Edge effects and vertical stratification of aerial insectivorous bats across the interface of primary-secondary Amazonian rainforest

PLoS One. 2022 Sep 23;17(9):e0274637. doi: 10.1371/journal.pone.0274637. eCollection 2022.

Abstract

Edge effects, abiotic and biotic changes associated with habitat boundaries, are key drivers of community change in fragmented landscapes. Their influence is heavily modulated by matrix composition. With over half of the world's tropical forests predicted to become forest edge by the end of the century, it is paramount that conservationists gain a better understanding of how tropical biota is impacted by edge gradients. Bats comprise a large fraction of tropical mammalian fauna and are demonstrably sensitive to habitat modification. Yet, knowledge about how bat assemblages are affected by edge effects remains scarce. Capitalizing on a whole-ecosystem manipulation in the Central Amazon, the aims of this study were to i) assess the consequences of edge effects for twelve aerial insectivorous bat species across the interface of primary and secondary forest, and ii) investigate if the activity levels of these species differed between the understory and canopy and if they were modulated by distance from the edge. Acoustic surveys were conducted along four 2-km transects, each traversing equal parts of primary and ca. 30-year-old secondary forest. Five models were used to assess the changes in the relative activity of forest specialists (three species), flexible forest foragers (three species), and edge foragers (six species). Modelling results revealed limited evidence of edge effects, except for forest specialists in the understory. No significant differences in activity were found between the secondary or primary forest but almost all species exhibited pronounced vertical stratification. Previously defined bat guilds appear to hold here as our study highlights that forest bats are more edge-sensitive than edge foraging bats. The absence of pronounced edge effects and the comparable activity levels between primary and old secondary forests indicates that old secondary forest can help ameliorate the consequences of fragmentation on tropical aerial insectivorous bats.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biodiversity
  • Chiroptera*
  • Conservation of Natural Resources
  • Ecosystem
  • Eulipotyphla
  • Forests
  • Rainforest*
  • Trees

Associated data

  • Dryad/10.5061/dryad.0vt4b8h2d

Grants and funding

Funding was provided by the Portuguese Foundation for Science and Technology to CFJM (PTDC/BIA-BIC/111184/2009), RR (SFRH/BD/80488/2011 and 2020.01129.CEECIND/CP1601/CT0004) and A.L.-B (FCT PD/BD/52597/2014). P.E.D.B. was supported by a postdoctoral scholarship provided by the FIXAM/FAPEAM (Edital 17/2014) and PNPD/CAPES (#88887.370067/2019-00). NY and JC were funded by the Natural Environmental Research Council (NERC) through the EnvEast DTP scholarship (grant number NE/L002582/1) and ARIES DTP scholarship (grant number (NE/S007334/1). Additional funding was provided by Bat Conservation International student research fellowships to AL-B and Fundação Amazônica de Defesa da Biosfera (FDB) to P.E.D.B. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. This research constitutes publication number 852 in the BDFFP technical series.