Bats weighing little more than the coins in your pocket are preparing to hunker down for winter.
Cumbria Wildlife Trust has highlighted the UK’s 17 breeding bat species as the mammals begin looking for suitable places to roost and hibernate until spring.
Among them is the common pipistrelle, one of Britain’s most widespread bats and a species likely to be spotted hunting around gardens.
The tiny mammal measures just 35mm to 45mm from head to body, with a wingspan of around 200mm to 235mm.
It weighs between 3g and 8g, with an average weight similar to that of a 20p coin.
Cumbria Wildlife Trust said: "Did you know we have 17 breeding species of bat in the UK?!
"Our smallest and most common species, the common pipistrelle weighs about the same as a 20p piece.
"At this time of year bats are looking for cozy spots to hunker down for hibernation until the spring.
"You can help create safe spaces for bats to roost by installing a bat box, helping encourage them into areas with limited available spaces."
There are 18 bat species living in the UK, 17 of which are known to breed here.
They vary significantly in size.
At the smaller end is the Alcathoe bat, which weighs between 3.5g and 5.5g and has a body measuring little more than 3cm.
It's weight is comparable to a 1p or 20p coin.
The species was only recognised as distinct in 2001 and has subsequently been identified at a number of sites in the UK.
In contrast, the noctule is one of Britain's largest bats, weighing between 18g and 40g and boasting a wingspan that can reach 400mm.
It weighs in at between roughly one-and-a-half to just over three £2 coins.
They can be found across much of England and Wales and into south-west Scotland.
Other widespread species include the soprano pipistrelle, found across most of the UK, and the brown long-eared bat, which is found across the UK but is absent from Orkney and Shetland.
Some species are considerably rarer.
The grey long-eared bat is restricted to a small number of colonies in southern England, while Bechstein's bat is one of Britain's rarest bats and is found in parts of southern England and south-east Wales, predominantly in woodland.
Greater horseshoe bats are now confined to south-west England and south Wales, while lesser horseshoe bats are found in Wales, western England and western Ireland.
Despite their small size, bats can live remarkably long lives.
Brown long-eared and greater horseshoe bats have both been recorded living for up to 30 years, while Daubenton's bats can live for up to 22 years and Bechstein's bats for up to 21 years.
British bats feed on insects and other small invertebrates, although their preferences differ between species.
Common and soprano pipistrelles predominantly eat small flies, midges and mosquitoes, while noctules eat insects including midges, mayflies, beetles and moths.
Brown long-eared bats have a varied diet including moths, beetles, flies, earwigs and spiders.
Daubenton's bats are closely associated with water and feed on small flies, caddisflies and mayflies.
They can take insects directly from the surface of the water using their large feet or tail membrane.
Bats navigate and hunt using echolocation.
They emit high-frequency sounds and use the returning echoes to detect their surroundings and prey.
Different species use different frequencies, which can help distinguish otherwise similar bats.
For example, common pipistrelle calls peak at around 45kHz while soprano pipistrelle calls peak at around 55kHz.
Unlike birds, bats do not construct nests.
Instead, they use roosts in locations including buildings, trees, caves, mines and tunnels.
Some also use purpose-built bat boxes.
Common pipistrelles, for example, can roost in building crevices, tree holes and bat boxes.
As mammals, bats give birth to live young and feed them with milk.
Many British species typically produce a single pup in a year.
Common and soprano pipistrelles give birth to one young in June or early July, while noctules usually have one pup but twins are sometimes recorded.
Young bats can develop surprisingly quickly.
Common pipistrelle pups are able to fly after around four weeks and can forage for themselves at around six weeks.
Bat roosts are also legally protected, making it an offence to damage or destroy a breeding or resting place or obstruct access to places bats use for shelter or protection.
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