Altitudinal Patterns in Two Syntopic Species of Sturnira (Mammalia: Chiroptera: Phyllostomidae) in the Montane Rain Forests of Argentina

Abstract

We evaluated altitudinal segregation in two Sturnira species as a mechanism allowing their coexistence. Tests were devised to discern between interspecific interactions and regional responses to geographic and environmental variables, using extensive capture data from 18 montane rain forest sites. No significant correlation between captures was found. Additionally and according to the hypothesis of historical occupation of highland versus lowland forests, each species has shown specificity in their response to the geographical and environmental variables. Our results indicated that abundance patterns in these bats likely result from the regional distribution of each species rather than local interactions between them, a pattern that may have ancient roots within the group.Abstract in Spanish is available in the online version of this article.

Composition, trophic structure and activity patterns of the understory bats of the Bitaco Forest Reserve

“…However, this relationship doesn't always exist or isn't significant (Sánchez and Giannini, 2014). Based on results from the present study, there was no evidence that would suggest that there is an effect of rainfall on the activity level of bats from the understory in the BFR.…”

“…Variations in air temperature are tightly linked to altitude (Graham, 1983;Soriano, 2000), as has been reported in several studies, is one of the environmental factors that strongly influences bat activity levels (O´Farrell et al, 1967;O´Farrell and Bradley, 1970;O´Shea and Vaughan, 1977;Soriano, 2000;Sánchez and Giannini, 2014). The variation in the temperature range registered in BFR was narrow, compared to historical records, which is characteristic of montane environments; however, our results showed that a greater number of individuals were captured at higher air temperatures, which suggests that air temperature had a significant and positive relationship on the activity of understory bats in cloud forests.…”

“…In general, it seems that precipitation increases the energetic cost of flight by creating thermoregulation problems associated with wet fur, and interferes with echolocation and the ability to detect food (Fenton et al, 1977;Voigt et al, 2011;Snell-Rood, 2012). Nevertheless, Sánchez and Giannini (2014) did not find a significant relation between the activity of frugivorous bats and rainfall.…”

“…For frugivorous bats, Sánchez and Giannini (2014) found that Sturnira lilium and Sturnira erythromos exhibited particular and contrasting responses to changes in temperature across and elevational range. Sturnira lilium captures increased at sites with high-temperature, whereas S. erythromos captures increased at sites with low mean annual temperature and narrow mean monthly temperature range, which characterize montane environments.…”

Structure of three subtropical bat assemblages (Chiroptera) in the Andean rainforests of Argentina

“…Because flight is a very expensive type of locomotion (Norberg 1995), resource availability may limit bat activity; for example, frugivorous bats reduce their foraging activity to preserve energy during periods of food scarcity (Ramos Pereira et al 2010). Climatic conditions may be determinant of abundance or presence of some species; for example, temperature range, maximum temperature of the warmest month and annual mean temperature determine the altitudinal distributions and abundances of Sturnira lilium and S. erythromos in the Yungas (Sánchez and Giannini 2014). Temperature seasonality is important in determining the latitudinal richness of Phyllostomid bats in the Atlantic forest (Stevens 2013).…”