaviour in four species of Myotis (Chiroptera)

We have compared the echolocation and feeding behaviours of Myotis lucifugus, M. californicus, M. volans, and M. auriculus based on observations and recordings of bats in the field. Myotis lucifugus and M. californicus appeared to detect prey at close range (≤ 1 m) and regularly made several attempts to capture insects over short distances; both used similar frequency-modulated echolocation calls. Myotis volans detected prey at greater distances (5–10 m), made only one attempt to capture insects per pass through a feeding area, and used an echolocation call with a distinct constant-frequency component. Myotis auriculus fed mainly on resting insects, mostly moths. The echolocation calls of this species were of shorter duration, lower intensity, broader frequency range with a higher frequency of maximum energy, and showed an initial upward sweep in frequency relative to the calls of the other Myotis we studied. Myotis auriculus did not increase their pulse repetition rate as they closed with stationary prey, and they appeared to fix on resting insects from about 2 m. This species rarely made more than one attempt to capture an insect per pass through a feeding area.