Thursday, 19 January 2017

Mink – Evil or Interesting?

A Talk by Dr Joanna Bagniewska to the Berkshire Mammal Group

6th October 2016


write-up courtesy of Edwin AR Trout, Berkshire Mammal Group

Dr Joanna Bagniewska, University of Reading

Opening the meeting Amanda Lloyd introduced Joanna as a zoologist specialising in behavioural ecology and invasive species research, gaining her MSc and PhD from Oxford University. Over the years she has undertaken research in five countries, having studied foxes and jackals in South Africa, wombats and wallabies in Australia, mole-rats in the USA, and both bees and mink in Britain. (Joanna observed that in view of mink’s past fortunes, she was one of few researchers able to wear her study species!) Currently Joanna works as a teaching fellow for the School of Biological Sciences at the University of Reading and has won awards as a science communicator.

She started by suggesting she was one of a minority in this country to admire the otherwise widely denigrated American mink, perhaps because she approached the subject from the point of ecology rather than conservation and control (where mink are considered pests). She defined them as mustelids and took a few moments to outline their ecology.

Mink Ecology

The American mink is native to North America, at least north of the south-western arid zone up to and including Alaska, but south of the high Arctic. Mink are to be found in areas of high water quality. They are small bodied – at 15-18” the males are twice the length of the females – and sexually dimorphic. In some areas males have shown a preference for eating rabbits (for which they have proportionately bigger jaws and teeth) and females – water voles. They are opportunistic feeders and both sexes will eat insects, fish and birds.

While native to North America, they have been introduced into Europe, Asia (especially Siberia) and South America (Patagonia in particular),

largely as a result of the former demand for their fur. In the 1920s and ‘30s they were farmed, but later, in the 1950s, many escaped or were released. They are now regarded an invasive species.

They have, in many ways, become too successful for their own good. Why? They are generalist foragers, with a broad diet: birds, amphibians, reptiles, rodents, insects, and crustaceans. They can hunt like foxes, climb like cats and swim like an otter. They are semi aquatic and very adaptable.

An Invasive Species

As an invasive species, what has been their impact? Traditionally, successful incoming species upset the balance of nature by:

  • Increased predation
  • Resource competition
  • Hybridisation
  • Disease transmission

Of these the first two are of most relevance, though there have been some recorded cases of interbreeding between wild and released mink in North America.

The problem of increased predation is exacerbated by the higher proportion of carnivores among invasive species. Carnivores make up 5% of mammalian species, but when invasive mammals are examined, that proportion rises to19%.

Direct predation by mink is most notable in the UK in the case of water voles. Female mink are the right size to enter voles’ underwater holes and the water vole population is declining fast. This is, admittedly, for various reasons, but the presence of mink is not helping. There is no problem with water voles in Europe, incidentally, but rather the Pyrenean Desman instead is vulnerable and declining.

The Landscape of Fear”
Other vulnerable species are ground-nesting sea birds, for which the security of islands and rocky

outcrops are no protection against the semi-aquatic mink. On arrival in a colony mink will behave like ‘a kid in a candy store’ and take as many as 100 chicks per night, with no sense of forward planning or restraint. Indirect consequences follow, as birds leave their nests – in fear or to protect their young by attacking predators – and the chicks or eggs succumb to the cold or neglect. The very presence of fear can have further negative effects on the predated population.

Over-sized, Over-sexed and Over here”
A notable impact of resource competition has been on the European mink, which is now limited to Estonia and the Pyrenees, as the American mink is sufficiently well equipped to out-compete.

American European
1310.2 g v. 976.6 g
size of female = size of male
litter of 6 v. litter of 2.5

The American mink is voracious and adaptable, and its European cousin is unable to keep up.

Another measure of its success lies in the competition with polecats and otters. When these species were declining in the 1920s-50s, mink expanded into their vacated niches, on both land and water.

Horrible – but Interesting

American mink are semi-aquatic BUT …

  • They are small, with a large surface area, and so loose heat quickly
  • Their fur is neither buoyant nor insulative
  • Their propulsion is inefficient – they swim like dogs rather than otters
  • Their paws have little webbing (more than polecats, but less than otters)
  • They have poor eyesight, especially underwater.

Is swimming innate and instinctive? It seems the young have to be taught, as indicated by trials on captive mink. Other tests suggest mink will work harder to get to water than even to obtain food! And mink spend much of their time in the water, diving for food.

Diving Behaviour

How do we study diving animals? It has been difficult until now. Research has focussed onterrestrial behaviour, which is more readily observable and can be indicated by footprints, scat and camera traps. For wild mink only ‘surface events’ have been traceable in the water, and underwater behaviour monitored only in captivity. Joanna’s research was the first monitoring of mink diving in the wild. Indeed, the only previous study of mammals was one of the platypus in Australia. Since then there have been studies of water rats and beavers as new data-logging technology becomes available. Devices small enough to be attached to mink can measure time spans, temperatures, pressure and acceleration.

Such data logging was first developed in the 1950s, weighing as much as 1.5 kg, based on ‘egg timer’ technology and recording output on paper. The first devices were used on Weddell seals. They were accurate to about 20 m and therefore only useful for extensive depths at sea. Now devices are digital, weigh 1g and are accurate to 3 cm, so may be used effectively in the shallow water of British rivers.

