The UK’s smallest bat species.

Soprano pipistrelle maternity roost

We’ve had an exciting start to the 2023 survey season: the highlight of the year so far has been a soprano pipistrelle ‘maternity roost’ in Wiltshire. Soprano pipistrelles are the UK’s smallest bat species. A maternity roost is a place where female bats get together in May/June to give birth. Each female can produce just one pup-per-year and has a lifespan of around thirty years. Over forty soprano pipistrelles were recorded leaving the gable end of this property in May, which means that surveys carried out later in the year should record around eighty inhabitants emerging as the juveniles cease clinging onto their mum and begin to fly independently. Pipistrelles are the earliest bat species to leave their roost to forage in the evening. All these females emerged within twenty minutes of each other, from around fifteen minutes after sunset. Watch a short compilation of the Soprano pipistrelles emerge in the footage we recorded below.

What Are Pipistrelles?

Soprano pipistrelle, Pipistrellus pygmaeus, and their close relatives the common pipistrelle, Pipistrellus pipistrellus, are the smallest and most common bat found in the United Kingdom. An adult of each species weighs around 5g and has a body length of 4cm. They can be told apart through the frequency of their echo-location, with common pipistrelle calling around 40khz, and soprano pipistrelle calling around 50khz.

A third pipistrelle species, the nathusius pipistrelle, Pipistrellus nathusii, is thought to be rarer in the UK, though this in part may be due to their being under-recorded and mis-recorded as other pipistrelle species. The nathusius’ pipistrelle, is larger than the other two species, weighing between 5.5 – 11g, and has a call frequency range between 36-62 kHz.

All three pipistrelle species are known as ‘crevice dwellers’, meaning they ‘roost’ or rest during daylight hours in tight crevices in thermally-stable places. In summer, when bats are active, they particularly enjoy roosting under roof tiles, in gaps in brickwork and under chimney flashing where the heat of the sun keeps them warm.

Daniel Ahern Ecology

Home Farm House, Humber Lane, Tidworth, Wiltshire, SP9 7AQ
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