1. Q. What’s the difference between bats and other mammals?
A. The bat is the only mammal capable of true and sustained flight.
2. Q. Why are the bats at Woodchester called horseshoe bats?
A. Because they have a horseshoe shaped flap of skin around their nose (the noseleaf).
3. Q. How big are they?
A. Greater horseshoes are about the size of a pear and typically weigh 20gm. They are 5 - 7cm long.
Lesser horseshoes are about the size of a plum and weigh about 5gm.
They are about 3.5 – 4.5cm long.
4. Q. What colour are they?
A. Greyish-brown, darker and browner on back than belly. Their hair is fluffy.
5. Q. What’s their wingspan?
A. Greaters: 35-40cm Lessers: 20-25cm
6. Q. Why do bats hang upside down in the roosts?
A. Mainly because it is easier to launch into flight. Their wings don't produce enough lift to take off from the ground easily. It also helps in avoiding predators.
7. Q. Isn't hanging upside-down uncomfortable?
A. A human would find it painful hanging from their arm for any length of time. The bats open their claws, find a surface to grip, then relax and use their weight to pull on the tendons attached to their claws and lock them in place. To let go, they have to flex their knees.
8. Q. Doesn't their blood run to their heads when they're upside-down?
A. No. They have one-way valves in their arteries.
9. Q. When are the baby bats (pups) born?
A. End June/early July; it depends a bit on the weather.
10. Q. How many babies does each mother bat have?
A. Only one. Multiple births are unknown in these bats.
11. Q. How much do baby bats weigh?
A. For greater horseshoes, about a third of the mother’s weight – they’re big
A good birth weight means the pups grow quickly and are sufficiently well fed by the autumn to survive their first winter’s hibernation.
12. Q. Does every mother have a baby each year?
A. No, sometimes they have a rest for a year. Lucky mummy bat!
13. Q. How long do the baby bats stay with their mother?
A. Greater horseshoes stay attached to and suckle from their mother for at least a month. They can fly by about 4 weeks and leave the roost to feed independently after two months. Lesser horseshoes tend to gain independence a little sooner, at 6 -7 weeks old.
14. Q. How long do horseshoe bats live?
A. Up to 32 years for greater horseshoes. For lesser horseshoes, the average is about 3 years, maximum 21 years.
15. Q. Where do they hibernate?
A. In caves. They like the temperature to be above 7°C.
16. Q. How far do Woodchester bats travel?
A. They typically travel 20-30km between winter and summer roosts.
The record is 180km (over 100 miles).
17. Q. What do the adult bats eat?
A. Broadly speaking they prefer; beetles April to June, moths June to August, crane flies end August and September. Cockchafers and spiders too.
At the end of August dung beetles are important to the baby bats on their first feeding flights.
The cows in the Woodchester valley are farmed organically. The farmer does not use chemical de-worming agents on them, so the cow pats are rich in dung beetles. This is part of the management of the site for the benefit of the bats.
18. Q. How do they find these insects?
A. Their eyesight is poor. They echo-locate – they ping out a very high frequency sound pulse (ultrasound) and listen for the echo from the insect. They then fly towards it, sending out more pulses of sound. With training they can home in on their prey.
Baby bats have to learn how to echo-locate. One reason the Woodchester colony does so well is that the valley is managed so it is rich in insect life. There are lots of big juicy dung beetles available when the baby bats start foraging. If you’re not very good at catching your dinner, it helps if there’s plenty around!
19. Q. Where does the sound come from?
A. The bats emit the pulses of ultrasound through their nose, rather than from the larynx. The shaped noseleaf helps focus the sound.
The bat can catch and eat insects while continuing to detect more food using its nose, so they have the distinction of being able to talk clearly with their mouths full!
20. Q. How long have the bats been at the Mansion?
A. A look at the bat gargoyles on the clock tower suggests that the bats in the valley were observed by William Leigh when he built the Mansion c1860. Living memory (not documented) cites bats in the Mansion during the Second World War. Dr Ransome’s studies began over sixty years ago in 1959.