Monitoring Programme
Joanna’s project monitored 16 distinct animals on the rivers Thames and Cherwell in Oxfordshire, generating 20 datasets, with a mix of males (six) and females. The programme was conducted over three seasons, spring being excepted on animal welfare grounds.

The method made use of mink rafts, by which an enticing ‘home’ or tunnel was placed on a floating platform away from the bank. Pliable clay would be spread on the base of the raft to receive the impression of foot prints should a mink investigate the tunnel. With the presence of mink thus established, the tunnel would be fitted with a trap and bait, and, if caught, the mink fitted with a collar and data-logger.

Quantitative Results
The collective results of the study indicated great variety in depth and duration, with a total range of 1 to 189 dives per day, with the greatest individual range between 5 and 143. It became notable that the smaller females were the more energetic divers, performing over 100 dives per day (as explained below). The time spent diving wasn’t long: a total of just 38.4 minutes per day on average, with 57.9 seconds the maximum individual dive-length recorded. Median depth times varied between 7.4 and 18.0 seconds.

(Previous studies had suggested even shorter times.) Diving was undertaken throughout the year, not just in summer as had been postulated, and 83% of dives took place in daylight – presumably in consequence of minks’ poor eyesight. The maximum depth of around 3 m was more an indication of river depth than diving ability.

Dive Clustering
The pattern of surfacing suggested that dives were clustered in bouts of activity and so was analysed according to the Hidden Markov Model (HMM). Three types of diving frequency were identified:

  • A “cluster” of multiple dives
  • Loosely aggregated: an “activity session”
  • Single or terminal dives

Temperature and Persistence
Mink experience a temperature range of 5-35 oC, in which temperature falls during activity. The body cools in water, and warms through when basking on the bank; it is typically 35 oC when sleeping, in the 20s when on land, and drops when diving. It is noticeable that dive effort is higher in females; female ‘persistence’ may extend to performing 80 dives in a row. Is this because they are excellent divers, or ineffective hunters who have to repeat dives to eat?

Either way, the smaller the mink the greater the persistence and this may be expressed as a negative relationship between temperature and bodyweight. Persistence is greater during the day, when temperatures are higher, and become more concentrated the shorter the day. That said, mink tend to be inactive 80% of the time, spending only 50 minutes or so in the water per day. Males are more nocturnal – perhaps, because of their size, they are less afraid of meeting otters?

Competition with Otters

Behaviour has altered over time, with the evidence of scat declining since the otter’s resurgence in the 1990. However, if other evidence such as footprints is taken into account, it appears that mink remain, but are no longer deliberately marking their territory. Otters are bigger, and may weigh 8 kg, so while the feisty mink might be prepared to fight, it wouldn’t,

wish to make a habit of it. So what seems to be happening is that when the nocturnal otter returns, mink behaviour adapts to the new circumstances and becomes diurnal, thus avoiding confrontation.

Conclusion

The survey testifies to the success of new TDR (Time Depth Recorder) technology and HMM techniques in monitoring the behaviour of otherwise difficult to observe species.

QUESTIONS

Have there been studies of the American mink in its natural habitat, North America?
Yes, in the 1940s and 50s, but mainly of terrestrial behaviour. There have been diving studies elsewhere, in Tierra Del Fuego for instance, where mink are diving in the sea, and of feeding in Sweden.

How long did the mink wear collars?
Joanna aimed to collect collars after three weeks, but if missed, they were designed to be readily biogradeable, rather than made of more durable leather.

Where do mink live?
They don’t excavate, but occupy existing holes. Sometimes these are in trees, but mink are particularly fond of rabbit warrens.

Are males and females mutually antagonisic?
Yes, males and females join only to mate. Mink of each sex maintain their own, linear, territories. The males occupy about 5 km, overlapping two of the smaller females’ 3km territories. Males will not tolerate each other. Mink are not social; apart from mothers and kits they do not share.

How related are they to the European mink?
Less so than previously thought; they are of a different genera. Indeed there is no knowledge of hybridisation. European mink used to be found in the Baltic states, Poland, Belarus and Russia south to northern Ukraine. No population is known to have existed in the British Isles.

Has the return of the otters in recent times deterred the mink?
It appears not, though it has affected the mink’s behaviour.



Monday, 5 September 2016

Dormouse Project, 1982-1994 and the first release of captive-bred dormice in the UK

A Talk by Dot Eaton to the Berkshire Mammal Group
3 March 2016

Over thirty years ago Dot was an animal keeper near Loch Lomond, when she formulated an ambition to build a captive-bred stock of British animals and reintroduce them to the countryside, but was warned there would be significant difficulties. Each animal would have to be vet-checked, landowners’ permission would be required, and some animals simply couldn’t be bred in captivity. However, she took heart from Gerald Durrell’s private assistant John Hartley and settled on dormice as her preferred species. At the time there was only one book on the subject, Common Dormouse by Elaine Hurrell, the daughter of Harry Hurrell. Eventually Owen Newman, a BBC cameraman, was recommended to her as someone with relevant expertise; someone who recently had even filmed a dormouse giving birth. It was Owen who trapped her first dormice at a location in Wiltshire, giving Dot three while retaining two for his own use. Dot had, by this time, qualified for a licence and Owen give her other dormice on subsequent occasions.

