Little is known about the hotly debated subject of the effect
or impact of luring birds with the aid of audio devices. What is
available is scattered knowledge, often anecdotal, spread across
literature and discussion groups on the Internet. There is no single-point
reference or compilation of these diverse,
polarized and often complicated, opinions at one place, making it even
more difficult for those interested to make an informed decision on
the subject.
The purpose of this article is to present -
in one place - available opinion, scientific
results, and laws and regulations concerning
the impact of call playback on birds.
♫
Call Playback:
Call playback to attract birds is variously referred to as
'tape-lure', 'tape playback', 'audio playback' etc. This is a
technique of playing back a sound to which a (most often unseen) bird
responds by calling back and/or
coming close to the the source of the sound.
It can be achieved by playing back pre-recorded calls, or recording of
a bird call in the field and playing it back, or by playing back a
hostile call which can be a predator call or a mobbing sound. The
equipment used can be tape recorders, Walkmans, mini-disc players,
compact-disc players, iPod's or similar. These devices are often
coupled with external speakers to boost the signal and can include the
use of portable megaphones.
The
length/duration of playback is one of the more contentious issues
surrounding the whole topic and there are as many opinions as people
who comment on this aspect.
Scientists, researchers, ornithologists, bird-ringers, poachers,
tour-guides and amateur birders widely and regularly use
call-playback. It is known to be a particularly effective tool for
bird surveys, field-experiments, migration study, bird trapping for
science and for food, and often to show ‘sought-after’ and skulking
endemics to paying birdwatchers.
Audio playback has
been proved to have an impact on bird behaviour. Many species respond
to the stimulus of conspecific activity by calling back in response,
and very often coming close to the source of the sound. 
However, call playback is noted to
have degrees of effectiveness and success is often influenced by
variables like season, species, time, appropriateness, experience of
the user, impact of overuse, and technical issues. Territorial
response is often the most commonly elicited behaviour, though fear,
hunger, and attraction of safe resting places can also be some of the
factors that draw reactions to call playback.
A study of all available references, pertaining to the subject. There
appears to be a paucity of any empirical research on the possible
effects of the use of playback to attract birds. Many of the more
descriptive inputs are
from people who use playback for their own purposes,
and are usually subjective or anecdotal.
On
the flip side are those
who oppose playback on ethical grounds.
There is common ground though as no one seems to support endless
playback at a single site and almost everyone seems to agree that
playback should be avoided wherever species of conservation concern
are involved. This does seem to suggest that, in the absence of
scientifically evaluated knowledge, most feel that it is pragmatic to
err on the side of caution and use common sense instead. Everyone
seems to agree that good or bad, playback does indeed affect bird
behaviour and is surely an intrusion.
♫
The Science
and Scientists:
As mentioned, it was not possible to trace any reviewed literature
dealing specifically with the scientific study of the effects of the
use of playback to attract birds. Most of the available scientific
literature covers behaviour studies and adrenocortical responses using
call-playback as one of the tools.
The available
writings suggest that responding to call-playback may incur energy
costs, disrupt social systems, lead to pair break-ups and cause
stress.
♫
Birdwatchers:
Bird lovers, birders, bird photographers are the one's who often use
call playback or have been around to see the effects of lures. Many have expressed surprise at the lack of any
scientific study which would have enabled them to take an informed
decision on the subject. Some felt that it was unethical to intrude
but some others felt that birdwatching itself is an intrusion and
call playback is only an extension of it and, therefore, as
acceptable as any other process of disturbing birds.
'
♫
Lawmakers, Regulators & Conservation
bodies:
There appear to be no blanket prohibition
or sweeping restrictions, in any country, on the use of call
playback to lure birds. There are location specific, playback
volume, season, time of day, and species risk based bans. Use of
restrictions to control call playback is more widespread and
prevails in many
areas
and locations. The most sweeping is the law in the United States of
America which prohibits the use of playback devices which cause
unreasonable disturbance at all National Wildlife Refuges.
Various countries/locations have
imposed need-based restrictions which can
be blanket - like in Sri Lanka, where playback is prohibited in the
Sinharaja Wilderness Area, or be species based like the one in Water
Treatment Plant in Australia where call-playback
for any species of crake or rail is not permitted.
♫
Published notes /
reports / articles:
In Tamil
Nadu, India trappers around Nagapattinam have been known to use
speakers attached on trees to trap wild
birds for food.
BirdJam, a bird song identification
tool maker for the Apple iPod® recommend against repeated playback to
elicit response and warn against continuous playback during the
breeding season.
This is
what we know. In the end it is for you to
judge for yourself!
____________________________
Sumit Sen
Kolkata, India
November, 2009
I make no claims that my
views are those of the 'Birds of India' website or those associated
with it.
END
What do we know about it?