January 2020 Student of the Month – Sam Browett

I’m currently in the 4th year of my PhD at the University of Salford, of which I work within the Molecular Ecology Group. This group works on many projects including species monitoring using eDNA, phylogeography, disease and evolution of animals and plants around the world. Our website has details of the fantastic people I have had the chance to work with.

Battle of the shrews

My PhD focuses on the recent invasion of the greater white-toothed shrew (GWTS; Crocidura russula) into Ireland. They originate from Northern Africa but managed to cross the strait of Gibraltar around the time of the last glacial maximum. This remarkable species has since expanded its range through Europe. In the early 2000’s the GWTS arrived in Ireland, likely by ferry. The GWTS is now expanding its range by an estimated rate of 5.5 km per year and already covers a large proportion of Ireland. Ireland’s smallest resident mammal, the pygmy shrew (Sorex minutus), is now rapidly being out-competed and completely replaced by the invasive GWTS. If this current situation continues, there will be no pygmy shrews left in Ireland in the relatively near future. Considering these two species co-inhabit other regions of Europe, my goal is to determine why they cannot coexist in Ireland.

Both shrew species are insectivorous, and previous studies led by my supervisor, Allan McDevitt, suspect that the GWTS is out-competing the pygmy shrews for food resources (McDevitt et al 2014). The first question of my PhD asks: are both the shrews eating the same prey species in Ireland? This is not an easy task. Considering the tiny size of these shrews (pygmies are 4 g, while GWTS are ~12 g), there is not enough patience in the world to sit in hedgerows hoping to see hundreds of shrews hunt their prey.

Thankfully, there is a genetic technique referred to as DNA metabarcoding that can identify multiple prey species from the DNA found in a predator’s stomach contents or faeces. The technique essentially isolates a short section of DNA that acts like a ‘genetic barcode’. By cross-referencing our barcode sequences to an ever-growing online database, this genetic barcode can differentiate between prey species consumed. This technique was used to determine the diet of hundreds of individual shrews around Ireland. We also compared Irish shrews’ diets to shrews in Belle Île (France), where they both co-exist in high abundances.

Preliminary results suggest that there may be some key prey groups that the GWTS is consuming in Ireland that have a downstream effect on pygmy shrews. To support any conclusions about this, I have generated data on the shrews’ gut microbiome (microbial species community) which can act as a proxy to the status of the animal’s health during the invasion. Linking these dietary and microbiome changes has not been done before in an invasive mammal system and can highlight the competitive advantage of the GWTS over Ireland’s pygmy shrews. I’m finalising results for this project now and will announce final findings on my twitter (@ShrewlockHolmes) – the results will be submitted for publication soon.

Fieldwork

The fieldwork was an eye-opener for me. Until my PhD I never considered how marvellous the small mammal world could be. The hedgerow systems in Ireland are flush with diverse life that I took for granted growing up. I now cannot pass hedgerows without considering what creatures dwell within and what they’re doing. You are bound to look strange sticking out of hedgerows with bags of traps, so inevitably people stop to ask questions. I have to say that there was phenomenal enthusiasm from the locals to learn about my work, the shrews and our entire small mammal community. People of all ages got excited when I was able to show them a pygmy shrew for the first time in their lives, even though they live just outside our doorsteps. The excitement of people learning or discovering something new in nature is why I got into science and a big influence to continue in this line of work.

I benefited from enthusiastic volunteers to help me with fieldwork (even in the rain and snow) and I am ever grateful for them.

Dreaming of dormice

by Lorna Griffiths

Adorable, big-eyed, sleepy furball or grumpy, bitey, snarly furball: which would you choose? Me, I chose both. It all began back in 2008 when I happened upon a flyer pinned to a noticeboard “The Lincolnshire Dormouse Group Needs You”. I took down the details, and a few weeks later found myself in a Lincolnshire woodland with a stranger’s hands down the back of my trousers. Horrified? No, I was having one of the most memorable moments of my life, for I had just witnessed something that has become all too familiar, a baby hazel dormouse running up the inside of my trouser leg. That tiny little soul stole my heart and ever since I have spent almost all my spare time studying these charismatic creatures.

Following a presentation that I delivered at the National Dormouse Conference in 2013, I was invited to attend an edible dormouse survey in the Chilterns, five years on and I continue to attend monthly monitoring sessions on these non-native dormice. In 1902, a small population of edible dormice were thought to have escaped from a private collection in Tring and established themselves in nearby woodlands. Being a species that favours beech woodlands, the animals thrived in the beechwoods of the Chilterns and have become well-established in the area.