Dot’s first breeding colony
In 1982 she moved to Chessington Zoo and started breeding her first colony, and when she relocated to Windsor Safari Park in 1988 she moved her dormice with her. She had a small shed, divided into four and fitted with a central red light, but something larger scale was required and Dot designed a new breeding unit. The journal Robin Page visited and wrote a very supportive article in Country Life, helpfully ending with an appeal for funds. A cheque for £2,500 duly arrived from Mrs T. Hesketh of the Valerie White Trust, and the new building was erected. It had eight enclosures divided by Perspex to prevent the transmission of disease. In each enclosure was paced one male and one or two females – 16 animals in all – and Dot filled them with fresh branches twice a week: Hazel, honeysuckle and rosebay willowherb. She had red lights fitted to allow her to observe the dormice from a adjoining corridor and thus improve her understanding of their behaviour and ecology.

Observations of dormice
Their first reaction on Dot entering the enclosure was to freeze stock-still. They weren’t particularly sociable and didn’t feed together. Rather, if the encountered each other, the dominant individual would maintain its place and the other would run away (and surprisingly fast). Consequently Dot realised that food supplies had to be distributed widely throughout the breeding unit. Having said that, several dormice would share a nest box; perhaps three or four together. Sadly she never saw the process of nest building – presumably as they were inside the nest-boxes – but she did see dormice stripping branches in preparation and stuffing soft honeysuckle bark into their mouths before taking it to a box. There are several nest types: two or three-leaf nests made by juveniles; round nests full of bedding as breeding nests; and semi-subterranean grapefruit-sized nests in which to hibernate. The latter are at ground level and built partly into scrapes to achieve as stable a temperature in winter as possible. The adult dormice emerge in May in time to breed. They run and chase each other for three nights before finally mating. Then, if pregnant, the female will retire to a nest after 30 days to give birth. After a further 30 days the juveniles appear. (If not pregnant the chasing resumes after about 10 days, but most litters are early.) When the juveniles emerge it is fascinating to observe their varied personalities and the mistakes they make. They don’t know to freeze and they miss branches when climbing; Dot realised they are very vulnerable in the early days of life. Indeed if the temperature falls to blow 10 oC for several concurrent nights, then – assuming the juveniles are not fully developed – the mother will go torpid and the youngsters will die. As a result there may be second litters to replace the losses. In mid August the adults fatten up to hibernate; the youngsters take longer to prepare for the winter sleep.

The reintroduction team
Dot realised that a number of skills were necessary for success, many of which she personally didn’t have, and so assembled a team of experts to help.
  • Martin Hicks
Ecologist in Hertfordshire
  • Dr John Lewis
Vetinary surgeon
  • Julian Ford-Robinson
Senior Science Master, Haileybury College
  • Prof John Gurnell
Behaviourologist at QMC, London
  • Steve Whitbread
Tracking specialist, Southampton University
  • Dot Eaton
Dormouse breeder

IUNC Guidelines
These govern captive breeding for reintroduction projects worldwide and are founded on several fundamental principles:

  • There should be evidence of former occurrence
  • The causes of previous loss should be understood and a result of human action
  • The factors causing extinction are to have been rectified
  • The proposed habitat should be suitable and of sufficient extent

All of these were met at the proposed site at Haileybury in Hertfordshire, as though the site was small (7 hectares), two substantial hedgerows linked it to extensive woodland nearby.

1992: The Reintroduction
On 18 August the dormice were placed in a cage and observed until 23 September when the hatch was raised. One dormouse ventured out along a branch and returned. Within half an hour the colony had moved into the wild. There were two family groups: a male, two females and two young in one, and one female and five young in the other. One juvenile was radio tracked and was found to have ranged 35m and back. Three others ranged by a similar amount that first month. (Perhaps the rest did too, but only some individuals were monitored.) Five more juvenile males were added the following year, and more the year after.

Further observations
It was apparent that the dormice liked to explore and spent little time on the ground. Their squeaking is much like that of a mouse

1994: Burnham Beeches
In 1994 Windsor Safari Park went into receivership and despite efforts to sell it as a going concern, it was finally sold for development as the new Legoland. Employees, including Dot and her husband, were evicted from their tied cottages. As well as the loss of her home, Dot had 97 animals to care for. Initially the dormice were taken to St Tiggywinkle’s, and then to Burnham Beeches were they and the breeding unit were offered a home by Mark Frater and Helen Reed, the keeper and ecologist there. Indeed, as well as feeding and looking after the dormice, Mark and Helen even built a second breeding unit. Eventually Dot arranged for a contract to assign ownership jointly with the Corporation of London (owner of Burnham Beeches). With others expressing an interest in the project, a Common Dormouse Captive Breeders’ Group was formed and continues to function to this day. Since 2000 the reintroduction programme has been administered by the People’s Trust for Endangered Species, which has now run as many as 25 such projects (involving partners such as London and Paignton zoos). Meanwhile Dot has been invited to speak at international conferences in Denmark and the USA, though without her own facilities, she is no longer been active in breeding dormice.

