Habitat: Occur in a variety of forested and unforested areas, at both high and low altitudes. They roost in caves, buildings, foliage and hollow trees.
Geographical spread: Entire southern Palaearctic region from Britain and Morocco to Afghanistan and Japan.
Current population: 4,000 (BBC Wildlife, April 1995). Size: Head and body length 35-11 Omm, tail length 15-56mm, and forearm length is 30-75mm.
Weight: 16.5-289.
Average life expectancy: About 30 years in the UK.
Normal diet: Insectivorous. Insects and spiders caught on the wing in flight and are taken back to the roost to be eaten.
Normal lifestyle: These bats begin feeding later in the evening than other bat species. They roost in moderate-sized mixed-sex groups for much of the year, although adult females segregate for birth and weaning. They hibernate during the winter mo nths in exposed sites, but awake readily and will also change their hibernating sites occasionally. It is important that humidity is fairly high (usually over 90%) to prevent excessive evaporative losses. Both males and inseminated females store viable s perm for up to 7 months. This appears to ensure that females are ready for ovulation and fertilisation as soon as conditions become favourable in the spring. Producing milk is energetically demanding for the female and it is therefore crucial that birth coincides with a period of consistently abundant food. In summer females, non-breeding adults and immature young form maternity colonies inside buildings. The females cluster together which helps to reduce heat loss and energy costs to each individual. M ales roost at another site during this period so as to decrease competition between the sexes for food. A single young is produced in late spring and sexual maturity is attained by 2 years of age (Lekagul and McNeely 1977). Females are usually 4 years ol d before their first pregnancy. In Britain Greater Horseshoe Bats have fairly poor breeding success probably due to the climate which means that in a cold year insects become unavailable. Lactating females require a continuous food supply if they are to provide milk for the young. Females will abandon their young after a few days if there are not many insects about.
Previous geographical spread: In the last 100 years they have decreased in distribution throughout their range in Europe and Asia from Britain and Japan. Extinct in northern parts of France and in some areas of eastern Mediterranean.
Reasons for decline: Declining due to disturbance of roosts in caves and buildings, vandalism, habitat modifications resulting in the loss of large insect prey and increasing use of insecticides for timber treatment that may be absorbed by bats. T he two major habitats for Greater Horseshoe Bats is woodland and adjacent old pasture, in the last 50 years these habitats have disappeared rapidly. Unfortunately these bats are also very susceptible to disturbance which can lead to changes in their beha viour.
Special effects: In the last century Greater Horseshoe Bat numbers have decreased by 98% to just 2,200 individuals.
File last modified Thursday, October 3, 1996