An ancient solution to a common problem

The importance of ancient woodland cannot be overstated. This invaluable habitat holds significant importance to British wildlife, offering a complex and mature habitat that is a nod to a once wilder Britain. An ancient woodland takes hundreds of years to establish, providing the conditions for a rich assemblage of plants, animals and fungi to thrive. To be defined as such, a woodland must have existed continuously since 1600AD. Ancient woodlands are sanctuaries for Kent’s lesser-seen species, including one of our most fascinating and elusive animals: bats.

The UK boasts 18 species of bat, which represent around a quarter of all British mammal species. The IUCN Red List for Mammals lists 4 of our bat species as Threatened, 2 as Near Threatened and 3 as data deficient. British bats are threatened by habitat loss and fragmentation, loss of foraging resources, disturbance, and the destruction of roosts. The mismanagement of woodland also poses a significant threat to bat populations, and the widescale loss of 70% of ancient woodland in the UK only serves to worsen their fate. In order to protect bats, we must protect ancient woodland.

Ancient woodlands are a bat buffet

Bats are skilled, acrobatic hunters and have evolved an efficient method of locating prey. Despite popular belief, bats are not blind. Using echolocation as their main tool for catching food, bats are able to make up for their limited vision through sound. Woodland edges are used as navigational landmarks, guiding bats to and from their roosts. Despite weighing no more than a one pound coin, the common pipistrelle - Kent’s most common species of bat - can consume a whopping 3,000 insects in a single night on the wing.

Bats rely on diverse insect populations for food, but due to changes in pesticide use and habitat degradation, native insect populations have drastically declined since the Industrial Revolution. A decrease in hedgerows, wildflower meadows and waterbodies and an intensive increase of pesticides has led to a nationwide decline in invertebrates, placing a significant pressure on bat populations.

Ancient woodlands are biodiversity hotspots. They support a wide variety of insects, including many specialist species that are rarely found elsewhere. They provide a varied range of micro-habitats, including ancient trees, dead and decaying wood, dense vegetation, leaf litter and open clearings. This mosaic of micro-habitats creates opportunities for fauna and flora big and small to exploit every nook and cranny of the woodland.

Oak trees alone support over 2,000 species in the UK, roughly 300 of which rely solely on the tree for survival. A single oak tree can provide a food source for bats for decades and even centuries at a time. Mature trees also create an ongoing supply of valuable decaying wood. Approximately 800 species of beetle - a favourite prey item of many bat species - rely on deadwood to complete their lifecycle. Ancient woodlands also support a whole host of woodland wildflowers and food plants that attract all important pollinators. From miniscule beetles and buzzing bees to beautiful butterflies and micro moths, ancient woodlands provide a rich community of insects to bats, birds, reptiles and amphibians.

Home is where the roost is

Ancient woodlands offer abundant and high-quality roosting opportunities for bats. Cavities and hollows in trees make the perfect roosting spot for several species of bat. Some species, such as the barbastelle and noctule bat, are considered woodland specialists. They make their homes in ancient or old growth woods, behind loose bark or in the cracks of damaged and dead trees.

With different species demanding roosting spots of all shapes and sizes, diverse and mature woodlands boast the variety that boosts bat biodiversity. Noctules - Britain’s largest species of bat - prefer the comfort of woodpecker and rot holes. Solitary male Noctule bats even rely on tree holes during the mating season to attract partners. Upon finding a suitable hole, the male will emit a range of shrill mating calls from the entrance of the roost and during flight, all while releasing a strong odour that is attractive to female noctules. The male will typically stay in their chosen mating roost for several weeks and will defend their roost from competing males. A male noctule bat can attract anywhere up to 20 females during mating season.

Respecting our elders

Veteran trees are particularly valuable to bats in British woodlands. Having stood the test of time, these mature trees are characterised by hollows, cracks and cavities that have formed over many years of growth and decay. These features provide excellent roosting opportunities for bats. Veteran and ancient trees often provide more stable and long-lasting roosting sites compared to younger trees due to their more established nature and density of attractive features. Some species, like the barbastelle, roost in trees year-round and favour woodlands with many veteran, dead and damaged trees. Droppings and parasites can accumulate in hollows overtime, therefore woodlands with an abundance of old trees allow bats to move flexibly between roosts.

Veteran trees underpin healthy woodland ecosystems, pumping a constant supply of deadwood into the soil that promotes diverse fungi communities. Deadwood also creates damp environments for moss to flourish and provides a vital food source to insects. Mammals and birds alike seek shelter in their canopies and humans reap the benefits of their hefty carbon storage. These ancient giants are one of our greatest wild assets, but if they are not afforded adequate protection, centuries of growth can be lost.

Observing bats in Kent

Bats are most active during the warm summer months and can be observed at both sunrise and sunset. They can often be seen flying low over waterways in search of insects, while some fly high in the sky or over grassland and trees. There's no one-size-fits-all approach to spotting Britain's bats!

Those interested observing these mysterious mammals will be pleased to learn that you don't always have to travel far. They can often be seen over streams, lakes, rivers, hedgerows and even your local park. Using a simple piece of equipment called a bat detector, budding bat fanatics can listen to bats as they dart and dive overhead. Bats echolocate at a pitch that is too high for human hearing to pick up. A bat detector uses a microphone to listen to these shrill noises and instead produces a frequency that can be heard with human ears. The device reads the frequency, and observers can reference this number against a field guide to identify the bat species. For example, brown long eared bats are known to produce calls between 25 – 50kHz; these calls are quiet and may be hard to detect, prompting many to refer to the species as 'whispering bats'.

Out of the 18 bat species located in Britain, 14 can be found in Kent. Most can be seen for a couple of hours at sunset and for around an hour at sunrise. Some bats, like the noctule, are early risers and are often the first to be spotted, sometimes even before sunset. Kent’s most familiar bat is the common pipistrelle, closely followed by its cousin, the soprano pipistrelle. Each species of bat echolocates at a different frequency. The common pipistrelle echolocates around 45kHz while the soprano echolocates around 55kHz.

Help us to provide a home for bats in East Kent

Covert Wood is a 26-hectare area of precious ancient woodland, situated in the Kent Downs Area of Outstanding Natural Beauty in East Kent. Comprised of towering oaks, beech, hornbeam and sweet chestnut, this striking broadleaf woodland has stood tall for centuries. Knotted mature trees, bountiful deadwood and swathes of woodland wildflowers provide the building blocks for insect diversity, ensuring a crucial food supply to birds, mammals, reptiles and amphibians. Sadly, Covert Wood is at risk of being sold piece by piece, making it impossible to manage for the benefit of nature.

Ancient woodlands now cover just 2.5% of Britain's landmass. If we do not protect and defend these age-old woodlands, we will deny future generations the chance to enjoy one of Britain’s most complex and diverse habitats. If ancient woodlands disappear, Britain’s rarest woodland species will follow suit. We have a rare opportunity to purchase a vast area of ancient woodland. With your help, we can help Covert Wood to reach its full potential.

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References

• IUCN red list
• Plummeting insect numbers 'threaten collapse of nature' - The Guardian