QUESTIONS & DISCUSSION
To which Martin Hicks, present in the audience, contributed.

Taxonomy – dormice are a group of their own, with two species in the UK: Common and Edible.

Breeding – litters of 2-6 juveniles. They remain in family groups for a while, both parents looking after the youngsters. Pairings are temporary, however, as dormice are quite promiscuous.

Physical characteristics – include a semi-prehensile tail and forward facing eyes

Behaviour – they are arboreal and nocturnal, but particularly active at dusk and dawn. They hibernate throughout the long winter months, though in Mediterranean countries the higher temperatures require much less hibernation. When torpid or hibernating, they are vulnerable to ground predators, such as badgers and wild boar, though dense vegetation protects them from the attention of owls. Their food supply, however, is adversely affected by the presence of the more vigorous grey squirrel.

Habitat – not just coppiced hazel, although that is most characteristic and 2-3 year old coppice is ideal, they will even be found at the edge of pine forests and where there is dense vegetation. However, it is habitat loss that has been the biggest cause of their decline; the loss of managed woods with lots of new growth, and the ripping out of hedges has isolated and exposed them. There has been massive change in the British countryside over the past century.
Edwin A.R. Trout
Berkshire Mammal Group

Scottish Wildcats And Mammal Conservation in Scotland

A Berkshsire Mammal Group Talk by:

Alicia Leow-Dyke, 3 December 2015


Opening the evening, Vice President of BMG, Melanie Orros, introduced Alicia as a friend from their MSc course at Imperial College some years ago and who has since spent time as a staff naturalist at the Aigas Field Centre in the Highlands on beaver demonstration and wildcat breeding projects – even appearing on television in Autumn Watch. Alicia went on to explain that the centre was built as a hunting lodge in the Victorian period and after 1947 was used as a retirement home. Then in the 1970s it was bought as a facility to encourage environmental education. Aigas is located near Inverness, , with trees surrounding the house, a loch nearby and extensive tracts of moorland beyond, amounting to 800 acres. Her time there gave her the opportunity to be involved with projects to conserve several species that are characteristic of the Highlands.

Scottish Wildcats

Alicia started with the Scottish Wildcat, or Felis silvestris grampia, which, since the extinction of the lynx, is the only naturally occurring feline in the UK. Some regard it a sub-species of the European Wildcat; others the local manifestation of a species common throughout the continent. There are related species in Africa, Middle East and Asia too. Wildcats were once found throughout Scotland and the rest if the UK, and not just in the Highlands.

Slightly larger than the domestic cat, males are around 8 kg; females, 3-5 kg. Their diet is varied, consisting of mice, rats, voles – even pheasants – but with a preponderance of rabbits.

The females have two estrus cycles, each lasting 8 or 9 days in Dec-Feb and May-July, though a second generally only if the first cycle has been unproductive. Gestation lasts around 60-68 days and most kittens are born in April or May. Litters vary between one and three kittens, but more often or not are two. They live for 13 / 14 years, though the oldest in captivity is 21.

They face a number of largely man-made threats. Loss of habitat is significant, particularly with the growth of plantations in the twentieth century; exotic species and regular planting creates a sterile monoculture, large, dead and dark, with few rocks and roots in which to den. They have been hunted in the past, as their soft fur was highly prized, and like other wildlife, they suffer from traffic accidents. Natural predators (particularly of kittens) include eagles and foxes, but the most characteristic threat is their propensity to hybridise.

The domestic cat derives from the North African wildcat, domesticated 8,000 to 10,000 years ago at a time coincident with the rise of agriculture. They have since spread with human migration. Differentiation between the domestic and wildcat is difficult. Wildcat skulls will stand on end without falling over. The intestine of the domestic cat is vastly longer than that of the wildcat – maybe three or four times the length. And there are genetic differences. But possibly easier are the distinctive markings of their pelts. Wildcat stripes tend to be much finer than a hybrid or domestic tabby, and the dorsal line in wildcats stops at the base of the tail.

Today there are perhaps 400 to 1000 wildcats in the wild, possibly as few as 100 reasonably pure bred cats, and they constitute one of the rarest mammals in the UK

Consequently a captive breeding programme was established at Aigas in 2011, and Alicia was its manager for four years. The first pair of cats arrived in March 2011, from a scientist’s private breeding scheme in Perthshire, and the second came a year later. A pair of kittens was born in 2012 and another two in 2013. (Incidentally, kittens’ eyes are blue at first, turning yellowy green after a few weeks.) The long-term aim, yet to be realised, is to release them in the wild.

In 2013 a Wildcat Group was established with the support of Scottish Natural Heritage and a six-year action plan was launched. 30-40 organisations are involved in various capacities: surveying habitat, identifying and preparing release sites, monitoring populations, neutering feral cats, promoting responsible cat ownership, and breeding wildcats.

One of the tasks is genetic testing. This can be on a variety of samples – hair, faeces or blood – of which the latter is best. Taking a leaf out of the Spanish programme for restoring the Iberian Lynx, which is some way in advance of the wildcat programme, the test is fulfilled by placing ticks in the cats’ dens which, when sated with blood, drop off their host and constitute the sample! Many of the wildcats tested have proved to 60-70% pure, with a proportion of domestic cat. Finding 100% wildcats is looking increasingly unlikely. What to do about hybridisation is a divisive issue, however. Some conservationists are purists, other accept a degree of hybridisation as healthy and a reflection of today’s reality. Supplementing the Scottish population with European Wildcats from elsewhere, say Turkey or the Levant, is seen as ‘Plan C’, because maintaining a distinctly Scottish identity is thought important. However, suitable European populations are being assessed for possible future integration.

