The ‘call’ of the birds, the sounds they make, differ from one species of bird to another. It is extremely hard, to learn the sounds from a textbook.
The ‘call’ of the birds, the sounds they make, differ from one species of bird to another. It is extremely hard, almost impossible, to learn the sounds from a textbook. We have to either observe and learn, or make use of reliable recordings available.
Like all the other behaviours we have seen so far, bird calls different not only from one species to another unrelated species, but also between closely related species of birds, and even within a species according to the gender, situation, and the purpose.
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| A vocalising mynah ©Bhavana |
We can broadly categorise the bird calls/vocalisations
into five groups.
1.
Song
Humankind has always been fascinated with the flight of birds, and the freedom it symbolised. Likewise, humans all over the world, from all cultures, have shown a fascination towards the song of birds as well. Great composers have tried to incorporate, to mimic, the song of birds in their compositions. Now, modern science is venturing into exploring the parallels between human language and birdsong.
Birdsongs are melodious, complex, and unique sounds.
They are sometimes a part of courtship or territorial claiming.
Birds are said to learn their song the same way in which a human infant learns its language. The young birds learn from their ‘tutor’ - adults of their species (mostly). Then, they practice the vocalisations until the sound that comes out corresponds with what they have in mind.
The songs of a certain species of birds can evolve not only through time, but also through space. Just like human language has various dialects, the birdsong of the same species can differ according to the region they live in.
The birds have a great sense of acoustics, and their songs are modified to suit the acoustics present in the environment. For example, the song of a bird in the city and that of a bird in a forest will differ in pitch, pace and complexity. Similarly, studies say that the height of the perch of the singing bird also influences its pitch. The level of noise in the surrounding environment is another factor that determines the pitch of the birdsong.
Birdsongs aren’t always beautiful solos. Sometimes,
there are duets and choruses as well!
Duets aren’t so common. It is reported that most birds that duet are seen in the Southern Hemisphere, and in these species, duetting commonly occurs between mated pairs. It is also said that more often, the female birds take the lead in the duet. Sometimes, these duets can extend to choruses.
In addition to singing, birds can produce a lot of other sounds. This is more like a conversation and it helps strengthen the bond between mates.
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The birds use their songs to define their territory. These songs not only help one bird to convey which area is his (or hers), but also for one bird to recognise its neighbours. Studies have shown that if a bird hears a song different to that of a known neighbour, it often sets out to investigate the new neighbour.
2.
Companion
calls/ Feeding calls: These are quite
soft calls, and can be heard during feeding time. Although common, these sounds
are quiet, and hence can be missed. Birds use these companion calls to keep
track of their feeding companions as they feed.
3.
Territorial
aggression: These are very
loud and aggressive vocalisations which are used by birds to defend their
territory from other rivals. Sometimes, this might mimic an alarm call. But
unlike with an alarm, where all the birds in that surroundings are involved,
only the (two or more) birds involved in a fight produce such vocalisations,
while the other birds in the area, which are not involved in the fight,
continue feeding and making soft companion calls.
4.
Juvenile
begging: These are the
sounds made by chicks, asking to be fed by the parent(s). These vocalisations
can be heard once the period of building nests and mating is over. Although
such vocalisations serve to convey the chicks’ want for food, they can also be
a signal to predatory birds, indicating the presence and location of easy prey.
Even when the adults birds in the area are making alarm sounds, the chicks are
not able to understand the significance of the alarms and will continue to make
the begging sounds.
5. Alarms: These are vocalisations which convey the message of danger nearby, whether it is a predator or another threat. Each species of birds can have more than one type of alarm call, to signal different kinds of danger. Interestingly, birds are familiar not only with the different types of alarms of their species, but can also identify the alarm sounds of other species of birds in the ecosystem. This gives a great advantage when it comes to survival.
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An Indian roller and a
crow, in an intense dialogue, an act of territorial aggression |
To know more about bird language, and survival and defence mechanisms, await the next article. It will also discuss about migration, and the self-care behaviours of birds.
Click here to read about the Locomotion of birds
Click here to read about feeding behaviour of birds.
Click here to read about Fascinating flight of birds
Click here to read about the breeding of birds
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