3. Foraging habitats in forests

#### 3.1. The importance of forests as feeding opportunities

The literature is rich in identifying the main forest characteristics utilised by most European bat species [2, 6], as forests undoubtedly remain complex environments offering foraging habitats for these species, even when insect populations fluctuate. Studying forest habitats rather than prey abundance can thus contribute to a greater understanding of foraging behaviours [52, 53]. Regardless of the species, certain forest habitats are more attractive than others, broadleaved forests above all [50, 54–59]. It is therefore difficult for a forest manager to apply bat-friendly practices without a precise description of the factors determining habitat selection. According to the numerous studies, forest management causes changes (in terms of the composition and the structure of a forest stand) that are either acceptable or not for bats, as foraging behaviour may be jeopardised [60]. Logging forests for timber production may therefore reduce a colony's ability to sustain itself due to a lack of feeding resources [60, 61].

#### 3.2. Favourable forest stands

At the bat community level, the silvicultural parameters that best explain the selection of certain forest habitats are that of structure, composition, and the quantity of foliage among other elements beyond the stand itself.

The maximal diameter of trees, different from stand age (but related) generally translates to a forest stand of overmature trees with the presence of microhabitats [10]. Microhabitats can even serve occasionally as refuge for bats that forage several kilometres from their roosting site, when weather conditions dramatically change [31]. Indeed, old forest stands are the most important habitats for bats as they offer a great potential for roosting [31, 60]. In a diverse forest landscape, bats will predominantly select broadleaved tree stands dominated by oaks and tend to avoid conifers [31]. This is in direct response to the entomological richness associated with these tree species [62]. Native Quercus spp. have the highest number of dependent insect species including various orders of saproxylics as well as defoliators (Coleoptera, Lepidoptera, Heteroptera, etc.). They are followed by Betula spp. which can sometimes have a greater number of individuals present but have less taxonomic groups associated with Salix spp., Crataegus spp., Prunus spp., and Populus spp. The first conifer species is Pinus sylvestris before Fagus spp. and Picea abies [63]. Moreover, the more the forest habitat is diversified, the more the insects' emergence is spread over time. For example, defoliators commonly emerge at different times in accordance with shade-tolerant and shade-intolerant trees [19]. In addition, a diversification of accompanying tree species and a strong presence of forest gaps in mature conifer plantations can have a positive impact on bat activity [64, 65], with bats contributing significantly to the control of insect pests in forests [66]. Furthermore, a higher density of vegetation and a greater heterogeneity from the ground to the canopy appear to increase bat species richness. Myotis bechsteinii principally forages within the dense canopy [31, 67] whereas Myotis myotis is a specialist of bare ground-dwelling prey [68]. Indeed, a complex structure of the forest with dense foliage, depressions, protuberances, and other ecotones is favourable to the development of different thermal and hygrometric conditions, the source of high entomological production [23, 69]. This can result in a higher activity of hawkers and gleaners [59, 70–72]. The latter forage for prey by gleaning insects from the substrate in dense foliage, while the former requires open spaces, such as forest clearings, paths, corridors, and edges even though they mainly hunt insects dependent on foliage [59, 70, 71]. Hence, the more diverse a forest is in composition, structure, and stratification, the higher bat species abundance and species richness will be [2]. Finally, additional forest environments such as streams and ponds, which present drinking sites for all individuals, also favour the occurrence of forest-dwelling bats [6, 7].
