Assessing trends in population size of three unmarked species: A comparison of a multi‐species N‐mixture model and random encounter models
Ecology and Evolution,
Journal Year:
2023,
Volume and Issue:
13(10)
Published: Oct. 1, 2023
Estimation
of
changes
in
abundances
and
densities
is
essential
for
the
research,
management,
conservation
animal
populations.
Recently,
technological
advances
have
facilitated
surveillance
populations
through
adoption
passive
sensors,
such
as
camera
traps
(CT).
Several
methods,
including
random
encounter
model
(REM),
been
developed
estimating
unmarked
but
require
additional
information.
Hierarchical
abundance
models,
N-mixture
(NMM),
can
estimate
without
performing
fieldwork
do
not
explicitly
area
effectively
sampled.
This
obscures
interpretation
its
requires
users
to
focus
on
relative
measures
instead.
Hence,
main
objective
our
study
evaluate
if
REM
NMM
yield
consistent
results
qualitatively.
Therefore,
we
compare
trends:
(i)
between
species,
(ii)
years
(iii)
across
obtained
from
annual
density/abundance
estimates
three
species
(fox,
wild
boar
red
deer)
central
Spain
monitored
by
a
trapping
network
five
consecutive
winter
periods.
We
reveal
that
provided
density
same
order
magnitude
boar,
foxes
deer.
Assuming
Poisson
detection
process
was
important
control
inflation
frequently
detected
species.
Both
methods
consistently
ranked
(between
trend),
did
always
agree
ranks
yearly
within
single
population
nor
linear
trends
(across
trend).
Our
suggest
are
generally
when
range
variability
large,
become
inconsistent
smaller.
Language: Английский
A random encounter model for wildlife density estimation with vertically oriented camera traps
Remote Sensing in Ecology and Conservation,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Dec. 1, 2024
Abstract
The
random
encounter
model
(REM)
estimates
animal
densities
from
camera‐trap
data
by
correcting
capture
rates
for
a
set
of
biological
variables
the
animals
(average
group
size,
speed
and
activity
level)
characteristics
camera
sensors.
REM
has
been
widely
used
setups
in
which
cameras
are
mounted
on
trees
or
other
structures
aimed
parallel
to
ground.
Here,
we
modify
formula
accommodate
an
alternative
field
view
acquired
with
vertically
oriented
traps,
type
deployment
avoid
theft
damage.
We
show
how
calculations
can
be
adapted
account
different
detection
zone
minor
modifications.
find
that
effective
area
close
rectangle
dimensions
influenced
properties
Fresnel
lens
camera's
motion
sensor,
body
mass
species
height
camera.
parameters
remain
same.
tested
modified
(vREM)
applying
it
wildlife
collected
traps
Bardia
National
Park,
Nepal.
further
validated
was
best
approximated
as
shape
using
maximum
likelihood
estimation.
Density
obtained
broadly
matched
independent
density
nine
previous
studies
varying
sizes
four
orders
magnitude.
conclude
these
modifications
allow
effectively
mammal
estimation
wide
range
sizes,
traps.
Language: Английский