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
