robby

Dawn is the best time of the day. Before the anthropogenic noise takes over, all you can hear is nature. Getting outside as the sun rises is an incredible musical experience. Before the sun has even peeped over the horizon, many birds are already active and starting to sing, but as the world is filled with light, the dawn chorus erupts.

Birds make noise for a variety of reasons. Vocalisation is the best form of communication for many species, as it means they can communicate over long distances. Various types of sounds indicate different messages. As vocalisations can be exhausting, it is important that birds get their message across succinctly.

Birds don’t make sound the same way that we do. They have a Syrinx, a specialised voice box which is located where the trachea splits into two separate bronchial tubes. This means that some birds are actually capable of making two sounds at the same time, with some species able to sing two different notes simultaneously and others able to make 30 sounds per second!

Singing is a useful tool for males as it is a great way to attract females. A strong, healthy song indicates a strong, healthy male; a male worth breeding with. As well as females, this message is also projected to other males, letting them know that the songs’ owner is not to be messed with. Some scientists believe that by singing first thing in the morning, the males are telling the world that they have survived the night and are ready for action. This is important because many species of female are most fertile in the early hours, so may be looking for a male at that time. Others have suggested that the dawn is the best time for singing due to other reasons, so the sound carries better or simply that the world is quieter so the birds know they have a better chance of being heard.

There are studies currently going on looking into the effects of anthropogenic noise on bird song and it is feared that the impacts are negative. With human noise getting louder, there are concerns that birds are struggling to get themselves heard. In fact, in cities, many birds sing louder and at a higher frequency than those in rural areas, potentially to try and be heard over the lower frequency sounds humans tend to produce. Birds living in cities are also thought to have a higher pitch, potentially to reduce the echoes as their voices bounce off buildings. This was originally reported as birds having “accents”, however the reality of this may be a bit less quaint.

As well as song, some calls you hear are warning calls. You may have never noticed, but there will be times when you are innocently walking somewhere and without realising it, birds will be warning each other of your presence. An alarm call, a sharp chirrup or tweet, lets other birds in the area known that danger (for example you) is lurking. One non-British species, the yellow-billed oxpecker (Buphagus africanus) is thought to warn other species when humans are in the vicinity. The oxpecker’s feed on parasitical ticks living on the skin of cape buffalo. It is thought that oxpeckers will sound an alarm call not only to warn each other of an approaching human, but to let the cows know as well, part of the symbiotic relationship these two species share.

For many birds, song and calls are innate, but this isn’t the case in all species, some learn through mimicry. Why birds mimic is still unknown. The main explanation is that it is a great way to expand the repertoire of calls a bird already has, potentially catching the interest of new females. These calls may not be just about attracting other birds, but also repelling them. By imitating noises perceived as alarm calls or threats, birds can use these sounds to put off any potential predators, either to safeguard themselves, their territory or even their food. Of course, some of these noises may be learnt simply by mistake as birds who mimic can pick up all sorts of interesting sounds and have been known to copy chainsaws, telephones and car alarms.

In fact, I recall a being in a zoo many years ago and listening to a mynah bird repeatedly call out “Son! Come and look at this!” – well it’s certainly one way to blow your trumpet hey?

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