During the week I work as an ecological consultant, specialising in mammals, but at the weekend you will either find me gazing adoringly at a placid little hazel dormouse sitting calmly in my hand, or donning a pair of thick gauntlets whilst wrestling the brutish beast that is the edible dormouse.

Both species are nocturnal, primarily arboreal and hibernate over the winter months. However, this is where their similarities end, having adopted completely different life strategies. The hazel dormouse tends to breed once or twice each year, with small litters averaging four young, whereas edible dormouse breeding is closely correlated with beech mast, and therefore in years when beech nuts are scarce, breeding is either significantly reduced or even non-existent. To counteract non-breeding years, large numbers of young are produced during high-fruiting years, with some animals producing up to eleven pups.

Size and weight differ enormously between species. The heaviest hazel dormouse that I have encountered was a 38g female in a Nottinghamshire woodland, a pinprick compared to the 350g edible brutes that I have met in the Chilterns.

Over the winter months you will find the hazel dormouse tucked up in a tiny woven nest below leaf litter, at the base of a coppice stool or beneath log piles. Edible dormice favour a different tactic, opting to hibernate below ground in rabbit burrows, disused badger setts and holes created by rotten tree roots. Although both species have a propensity to hibernate alone, on occasions the edible dormouse has been found to hibernate communally with one or two others.

If you take a walk in a Chilterns woodland at night, you may be lucky enough to hear the vocalisations of edible dormice echoing loudly through the trees. The hazel dormouse on the other hand is far more discreet, with barely audible whispers, often undetected by the human ear.

One obvious difference between the two species is the colour, one is golden brown, the other silver grey, and finally, their temperament. The hazel dormouse is British through and through, with impeccable manners, patience and good grace, whilst the non-native edible dormouse is terribly impolite, impatient and is prone to temper tantrums. However, despite their roguish nature, one has to appreciate the tenaciousness of the edible dormouse…preferably from afar, and with full body armour. My heart though, will forever belong to the sweet-tempered, especially endearing, hazel dormouse.

Get involved!

Autumn and winter are the best times for searching for hazel nuts as the vegetation is scarce and nuts are easier to find discarded on the ground. Different species of small mammals leave distinctive markings on hazel nuts, meaning you can identify which creature nibbled the nut!

Hazel dormouse: opening has a smooth inner rim with tooth marks on the outside of the nut at an angle to the hole 

Voles: tooth marks across the inner rim of the nut but don’t leave any marks on the out of the opening

Mice: tooth marks both on the inner rim of the nut and also on the surface, around the edge of the hole

Squirrels: usually just cracked in half, no obvious ‘opening’

So why not go on a Nut Hunt this autumn and let us know what you find using our Mammal Mapper app? If you take a really clear photo of the openings on the nuts you find and add these to your Mammal Mapper records then we can easily verify your records and add them to our system confidently. Going on a nut hunt is a fantastic way to spend a day outside in nature. You can also check out a handy Nut Hunt guide from PTES here.

Just like Lorna mentions at the start of the blog, you may find that a local dormouse group needs your help! If you’re keen to help out, consider contacting a group to see if they need any help. These are the groups we know about:

Lincolnshire dormouse group

Nottinghamshire dormouse group

Kent Mammal Group

Devon Mammal Group

Go to our National Mammal Week page to find out what’s happening each day this Mammal Week! Make sure you are following #MammalWeek and #MammalsMatter and keeping an eye on our social media feeds for all things Mammal Week related. You wouldn’t want to miss out on our prizes would you?!

Did the bat cross the road?

by Domhnall Finch

Movement ecology is fast becoming a key aspect to species conservation; not only do we need to know which habitats species occur in or are abundant within but we also need to identify how they move between these habitats. This issue is becoming ever more critical with the rapid expansion of urbanisation and intensification of agricultural practices acting as barriers or large ‘deserts’ of unsuitable habitat causing fragmentation at a landscape scale. These challenges are particularly important for mobile species such as bats.

Due to these pressures, my PhD research aims to inform landscape scale management of the greater horseshoe bat (Rhinolophus ferrumequinum). This PhD is in association with the University of Sussex, Devon Wildlife Trust and the Vincent Wildlife Trust. As part of this work, we are using experimental designs to mimic the impacts of traffic noise as well as streetlights on bat activity and behaviour. To test the impact of traffic noise on bat activity we created a phantom road by playing traffic noise through speakers along linear features that had not been exposed to such noise before. Our results suggest that traffic noise alone affects both activity and feeding levels of the entire bat community; highlighting yet another mechanism to which roads can act as barriers to the movement of bat species.

