Tuesday, 28 July 2009

Twins?


The twins with mum. (c) P and M Grimsey.

We have a guest blog this week by our Out of Hours volunteers, Peter and Margaret Grimsey who had a rather interesting batty experience recently.

On the morning of the 29th June, we received a call from Martin Hoare at Stonor Park, to say that they had found a grounded mother bat with two babies. The idea seemed highly unlikely, but so was finding three grounded bats together, so we set off to investigate.

Stonor is one of England’s oldest manor houses. It has been owned by the same family for 850 years and is situated in beautiful parkland with a freely roaming deer herd. When we arrived, the inside of the house was cool, despite the day already getting gradually hotter; two metre thick walls tend not to warm up too quickly!

We found the three bats. All were common pipistrelles with one confirmed lactating female. Martin explained that certain doors of the old house tended to leak during wet weather and it was the practice of the housekeeping staff to put an old towel across the bottom to soak up the water. This morning the housekeeper had spotted the bats just before shaking the towel outside. With admirable quick thinking, she had carefully collected the brood in the towel and found a box to keep them in.

Once home, we always allow the bats to settle before making a full examination. However, that evening it did quickly become apparent that at least one of the bats was a baby (it was suckling mum!).
Over the course of that evening and the following morning, we gave mum wax worm innards, which she took immediately. The bat who wasn’t suckling took Esbilac milk formula from a paint brush, and both “babies” had a few licks of a wax worm innard.

On 1st July we examined and weighed all three:

Pip 45 Female, lactating, weight - 5gms, forearm - 32.7mm
Pip 45 Female, fully furred, weight - 3.8gms, forearm - 27.3mm
Pip 45 Male, fully furred, weight - 4.4gms, forearm - 29.1mm

At this point, we wondered whether the trio was actually a mum with female offspring and a male companion. However, over the following days, we got into the routine of supplement feeding which ever juvenile was not being suckled, and discovered that she was, in fact, suckling them both.


For the next few days we were leaving 20 worms for them each night and morning. The trio were disposing of up to 40 worms in 24 hours. So the juveniles were clearly feeding themselves.

By July 7th, all of the bats had shown signs of improved health and had increased in weight and measurements of their forearms. By the 10th July, the bats were self-sufficient and we had seen them all flying in their cage so we arranged with Martin to return to Stonor and release them. The weather, which had recently been wet and windy, looked like staying fine.

We had been thinking for some time how best to achieve release as we did not want mum to get separated from the juveniles. Clearly, the bat held at arms length method could not be used, and we also felt that an open box, put high up with the bats in, would be risky, as one bat might panic and fly out before the others were ready.

Eventually we made up a soft pocket from the hood off a body warmer. Our plan was to place the bats inside and then position the pocket in a suitable release spot. The bats would be warm and they could creep out in their own time after they, or at least mum, had the chance to recognise the surroundings. (We are fairly convinced, from observations made during previous bat releases, that bats can recognise the smell of an area.)

Martin met us and we decided to put the bats on a high wall under an overhanging fig tree. The bats were carefully lifted off their hot water bottle and placed on the wall in their cosy pouch at about 9pm. After seeing several faces peeping out of the pouch we watched mum fly off after about half an hour. We watched until it got too dark and mum returned several times calling to the babies, and we heard them respond. We were also able to pick up mum’s feeding busses as she over flew us. But it was too dark to see and the babies did not seem to have flown.

The following morning Martin rang us to say he had been out early to check and the pouch was still in position and dry under the fig and the bats had gone. We can only assume from this that the release had been a success.

We are very grateful to Stonor Park and Martin and Caroline Hoare for their help and care for the bats, and for giving us the chance to experience what we feel to be a very rare bat event.

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