40 BBC Wildlife September 2020Water vole: Drew Buckley/Alamy; snipe: Thomas Hanahoe/Alamy; otter: Tony Phelps/AlamyBEAVERS
Radio-tagging and tracking became
costly and risky, due to the beavers’ semi-
aquatic lifestyle, so the teams in Devon
instead worked with what was available to
them: gnawed saplings, stripped bark, stick
piles, ‘thatched’ lodges, exit slips into the
river, castoreum-bound scent mounds- a wealth of information pointing to a
thriving population.
Such signs were noted, geotagged
and inputted into revealing maps of the
catchment, finding a consistent tendency
for the beavers to be most active towards
the south-west regions. Flood-risk
properties there have measured noteworthy
decreases in ‘peak flow rates’, due to the
nearby dams. While it’s wise not to label
beavers as a ‘super-solution’, there is no
doubt that they are a cost-effective ally in
Britain’s response to flooding.
Contrary to popular belief, not all
territories contain a dam. In 2019,
justunderhalfofthoseknownonthe
WATER VOLES
Despite the presence of
non-native American mink,
the trial has discovered that
water voles (now rare in
Britain) are colonising new
wetlands and pools created
from the beaver dams.SNIPE
Marshland created by the
beavers has attracted large
numbers of snipe. Historic
loss of wetlands has caused
steep declines in snipe
populations, particularly in
the south-west of England.OTTERS
Otters rely on natural holes
in the riverbank for holts.
Surveys during the trial
recorded otter spraint in
the collapsed chambers of
unused beaver lodges – they
seem to benefit otters’ needs.EUROPEAN EELS
European eels comprised
2.3 per cent of fish surveyed
in 2019 from a tributary of
the Otter. Sediment lurking
in beaver pools creates the
ideal habitat for these fish
to rear their young.Good in uence: bringing back beavers has a knock-on e ect
Four species that have bene tted from the resident dam builders in Devon.
We round a bend
through a copse
of poplar trees
and I encounter
another world.