Case Study: Managing Farmland for Grey Long-eared Bats

Author: Craig Dunton, Grey long-eared bat Project Officer, Bat Conservation Trust

Species: Grey Long-eared bat:

© Craig Dunton/www.bats.org.uk

 

Why is farmland important for this species?

With as few as 1000 individuals In the UK, the grey long-eared bat is one of our rarest mammals. Their distribution is restricted to the southern coast (Devon, Dorset, Somerset, Hampshire, Isle of Wight and Sussex) and there are only 9 known maternity colonies; meaning that this species is on the brink of extinction in this country. Currently, work is being carried out to conserve this species as part of 'Back from the Brink' – a Heritage Lottery funded conservation project aiming to save 20 species from extinction. https://naturebftb.co.uk/

Farmland is vitally important to all bat species. 70% of land in the UK is used for agriculture, so for very mobile species that utilise the whole landscape, farming practices can have significant impacts on bat populations. Some bat species are more resilient than others, but for those that have very low populations, are particularly sensitive to light and disturbance, and have very specific habitat requirements, there are significant threats to their survival.

Like all bats, the grey long-eared bat needs some key elements throughout its range in order to survive and thrive.

Roosts: Bats utilise a wide variety of structures to roost in, as their requirements change throughout the year. Roosts are needed for different activities – hibernation roosts, maternity roosts, night feeding roosts (for some bats) – these are all needed at different times of the year, and different bat species choose different structures for different activities.

Many bats hibernate underground, using caves, mines, cellars and tunnels that have a cool and constant temperature that bats need to hibernate. Many farms have these types of features, so it is important to be aware of their importance for bats. Some bats roost in a variety of different tree features; cracks, splits, woodpecker holes, loose bark – so it is important to retain trees that have ‘interesting’ features.

Grey long-eared bats are mostly associated with man-made roosts – usually the roof spaces of large, traditional, stone buildings with slate roofs. There are some records of them using caves and rock crevices, but no records of them using bat boxes in England.

Many buildings on farms can provide important roosts for grey long-eared bats, particularly large stone buildings with slate roofs and large, open roof voids. These can provide vital maternity roosts, temporary day and night roosts and opportunities for hibernation. As all bat species are protected, if you are planning to carry out any work that might impact bats or their roosts, the National Bat Helpline will point you in the right direction, please email enquiries@bats.org.uk

Foraging sites: As with roosts, different species of bats have different types of habitats that they favour for foraging. All UK bat species are insectivores, and depending on their size, flight habits and other physical adaptations, different species need different insect prey and therefore different habitats for foraging in. Greater horseshoe bats are large bats and so favour large prey, particularly around the maternity period. Cockchafers and dung beetles are their food of choice. Daubenton’s bats are often seen foraging over water, trawling insects from the surface of the water with their specially adapted, large hairy feet.

Grey long-eared bats have a close association with unimproved lowland grassland and riparian (wet) habitats such as meadows and marshes.

Managing permanent pasture more extensively with very low or no inputs will benefit grey long-eared bat populations, offering more opportunities for invertebrates including the moths and craneflies that grey long-eared bats favour. Managing land to maintain or increase species diversity (more flowering plants) as well as structural diversity (a range in sward height), will give insects food and shelter resources. If possible, consider transitioning land back to hay meadow management as opposed to silage production, as this allows insects and plants to complete life cycles and thrive.

In terms of cultivated land, increase pollen and nectar plots and wildflower margins, and manage by cutting or grazing to maintain plant diversity. These areas alongside trees and tall hedgerows have proven benefits for some bat species. Minimise pesticide use and consider crops that contain lots of flowering plants such as herbal leys.  Within arable land, conservation headlands or low input cereals can be beneficial if management results in increased invertebrate numbers. These are all ways of increasing foraging opportunities on less productive areas of land for grey long-eared (and other) bats.

Farming organically has many advantages, including huge benefits to biodiversity, natural resource protection and reducing greenhouse gas emissions. Following organic principles should be considered if aiming to encourage bats and other biodiversity.

Connectivity: For so much of our wildlife, good habitat connectivity is critically important. Linear features in the landscape such as hedgerows, watercourses and ditches, enable different species to flow freely through the landscape, enabling opportunities for feeding, interacting and breeding. For bats, good connectivity is vital, as many bats use linear features to navigate through the landscape, using their echolocation to move from roosting sites to foraging sites. When these features are well managed, they can also provide foraging opportunities as well as providing obvious features to allow free movement. Extensive hedgerow management (2-3 year cutting cycle) allows hedgerow plants to flower and fruit, providing vital resources for insects. Buffer strips along streams and rivers not only provides increased opportunities for foraging, but can also protect watercourses from nutrient and pesticide run off, protecting aquatic flora and fauna.

For more information on land management for grey long-eared bats contact Craig Dunton (Grey long-eared bat project officer) on cdunton@bats.org.uk