Our latest Planet PK exhibition ‘Airymouse’ is all about bats! Following surveys in the valley carried out by Cove Ecological, we discovered that we have a population of pipistrelle bats as well as the rarest species of bat in Cornwall, the greater horseshoe bat. Recently we have been looking at the relationship between bats and their main prey moths and how the two have evolved over millions of years to outsmart each other!
To hunt for prey, bats emit high-pitched noises with their larynx and listen to that noise bounce back off the objects around them, creating a map of the landscape and its contents. This is called echolocation and bats have been utilising it with great success for at least 52 million years. Moths are bats’ main prey, and bats are the primary predator of moths. Because of the bats, amazingly accurate method of hunting, moths and bats have been in an evolutionary arms race.
Certain species of moth have developed ultrasound-sensitive ears to detect approaching bats. Many can also then emit a high-frequency noise by rubbing their legs on special scales located on their genitals, warning bats that they are toxic and shouldn’t be eaten. However, this warning is often a trick, as non-toxic moths will mimic the sounds of toxic species to avoid being hunted. It is thought that this defence mechanism might have originally been used by male moths to attract a mate, but it has proven useful in the fight against predators. Another use of this high-pitched squeak is to confuse nearby bats and jam their echolocating abilities! Around 20% of moths globally use some form of anti-bat ultrasound including bat detecting ears, sound-triggered defensive flight and ultrasound production.
However crafty moths may be, bats still have ways to catch them. Hunting bats won’t only catch moths in flight, but also pick them off branches, bushes, and leaves as they rest. Some bats are even producing echolocating sounds at a higher frequency that moths cannot hear in order to sneak up on them successfully.
Studies conducted by wildlife charity Butterfly Conservation show a 33% decline in moth populations across Britain in the last 50 years. This is concerning as, as well as being amazingly interesting and beautiful creatures, moths are vital to ecosystems in the UK. They are responsible for pollinating plants, distributing seeds, and providing food for predators such as bats, frogs, lizards, rodents and spiders. Their decline is largely due to pesticide use, light pollution, human disturbance, and habitat loss. A decline in moths will create a knock-on effect and harm other species that rely on them, so protecting and conserving the remaining populations is of utmost importance.
Garden management is a great way that anyone can get involved with helping moths. Butterfly Conservation suggests the best way to manage your garden is to manage it less! An overly preened and manicured garden is not beneficial to wildlife. Grasses, hedges and trees that have been allowed to go a little wild are a perfect environment for moths to thrive, and for other animals to benefit too!
Maeve Cushla, Planet PK, Young Curator
All Photos are credited to Laura (@Laulovesnature)