At Aigas the breeding facilities allow for enrichment activity, with aerial walkways, swings etc, to mimic conditions in the wild. The food is natural – rabbits, venison – though males and females are allowed to run together (which they wouldn’t normally, the males being solitary) to maximise the opportunity for breeding. They even have “starve days” to reflect the vagaries of hunting. The kittens stay with their parents for a year, then the males and females are separated to avoid in-breeding

QUESTIONS

The talk was suspended briefly for an impromptu discussion, the answer to some of the questions being incorporated, where applicable, in the account above.

Can you handle them – are they fierce?
You don’t handle them except for testing and separation, as they will spit, jump and use their claws freely. You need thick gloves and the rapid administration of anaesthetic!

Is it possible to establish for how long wildcats have hybridized with domestic cats?
Yes, over recent generations. A longer-term test is being developed in Switzerland.

Does hybridization make a difference to behaviour?
With 60-70% wildcat genes, there seems to be little difference between pure and hybrid in terms of either fierceness or fertility.

Do they purr?
No. They wail, caterwaul and hiss, and the kittens squeak.

Their characteristically flattened ears suggest aggression. Do they prick up their ears?
Dificult to say as they are usually aggressive in the presence of humans.

Have they been vaccinated at Aigas?
No, not yet

Is there any radio-tagging to establish range or behavioural patterns?
No, as the cats have not yet been released, but camera traps have given an indication of the movement of wildcats. The full range is not established and promises to be difficult, as wildcats keep on the move, denning overnight and moving on (except when with kittens).

Are they arboreal?
They do climb trees, and like to perch high up on a prominent branch, but they don’t climb to the tops and don’t sleep in trees

Red Squirrels

Reddish fur in summer and duller brown in winter, with characteristic ear tufts, the Red Squirrel lives in coniferous and broadleaved woodland, occupying 3-7 hectares or so. Its life span is 5-6 years. The squirrel has a varied diet of cones, seeds, nuts and berries. Nibbled pinecones are a telltale sign, with an uneaten ‘handle’ where they hold the cone. They stash food in Autumn, but their memory isn’t good and they often forget where food is stored.

Red Squirrels can be found throughout Europe, Siberia (except in the Arctic north), Manchuria and Japan. They have been introduced to Georgia in the Caucasus. In the UK, however, they have retreated in the face of expansion by the incoming Grey Squirrel. In the 1940s they were all over the country; Greys were only in the South East and southern Midlands. Now Reds are found mostly in Scotland – the Highlands, Southern Uplands, Cheviots – along with Anglesey, Brownsea Island and the Isle of Wight. There are 120,000 Reds in Scotland, with 15,000 in England (of which 60% in Northumberland.)

It is a misconception that the Grey attacks the Red; the problem is more to do with food resource competition and especially the spread of squirrel pox, of which the Grey is a carrier and to which the Red is susceptible. However, Reds do better in pine forests, as the Greys are heavier and less able to make use of the flimsier branches of coniferous trees. There is also an active policy of controlling Greys in Scotland.

Pine Martens

Linked to the above is the recovery of Pine Martens in Scotland (and to a lesser extent, the rest of the UK. For some they amount to a conservation tool for controlling Grey Squirrels. The population recently was 3,500 in the UK and rising, with 3,000 or so in Scotland. They are natural in the Highlands and, since 1990, are reappearing in the borders with the odd one popping up in the Cheviot Hills and North Yorkshire. In Wales the Vincent Wildlife Trust has been active with the reintroduction of 20 animals and there has now been a sighting in Shropshire. They also appear naturally in Ireland.

Like Red Squirrels, they have two moults and are redder in summer. Significantly, each animal has specific markings on its distinctively pale bid, making identification of individuals possible.

Pine Martens eat berries, nuts, mammals, birds, eggs – even peanuts and jam! They opportunistic and will enter buildings for food and shelter. Alicia showed pictures of one such creature that had taken up residence in a hide at Aigas in order to forage on peanuts. Naturally Pine Martens live in rocks, caves, roots and up trees, though now make use of next boxes devised by the Vincent Wildlife Trust.

Badgers

There are thought to be 250,000 in Britain, of which 25,000 are in Scotland, but their behaviour is different in the north due to the marginal habitat and the associated paucity of food. They tend to live in smaller groups: 6 to a sett, rather than up to 25 in some parts of England. At Aigas there are usually 3 or 4 per sett, with several setts in the area. It is difficult to identify individuals, except by the battle scars borne by some of males. Despite the lower density of traffic in Scotland, there are appears to be no respite for the badger, which all too often ends up as roadkill. However, with no Bovine TB in Scotland, farmers offer much less of a threat to badgers.

Beavers

There have been various projects to reintroduce beavers to Scotland: Knapdale and the River Tay, as well as Aigas in 2006.