Currently there is overwhelming evidence that bat communities are strongly affected by light pollution. To try to reduce such impacts, this summer we have been testing new ‘eco-friendly’ streetlights on bat activity, particularly for the highly light sensitive greater horseshoe bat. For this, we created a phantom street in the environment erecting streetlights with either ‘normal’ white LED streetlights on them or new red lights (a description of a similar project can be found here https://royalsocietypublishing.org/doi/10.1098/rspb.2017.0075). We are currently working our way through the data now and hope to have the results of this experiment very soon.

The more we learn about the impacts of anthropogenic pressures, such as lights or traffic noise, the more we can strategically plan to limit their impact on our landscape. For this, we are currently developing a predictive tool to investigate functional connectivity within the landscape for greater horseshoe bats. We hope that this tool will allow authorities, such as county councils, to visualise where the bats might be flying, which routes they are taking at a landscape scale and how best to plan future developments. We hope that these sorts of innovative designs can help us mitigate the impact of anthropogenic pressures on nocturnal species, increasing free movement at a landscape scale. Resulting in higher connectivity between habitats and meta-populations in the environment.

Get involved!

One of the best things you can do to help bats from the comfort of your home is to turn off the lights! If you can’t turn off your indoor lights, at least consider turning off outdoor lights when they’re not needed, and keeping curtains closed to prevent your indoor light from spilling out into the night.

Go to our National Mammal Week page to find out what’s happening each day this Mammal Week! Make sure you are following #MammalWeek and #MammalsMatter and keeping an eye on our social media feeds for all things Mammal Week related. You wouldn’t want to miss out on our prizes would you?!

Building bridges (and dams)

by Roisin Campbell-Palmer

Next to humans and elephants, beavers are arguably the most impactful of engineers. They are critical creators of lifescapes, which are exploited by a whole host of associated wildlife species. Once common in Britain, beavers were hunted to extinction in the 1600-1700’s for their valuable pelts, scent glands and meat. This pattern of destruction that culminated with their near entire removal of both beaver species from water sheds worldwide precipitated ecological decline. If left to their own devices beavers play a crucial role in wetland ecology, species biodiversity and can provide important services such as habitat creation and water management. This can be challenging in modern and often heavily modified landscapes. Reintroducing beavers, though controversial with some land users, ultimately restores riparian ecosystems if we are prepared to tolerate their activities.

Beavers are fascinating animals, though typically secretive and unseen by many, their activities and field signs often fascinate. Being a part of many groups visiting beaver sites both in Britain and Europe, the excitement demonstrated by many in finding a freshly gnawed stick or seeing a dam is repeated over and over. Having worked with this species for over 11 years in Britain, I recently undertook field work on behalf of Scottish Beavers to re-trap and sample beavers in Knapdale, home of the first official release. This felt like a completion of a journey where we first released Norwegian animals 10 years previously. Even coming across one of the original males, Bjornar, on a remarkably calm and dry evening on the boat. Though looking aged with greying muzzle, he was still holding his territory and obviously adapting well to life in Scotland.

The story of the beaver’s return to Britain is long and haphazard but still has some way to go. Currently we have an ad hoc mix of dispersed wild populations in almost the opposite corners of the country, both licensed and unlicensed. Their genetic integrity is unclear. Enclosed families are scattered through a broad range of projects throughout the wider landscape. There is ample scope for improvement in regards to the beavers’ current status in Britain. At a time where biological collapse is occurring it is essential that this species that can rebuild complex landscapes and the life they contain is restored more widely in Britain. Though we shouldn’t underestimate their potential impacts on some landowners. The achievement of this will only prove possible if beavers can be tolerated and negative impacts managed in a pragmatic fashion.

Get Involved!

Today, our Beaver Ecology and Conservation training course is taking place in Devon. We’ll be sharing photos and videos of the day live as they go ahead so be sure to keep an eye on our social media feeds! If this takes your fancy, check our list of training courses here.

We’re currently collecting data on the distribution of riparian mammals (those living on waterways) in our project Walk This Water Way. Just use the Mammal Mapper app to record any signs or sightings of these lovely creatures whilst walking at least 600m along a waterway (e.g. river, canal etc) and enter the survey ID as ‘WTWW’. 

Go to our National Mammal Week page to find out what’s happening each day this Mammal Week! Make sure you are following #MammalWeek and #MammalsMatter and keeping an eye on our social media feeds for all things Mammal Week related. You wouldn’t want to miss out on our prizes would you?!