Echolocation behavior and signal plasticity in the Neotropical bat Myotis nigricans (Schinz, 1821) (Vespertilionidae): a convergent case with European species of Pipistrellus ?

Abstract

We used both field and flight cage observations to investigate the echolocation and foraging behavior of the seldom studied, small, aerial insectivorous bat Myotis nigricans (Vespertilionidae) in Panama. In contrast to its temperate congeners, M. nigricans foraged extensively in open space and showed an echolocation behavior well adapted to this foraging habitat. It broadcast narrowband echolocation signals of 7 ms duration that enhance the chance of prey detection in open space. Because of rhythmical alternations of signal amplitude from signal to signal in our sound recordings of search signals in open space, we conclude that the bats scanned their environment with head movements, thereby enlarging their search volume. In edge-and-gap situations, and in the flight cage, M. nigricans introduced an initial broadband component to its search calls. In the field and in the flight cage, M. nigricans hawked for prey in aerial catches; gleaning was never observed. M. nigricans demonstrates call structures, such as narrow bandwidth and rather long signals adapted to foraging predominantly in open space. Moreover, call structure is highly plastic, allowing M. nigricans to forage in edge-and-gap situations also. These adaptations in call structure and plasticity have evolved convergently at least twice within the genus Myotis. Finally, M. nigricans echolocation and foraging behavior parallels that of the small, aerial, insectivorous pipistrelle bats (Vespertilionidae), which are not closely related to M. nigricans but forage in similar habitats.

Tiger moth responses to a simulated bat attack: timing and duty cycle

“…This closely matches the dominant frequency in the biosonar cries of ten insectivorous bats known to occur in the area of Ecuador that we sampled (P. Jarrin, personal communication, from survey at Tinalandia, Eucador) (Albuja-V., 1999): -59.6±23.7·kHz [Tadarida brasiliensis (Simmons et al, 1978) Clicks, number of microclicks in the active modulation half-cycle; intensity, peak equivalent sound pressure level in decibels (dB pe SPL); isi, intra-cycle silent interval. (Belwood, 1988); Molossus molossus (Kössl et al, 1999); Rhynchonycteris naso (Fenton et al, 1999); Myotis nigricans (Siemers et al, 2001); Peropteryx macrotis, Mormops megalophylla, Eptesicus furinalis and Myotis keasyi (Rydell et al, 2002)]. However, this close match in frequency should be interpreted with caution as we have no way of knowing if the bat and moth assemblages were sampled randomly or the predator/prey dynamics between these assemblages.…”

Bat flight with bad wings: is flight metabolism affected by damaged wing membranes?

“…Bats with damaged wing membranes, probably caused by a predator, were encountered during routine mist-netting at daytime roosts of M. albescens and M. nigricans. Both species are common aerialhawking insectivorous bats in lowland regions of the subtropical and tropical region of the New World, where they forage in the open space of rainforest gaps (Siemers et al, 2001;Rex et al, 2008). Bats were captured between 17:00h and 19:00h in front of buildings, using 6 and 9m mist nets (2.5m height, Ecotone, Gdynia, Poland).…”

Echolocation and passive listening by foraging mouse-eared batsMyotis myotisandM. blythii

“…Echolocation is highly adaptable, offering one of biology's most compelling examples of convergent evolution (Siemers et al, 2001;Jones and Teeling, 2006). Echolocation call design is often shaped by environmental factors such as the proximity of clutter, and is therefore related to niche differentiation.…”