The herbivorous Castor fiber – which, contrary to widespread assumption, doesn’t eat fish! – is similar to the smaller North American beaver and can be found across Eurasia from Britain to Mongolia. In Europe it survived persecution mainly in Scandinavia. Otherwise it was hunted to extinction – by C14th in England and C16th in Scotland – for their fur and medicinal qualities ( salicylic acid). By 1900 only 2,000 or so were left in Europe, while now there are 700,000! Indeed there are so many that in some jurisdictions – Lithuania and Bavaria, for instance – hunting in October is permitted to control numbers.

The first reintroduction to Scotland was at Knapdale, were three or four families were brought in from Norway. In 2010/11 a separate group of beavers were found in the wild on the River Tay, numbering as many as 150-200 individuals at present. It isn’t known if they were illegally released, or escaped, but there presence in an agricultural district enables useful comparison with the forested habitat of Knapdale. A decision by the Scottish government is due in 2015 on whether to allow a more widespread reintroduction, though it looks increasingly likely to be deferred to next year. Without human intervention colonisation would be slow.

In 2015 the beaver was reintroduced to England too, with the discovery of a pair on the River Otter in Devon (now with an additional three youngsters). An initial decision to remove them as ‘non-native’ was rescinded in response to public opinion, on the condition they were tested for atapeworm to which beavers are susceptible. They were clear, so Defra permitted their continued presence on the Otter for five years’ monitoring by the Devon Wildlife Trust. There are plans for a reintroduction to Wales, too, with sites prepared for future occupation.

QUESTIONS

How far would beavers spread?
They are quite territorial and it depends on population pressure. If the group is large, the 2-3 year olds will disperse some distances, but if the group is small, with sufficient habitat for the resources it needs, then the juveniles will remain close by. So in the five years permitted in Devon they won’t go far.

How do they interact with otters?
They generally get along. The main risk is the vulnerability of vole-sized beaver kits in May/June, as if an otter enters the lodge he/she will kill them. Usually, however, the otter is curious, teasing the beaver, which in turn simply ignores the attention.

DISCUSSION

Opening up for discussion at the end of the talk, questions returned to the Scottish Wildcat. Would there be conflict with the lynx should the latter be reintroduced? It would be a cause for concern, but largely for pressure on food resources (rabbits, especially), rather than on the risk of predation. Other questions related to the preparation for future release. Is there a risk of habituation? Yes, so although the adults are for breeding and will not be released, the kittens are left alone as much as possible. However, the lengths of disguise are not resorted to with wildcats as with the bustard chicks in Somerset; wildcats would not be fooled by a stripey onesie!

Edwin A.R. Trout
Berkshire Mammal Group



The contribution a small commercial reserve can make to Leopard Conservation in South Africa

A BMG Talk by Tara Pirie, 4 February 2016

Tara explained that she had spent ten years in South Africa, as a guide for the first seven and then embarking on a PhD toward the latter end of her time there, while working at Ingwe Leopard Research. (‘Ingwe’ means ‘Leopard’ in the local language.)

Leopard Conservation

Like other animals leopards are threatened by habitat loss, food depletion and conflict with humans, and Tara made the case for their conservation, and that of similar predator species. One argument is ecological – often the loss of an apex predator will cause a trophic cascade in the food chain, or a meso-predator release. Another is economic – leopards are highly charismatic animals and the tourism they support is economically beneficial to host societies.

Threats to leopards
Most important is conflict with farmers, though livestock deaths are not always caused by leopards: disease, accidents, etc can create an exaggerated impression. Even the presence of its spoor does not necessarily mean the leopard killed the livestock. (If the wound is not obvious it is possible to lift the skin to see where bruising occurs: leopards go for the throat.) Other human-related threats include:
  • Hunting. Permits for culling, taking out problem animals and trophy hunting
  • Trapping, snaring, poisoning – often for food
  • Road deaths – accidental and avoidable
Tara cited the instance of a road with tall grass growing on either side, on which four leopards had been killed a year; this was one of the triggers for Will Fox to set up Ingwe Leopard Research. When he arranged to have the grass cut there were no known deaths in the following three years.


Ingwe Leopard Research

Ingwe Leopard Research in Mpumalanga Province was set up in 2011 with a triple purpose: research to support conservation with evidence; raising awareness, and supporting sustainable tourism.

Research
Although Tara is back in the UK, the research work is ongoing, supported by the income from running safaris. Government sites offer legal protection, but contain only 25% of the leopard habitat in South Africa; up to 75% falls outside formally protected areas and leaopards are known to roam freely. Permits to kill leopards cost R10,000 (£500) and are relatively affordable. Ingwe undertakes the only leopard research in the province outside Kruger National Park, generating data to formulate informed decisions. It also gathers data on other carnivores such as genets and hyenas.

Raising awareness
One of the fundamental tasks is to encourage an interest in conservation among the local people, and an attitude where leopards are valued rather than perceived as a threat. Tara described a two-pronged approach:

School visits
Ingwe helped with fund-raising, offering lessons in computing, repairs to building etc. After some months of involvement in the school Tara finally discussed the purpose of Ingwe’s work with the headmaster, but only once he had raised the subject. It transpired the locals were concerned about the presence of leopards as a threat, much as with the lethal snakes that abound in Africa. Gradually Tara encouraged them take a more positive view.

