An interesting cellar with bats, birds and butterflies

Garth Lowe

My long term study of swallows in Alfrick on the edge of west Worcestershire, takes me into odd places including a large cellar where Swallows have been nesting for many years. In the middle of August 2014 while checking a nest that had already produced chicks, the owner told me about other surprising occupants.

In the gloom at the back section my torch lit up a Lesser Horseshoe Bat hanging like the proverbial plum! (01). It failed to wake up for the few minutes that we were there, and was obviously well into “shut down mode”. Small movements from it indicated it was definitely alive: but why had it gone into hibernation mode in a summer month? The weather had cooled down from previous weeks but not so critical that it would send a bat to sleep. By the pile of droppings beneath it, this must be a favourite place for it to hang out safely.

Right at the back of the cellar more sleeping creatures were found hanging on the ceiling. There must have been half a dozen each of Small Tortoiseshell and Peacock butterflies looking like they were heading for a very long wait till spring. It may be that having located the cellar they reawaken on good autumn days and go outside to top up on available nectar sources. One hopes the sleeping bat does not wake up to find them for a snack!

Sleeping with the butterflies were also a few of the only moth we have that hibernates in the adult form, the Herald; they too have a long wait until spring arrives. This is a fairly common moth with distinctive wing shape and wing markings and can also be the first moth to be seen every year and possibly also the last (02).

One month later another visit was made to check the Swallows had all flown, only to find probably the same bat still there. This time it was fully awake and found hanging in another spot and then fluttered around in the gloom. It appears that when it goes torpid it must hang in exactly the same place as there was a distinct black patch of dropping on the ground beneath it.

On this visit there were in fact butterfly wings lying around, one being from a Red Admiral, so it does look as though the bat snacks on them, probably when they fly in during the day and the bat is awake and picks them up on its echo location system! A better inspection is needed when the bat is not in residence to comply with the restrictions on people entering a known bat roost. Other butterflies and Heralds were still clinging to the ceiling, so they may have been the lucky ones that flew in or out while the bat was fully asleep. One Peacock was aroused by my movement and maybe torchlight and it did the noisy flicking of wings and flashing the beautiful eye spots that they do to deter predators while they are torpid.

A final check at the end of October found a single Tortoiseshell and 16 Herald moths: there were probably more tucked away in the timbers, but the fact there were also two Lesser Horseshoes fast asleep and not wanting to disturb them time to explore further was limited.

Other temporary inhabitants of the cellar back in the spring had been a family of Wrens. The lazy or smart male, whichever way you look at it, had used an old swallow nest attached to a beam, and only had to put a roof on it to try and attract a female. Male Wrens are of course quite unusual in as the male does the building of more than one nest and takes the lady of his choice on a round of inspections! This time he was successful in persuading her that this was a secure site. Interestingly both the Wren and a pair of Swallows nested very close together, with only a main supporting beam between them!

In the past both Robins and Blackbirds have also found the cellar a safe place to rear a family, so that makes a grand total of seven species using this damp gloomy underground space with an approximately five foot wide door at the bottom of some steps.

Images

01. Lesser Horseshoe Bat hanging like the proverbial plum. Garth Lowe

02 Peacock butterfly and Herald moths. Garth Lowe.