INTRODUCTION

Greece hosts 36 out of the 46 bat species (Chiroptera) of Europe. All bat species are strictly protected under the Habitat Directive (92/43/EU, Annex IV), while 13 are also included in Annex II of the same directive. Two of those species, Barbastella barbastellus and Myotis bechsteinii, are also Special Areas of Conservation characterization species, due to their strong dependence on mature and dead trees, the loss of which is threatening their populations. Bats play a significant role in ecosystems as they are top night predators. The fact that they consume high numbers of insects, many of which are parasites for agriculture or an annoyance to humans, also makes them useful to us. Calculations in the USA estimate that the value of bats for agriculture ranges between 3.7 to 53 billion dollars per year, the equivalent amount that would have been spent on pesticides (Boyles et al. 2011). More than 1,400 bat species exist in the world, most of them being insectivores, while many feed on fruits, seeds, and nectar, thus playing a crucial role in plant pollination, agriculture and forest regeneration.

Agroforestry systems host a significant number of strictly protected bat species

Bats And Agroforestry Systems

Agroforestry systems are used by the majority of bat species of Greece for food and possibly also for roosting and reproduction, when they include old and dead trees or other types of roosts (caves, mines, rock crevices) or simply for commuting to other roosting or feeding sites, as this kind of habitat improves landscape connectivity. Landscape elements, such as hedgerows, help bats in navigating from one habitat to another. The value of agroforestry systems increases when they include water bodies, such as creeks, permanent or temporary ponds as bats visit them for drinking water and preying on insects that emerge from water or live in the riparian zone. Even cattle troughs can be valuable for bats, especially in areas with limited water.

On islands, forests and agroforestry systems feature relatively high bat species diversity and are preferred by species that on the mainland depend on other habitat types, such as wetlands (Kafkaletou-Diez et al. 2022, Davy et al. 2007). Especially in areas like Crete, where undisturbed, especially wooded, surfaces are rare, the significance of agroforestry systems is even higher, as they support an important number of bats, not only of forest-dependent species but also more generalist ones. At least 14 of the 17 Cretan bat species occur in agroforestry systems with 13 species recorded in mixed forests (pine, cypress, prickly oak, etc) and 12 in prickly oak (Quercus coccifera) forests. Pine and cypress forests have fewer species (9 and 7 respectively) (Benda et al. 2019). Forested areas have a higher abundance of bats than shrublands, olive groves and settlements in Crete, and come second – in terms of bat abundance – after the wetlands with rich woodland vegetation (Georgiakakis 2009).

Pipistrellus hanaki is a unique species of forest-dwelling bats found in Crete, that also occurs only in Cyrenaica, Libya (Benda et al., 2004; Hulva et al, 2007). It uses a variety of roosting sites (rock crevices, buildings, tile roofs, electricity pillars, cracks, and tree hollows), but feeds almost exclusively around mature trees at 3 km radius from the roosts. The species is abundant in mature clumps of the species Quercus coccifera, Q. ilex, Q. macrolepis, Q. pubescens, and Acer sempervirens, but also in areas with mixed cultures of Ceratonia siliqua, Olea europaea and various Prunus species, like in creeks with Platanus orientalis, Castanea sativa, etc (Georgiakakis et al., 2018). It is worth mentioning that the occurrence of Nyctalus leisleri in Crete has been found only in two sites in the Chania Regional Unit, both in creeks with chestnut and plane trees. Other potentially suitable sites on the island for the species are mainly forested areas or/and wetlands (Benda et al., 2019).

Agroforestry systems are also important for Rhinolophus hipposideros, a species which uses mosaics of agroforestry and agrosylvopastoral areas. It is threatened in Mediterranean countries due to the abandonment of traditional agroforestry practices, pesticides, intensive agriculture and the destruction of old houses (Papadatou et al. 2011). In olive groves, not only species numbers but also bat activity is reduced with the increase of the intensity of cultivation processes. Large monocultures seem to be used by bats mainly for commuting rather than feeding (Herrera et al. 2015), which shows that bats need mosaic landscapes and traditional agricultural practices.