Helping
riparian mammals recover, especially otters and water voles, and
using people in partnership to understand where these animals
actually are, is how Jim set out his theme – and to encourage a
landscape approach to nature conservation.
1. Otter and Water
Voles
Otters
have been in tremendous decline since the 1950s – caused by DDT
pesticides and, to a lesser extent, hunting – surviving only in the
South West and Wales. Interestingly, a 1905 book on hunting reports
an otter hunt in Chiddingfold where Jim now lives. Now, however, the
otter is present in every county in England, though still scarce in
the South East; the North Downs act as a watershed and otters are few
south of them, in Hampshire, Sussex and Kent.
Water voles
Hedgehogs
excepted, the water vole is Britain’s most rapidly declining
mammal, a fate propelled by intensive agriculture (ploughing up to
the bank, for instance), development of the flood plains, even a lack
of management that allows the growth of scrub and trees to prevent
the lush vegetations that voles need. On top of this, the American
mink is a modern menace. Smaller in size than the otter, the mink
has a white chinstrap rather than bib, and creates a bow wave when
swimming. Interestingly, when their territories overlap with those
of polecats, the sex bias of the latter is affected, with a
diminishing number of females.
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| Jim Jones |
The status of river mammals in
Surrey
The
current distribution map includes records dating back 15 years and so
must be regarded as an unreliable reflection of population. Otters
are recorded on the Mole and Eden to the east of the county, with
more coming into the catchment of the River Wey from Hampshire. The
pattern is more marked in the case of voles; ten years ago they were
on the Mole, but now are just on the Wey, while mink are found
throughout the county, even the central Surrey Hills.
Record keeping
Local
records are sent to the National Water Vole Database & Mapping
Project, 2009-14, from which ‘alert maps’ are produced and both
local and regional key areas proposed for conservation.
2. Water vole recovery
plan
A
six-point plan to reverse the trend was introduced when Jim became
Wetlands Officer:
Going
back to the existing sites for a status update
Reintroduction
of animals if needed
Inform
local authority planning departments
Habitat
management where existing sites are suitable
Creation
of new habitats in key areas if needed
Mink
control – a collective action with landowners, at catchment level.
3. RiverSearch
Building
on previous attempts at surveying ‘wet’ mammals, and the work of
river wardens, RiverSearch was launched in 2012. Taking its
inspiration from the work of Darren Tansley of the Essex Wildlife
Trust from 2007, it collects data on the otter, water vole, water
shrew and harvest mouse. Starting from scratch, Surrey’s new
volunteers are trained at Darren’s house. Volunteers are asked to
adopt a one km stretch of river and monitor it at least once a
season. The resulting data are captured by a river co-ordinator for
prioritisation and planning.
117
volunteers recruited
82
volunteers trained
71
stretches of the Wey and Mole covered
23 mammal surveyors trained
Vole
Patrol 2015 is a 60-site survey on the Wey, Mole and Blackwater.
There was also a vole-raft project conducted by Nick Mason of
Nottingham Trent University, designed to indicate the presence of
voles by the traces of excrement left behind. Negative results were
obtained at 20 to 30 sites, before Nick moved on and found success in
Hampshire.
Vole Reintroduction
Several
suitable sites have been identified, including Stoke Meadows, next to
the A3 at Guildford, and Nutfield Marshes at Redhill. If no voles
are located, then reintroduction on these sites will be attempted.
However, £150,000 would be needed to prepare the sites.
Otter surveys
The
5th
Otter Survey of the UK identified two positive sites were in Surrey,
and Jim’s Otter Bridge Blitz of 2014 found spraint under selected
bridges around Guildford.
Photography project
A
University of Surrey / SWT project was established in 2013 to monitor
the riverbanks with cameras. Aaron, a student at the university,
installed live-action camera traps and succeeded in obtaining lots of
otter pictures that year, supplemented by images from John Hawkins
Wildlife Photography. Analysis of the frequency of visits to the
traps indicated a pattern a couple of days’ activity followed by
absences of either one or two weeks before returning. This was in
July and August when such a level of activity is atypical of otters.
Eventually one animal was found, injured or unwell, and while at the
sanctuary, it was discovered to have been ‘chip-and-pinned’ by a
Somerset Hospital that had released one originally from Devon and two
originally from North Wales. (Out-of-area releases – possibly due
to overcrowding – can be problematic and spread diseases such as
liver fluke.) However, no sightings of otters have since been
reported in Surrey and presumably they have moved on.
4. Landscape
Jim
seeks bigger, joined-up landscapes and asks how mammal projects can
indicate or even initiate progress toward this aim. He points to
‘catchment partnerships’ and notes that RiverSearch also monitors
pollution, barriers and the presents of non-natives, besides helping
in practical work of enhancing channels and maintaining the banks.
He gave examples of multiple-benefit projects: Wey Meadows and Wet
Heath & Mire Project (Devil’s Punchbowl)
5.
Surrey Harvest Mouse
Increasingly
found in wetlands, harvest mice are a monitor of how joined-up the
landscape might be. For the Surrey project the team experimented to
establish which traps would be best: Longworth (“best”), plastic
(“OK”) and Sherman (“hated”) – at stalk height or on the
ground. Apparently the position made little difference, but many
more were found in the morning than after midday. 26 mice were found
in one field alone.
Second Phase: Genetics
Genetic
testing, by fur plucking, is seeking to establish connectivity or
insularity of population. Testing is conducted by the university at
Brighton. For success 15-20 animals are required per site, and so
volunteers are being trained to search for nests. The first four
yielded nothing, but the fifth site, 18; the last, 32; the current,
10 and counting. This is exciting stuff – the first project in the
UK to look at population genetics; the only other is in Taiwan, with
which Jim keeps in correspondence. Harvest mice inhabit the entire
Eurasian land mass.
Questions and
Discussion
-
Will otters benefit if mink numbers are reduced? Probably not, as
they co-exist relatively independently.
-
How does the European mink interact with voles. Not sure, but less
aggressive than its American counterpart.
-
If banks need management, then perhaps riparian mammals are being
artificially encouraged by conservationists? Why bother? Because
the rest of the landscape is also artificial and man has assumed the
responsibility of attaining balance.
-
Is harvest mouse trapping only conducted in the autumn? This is the
peak time in terms of population. 90% die over winter and the
population has to recover in the spring.
-
Harvest mice are increasingly found in wetland sedges. Perhaps they
always were there, if not as noticeably as in arable grasses. They
have declined in fields, but still continue especially around the
edges and near the hedgerows.
-
RiverSearch is sponsored by the brewer, SAB Miller.
-
No sign of otters in 2014 after losing sight of the 2013 family.
They travel throughout a 40-50km range, at very low density. There
are only ten along the River Itchen in Hampshire!
Edwin
A.R. Trout,
Berkshire
Mammal Group
