Vertical stratification in bat assemblages of the Atlantic Forest of south-eastern Brazil

Abstract

Abstract:Tropical forests are three-dimensional spaces with species and resources heterogeneously distributed. The vertical stratification of tropical forest biotas has been observed for several organisms and regions, but, surprisingly, the vertical structuring of large areas of important tropical forests, such as Brazil's Atlantic Forest, remains poorly studied. Here, we addressed the use of different Atlantic Forest strata by bats, comparing ensemble composition and relative abundance between the understorey and the canopy. A total of 618 bats belonging to 31 species and four families were recorded, including 11 species of frugivores and seven species of gleaning insectivores, the two trophic guilds predominantly represented in our sampling. Fifteen species were captured exclusively in the canopy, and six exclusively in the understorey, and many of those species were represented by a low number of captures (<5). The bat species composition, richness and relative abundance between canopy and understorey strata varied.Chiroderma villosumwas exclusively captured in the canopy,Artibeus lituratuswas netted predominantly in the canopy andCarollia perspicillataandDesmodus rotunduswere mostly captured in the understorey. Although processes such as resource partitioning between species and ecomorphological constraints may explain the differential use of forest strata, this remains little understood because of the scarcity of data for the Atlantic forest canopies.

Use of forest strata by bats according to wing morphology and habitat complexity in a fragment of tropical dry forest (Colombia)

“…These species have also been recognized as understory foragers in previous studies, regarding wing characteristics and resource specialization, two elements that are complementary for explanatory purposes in this context (Rex et al 2011). The results of this study provide broad support to other authors' observations (Simmons & Voss 1998, Cosson et al 1999, Bernard 2001, Kalko & Handley 2001, Rex et al 2011, Gregorin et al 2017, which indicate that bats intensively use different layers of the forest, from the ground to the canopy level. As such, the integrity and complexity of the forest are important factors affecting the composition, abundance, and probably the function of bat assemblages.…”

“…This study could be complemented with acoustic monitoring for the inclusion of the aerial insectivores (mostly vespertilionids and emballonurids) for a more representative sample. However, we proved that the use of canopy and understory mist nets is very important when conducting bat inventories in highly diverse tropical forest (Pereira et al 2010, Rex et al 2011, Gregorin et al 2017).…”

“…In addition, these frugivore species often carry fruits equivalent to 40% of their body weight, these aspect ratio values may potentially compensate the effort of transporting these great loads, enabling them to reduce their speed when flying through vegetation (Norberg & Rayner 1987). The species of genus Artibeus are commonly captured in neotropical forests in all vertical stratum, but it is generally assumed that large species, such as A. lituratus, are canopy-foragers (Voigt 2010, Rex et al 2011, Gregorin et al 2017).…”

“…Fig-eating bats with larger body mass usually harvest fruits in the canopy, suggesting that the fruit type consumed also exerts strong pressure on the vertical distribution of bat species (Voigt 2010). Studies performed by Bernard (2001), Kalko & Handley (2001), Pereira et al (2010) and Gregorin et al (2017) suggested that U. bilobatum is specialized in canopy foraging as they are consumers of Ficus spp. commonly located in the canopy and subcanopy layers (Handley 1991, Kalko et al 1996, Calonge 2009).…”

Effects of Forest Fragmentation on the Vertical Stratification of Neotropical Bats

“…60% of all known animal and plant species in only 8% of the planet's surface [1]. This diversity is largely mediated by the complex stratification and multidimensionality of tropical forest canopies, which allow for additional niche space and facilitate the coexistence of a large number of species in the same geographical area [2][3][4]. However, biological assessments across the tropics tend to be largely limited to understory-level surveys that under-represent species associated with higher forest strata [5].…”