Bats in the Moat

This week we attended a bat evening at Fort Burgoyne. As our country’s closest point to Continental Europe, Dover has more than its fair share of castles and forts and I get a bit confused between them all, but Fort Burgoyne is positioned behind Dover Castle to protect it from a land-based attack.

Across the parade ground at Fort Burgoyne

Fort Burgoyne is one of the Palmerston Forts, built in the 1860s following concerns about the strength of the French navy. There was much debate in Parliament as to whether the cost could be justified, but Lord Palmerston, who was Prime Minister at the time, strongly promoted the idea. He was concerned that the French could land elsewhere along the coast and attack Dover Castle from the rear.

A Second World War blast wall obscures much of the frontage of the fort
The extensive buildings are now disused and generally in a poor state but have become an important swarming and over-wintering site for bats

In 2014 The Land Trust acquired the fort and hopes to manage it for the benefit of the community by running events and training sessions and also leasing sections out to local businesses. The band of enthusiastic staff members include a ranger who monitors and encourages wildlife – on the last inspection of his twenty-eight reptile sampling squares on the site, he found ninety-nine slow worms.

Our bat evening started with a talk on bat ecology in the stables and we then descended into the depths of the fort with torches to be shown some of the nooks and crevices where bats return every year to overwinter. Then, as it started to get dark, we walked down into the moat with bat detectors:

Dropping down into the moat at heavy dusk

The group had been lent a selection of different detectors with the most basic ones starting at a cost of around £100 and the most sophisticated at £1,600. We had brought along our own Magenta detector and were pleased to see that this was the one being recommended as the best entry-level detector.

There are eighteen species of bat in the UK, which is actually nearly a quarter of all British mammal species. Their echo-locating calls are pitched at different frequencies and can be used to identify the species even if you can’t see the bat.

On this basic Magenta detector, you dial up the frequency of the bat you think might be around and the device converts its calls into frequencies that we humans can hear. Standing in the moat, overhung with trees, and looking up at the rapidly darkening skies we set our detectors to 45kHz and we could see and hear common pipistrelles erratically flying around us, which was really quite a magical experience.

The downside of these cheaper detectors is that, if there are other species of bats around, you won’t hear them unless you are tuned in to their frequency. The more expensive detectors scan all the possible wavelengths and report on any calls, whatever the frequency.

A common pipistrelle in the hand. Photo credit: Drahkrub on Wikimedia Commons

Back in the meadows, the reptile ecologist continues to make monitoring visits after a hundred and four of these legless lizards were relocated here a few years ago. This is his photo of the sight that met him under one of our sampling squares this week – he was very pleased:

I looked under the same square the next day and they were all still there and I’ve included my photo as well because, although the light is less good, the animal on the right is in the process of shedding its skin which is interesting:

It’s a bit difficult to count, but possibly around seven to nine of them here

It is a glorious buttercup time in the meadows:

Fox with rabbit amongst the buttercups

Another rabbit – I assume it is being carried back to cubs, since this fox shows signs of lactating. We haven’t seen a fox cub in the meadows yet this year:

This same fox with that fur loss at the base of her tail is on the left here at peanut time as well:

The One-eyed Vixen and her mate, long-standing residents here, have had a worryingly bad dose of mange over the winter and, under the advice of The Fox Project charity, I have treated them with both Arsen Sulphur and then with Psorinum when that didn’t appear to have worked. I am relieved to see that now ginger fur is growing back on her flanks:

The One-eyed Vixen. I have lost count of the number of times I have treated this fox for mange – four or five I think
And her mate with his characteristically crooked tail, currently devoid of fur

The only fledglings that have been seen on the cameras so far this spring are magpies, but they are making up for that by appearing on as many cameras as they can:

Both rabbits and magpies love this trunk:

Although it seems to have stopped raining for now and the sun has come out, the weather has remained quite cold and windy here on the coast. Butterfly numbers are still low but we are enjoying seeing green hairstreak, speckled wood, small heath and wall fluttering around the meadows at the moment:

We have also spotted these day-flying moths:

Least black arches
Nematopogon sp. I don’t yet know why these longhorn moths have developed such ridiculous antennae. It makes it so difficult for them to fly in breezy weather
The cucumber green orb spider, Araniella sp, doesn’t hide because it relies on its colour for camouflage as it tries to catch flying insects in the small web that it strings between leaves. Although it had got its colour matching slightly wrong here, it had nevertheless caught a fly by the next time we looked

After weeks of speculation and increasing excitement, the tawny owl box in the wood has been opened by the licensed bird ringers and found to be empty. This was disappointing:

Since there had been so many photos of an owl in this box, we now think that it was the male roosting up in there while the female and chicks are elsewhere

While they were in the wood, they also looked in a second tawny box that we have up – a box that I have not had a camera on:

This one contained a nest full of baby great tits. With an entrance hole that large, how will they possibly survive predation by squirrels or woodpeckers?

We have just carried out the May tour round the dormouse boxes as the wood heads into its second year in the National Dormouse Monitoring Programme. As expected at this time of year, a lot of the boxes were occupied by nesting blue tits:

Very young chicks
And slightly older ones

Four of the thirty boxes in our section of the wood had dormice in them. The animals are weighed, sexed and aged before carefully returning them to their box.

A dormouse in his weighing bag
Two of the boxes had pairs of dormice in them and we are hoping for young next month

Green woodpeckers no longer seem to be using the hole in the cherry tree that I have a camera on and I suspect that there has been conflict with squirrels. The camera did get this action shot of a buzzard though:

A sparrowhawk wades put onto the new pond:

John the bird ringer wanted to photograph bullfinch and set up his hide next to one of the ponds in the wood that bullfinch have regularly been visiting:

I have a trail camera on this pond and so can confirm that the bullfinch immediately stopped visiting once the hide went up – and the hide was there for several days to give the birds a chance to acclimatise. John did, however, get some other nice photos of jay, chiffchaff, green woodpecker and robin whilst he patiently, but fruitlessly, awaited his target bird:

He has also been deploying his hide at a nearby old orchard, and I finish today with some photos of turtle dove and mandarin duck that he has taken there:

Neither of these species yet grace the bird list of the meadows or of the wood but I haven’t lost hope.

2 thoughts on “Bats in the Moat

  1. Truly stunning pictures yet again. You have a great talent (and presumably reasonably decent camera)

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