| Wake
up to a chirpy sound
By Malaka Rodrigo
Birdsong is one of nature's most fascinating sounds.
Many musicians and composers have been enchanted by the perfection
of the melody. Birds sing everyday. Even in an urban environment,
you can still listen to many beautiful songs, especially at dawn.
But our busy lifestyle gives us little time to enjoy these morning
melodies.
Providing
an opportunity to all to listen to these fascinating sounds, is
the "Dawn Chorus Day " celebrated internationally on the
first Sunday of May. Participants have to get up early and catch
the first bird sounds of the day. It's a simple, yet refreshing
exercise you can practise daily. All you need to do is wake up early
before the sunrise and keep listening…
Why
morning?
The dawn-chorus begins well before sunrise - remember
the sky begins to lighten an hour before sunrise. Researchers propose
many ideas why dawn singing is so dramatic. Perhaps males sing at
dawn because that is the best time to attract females. Furthermore,
dawn-chorus conditions are often too dark to forage, so singing
then is an efficient use of time. Or perhaps singing at dawn is
especially important for territory defence; dawn follows the longest
period of inactivity, and predation occurs at night, too, so dawn
might be an important time for a bird to proclaim "I am still
alive" and "This territory is still mine."
At
dawn, the air is often still and sound carries further. It has been
calculated that songs produced at dawn could be twenty times more
effective than those produced at mid-day. Increased humidity often
seems to stimulate birdsong (high humidity enhances sound transmission)
and even rain may not depress the chorus. Each bird chimes in at
a slightly different light level.
How
birds make sound
Birds do not have lips to form sounds, like humans do.
Watch a bird sing and its beak will open but not move like our mouths
do! Then how do birds produce such a complex variety of notes? How
do they sing non-stop for minutes on end without pausing to catch
their breath? The vocal skill of a bird derives from the unusual
structure of its powerful vocal equipment, the syrinx. It is the
sound-producing organ in birds. The syrinx contains membranes which
vibrate and generate sound waves when air from the lungs is passed
over them. When the syrinx vibrates, it generates the sound. The
muscles of the syrinx control the details of song production; birds
with a more elaborate system of vocal muscles produce more complex
songs.
A
call and a song
A brief sound of simple acoustic structure, call notes
can be divided into at least ten different categories. (General
alarm calls, specialised alarm calls, distress calls, aggressive
calls, territorial defence calls, flight calls, nest calls, flock
calls, feeding calls, pleasure calls etc.)
There
are essentially two reasons why the male birds sing. The first is
to advertise themselves to potential mates and the second is to
warn potential rivals not to intrude onto their territories, and
so in this way to avoid physical fighting with a rival male.
Birding
by ear
When it comes to finding and identifying birds, sound
can be as important as appearance. Learning to recognise bird sounds
will increase your enjoyment of birding enormously. While bird-watching,
many times the birds refuse to come out onto a branch where they
can be seen. How many times have you heard a bird but have been
frustrated because no matter how diligently you search for it, you
can't quite see it. Being able to identify a bird by its song is
invaluable. Sometimes just knowing the species will give you clues
of where to focus your binoculars to see the elusive feathered creature.
Learning
bird sounds
A unique sort of vocabulary is used by the authors of
field guides to transcribe bird sounds. When reading descriptions,
the easiest to remember and imagine are those that are onomatopoeic,
or imitative of the actual sound. A classic example is the 'did-you-do-it'
call of the Red-wattled Lapwing, which sounds exactly as it is written.
Other songs and calls are not as easy. Songs are often described
as melodious, clear, whistled and slurred. Calls may be described
as a harsh chatter, buzzy trill, or rattle call.
The
Field Ornithology Group of Sri Lanka based at University of Colombo
is coordinating Dawn Chorus Day in Sri Lanka. You can get assistance
in identifying the birds and the sounds from the group which is
led by veteran ornithologist Prof. Sarath Kotagama. The fogsl is
open to all bird enthusiasts and members can learn more about birds
by attending its monthly lectures. Interesting facts about bird
songs can be obtained during the month of May via fogsl’s
email network.
Fogsl
invites all to participate in this refreshing exercise with family
and colleagues. Once you have made the observation, you can note
it down and then post, email or fax fogsl the list of birds you
heard. They will send it to the records of the British Trust of
Ornithology, who coordinates this event around the world. Observations
done during the first week of May will also be accepted.
So
get up early before sunrise and keep listening..! |
