Main image courtesy of Hugh Clark/www.bats.org.uk We’ve reached the ninth and last article in our series on Norfolk Wildlife Trust’s 9 for 90: nine species which have been chosen to represent nine key Norfolk landscapes in which we work. Until now all of the species we have covered have been colourful, loud, charismatic or at least easily recognised. The spoonbill, which represented the Cley to Salthouse Living Landscape is big and bizarre and is recolonising the UK after hundreds of years of absence. The stone-curlew is noisy, distinctive and intimately associated with the Brecks Living Landscape. The white-tailed bumblebee, which we chose for the urban landscapes in which we work with people and wildlife, is cheery, charismatic and known to everyone.
All bats are special; all bats are unsung too. But the barbastelle is Norfolk’s most special and unsung bat of all.
One species in our 9 for 90, however, is little known. Indeed, asked about a barbastelle bat, most people will shrug and confess they have never heard of it. They may have heard of common pipistrelle bats. Perhaps even a brown long-eared or a noctule. But a barbastelle? The barbastelle represents the last of our Living Landscapes, the Claylands. Unlike the Brecks, the Bure Valley in Broadland, or the Gaywood Valley which runs through King’s Lynn, the Claylands Living Landscape is little known by naturalists, as little known, in fact, as the barbastelle bat which is its chosen species in the 9 for 90. The Claylands is a large area of South Norfolk which has distinctive soils, a mix of Late Cretaceous chalk and Jurassic clay jumbled together by the Anglian Glaciation at the start of the Ice Age. These heavy soils were hard to cultivate prior to the Industrial Revolution, so a landscape developed here of small fields, more easily ploughed by ox and horsepower, bounded by thick, biodiverse hedges. This mediaeval landscape has maintained much of its character until today and is still dotted with old ponds, dug for clay for construction, village commons which have never been sprayed, veteran trees and patches of ancient woodland.
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NWT Ashwellthorpe Wood Reserve Richard Osbourne
Most of our Living Landscapes are home to charismatic, much-loved wildlife, the sort of species which feature on the front covers of books. The Cley to Salthouse Living Landscape is celebrated for its nesting avocets and bearded tits and the very rare birds it regularly attracts. The Upper Thurne Living Landscape in the Broads has cranes, bitterns, swallowtails and otters. In the Brecks Living Landscape there are stone-curlews, woodlarks, scarce emerald damselflies and goshawks. While they may not be so famous, they may not feature in the A-list, many nationally rare or declining species inhabit the Claylands too. It is fitting that the 9 for 90 species for the unsung Claylands Living Landscape should be at once both very special and itself almost wholly unsung. All bats are special; all bats are unsung too. But the barbastelle is Norfolk’s most special and unsung bat of all. Let’s begin by getting to know bats in general. In the world more than 1,300 species of bat are known. Estimates vary but assuming there are 5,500 species of mammal in the world (yes, bats are definitely mammals) very roughly a quarter of all mammal species are bats. In the simplest terms, this means that bats are supremely good at what they do. When you look closer you find that bats do widely different things across the world. What unites them all is that they are the only flying mammals on earth. Flying squirrels, Australasian gliders and colugos can all glide, but only bats can truly fly. Beyond this common thread, bats do an astonishing range of things and they do them astonishingly well. Around the world there are bats which eat fruit, bats which eat frogs, bats which eat fish, bats which eat other bats, bats which eat pollen and a minute number of bats which drink blood (though these get far more than due hype in the media). The eighteen species of bat which breed in the UK (which also represent around a quarter of mammal species found here) have three fundamentals in common. All eat insects, all use echolocation to find them, and all must hibernate. As many bat species fly, including all UK species, they emit streams of high-pitched calls. The returning echoes allow them to build a minutely detailed mental map of their surroundings. This is echolocation and in this way they not only navigate through the landscape and avoid danger in pitch darkness; they also catch the thousands of insects a night that their racing metabolisms require. In warm regions of the world there may be food available year round. Depending on their biology, bats may migrate seasonally but hibernation is unnecessary. Here in the UK, even with the recent trend towards milder winters, there is generally too little insect food for bats from November to March, so all of our species are obliged to hibernate. Hibernation is not, as it is often termed, sleep. It is a state of torpor, during which metabolic rate is greatly lowered, with energy use reduced accordingly. It could be compared to a television which has been left on standby, ticking over but hardly using energy. In preparation for hibernation bats must build fat reserves, catching countless thousands of insects in late summer and autumn. Bats usually hibernate communally in cool, still environments, such as caves and cellars (themselves scarce resources in most landscapes). Amazingly adult female bats will most likely have mated in late summer and autumn but, by storing sperm, put off egg-fertilisation and pregnancy until spring. In this way they avoid the heavy metabolic toll of feeding an embryo while they themselves are torpid. Bats, you’ll have realised by now, are remarkable animals, superbly adapted to the environments in which they live. Yet most of us have little interface with them. As children many of us can hear them: not the clicks they make when echolocating, which are outside human hearing, but the lower-pitched squeaks they use in social interaction. By adulthood many of us have lost these sounds and become almost unaware of bats unless they swoop low over us on summer evenings spent outdoors. But bats are all around us, engaged in astonishing biological feats: pulsing their millions of tiny calls into the night from late winter to late autumn and using them to make maps in the darkness; lowering their metabolisms to a handful of heartbeats per minute in winter and raising them again until their hearts pump many hundreds of times per minute in flight. Some species of bat are widespread and still common in the UK, genuinely all around us. Parks and gardens everywhere have common pipistrelles and, if there is water, there may well be soprano pipistrelles too. The barbastelle, on the other hand, our 9 for 90 species for the Claylands Living Landscape, is both rare and specialised. It is found only in the south of England and Wales, with very few breeding colonies known. According to the Bat Conservation Trust barbastelles seem to favour pastoral landscapes with patches of deciduous woodland and water bodies. And this is why the barbastelle holds its own in the Claylands, an ancient landscape of pastures, woods and ponds, a landscape ideally suited to the needs of a rare bat.
Frosty Morning Caister St Edmund Elizabeth Dack
The barbastelle is hard to see, far harder even than the stone curlew or nightjar. Dedicated Norfolk naturalists may pass their entire lives without knowingly encountering one. Yet it is the perfect symbol for the Claylands Living Landscape. It is an animal of the secret places, the quiet lanes and forgotten commons, the neglected ponds and great dense hedges which give this landscape its character. Beneath the barbastelle’s dark, little known wings innumerable other species, rare and common, thrive in the Claylands. The hedges ring with the cheery songs of chaffinches and yellowhammers and barn owls haunt old pastures in search of voles. Great crested newts flash their flag-like tails in old ponds and nearby water voles nibble grass and sedge. In verges rare sulphur clover blooms and woods blaze with the flowers of early purple orchid, bluebell and wood spurge. These wonderful plants and animals, and many more, still inhabit the centuries-old, unsung landscape of the Claylands, because it has kept its character, because it is more intact than any other Norfolk landscape. It is a quiet Norfolk treasure and proudly it is still home to a very rare bat.