Grantham Ecology

Scientists have just announced the discovery of a new carnivorous mammal in South America, named the olinguito. It is a member of the raccoon family and is the first new carniverous mammal to be discovered in the western hemisphere in 35 years.

Two of the reasons cited for the ability of the olinguito to evade description for so long is its habitat and behaviour – it lives in the cloud forests of Columbia and Ecudor and spends its time in the canopy where the dense mists conceal it, moving only at night. The team leader Kristofer Helgen said that ‘the age of discovery is not over’. Whilst this statement may seem plausible in tropical rainforests where great expanses of inaccessible habitats could conceal new species, you would be forgiven for assuming that the stable of mammals in the UK is… stable! For starters, this is one of the most densely populated places on the planet; then take into account the huge number of amateur naturalists, both past and present who dedicate their time to studying their local patch or favourite taxa; and then there is sad fact that we are really rather poor in mammalian fauna, having exterminated anything which might compete with us hundreds of years ago.

But there is one group of species which can still turn up surprises, even now. Bats share some of the characteristics of the olinguito which have allowed it to remain a mystery until now; that is they emerge at night, concealed by the darkness and move around on a plane above our own. Other characteristics condusive to crypsis include their habit of roosting in crevices and cracks, deep in tree cavities or high in caves, and their communication in ultrasound, so that only the low frequency social calls, or the echolocation of noctules, can be heard without a detector to convert the sound down into our range.

In 1993, it was first suggested that the pipistrelle bat, our most common species, actually comprised two cryptic species, the common and the soprano pipistrelle, the latter so named because the frequency of its echolocation is at a higher pitch than the former. Although these two species are similar, they can be quite easily told apart with characteristics such as wing veination, the presence of a ridge on the nose, the colour of the face and the difference in smell. If these two species were – say – butterflies, it is almost without question that they would have been separated as distinct species many years ago, but our most common bat escaped such detailed scrutiny as recently as 20 years ago.

In 2010, the presence of another cryptic species was discovered, the Alcathoe is a small myotis species alongside the whiskered and Brandt’s bats. This was not a new species – it is well known on the continent – but nobody realised that populations existed in this country as well. Work is still ongoing to establish just how widespread this species is and Philip Brown of Bristol University is asking anybody undertaking trapping work to describe any small myotis bats caught and send the details, along with droppings, to him to try to describe more fully and understand more accurately the status of this species in the UK.

The Nathusius pipsistrelle is a species which was previously thought to be a migratory vagrant but was first confirmed breeding in the UK in 1997 and its range within the UK has expanded year on year, partly as a result of increased survey effort but also believed to be a response to climate change as identified in this paper by Lundy et al. from 2010. This is a highly mobile species which is easily able to adapt to changing conditions and its increasing prresence in the UK is consistant with a continental scale change in range. The Bat Conservation Trust (BCT) run a Nathusius pipistrelle monitoring scheme in september every year – this is the month when the UK population is at its peak when bats arrive from the continent. If you would like to get involved with the surveys, you can find out more and sign up here.

There are a number of other species which are currently recorded as vagrants in the UK but it is possible that some of these may be resident now or may become so in the future as a result of climate change. These include the Kuhl’s pipistrelle and the parti-coloured bat – you can find out more about them in this factsheet from the BCT.

Bats are studied mainly through their echolocation using bat detctors, by observing them in flight when emerging from or re-entering a roost or commuting and foraging in the wider environment. This generally requires specialist kit to determine which species is being observed and despite the abundance of volunteers and professionals, the proportion of the population who would be able to identify bats, compared with those who could identify common butterflies and garden birds, is very low. Even more rarely are bat workers able to catch and inspect the bats they study, and even then it is possible that unusual bats may be regarded an unusual specimen of a known species rather than something otherwise unknown such as the Alcathoe.

The increasing ease with which DNA samples can be analysed may help to identify new cryptic species or confirm the presence of continental species within the UK which the progression of climate change may encourage.

Since 1993, we have identified two new species of pipistrelle to be resident in this country and there is the possibility of a fourth species joining the line-up in the near future. South America may have a new species of carnivorous mammal, but the best bet for the next new British discovery has to be within the bat world.