Small mammals from the Seasonally Dry Tropical Forests of the Huallaga river basin and new records for San Martín department, Peru

The Seasonally Dry Tropical Forests in Peru are well known for their bird and plant diversity and endemicity, but little is known about the diversity of small mammals. We report the diversity of small volant and non-volant mammals from the Seasonally Dry Tropical Forests of the Huallaga river basin in the San Martín Department, working on both sides of the river, making a sampling effort of 3060 traps-night for non-volant and 104 mist nets-night for volant mammals. We recorded 29 species, including five marsupials, three rodents, and 21 bats. Among the bats, phyllostomids were the most diverse group with 16 species. Short-tailed Spiny-rat, Proechimys brevicauda (Günther, 1877) and Seba's Short-tailed Bat, Carollia perspicillata (Linnaeus, 1758), featured the highest relative abundance. In addition, we report the first records for the San Martín Department of Peropteryx macrotis (Wagner, 1843), Saccopteryx bilineata (Temminck, 1838), Lonchorhina aurita Tomes, 1863, Vampyriscus bidens (Dobson, 1878), and Myotis simus Thomas, 1901. The species richness and diversity indices indicate the study site has a high diversity value; however, fragmentation and rapid changes in land-use are the main threats faced by the biodiversity of these dry forests.

REFUGIOS Y SITIOS DE PERCHA DE Saccopteryx bilineata Temminck, 1838 (Chiroptera : Emballonuridae) EN EL CARIBE COLOMBIANO

Saccopteryx bilineata is a bat of wide geographical distribution in the Neotropics, but in Colombia there is very little information about its biology and roost ecology. This contribution presents a description of the shelters that S. bilineata uses in the Colombian Caribbean region, especially in areas of tropical dry forest. Although it has been documented that it shares shelters with many species of bats, this work presents the first record where S. bilineata shares refuge with Molossus molossus and the use as shelters or roosting sites of species of Brownea ariza, Caesalpinea coriaria and Ceiba pentandra. The high ecological plasticity of the species is ratified in terms of the use of available environments and shelters, as well as cohabiting with other bat species.

Temperature, rainfall, and moonlight intensity effects on activity of tropical insectivorous bats

The extrinsic factors that most influence animal activity are weather and light conditions, which can be assessed at hourly, monthly, and even lunar-cycle timescales. We evaluated the responses of tropical aerial-insectivorous bats to temperature, rainfall, and moonlight intensity within and among nights. Temperature positively affected the activity of two species (Cormura brevirostris and Saccopteryx bilineata). Moonlight reduced Myotis riparius activity and increased the activity of Pteronotus rubiginosus and S. leptura. Rainfall can promote an irregular activity peak during the night compared to nights without rainfall, but the bats in our study were not active for a longer time after a rainfall event. Our findings indicate that moonlight and temperature are the variables with the highest impact on the activity of tropical insectivorous bat species and that some species are sensitive to small variations in rainfall among and within nights.

General isochronous rhythm in echolocation calls and social vocalizations of the bat Saccopteryx bilineata

Rhythm is an essential component of human speech and music but very little is known about its evolutionary origin and its distribution in animal vocalizations. We found a regular rhythm in three multisyllabic vocalization types (echolocation call sequences, male territorial songs and pup isolation calls) of the neotropical bat Saccopteryx bilineata . The intervals between element onsets were used to fit the rhythm for each individual. For echolocation call sequences, we expected rhythm frequencies around 6–24 Hz, corresponding to the wingbeat in S. bilineata which is strongly coupled to echolocation calls during flight. Surprisingly, we found rhythm frequencies between 6 and 24 Hz not only for echolocation sequences but also for social vocalizations, e.g. male territorial songs and pup isolation calls, which were emitted while bats were stationary. Fourier analysis of element onsets confirmed an isochronous rhythm across individuals and vocalization types. We speculate that attentional tuning to the rhythms of echolocation calls on the receivers' side might make the production of equally steady rhythmic social vocalizations beneficial.

Emballonuridae Gervais, 1855 (Chiroptera) of Reserva Biológica de Saltinho (Atlantic Forest), in Brazil, revealed by echolocation

Seventeen species of emballonurid bats are known in Brazil, but their distribution is often determined by patchy records. However, due to almost species-specific calls, echolocation can help to refine the distribution of emballonurids. Here we use acoustic samplings to assess and complement the list of emballonurids of Reserva Biológica Saltinho, an important Atlantic Forest remnant in Pernambuco state, Northeastern Brazil. We positively matched calls of Saccopteryx bilineata (Temminck, 1838) that was foraging along forest edges. However, a series of calls significantly different from those emitted by S. bilineata indicate the presence of a second Saccopteryx sonotype in the area. The lower frequencies in this sonotype presumably came from a larger species, indicating the possible existence of an undescribed cryptic species of Saccopteryx. We also detected Centronycteris maximiliani (Fischer, 1829), recorded 35 years after its first record in Pernambuco, and an undetermined species of Peropteryx Peters, 1867. Our data proved that echolocation is a very useful technique for inventorying poorly known and hard-to-capture emballonurid species, with the potential to reveal the cryptic richness.

Responsiveness to conspecific distress calls is influenced by day-roost proximity in bats ( Saccopteryx bilineata )

Distress calls signal extreme physical distress, e.g. being caught by a predator. In many bat species, distress calls attract conspecifics. Because bats often occupy perennial day-roosts, they might adapt their responsiveness according to the social relevance in which distress calls are broadcast. Specifically, we hypothesized that conspecific distress calls broadcast within or in proximity to the day-roost would elicit a stronger responsiveness than distress calls broadcast at a foraging site. We analysed the distress calls and conducted playback experiments with the greater sac-winged bat, Saccopteryx bilineata , which occupies perennial day-roosts with a stable social group composition. S. bilineata reacted significantly differently depending on the playback's location. Bats were attracted to distress call playbacks within the day-roost and in proximity to it, but showed no obvious response to distress call playbacks at a foraging site. Hence, the bats adapted their responsiveness towards distress calls depending on the social relevance in which distress calls were broadcast. Distress calls within or in proximity to the day-roost are probably perceived as a greater threat and thus have a higher behavioural relevance than distress calls at foraging sites, either because bats want to assess the predation risk or because they engage in mobbing behaviour.