South Dublin Branch Dawn Chorus

The Dawn Chorus

Sunday 14th May 2006 is International Dawn Chorus Day, the day when wildlife enthusiasts the length and breadth of Ireland will set their alarm clocks a little earlier than usual and go out to enjoy a morning of beautiful birdsong. Of course, that isn’t the only day on which you can experience the marvel of the dawn chorus; the birds will be in full voice throughout late spring and early summer, and the best time to hear them is in the twilight period just before the sun comes up. We call this natural phenomenon a chorus because, to our ears, all the different species of birds singing their different songs at the same time sounds like a beautiful choir. As in a choir, it seems to us that each bird has its own part to play and its own melody to contribute, and it perfectly represents the harmony and balance of nature and the joys of spring.

The birds themselves, however, don’t see it this way at all. The male birds (and in most species it is the male who does the singing) are singing to advertise that they are defending a certain patch of territory from other birds and to attract a mate by showing that they are fit and healthy and able to provide well for chicks. In fact, as far as we can tell they are completely oblivious to the sounds of the other birds around them, and what we perceive as beautiful singing is really just them shouting at the top of their voices: “Hey, look at me. This tree belongs to me, and the rest of you males better keep away. By the way, ladies, aren’t I in good condition? Look at all the nice territory I own. Wouldn’t I make a great dad?”

So what is so special about the dawn chorus anyway? Woodland and garden birds sing throughout the day, so why not just listen to them then? Well, that is certainly a very worthwhile thing to do, but the most amazing thing about the period just before dawn is the sheer number of birds that are singing and the high volume of their songs. People who have never before experienced a full dawn chorus in a woodland park or even a well-wooded garden are often astonished by how many birds seem to be involved. You might think that you have a lot of birds in your garden or local park, but until you hear the dawn chorus you honestly have no idea how many are there. So why are the birds so busy at this seemingly unsociable hour, and why does the chorus stop once the sun has risen? Well, the most important thing to every bird is to make sure it has enough food to eat. Very early in the morning, before the sun is out, the insects and other creepy-crawlies that they like to eat are not up and about yet, and it is too dark for the birds to go looking for food anyway. They need to advertise themselves and their territories on a daily basis, so it is thought that they just get most of it over and done with at a period when it won’t use up valuable feeding time. They can then use the rest of the day for foraging, perhaps with a bit of singing thrown in every now and again for good measure, just to remind everyone who’s boss.

We are learning new things about the dawn chorus all the time. For example, it has long been noticed that some species of birds, such as Robins, Song Thrushes and Blackbirds, start to sing much earlier in the morning than others. In fact, it might take up to an hour and a half for birds like Blue Tits and Chaffinches to join in the chorus, but until recently no-one knew why this was the case. A couple of years ago, however, scientists realised that it was the species of birds that had the biggest eyes that start to sing the earliest, and their research indicates that this is the case with songbirds all over the world. Bigger eyes mean better eyesight in the low pre-dawn light, meaning that birds with big eyes can be on the lookout for predators and other dangers when they are loudly giving their location away to any creature that is in earshot. The birds with small eyes have to wait longer until they can see well enough to know it is safe for them to sing. Makes sense when you think about it like that, doesn’t it?

Certain very common species, such as Wrens and Dunnocks, are often overlooked in parks and gardens, as their very secretive habits make them difficult to see. These birds have very distinctive songs, however, and when they participate in the dawn chorus it gives us a chance to locate them and check just how many of them there are. It is also often the case that the bird species with the dullest, drabbest plumages have the most complicated and musical songs. Brightly coloured and conspicuous birds, such as Great Tits and Blue Tits, can demonstrate how fit and healthy they are by showing off the condition of their feathers, so their songs are often quite simple and basic, serving just to identify their territory. The dull, shy birds, such as the Wren, can’t do this, so they convey all this information in their complex and vigorous songs, and that is why they sound so pleasant to us humans. Perhaps the most famous songbird of all is the Nightingale, a bird that is only a very rare accidental visitor to Ireland but that is widespread in parts of Britain and continental Europe. To look at it is nothing special, just a small plain brown bird that likes to hide in thick bushes, but when it opens its beak to sing it produces a song so exquisite that it has inspired poets and authors for centuries. The most celebrated songster amongst Irish birds is probably the Blackcap, a drab member of the warbler family that, because of its beautiful song, has sometimes been called the ‘Irish Nightingale’.

- Niall Hatch