Wildlife Underpasses Can Reduce Amphibian Road Deaths by More Than 80%: Study

Amphibians
like

frogs
and
salamanders
face
mounting
threats
around
the
world,
including

habitat
loss,

climate
change,

deadly
fungus
and
road
mortality.

Roads
pose
an
immediate
danger
by
cutting
amphibians
off
from
crucial
migration
corridors
and
putting
them
in
the
path
of
vehicles,
which
kill
millions
of
animals
annually.

Now,
a
first-of-its
kind

study
led
by
researchers
from
University
of
Vermont
(UVM)
shows
that

wildlife
underpasses
can
reduce
amphibian
deaths
by
more
than
80
percent
while
helping
to
preserve

ecosystems.

Over
a
decade
of
research
by
scientists
and
citizens
from
the
Vermont
Agency
of
Natural
Resources,
the
local
community
and
University
of
Vermont
assessed
the
effectiveness
of
a
pair
of

wildlife
underpass
tunnels
installed
under
a
road
located
in
Monkton,
Vermont,
a
press
release
from
UVM
said.

A
frog
attempts
to
cross
a
road
in
Monkton,
Vermont.
Joshua
Brown
/
University
of
Vermont

The
two
underpasses
led
to
an
incredible
80.2
percent
fewer
amphibian
deaths.

“It
was
surprising.
I
knew
that
underpasses
would
work,
but
I
didn’t
think
they
would
be
that
effective,”
said
lead
author
of
the
study
Matthew
Marcelino,
an
ecologist
at
UVM.
“And
when
we
took
climbing
amphibians
out
of
the
picture
—
which
in
our
context
are
primarily
spring
peeper
frogs
—
we
noticed
a
94%
decrease
in
mortality
in
the
treatment
areas.”

The
research
team
monitored
the
road
mortality
of
amphibians
in
the
area
from
2011
to
2015
before
constructing
the
underpasses
and
from
2016
to
2022
after
construction.

They
compared
three
zones:
the
first
a
treatment
with
underpasses
and
wing
walls;
the
second
a
buffer
area
at
and
beyond
the
edge
of
the
wing
walls
and
away
from
the
tunnels;
and
the
third
a
control
area
far
away
from
the
infrastructure
changes.

Standardized
surveys
were
conducted
during
brief
spring
migration
windows
across
a
dozen
species
of
toads,
frogs
and
salamanders.
Initially
the
team
found
a
total
of
5,273
amphibians,
including
2,545
peeper
frogs
—
almost
70
percent
of
which
were
deceased
—
and
1,702
spotted
salamanders,
almost
half
of
which
were
also
dead.

The
death
rates
were
significantly
lower
in
treatment
and
buffer
areas,
where
the
animals
had
been
using
the
tunnels
rather
than
being
displaced.

The
study
is
the
first
to
provide
long-term
evidence
of
the
effectiveness
of
amphibian-specific

wildlife
underpass
tunnels
in
the
northeastern
United
States.
It
highlighted
that
design
details
such
as
wall
height
and
angles,
materials
and
tunnel
layout
make
a
difference.

“Amphibians
—
frogs,
toads,
and
salamanders
—
play
vital
roles
in
ecosystems
and
are
highly
sensitive
to
environmental
disruption,”
the
press
release
said.

Many
amphibians
in
Vermont
and
a
large
portion
of
the
Northeast
spend
most
of
their
lives
in
upland
forest
streams
or

soils,
including
long
winters
underground.
They
emerge
in
early
spring
on
temperate,
rainy
nights
to
begin
their
migrations
from
woods
to

wetlands,
flooded
meadows
and
ponds
to
breed.

“It’s
usually
sometime
between
late
March
and
late
April,”
explained
ecologist
Brittany
Mosher,
senior
author
of
the
study
and
a
professor
at
UVM’s
Rubenstein
School
of
Environmental
and
Natural
Resources.
“Many
species
will
breed
in
the
same
ponds.
So
it’s
not
just
a
single
species
migrating
—
it’s
many,
many
species.
And
oftentimes,
we
see
hundreds
or
thousands
making
this
movement
all
at
the
same
time.”

Roads
frequently
stand
in
the
way
of
amphibians’
journeys
from
upland
forests
to
aquatic
habitats.

“Planners
—
state
and
federal
transportation
planners
—
often
build
roads
between
these
steeper
forested
upland
habitats
and
nice
flat
aquatic
habitats,”
Mosher
said.
“So
the
roads
are
placed
exactly
in
the
wrong
spot
if
you
were
an
amphibian
planner.”

Because
they
are
small
and
move
slowly,
amphibians
are
particularly
vulnerable
to
vehicle
collisions.

“Unlike
larger
mammals
that
might
dart
across
a
road
in
seconds,
frogs
and
salamanders
can
take
several
minutes
to
cross
—
and
with
hundreds
migrating
at
once,
mortality
rates
can
be
staggering,”
the
press
release
said.

The
cost
of
the
0.81-mile
stretch
of
road
that
the
underpasses
cover
was
$342,397
—
much
lower
than
that
of
large
overpasses
and
underpasses
designed
for
mammals,
which
can
run
anywhere
from
$500,000
to
almost
$100
million
each.

The
amphibian
underpass
design
features
two
concrete
tunnels
that
are
four
feet
wide
with
wing
walls
that
help
guide
them
toward
the
tunnels
and
underneath
the
road.

The
Lewis
Creek
Association
used
wildlife
cameras
to
count
2,208
amphibians
using
one
underpass
in
2016.
Other
animals
also
took
advantage
of
the
tunnels,
including

bobcats,
porcupines,

bears,

snakes,

birds
and
racoons.

The
researchers
emphasize
that
their
findings
should
be
used
as
a
model
for
policymakers
and
road
planners
across
the
country.

“This
study
provides
strong
evidence
that
wildlife
underpasses
work,”
Marcelino
said.
“We
hope
this
will
encourage
transportation
departments
to
include
them
in
future
plans,
when
building
or
repairing
roads.”

Mosher
added
that
the
underpasses
are
not
only
helpful
for
amphibians,
but
demonstrate
that
communities
can
work
together
to
protect
local
wildlife.

“This
story
began
with
local
community
members
who
were
engaged
and
concerned,”
Mosher
said.
“And
it
provides
a
view
for
how
other
communities
can
protect
their
amphibian
populations
too.”

The
study
highlights
the
crucial
role
of
research,
community
engagement
and
investment
in
targeted
infrastructure
to
support

biodiversity.

“Conservation
takes
commitment,”
Marcelino
said.
“But
when
we
invest
in
good
tools
and
take
the
time
to
do
it
right,
the
payoff
for
ecosystems
and
wildlife
can
be
enormous.
These
are
beautiful
creatures
—
so
beautiful,
so
ancient.”

The
findings
of
the
study,
“Assessing
the
Efficacy
of
Wildlife
Underpasses
in
Mitigating
Amphibian
Road
Mortality:
A
Case
Study
from
the
Northeastern
United
States,”
were
published
in
the

Journal
for
Nature
Conservation.

[embedded content]