Work with farmers
Influencing farmers was difficult to start with, but by listening to them in the pub – rather than preaching at them – and indicating she understood their wish simply to earn a living, she was given a month’s trial with one of the more prominent locals to demonstrate the leopards were not an active threat. The trial was successful and the leopards remained untouched thereafter! All permits have subsequently been rescinded.

Leopard Ecology

In describing the characteristics of leopards Tara quipped they often “hadn’t read the script”. Received wisdom suggests they are:

Highly adaptable.
They are known to eat as many as 92 prey species ranging up in size to eland calves and juvenile giraffes, and one has even taken on a 3m crocodile. They can carry their own body weight up into a tree. But the optimum size is the 25kg impala. Surprisingly, they will also eat fish.

Solitary
Not always. Though males usually are, mothers spend 90% of their time with cubs. However, Tara has also seen males spending time with their offspring (sons) up to three years old, even from different litters. Such behaviour has also been reported in the lower density populations of Namibia, so is not unique to Ingwe.

Territorial
Both males and females have their own, often overlapping, territories. Acquaintances are more likely to be accommodating, and submissive individuals will tolerate incursions. ‘Territory’ is not absolute: more of a ‘core area’, one that will be defended. They defecate in prominent places as a visual sign of their residence, and will claw trees, scent mark (their odour smells of popcorn) and call. The sound of the leopard call is like that of a saw, usually four repetitions for a female; as many as ten for a male.

Nocturnal
Not always. Though adult males seldom appear, females can be seen in the heat of the day, and are more likely to come out on overcast days or in winter.

Savannah dwellers
But they also live in rocky environments and they are the most widespread of the felines: from Cape Town to the Amur Valley in Siberia and down to Indonesia. The leopard is the last of the ‘Big five/ to remain free-roaming.

They were classed ‘near threatened’ in 2008, but are so elusive there are no accurate records. One estimate of 600,000 in South Africa has been dismissed as absurd. But there are 150 CITES in South Africa every year, and seven in the province. See Swanepoel 2013 for distribution of suitable habitat based on knowns populations both in the Transvaal provinces and the Cape.

The Thabo Tholo Wilderness Reserve

The work of Ingwe Leopard Research’s work in the reserve has helped establish density, calculate home ranges and characterise habitat selection.

Spoor/tracks
Tara trained volunteers to locate and identify leopard tracks. They have a three-lobe pad and four oval toes with no claw marks. Left and right are distinguishable. Trackers were to take photographs with a ruler included for scale (see page 4), but there was considerable difference in determining accurate measurements – typically the margin of error is between 1-2 cm.

Camera traps
Tara established a camera club to fund camera traps in return for access to the best photographs, and somewhat against expectation this was highly successful. As many as 50 cameras were obtained over a three-year period. They were placed 45cm above the ground, 2.5 km apart (the smallest leopard range is 3.2km), and were distributed accorded to biome: grassland (30%) or savannah (70%). Several of the traps were productive in generating evidence of leopards. However, other creatures were photographed too: samango monkey (a forest dweller), Cape fox (on the edge of his distribution), and several others. Interestingly the trackers found evidence of these creatures long before the cameras, the presence of leopards being the only exception!

ID Kits or ‘Spot the Difference’
Each animal has individual markings that can be checked against the ID guide, comparing say three or four areas of the pelt: neck, leg, flank, etc. Many leopards have a ‘necklace’. Often it is only the leg that is in sufficient focus in photographs, momentarily static when passing a camera trap.

Sex
Size or build is not always a reliable guide. The leopard known as Long Legs was large and muscular, and it was only later she was identified as a female when pictured with a cub.

Age
Their initially pink noses get blacker with age. Diamond Girl was about 8 or 9; Ru about 4 at the time (now 6 or 7). Look for scratches on the nose and tatty ears as a sign of age. The dewlap forms when older, though it was less noticeable at Ingwe where the leopards do not have much competition and so do not hoist their prey into trees, thus the neck muscles are less developed.

The local leopard population

Spatial Explicit Capture Recapture Model software was used to analyse data. 28 individual leopards were identified over the three-year period – 15 adults, 9 sub adults and 4 cubs – with four resident in the reserve. 11 cubs were born on site.

Diamond Girl - dominant female, with territory in the central area
Pippa - to the west
Ru - a young male, based in the south 
Big D - male with a large territory overlapping all three of the above

Six cameras displayed a lot of activity, including shots of otherwise unknown leopards. Tara thought this particular area could be a dispersal route for leopards passing through and the hypothesis was supported by groups of holes in the fence at NW and SE extremities.

Golden leopards
A sandy coloured leopard with brown spots appeared on three cameras over two nights. Another similar variant, a six-month-old born to normal-coloured Pippa, has also been seen. That’s two with a particularly rare colour variation, possibly caused by a recessive gene. There are only five records of similar creatures between 1900 and 1950 – all in India. The next was in 2012 in Madekwe. In total there have been 12 in the world; 7 in South Africa. Five of these (71% are in the Lydenburg area and 29% in Thaba Tholo. This suggests inbreeding.

