BATS
Bats are amazing animals that are important to ecosystems in the UK and worldwide, whether as 'pest' controllers, as the primary predators of night-flying insects or, as pollinators, with the fruit and nectar feeding bats, who pollinate many plants, including an estimated 450 commercial plants used by us. Foods such as bananas, peaches, guavas, mangoes, avocado, figs, dates, papaya, almonds, cashew nuts, vanilla and other products such as tequila (from the agave plant), carob and many more.
We have 18 species of bat in the UK, all insectivorous, and all of which are protected under European law.
Bat populations in the UK have declined dramatically over the past century due to persecution and habitat loss. However, some UK bat species have recently shown some signs of increasing, so there is hope.
Bat don’t make nests, they rely on finding suitable places to rest, known as a roost. The 18 species not only have varying preferences from each other, but each species has different requirements within themselves, such as, summer compared with autumn, winter and spring, a breeding female compared with an individual male and so on...
A good place to start to find out more about the different species of bats found in the UK is from the British charity Bat Conservation Trust http://www.bats.org.uk/pages/uk_bats.html or with this link for Young People’s Trust for the Environment http://ypte.org.uk/factsheets/bats-british
Bats and Boxes
Bat boxes are artificial roosts designed to provide bats with alternative resting places or to encourage bats into areas where there are few existing suitable roost sites. Providing bat boxes can increase opportunities for roosting bats but it can take a while for bat boxes to be used regularly, particularly where several suitable alternative roost sites exist.
Bat boxes can have an important additional function in encouraging interest and educating members of the public about bat conservation. The correct design and placement of boxes will help increase the likelihood of their uptake by bats.
Bat roost preferences
Some knowledge of what bat species are in your local area and their preferences will help you choose the best possible box type. Some species such as horseshoe bats and grey long-eared bats do not use bat boxes. Microclimate within a new roost is a very important factor in terms of increasing the chance of successful uptake by bats. In general, they prefer warm spaces in the summer for rearing young and cooler spaces in the winter for hibernation.
Orientation and location
Structures for summer roosting should be positioned where they are sheltered from the wind but unshaded for most of the day. Summer maternity roosts (in the northern hemisphere) should be on a south-easterly to south-westerly aspect. It is always best to provide a number of different options for bats so that they can choose the most appropriate temperature based on their needs. This can be achieved by grouping a few bat boxes each with a different aspect; two or three boxes is preferable to one, although a single box still has a chance of being used depending on the bat species that use the local area. Three boxes can be arranged around the trunk of larger trees. Bat boxes are more likely to succeed in areas where there is a good mixture of foraging habitat, including trees, and a source of water (most maternity roosts are located within a short distance of permanent fresh water such as a stream, pond, river or lake). Bat boxes in areas with few other roosting opportunities are also likely to be more successful. Bat boxes should also be located close to unlit linear features, such as lines of trees or hedgerows. Bat species use these features for navigation between their roosting sites and feeding grounds and to avoid flying in open and exposed areas. Ensure the bats approach to the box is not impeded, for example by branches – clear away underneath the box so the bats can land easily before crawling up into the box.
Other considerations
Bats are nocturnal and adapted to low light conditions. Artificial light sources should not be directed onto bat boxes or flight paths as most bat species find artificial lighting very disturbing.
Types of Ecostyrocrete bat boxes
Hollow – small, medium and large. Crevice – with one, two, three or four crevices.
What type of bat might use what type of box?
Extract taken from Bat Mitigation Guidelines 2004 – English Nature