Greater horseshoe bats at Heligan

Heligan is home to 7 out of 16 British bat species. There have been horseshoe bats roosting in the old building where these images are coming from for many years and numbers have been fairly stable. This spring we have been watching 6 individuals on camera roosting together in exactly the same spot each day. They are bachelors and have probably not mated this year. Woodland and farmland management across the Heligan estate is focused on securing and increasing species diversity in a range of small but varied habitats. High-quality foraging areas are essential for the survival of greater horseshoe bats; cattle grazed pasture and thick hedgerows both encourage insect numbers. A staggering 91% of the UK population of greater horseshoe bats has been lost this century mainly due to the increasing use of pesticides in roofs and a reduction in insect numbers due to modern agricultural methods. The reduction in number of safe, secure roosts is also a problem as more building are converted and fewer places remain derelict.

Recognition and Habitat

Weight; up to 35 g and 7cm in length. Bats are flying mammals and belong to the order chiroptera meaning ‘hand wing’; bat wings are elongated finger bones with skin stretched between. Fur is fluffy and buff coloured with dark ends. They are easily identified by the horseshoe-shaped flap of skin around nostrils.  Greater horseshoes now found only in Wales and the South West probably because of the warmer climate, increased number of insects during the colder months and suitable hibernation locations. Populations are localised and rare. Emerge 25 minutes after sunset and return 5-30 minutes before sunrise. Greater horseshoes wrap their wings around their body and hang from their feet.

Predators and Prey

Predated by birds of prey and domestic cats. All British bats are exclusively insectivorous feeding on moths, beetles, lacewings, midges and mosquitoes plucked from the grounds, leaves, above water and in mid-air. They drink while hovering or in flight, gave good eyesight and a developed sense of smell. Echolocation is used to pin point prey; the bat emits high frequency sounds which bounces back from objects as echoes received by the bat – the bat deciphers the information and uses it to locate prey and negotiate safe flight paths. The horseshoe-shaped piece of skin seen on the face helps focus the sounds the bat emits and make their echolocation calls very directional.

Life Cycle

Hibernate in quiet places such as caves or similar environments during winter in a state of ‘torpor’ (they lower their body temperature and heart rate). May travel up to 10km in winter in search for roosts with the correct temperature and feeding sites. They survive on body fat. Hibernation is interrupted between once a day and once every 6-10 days (depending on the temperature and time of year) to feed near the cave entrance or change roost site. Greater horseshoes are polygamous and mate from autumn to spring (mainly autumn), the sperm is stored in the female's body until spring, when it fertilises her egg.  One pup is born per mum in June/July but the exact timing of this is thought to relate to Spring temperature fluctuations with young being born earlier after warmer springs.  Adult males may be found in nursery roosts but leave when the young are born in mid summer.

Legal and Conservation Status

Greater horseshoe bats are on the verge of becoming a threatened species worldwide and receive considerable legal protection (Wildlife and Countryside Act 1981: 1994 Conservation Regulations) in light of their dramatic decline in the 20th century. It is an offence to kill or injure a bat, to have a bat as a pet, or to damage or destroy a roost. Different types of buildings are required  for activities such as mating, breeding and roosting. Greater horseshoe bats may also be at risk from chemicals used in roof timber treatment.

Did you know?

Greater horseshoe bats live longer than any other European bat; the oldest individual ever recorded lived was 30 years old.