LAST SEEN OVER 20 YEARS AGO
The first field study using AudioMoth aimed to identify
the only cicada species native to the UK, the Cicadetta
montana, which was last seen in the New Forest
National Park over 20 years ago. Cicadettas spend
most of their lives underground as nymphs, emerging
as adults every seven years or so, and the high-pitched
call of the adult, at 14kHz, is out of the hearing range of
most adults, making it difficult to search for in manual
surveys. As a result, 87 AudioMoths were deployed in
four New Forest locations for up to three months at a
time from spring 2016 until early summer 2017.
Although no native cicada was identified during the
study, the detection capabilities of the device were
tested by playing cicada recordings captured in
Slovenia (where the Cicadetta montana is commonly
found) along with background noise captured in the
New Forest. Impressively, the detection algorithm
achieved a true positive rate of 0.98 and a false
positive rate of only 0.01.
As AudioMoth is capable of recording the highest
frequency bat echolocation calls in the UK, which
come from the lesser horseshoe bat at over 100kHz,
they also make ideal tools for organisations working to
conserve bat populations. Since launching the British
Bat Survey in 2017, the Bat Conservation Trust has
freely provided AudioMoths to volunteers participating
in the annual study each year.
This year’s survey focused on discovering
how much time is needed to collect the amount of
data required to estimate population trends for rarer
bat species in South West Britain. Volunteers received
a survey kit containing an AudioMoth, a waterproof
case, and memory cards for as many
non-consecutive nights as possible between
1st July and 11th August 2019. At the end of
the survey, participants are provided with a
list of all the bat species that they detected
and the data is used to determine the best
survey methods for a large-scale roll-out of
the British Bat Survey next year.
If you would like to get your hands on an
AudioMoth for the 2020 British Bat Survey,
visit bats.org.uk for more details. Or, if
you’d like to build your own AudioMoth from
scratch, visit openacousticdevices.info to
find all of the open-source documentation
you need to get started.PRICE DROP
The bill of materials
cost for the AudioMoth
is around £35 per unit,
but researchers can get
their hands on working
devices just as cheaply
by joining online
collective purchasing
groups to bulk order
devices from web-
based PCB assemblers,
such as CircuitHub. The
most popular site so far
is GroupGets, which has
run several successful
‘group buy’ campaigns
for the device, priced
around £40 per unit.SPARKLeft
Be part of a team of
volunteers and hike
to predetermined
sites on public and
private land to deploy
sound recorders, and
retrieve them after a
few days
Below
Volunteers are busy
deploying AudioMoths
throughout
Sonoma CountyRight
The main mission
of Soundscapes to
Landscapes is to
advance the science
of global biodiversity
monitoring from
sensors in space“THEIR TASK WAS
TO SURVEY A SINGLE
1 KM SQUARE”