Black panthers
These are caused by an excess, rather than insufficiency, of pigment. They appear in greater numbers and are to be found notably in Tanzania and Malaysia.

Summing up

Empathy and Education’. Combined with active research, KLR’s approach has paid off. Pippa was one of the leopards licensed to be shot, but is still alive. Hunting licences have now been banned for the year (despite their value as an income generator) and Mpumalanga Parks and Tourism Authorities wish to make use of Ingwe’s data.

DISCUSSION

Is the threat of poaching or even trophy hunting, exacerbated by the publication of research information? Yes, though on the other hand, conservation requires the cooperation of local people who won’t know if not informed. It is a balance; there is no easy answer.

Do leopards take livestock as easy prey or just when game is inadequate? Generally an individual sticks to a preferred species if the option is available. They seldom get a taste for sheep – indeed they are on camera as turning up their noses at sheep carcases. Problem animals are few and at Ingwe they all appear well fed.

Why the colour variation at Ingwe? White impala and black serval are also in the area inhabited by the golden leopards. The latter may have increased through isolation caused by key leopards being taken out.

Is the colour variation associated with health problems? Not known, but the black colouring of Malaysian leopards has equipped them well for the jungle.

Are the smaller leopards of the Cape a sub species? Not at present, though some scientists are pushing for this classification.

Do we know anything about the historical density trends; has there been a bottleneck? Not known.

There has been little dialogue between the various leopard projects being conducted, though that is starting to change.

The ratio of sexes is roughly even.

What is the level of human population at Ingwe? Low density; sparse farming at the borders.

The surrounding game fence is the normal type, but now has 1,500 holes, of which 900 are leopard sized. It is now thought best to keep the holes, as fences do not keep leopards out. One has even been through an electric fence!

25 kg of prey lasts for about a week, as the leopard changes from full to empty. Females hunt more frequently when they have cubs. If relying on guinea fowl, say, hunting may be required twice a day. But leopards are opportunists and if they gorge on kudu, will take a week and a half and more, to digest.

Listen, don’t talk!” – Tara reiterated her approach. Locals will tolerate a degree of loss, but only up to a point. Work with them to meet half way, she urged. At Ingwe many children have seen no wildlife locally and are now looking with fresh eyes.

Edwin A.R. Trout
Berkshire Mammal Group
 
identifying pelt markings

identifying pelt markings

Distinctive paw prints (above)

Photos courtesy of Tara Pirie


Monday, 1 February 2016

February 2016 Mammal of the Month - The Wood Mouse

Wood Mouse - photo Becky Thomas


Happy February everyone! Time for our next mammal of the month.

February's should be a bit easier to spot than January's otter. This month it's the wood mouse. This is the mouse you're most likely to see in most parts of Berkshire, including urban areas, and by far the most common species that we find in our live trapping surveys.

Our top facts for the wood mouse are:


1. They can be easily distinguished from field and bank voles by the size of their ears - as you can see from the photo they are rather large. Those of voles are hardly visible in comparison. See here for other species that they could be confused with and how to tell them apart.


2. They are prolific breeders! The usual season is March to October but can be all year round if there is enough food. Females are able to get pregnant again very soon after each litter.


3. They store food in caches in underground burrows


4. They nest together in groups over the winter


5. They are an important source of food for many other species - anything from foxes to owls (and of course pet cats!) will eat them.

Please record any sightings via
our recording page - we really appreciate all of your records and don't forget, it's not just sightings of the mammal of the month that we're after but any sightings or signs of any wild mammal.

Find out more with the Mammal Society's fact sheet for the species.

Tuesday, 5 January 2016

January 2016 Mammal of the Month - The Otter



Otter - photo credit: Becky Thomas
Season's greetings everyone and wishing you all the very best for 2016.

Our first Mammal of the Month for the new year is.... the otter.

Our top five facts for this often secretive species are:

* They can live up to 10 years in the wild.

* Young are born in dens called holts and the mother looks after the cubs alone.

* They can have very large territories - up to 20 km of river!

* Their poo is called spraint - it smells sweet and musky and is often the only way you know that an otter is in the area.

* After almost disappearing from much of Britain in the last century they are now making an impressive come-back - BMG even has a record from very close to the Oracle Shopping Centre in the centre of Reading.

Find out more about the species on the Mammal Society's fact sheet at:

Otter fact sheet

and please record any sightings (of them or their signs) at:

BMG recording



Thursday, 3 December 2015

December 2015 Mammal of the Month - The Harvest Mouse



Photo Credit: Reg Mckenna via Wikicommons
 
We're pleased to announce that our Mammal of the Month for December is the harvest mouse!

Our top five harvest mouse facts are:

  * They have 2-3 litters a year

  * They weigh just 4-6 g on average

  * Spotting a nest is the easiest way to detect their presence. These are built at least 30 cm above ground in  grasses or reeds and can be up to 10 cm in diameter for a breeding nest

  * They have prehensile tails - useful for climbing!

  * They live 18 months on average.

Find out more about the species with the Mammal Society's fact sheet at:

Harvest Mouse Factsheet

and don't forget to record any sightings or signs of these or any other mammals for us at:

Mammal Records

Check out the great photos of the harvest mouse nests found on the recent training day - posted a few weeks ago on the BMG Facebook page.