New research has assessed bat populations in forests that are managed in different ways and highlighted good management practices for bats

New research, just published in the journal Forest Ecology and Management, has examined bat populations in deciduous forests that are managed in different ways. The work not only reveals the management practices that are good for bats, but also highlights the structural features that are beneficial for individual bat species.

Changes in forest management have been linked to decreases in birds and other wildlife, but little is known about the effects of such changes on our bat populations. All 17 species of bat that breed in the UK use forests and many rely on semi-natural deciduous forests. With increasing pressures on our forests and their bat populations, it is important that we better understand how different types of forest management affect their use by bats.

Lead author Danny Alder used special acoustic recorders to capture echo location and other calls from bats at the study sites. This enabled him to identify the species involved and measure their activity in the various forest habitats. Danny collected data on the structural features of forests, many of which are the result of the management practices used. Characteristics such as the degree of roofing, the size of the trees, the density of the basement and the amount of standing deadwood can influence the suitability of a forest for bats.

Barbastelle Bat, copyright Mark Hows, from the Surfbirds Galleries

Eleven bat species were identified, including the rare barbara site, and there were marked differences between the various types of forest management in terms of bat occupation and activity. ‘Irregular High Forest’, a type of forest in which the forest ecosystem is kept intact through selective felling and characterized by its mixed-size trees and complex structure, had the richest bat community and the highest occupancy rate for most bat species.

The study shows how features associated with irregular high forest stands, such as deadwood, undergrowth structure, open canopy areas, and larger trees, benefited several bat species in different forage guilds. Barbastelle – a low-level collector – had been associated with areas with more open canopies in all different types of inventory management, although the populations were highest in the irregular forest stands. The importance of these and the other highlighted features should be taken into account when considering how best to manage forest areas for bats.

Danny Alder commented, “Through our work we have identified important links between bat species and forest structure, and demonstrated how the management practices associated with irregular high forest promote many of the structural features that positively affect bats. Also importantly, our study shows that an emphasis on non-interference as an appropriate forest management treatment for bat conservation can be misleading without understanding the structural features present. “

Stuart Newson, BTO, commented, ‘Using passive acoustic monitoring to survey bats is not without its challenges. Identification is particularly difficult, not least because bats make a variety of calls and there are great differences between individuals and species. Using the cutting-edge analysis tools developed at BTO was very useful in this project to help identify these difficult species. ‘

Andy Poore commented, “Rushmore Woods is of very high value for biodiversity. For 30 years we have been developing an approach with which this interest can be secured and strengthened in a cost-effective way and which can be used as a supplement to hold-down management traditionally but economically very difficult to maintain. Irregular high forest with integrated undergrowth creates exceptionally complex habitats and it is very encouraging that its value is confirmed by this study. “