Focus on the Greater Mouse Eared Bat: Interview with The Bat Trust

gme bat

(Photo courtesy of the BBC)

Bats are one of the more surprising and interesting animals in the UK. They are the only flying mammal in Britain and they have a reputation as being a dangerous creature. But these tiny animals are actually extremely useful to the environment – controlling pests, helping to disperse seeds and pollinating plants. They are a species we should be protecting, rather than fearing.

Despite making up 20% of the worldwide mammal population, many species of bats are in trouble and need serious help to ensure their survival. One species which has been declining in the UK in the Greater Mouse-Eared Bat. The Greater Mouse-Eared Bat (Myotis myotis) was officially declared extinct in 1990. It had suffered a severe decline during the 70’s and 80’s ending with the disappearance of the last known colony in 1985, just outside of Bognor Regis. It is unconfirmed what happened to the group; however a nearby house fire is thought to be to blame. 25 years later, a lone female was found in the area. She was underweight and unfortunately did not survive long after discovery. An inspection of her teeth showed that she was rather old and thought to be one of the last members of the original colony. This species of Bat generally has a life expectancy of up to 18 years. This seemed to be the end however a year later, in 2002, a young male was found in Sussex.  The Sussex Bat Group discovered the youngster hibernating, so they ringed it to ensure they could keep an eye on the individual and the species. Since then, the juvenile male has been recorded at the same site year after year. Elsewhere in Europe, the species is doing well and it is unsure whether this male has found its way to Britain from another country or whether he is a remainder of the 30-strong colony which once lived in the area, although the fact it has been found so close to the original colony’s site suggests it is more likely to be the latter.

Many species of bats are under threat in Britain and across the World today. The Greater Mouse-Eared Bat has suffered from habitat destruction, disturbance and modern chemicals used in timber roofing. The bats tend to roost in roofing during the summer and caves and mines during the winter months. With more chemicals in our building materials which are potentially poisonous and improvements in our building techniques meaning less holes for the bats to use as entrances, long term roosting sites have become increasingly difficult to find. Development has also had a negative impact on the bats’ hibernation sites. These bats only have one pup per year, which can also impact on their survival. Breeding occurs in March. Hibernation occurs in roosts with temperatures between 7 and 12 degrees centigrade during October to March. Colonies can have as many as 1000 members roosting together. The Greater Mouse-Eared Bat is the largest species of Bat in the UK. They can weigh up to 40g and can have a combined head and body length of 80mm.  Their wingspan is broad and can reach up to 450mm.Their diet consists of insects such as beetles, spiders, moths and crickets caught using echolocation of between 22 and 86kHz.

So what is the Bat Conservation Trust doing to protect this species? Dr. Joe Nunez-Mino, Director of Communications and Fundraising with the Trust, explains a little about his role and that of the Trust and what they are doing to secure the future of the Greater Mouse Eared bat, along with all other British bat species:

– Hi Joe! What is your role within the Bat Conservation Trust?

I am the Director of Communications and Fundraising and I started here at the end of January 2014

 – What is it about bats that you love?

Throughout my conservation career I have worked on a number of projects that focused on unusual and misunderstood wildlife. The list includes venomous mammals in the Caribbean and cloud forest dung beetles. Bats are found across the world but unfortunately they are often vilified and misunderstood. The majority of people don’t know just how much they do for us. The great majority of bat species (around 70%) feed on insects and other invertebrates, a world without bats would be a world with a lot more biting insects as well as insects eating our crops and damaging our gardens. So even if some people can’t appreciate the beauty and wonder of bats, they should be able to value the fact that they provide a very valuable service. In the tropics, bats that eat fruit help to disperse seeds and in so doing help forests to regenerate Bats are the second most species rich mammal group and come in all shapes, sizes and colours so there is something for everyone to admire. The largest bat, the giant golden-crowned flying fox from the Philippines has a wingspan of 1.7 m and weighs 1.2 kg, while the smallest is the bumblebee bat from Southeast Asia weighs less than a five pence piece (around 2g). Although most bats are dark in colour, the Honduran white bats look like tiny cotton wool balls when they are at rest while the painted bat from Asia is a striking orange and black.

– How did you get into your job?

