Comparison of the Foraging Activity of Bats in Coniferous, Mixed, and Deciduous Managed Forests

Abstract

The aim of this study was to compare the foraging activity of bats in coniferous, deciduous, and mixed forests and to test whether this activity was subject to seasonal variation. Sample points were selected in stands of similar spatial structure in coniferous (Pinus sylvestris L.), in mixed (Pinus sylvestris and Quercus petraea (Matt.) Liebl.), and in deciduous (Quercus petraea) managed forests in western Poland. Bat calls were recorded using automated ultrasound recording devices (Batcorder 3.0, ecoObs, Nürnberg, Germany) during five consecutive nights from May to September in each of the six stands. A total of 4,250 bat passes were recorded. Overall, 63.1% of bat passes were identified to species, 31.6% were identified to genus or sonotype group, and 5.3% remained unidentified. In total, eight species of bats and seven sonotype groups were recorded. The dominant species in all types of forests were Pipistrellus pygmaeus (44.5% of recorded bat passes), followed by Nyctalus noctula (10.3%) and Pipistrellus nathusii (5.7%). There were no significant differences in the total activity of bats between the three types of forests; however, high seasonal fluctuations in bat foraging activity were found. This study demonstrates that when coniferous, deciduous, and mixed stands with similar spatial structure are compared, forest type does not affect the foraging activity of bats.

Exceptionally Uniform Bat Assemblages across Different Forest Habitats Are Dominated by Single Hyperabundant Generalist Species

“…The available acoustic data on forest bat assemblages in lowland Poland are scarce, restricted to just a few woodland areas [13,17,[66][67][68], making broadscale comparisons, including cluster analysis, virtually impossible. Thus, we restricted our clustering test solely to capture data, as they are available in numerous locations in all geographical regions, usually collected as a basis for local bat surveys (Table S2).…”

“…To our knowledge, the only other forest in the Central European nemoral zone where P. pygmaeus has been recorded as dominating in all sampled habitats is Włoszczakowice Forest District in western Poland. P. pygmaeus accounted for 42-48% of echolocation call sequences there, depending on the forest type [17]. The species might, however, predominate in some extremely depauperated bat assemblages, for example, in northeast Scotland [71].…”

“…These species are adapted to these distances through different wing shapes, flight speed, and maneuverability [11], but also echolocation call designs [12]. The strong variation in the structure of forest bat assemblages is also caused by the tree stand age [13,14], level of natural and human-made disturbance [15], proportion of particular tree taxa [16,17], volume of deadwood [18], elevation [15], size of forest patch [19], location within the patch [20], and land cover adjacent to its borders [14]. As the bat faunal size correlates with the availability and diversity of roosts [21], while even closely related and morphologically similar species differ in roost selection [22,23], the structure of bat assemblage foraging in woodlands might be expected to result from the presence or absence of particular roost types, either within the forest or in its close neighborhood.…”