22 people ventured out on a lovely evening to tour one of the oldest nature reserves in the country, to gather information about what species of bat can be found there, and what they are doing. The hoots of tawny owl, and the rasping calls of dark bush-crickets, and the tractor-like churr of long-winged conehead bush-crickets, accompanied them as they investigated the reserve, stopping off at the Rothschild Bungalow, and the two meres.

The echolocations of common pipistrelle bats were picked up using electronic bat detectors around most of the route followed, with the occasional soprano pipistrelle also detected. At the meres, the shallow fenland lakes, bat activity was concentrated, with a range of species drinking and feeding. The bats were calling so quickly, in order to locate and catch the small flies, that the very fast echolocation sounded like they were blowing raspberries.

The rare barbastelle was also detected, in the more wooded parts of the reserve, and while walking along the Great Raveley Drain, the noctule, one of our biggest bats, was encountered, its noisy, ‘chip-shop’ call pulsing out from the detectors.

The finale came on the return to the entrance to the reserve, watching pipistrelle bats chasing moths over the water, their nimble, aerial manoeuvres showing off their flying prowess. Check the sightings page for more information.

Earlier that day, a bird survey was also carried out at Woodwalton Fen. With the abundant fruit on the shrubs at this time of year, various birds were feasting on their migration south. Blackcaps and whitethroats were in good numbers, as were the young reed warblers, which will now be leaving us for most of the year, but hopefully returning to breed next year. As the autumn migration has begun, swifts are suddenly absent from the skies and swallows are flocking in large numbers. Wheatears are appearing on the dirt tracks in the Great Fen, and yellow wagtails are, once again, gathering in flocks on their way south, often around the cattle.

Out in the grasslands of the Fen, birds of prey are out and about. Kestrels bred well this year, and they can often be seen perched on the seasonally provided hay bales. Also, a short-eared owl was spotted; more will follow, with as many as 16 or more hoped for this winter. Resident species are still breeding, including grey partridge, the second brood of the year spotted in the Fen, which is very encouraging, following the successful breeding of another ground-nesting bird this year, the lapwing. It is also a time when we survey the ditches, to provide information that guides the management of the Great Fen. As well as plants, we also encounter a host of wildlife; from marsh harrier to kingfisher, from water vole and brown hare to Chinese water deer, and many dragonflies and the occasional wasp spider, a relatively recent colonist, the female stunning, with her yellow, white and black stripes. Moths can also be interesting at this time of year, and once again, out on the grasslands of the Great Fen, a vestal was encountered. This beautiful little pink moth is not commonly recorded in the Fen, but is a fairly frequent migrant from southern Europe and Africa.

With so much to see it is worth visiting the National Nature Reserves, or the land under restoration, such as on the Last of the Meres Trail, including the Trail’s Northern Loop, or the Dragonfly Trail, which can now be accessed once again form the Great Fen Information Point at New Decoy.

Henry Stanier (Great Fen Monitoring & Research Officer)