I did not, by any means, take a traditional route into conservation. I did my undergraduate degree in life science at the University of Westminster and specialised in Ecology. At the end of this I became rather disillusioned with academia so I ended up going into the world of business. I eventually became a company shareholder and director, all whilst working on a voluntary basis with a variety of small UK based charities such as British Trust for Conservation Volunteers (BTCV), PlantLife International and The Woodland Trust, amongst others. Then I enrolled to do a part-time masters in Environmental Science at Birkbeck College (University of London). Over the duration of the course I became very conscious of the desperate environmental situation in many tropical countries. In the middle of my masters I enrolled on an expedition training course with Frontier. I spent six weeks in Madagascar and I was hooked. the following year after finishing my masters I was offered a sponsored place to do a second masters in Forest protection and conservation at Imperial College, London. I did my thesis in Parque Nacional Cususo (Honduras, Central America) with Operation Wallacea. After completing my masters, I continued to do research in PNC for the following 5 years, initially on a freelance basis and subsequently as part of my PhD at the University of Oxford in ‘Biodiversity Indicators and Conservation Priorities’.

– How important are bats to Britain’s ecology?

Bats are top predators which feed primarily on insects although some (e.g. Brown long-eared bat and Natterer’s bat) will also eat spiders. In the USA a monetary value has been placed on the work that bats do in terms of eating potentially harmful and damaging insects, the lower end of that estimate is $3.7 billion a year. There is no question that they are very important especially when you consider that even our smallest and most common bat, the Common Pipistrelle, can eat several thousand insects in one night.

– What are the main problems which bats face in the UK?

Undoubtedly, habitat destruction which includes both roost destruction as well damage to areas that bats can travel through and feed in. Although some bat species can live in towns and cities, others need woodland to survive (e.g. Barbastelle). Lighting can also have a very negative impact on bats since it can effectively prevent use of an area.

Most bats use a range of different roosts throughout the year, hibernation roosts in the winter and maternity roosts in the summer. The loss of just one roost can make an area unsuitable for bats. Many species of bat have become increasingly reliant on roosts  in buildings especially as natural roosts have become scarcer. This can cause increasing human-wildlife conflict particularly when people have misconceptions of bats.

– The Trust recorded a single Greater Mouse-Eared bat in the UK in 2012. Is the bat being monitored? Is it still in the UK?

Yes, this winters survey has confirmed that it is still in the cave that it hibernates every year.

– Why is there only one individual of this species in the country?

The species was declared extinct in 1990 when a lone 17-year-old male did not return to his hibernation site in Sussex. Before then, the last known colony was a few miles from Bognor Regis and contained several females until 1985 which was the year of their mysterious disappearance. Their departure happened around the time that a nearby cottage was destroyed by fire and as the females tend to form maternity colonies in attics they may have perished in this incident.

However, in January 2001, an emaciated female was found in Bognor Regis but died shortly afterwards. It is thought that she may have been moving between hibernation sites and was caught out by the cold weather. From her worn teeth she was presumed to be quite old. She was found within five miles of the last known colony. Then in 2002, a juvenile male was discovered hibernating in Sussex and has since been recorded annually to this day.

– The Greater Mouse-eared bat’s worldwide classification has changed since 1994, going from vulnerable to least concern. Why is this? And does it tell us anything about future conservation within the UK?

The species seems to be fairing fairly well in mainland Europe and the UK was probably always in the outer limits of its range. We don’t know what will happen over the next few years and how the species will respond to a number of different factors. Climate change could potentially make the UK more suitable but then habitat loss may mean the habitat it needs is simply not available.  

– What, if anything, is the Trust doing to protect this species?

Bat Conservation Trust works along many local bat groups to raise awareness of all bats as well as carrying out investigations to find out more about their mysterious life’s. We will continue to monitor how many of our bats are doing thanks to the help of citizen scientist which take part in the National Bat Monitoring Programme.  

– Will the Trust be reintroducing another other Myotis myotis individuals to attempt to breed them or will the last individual be left to become extinct naturally?

No, we will not be introducing bats. Moving bats from one place to another is never advisable and as I said previously the species appears to be doing well across Europe.

– What is the trust doing to protect all other bat species?

We will continue speaking up for bats and spreading the word as to why they are so important. The law is very clear about the high level of protection that bats get in the UK but we need to continuously uphold and help to make sure laws are enforced appropriately. The last century saw a dramatic drop in bat populations in the UK, we are seeing some signs of a recovery for some species but we need to continue to work with more people to ensure this continues. One critical part of our work is the National Bat Helpline which offers free advice to people who find bats in their home and can even put people who find a bat in distress in touch with a bat carer.

– What can the public do, or not do, to aid bat conservation?

The public already do a lot to help us but we are very keen for people to get involved. Help can range from volunteering at one of our events, raising money for the work we do or helping with the National Bat Monitoring Programme. Just becoming  member of Bat Conservation Trust helps to add your voice to ours and makes us stronger advocates for bats.

Thanks very much Joe. You can learn more and support the Bat Conservation Trust here:


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