How do bats choose roosts in urban areas?
Bat surveys start with a visual inspection assessing the potential a property has to house roosting bats. To do this, we need to understand what bats are looking for. This blog is designed to give you an insight into the features we look for, but if you need a bat survey (or think you may in future) it’s best to reach out to our team of ecologists for advice!
So, what are bats looking for when finding a roost?
Location, Location, Location
Location matters to the bats just as much as it does to us. Bats need access to suitable foraging habitats, including parks, gardens or water bodies. These areas have abundant insect populations, allowing the bats to forage at night before returning to their roost to rest during the day.
Even the most perfect roost opportunity is unlikely to be used if there isn’t suitable habitat nearby. That’s why we always consider the surrounding area when completing your bat surveys.
A Cosy Spot
Bats don’t create their roosts, they take advantage of existing features. Each species has their own preferences, but in general loose tiles, gaps in boarding, cracks in masonry, and attics and roof spaces provide a cosy place for bats to rest. Our most common bats, pipistrelles spp, can fit in a crevice just 10-15mm wide!
When these features are matched with a stable temperature and humidity, they are even more appealing. In summer, females gather in maternity roosts to raise their pups. The pups need warmer conditions than adult bats, so a south facing roof or a space above a hot water tank gives them the conditions they need to grow.
Neighbourhood Watch
Bats are vulnerable when entering and leaving their roost. Finding entrances that are protected and concealed from humans and predators is essential for their safety, but this needs to be balanced with enough clear air for the bats to take off.
Cat Attacks and Bat Roosts
A recent forensic study showed that two thirds of bats ending up in care had been in contact with domestic cats. A small proportion of cats account for the majority of bat attacks, so if your cat has brought home a bat we recommend keeping them indoors at dusk and dawn when bats are active.
Traditions
Bats will return to the same roosts year after year, assuming conditions remain suitable. Bats are long-lived animals, who regularly navigate between their preferred roosts for each season. One particular individual known by the team was at least 14 years old at her last sighting, she was a soprano pipistrelle with a ring and one ear missing who was seen in the same hibernation site several years in a row!
Artificial Structures
If you would like to support bats in your area, you can provide bat boxes. These provide similar features to ‘natural’ roosts and help to support urban bats. We regularly install bat boxes as compensatory roosting opportunities when bats must be moved under licence!
If you think you might have bats, you don’t need to do anything unless they are causing a problem or you may disturb them or their roost as part of proposed works. If this is the case, get in touch with our team of specialist ecologists for advice and support here.
If you need a bat survey (or think you might) get in touch with our team of specialist ecologists!
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