DOI: 10.5061/dryad.9rb48c5
title: Data from: Subtle changes in elevation shift bat-assemblage structure in Central Amazonia

description: The distribution patterns of animal species at local scales have been
 explained by direct influences of vegetation structure, topography, food
 distribution and availability. However, these variables can also interact
 and operate indirectly on the distribution of species. Here, we examined
 the direct and indirect effects of food availability (fruits and insects),
 vegetation clutter and elevation in structuring phyllostomid-bat
 assemblages in a continuous terra firme forest in Central Amazonia. Bats
 were captured in 49 plots over 25-km² of continuous forest. We captured
 1138 bats belonging to 52 species with 7056 nethours of effort. Terrain
 elevation was the strongest predictor of species and guild compositions,
 and of bat abundance. However, changes in elevation were associated with
 changes in vegetation clutter, and availability of fruits and insects
 consumed by bats, which are likely to have had direct effects on bat
 assemblages. Frugivorous-bat composition was more influenced by
 availability of food-providing plants, while gleaning-animalivore
 composition was more influenced by the structural complexity of the
 vegetation. Although probably not causal, terrain elevation may be a
 reliable predictor of bat-assemblage structure at local scales in other
 regions. In situations where it is not possible to collect local
 variables, terrain elevation can substitute other variables, such as
 vegetation structure, and availability of fruits and insects.
description: Bats, terrain elevation,
 fruits and insects from 49 plots at Reserva Florestal Adolpho Ducke, State
 of Amazonas, Central Amazonia, Brazil.We conducted the study
 in Reserva Florestal Adolpho Ducke (02°55'-03°01' S;
 59°53'-59°59' W; Ducke Reserve hereafter), located on the
 outskirts of Manaus (Km 26 on the AM-110 Highway, Amazonas State, Brazil).
 The reserve is included in the Long-term Ecological Research Program of
 the Brazilian National Research Council (Programa de Pesquisas Ecológicas
 de Longa Duração – PELD/CNPq) and harbors 10,000 ha of mature terra firme
 forest. We captured bats in 49 plots, 24 of which are in riparian areas
 close to watercourses, and 25 in non-riparian areas. We captured bats
 using eight ground-level mist-nets (12×3 m, 19 mm mesh, Ecotone®, Poland)
 per plot between October 2013 and February 2014. Each plot was sampled on
 three non-consecutive nights, totaling 7056 net-hours (1 net-hour = one
 net open for one hour). Nets remained open between 1800 and 0000 h, and
 were checked every 15 minutes. Each captured bat was identified and
 allocated to a foraging guild: gleaning animalivores, frugivores, aerial
 insectivores, nectarivores, and sanguivores. We extracted the terrain
 elevation data for each plot from Shuttle Radar Topographic Mission (SRTM)
 in 90 m resolution rasters images provided by The Global Land Cover
 Facility (http://www.landcover.org). The geographical coordinates used to
 obtain terrain elevations were measured at the midpoint of each plot, and
 we used the ‘Point sampling tool’ from 2.2.0 Valmiera Quantum Geographic
 Information System software (QGIS) to extract the elevation values. We
 actively search for plants with mature fruits in an area of 600 m2 located
 along each plot. We visited each plot three times during daylight hours on
 the days preceding the nocturnal netting sessions in order to find plants
 of the given genera with available fruits on the same night as bat
 captures. Plants with fruits were identified to the genus level and fruit
 availability was quantified as the number of plants with fruits per plot.
 We quantified insect availability as the mass of insects collected by
 light traps, which consisted of 20 cm diameter cones inserted in plastic
 pots of 100 ml containing a 70% alcohol solution and detergent. A
 flashlight with 10 white LED bulbs pointed at the cone was set above the
 cone to attract insects, which were retained in the plastic pot. We
 installed two light traps in each plot, positioned at 65 and 130 m distant
 from the closest mist-net and along the central line of the plot and
 placed at a height of 1.5 m from the ground. The distances between the
 nets and the insect traps minimized the capture of insectivorous bats
 attracted to the light traps. We turned on the light traps at 1800 h on
 bat-capture nights and turned them off after 48 hours. Light traps
 functioned during the day and night, but probably attracted insects only
 at night. Each plot was sampled during two days three times, totaling
 28224 trap-hours (1 trap-hour = one trap lit for one hour). Collected
 insects were dried on filter paper to remove excess alcohol and weighed
 individually on a precision balance (limit of reading 0.0001 g; Ohaus
 Discovery, Pine Brook, New Jersey). To estimate the total mass of insects
 collected in each plot, we combined the six insect-sampling nights of each
 plot. We identified the insects to the level of order.Bats_Ducke_data_metadata.xlsx