Bats about Ffynnon Beuno!!

One of the many benefits of managing the land without chemicals is the huge abundance of biodiversity this encourages. In the warmer months, the fields are alive with the gentle hum and buzz of millions of insects going about their business and even in the colder months, a warm afternoon can see clouds of little insects appear to bask in the unexpected sunshine above the stream. The insects are at the base of a pyramid of life and a healthy, diverse population in turn supports a lot of birds and mammals.

Ffynnon Beuno sits in a deep cleft sandwiched between a Nature Reserve (The Graig) and farm fields above and behind. It often enjoys its own microclimate and the topography creates thermals which are used by buzzards to gain altitude to hunt in the valley. It also concentrates warm eddies and it is in this environment that many bats like to hunt. They can often be seen swooping dramatically through the valley, catching insects on the wing and we spend many a summer evening with a bat detector listening to numerous different species chattering away.

In winter, the Ffynnon Beuno and Cae Gwyn caves are home to a colony of rare lesser horse shoe bats (Rhinolophus hipposideros) one of the smallest British species, being about the size of a plum. Like its bigger cousin the greater horseshoe bat, the tiny mammal has a complex structure in the middle of its face called a nose leaf which aids it in echo location – the shape of which gives the bat its name. Unlike any other bat, the horse shoe bat can rotate its ears to help in the search for prey and hunts with its feet by snatching prey from sheltered hedges and walls. They mainly hunt for flies, midges, small moths, caddis flies, lacewings, beetles, small wasps and spiders and rarely fly more than five metres above the ground. The tiny creature only weighs about 5g but can live for up to 25 years!

Lesser horseshoe bats were originally cave dwellers – and in Ffynnon Beuno they still are – but more often summer colonies are now found in the roofs of larger rural houses, churches and stable blocks although they can also be found in cellars or tunnels. They prefer access through an opening that allows uninterrupted flight to the roof apex. The reason for this is the unique design of this particular type of bat – there is very limited flexibility in the animal’s pelvis which means that the bat is unable to land and then crawl into a safe place unlike other bats. They need wide open entrances to fly into then roost and along with habitat loss, this is one of the reasons for their decline as old fashioned open barns are now rare
Ffynnon Beuno and its neighbour Cae Gwyn are key winter hibernation sites so over the season, we keep any disruption to an absolute minimum. Lesser horsehoes have a very low body fat percentage and bats can burn a lot of essential reserves when roused unnecessarily when they are hibernating. The populations are counted first in November and then in January – the count is done by licenced bat experts and we rarely enter the cave during hibernation periods. Oddly, it isn’t noise or light that wakes the bats but temperature changes so the counts are done with just two people and LED lights as even human body heat can rouse them.
We are delighted to say that the bat colonies in the valley have grown since early records kept since the 90s with about 250 across the whole valley although the species is still endangered. Only 12000 are thought to exist mainly in Wales and Western Ireland so we are very privileged to look after ours.