Why do birds sing most in the morning?

When I am on safari one of the best things, in my opinion, is listening to the birds waking up while still lying in bed.

The dawn chorus is a worldwide phenomenon and I’m often asked about bird song, so I thought it would be worth exploring some theories behind bird song and, especially, why birds sing most in the morning.

It’s something that fascinates me a lot.

There are two parts to the question:

Why do birds sing?

And why do they sing most in the morning?

07

NOVEMBER 2020

Behavior

Birds

Song

About the first question, the answer is to attract mates and to claim their territory and these two actions aren’t mutually exclusive: as a male bird you can sing to both let the other males know that you’re still in your territory, and let females know that you’re looking for a mate.

For some species you can even tell what the bird is actually trying to say just by listening to its song.

For example, nightingales are well known in Europe for their beautiful song, but it’s not unusual to hear them singing here in Africa during the non-breeding season too.

The difference is that here, I’ve never heard the typical long whistle notes that are so common in the breeding season.

You can listen to their song by clicking here.

They also sing very much during the middle of the night before they find a mate, and it seems that these whistles are for attracting females, which obviously isn’t usuful when not breeding.

Luscinia megarhynchos africana (Common nightingale)

Foto di Dikky Oesin

For some species, song is probably very important for attracting females , particularly, for species which apply mimicry. Like Ruppell’s Robin-chat, many birds are accomplished mimics, and observations suggest that the more varied an individual male’s repertoire, the more attractive the male.

The most evident example of this is the Marsh Warbler, a species that we largely see on passage here in Kenya during its migration to South Africa from Europe and Asia.

In what has become one of the classic studies of song mimicry, 30 individual males were recorded during the breeding season and the songs have then been analysed, discovering that the species mimicked were 212, 113 of which were African species!

On average, each male knew the songs of 76 different species, mainly African.

But why do they do this?

Cossypha semirufa (Ruppell Robin chat)

Photo by Pierre Chabot – Thanks to www.oiseaux.net

Acrocephalus palustris (Marsh Warbler)

Well, it seems females prefer the males that have the most varied songs and males which can learn lots of various songs have definitely got some good mental skills which, in theory, could be connected to their ability to find food, avoid predators and help to raise chicks.

So there’s not only the intention of letting a female know that you’re around, like the nightingales do, but there’s a real competition to be the best singer of all.

As written before, it’s not only about attracting a mate. Even after finding a female and during the nest care many species keep singing: this is evidently related to territory defence. 

This behavior is really successfull and we know that thanks to an interesting experiment where birds have been removed from their territories and the time it took before other birds come and occupy the areas have been recorded: it was pretty quick.

But if you play a tape recording of the song of the resident male, even if he has been removed, it takes a lot longer.

This means that birds looking for a territory recognise individual songs and as long as the territory owner is still around, or presumed to be, and still singing they will not disturb trying to take over.

Now, this is my answer to why birds sing. But here in Africa there’s a complication we should take into account: here, many female birds sing too. This is not unknown in Europe and Asia, but it’s pretty uncommon. And many african species engage in complex duets, with both male and female taking part singing.

Why?

There’s no a good answer to this yet, but a couple of interesting theories are being developed that are worth mentioning.

First of all, birds residing in the tropics tend to live longer. They do things slowly, and it’s more difficult for them to raise young than in more temperate regions. So they stay with their partner longer, often holding territories year-round: a reason more for females to be involved in territory defence too.

The other theory is that here in Africa the seasons could be harder to identify too , especially in the forests, with breeding possible much of the year. For sure the bulbuls in my garden think it’s good to nest all year around! 😉

But birds don’t tend to keep their ovaries and reproductive organs ready to breed year round: it would be a waste of energy to carry around fully developed genitalia if you’re not going to use them, and flight would be tricky as well.

So in a less seasonal environment, how do both male and female be sure they’re in breeding condition at the same moment?

Well, maybe, by singing to each other. There’s some evidence, by the way, that song can help bring on breeding condition in some birds.

But these are only hypothesis.

Pycnonotus tricolor (Dark-capped bulbul)

Acrocephalus arundinaceus (Great reed warbler)

Good, we have tried to answer why birds sing. Let’s try now to understand why they sing most in the morning. 

Even here, there are lots of theories which are not mutually exclusive.

All of these theories start with the assumption that singing is essential, for the reasons we’ve said before, but it’s costly in terms of time and energy: another reason, by the way, why females might choose males that sing more, being this a display of strength.

 

So the birds must decide when and how much to sing.

One of the oldest theory is that they sing in the morning because it’s still too dark to be out looking for food, a good moment to sing actually. That’s a fairly solid idea, but it doesn’t really explain why they sing more in the morning than in the evening, when the light fades as well, or even in the middle of the night.

Another idea is that the conditions early in the morning, often cool and with lower humidity than the rest of the day, might be particularly good for letting the sounds of the song carry further, even if recent experiments suggest that actually the middle of the day might be the best time to sing if acoustic conditions are present.

The third, and in my opinion most interesting theory, is that birds sing most in the morning because that’s when, most days, they have got spare energy to use up.

And above all, we have to take into consideration that the world is variable: the conditions you find today such as how difficult it’s to find food, temperature, how long you have to sit out a rain storm, are all variable day to day.

This idea starts with the same assumption of the others, which is singing is important and essential, but other activities are important too, like feeding, sleeping, etc.

When you go to bed at night, you don’t know how cold the night will be, and when you wake up in the morning, you don’t know how long you’ll have to spend before to find the food you need.

 

This theory, basically, says that birds are playing a survival game, like any other animal actually. Each day they need to find enough food to survive the following night, because they can’t feed when it’s dark (I am talking about passerine birds, of course).

Now, birds live very close to the edge much of the time and each night they loose a considerable amount of weight just for keeping themselves warm: if they don’t start the night with enough extra fat to burn they could easily die overnight. So, because they don’t know exactly how cold each night could be, the only way to be sure to survive is to get enough fat to burn in the coldest night ever.

Most times, as you can imagine, it happens that the night is not so cold and when they wake up in the morning, they’ve got some spare energy to use before to start feeding again: the ideal time to sing.

Even during the day they don’t know how tough it will be to find enough food by the evening, so once they start feeding they do that like mad for a bit, just in case it’s more difficult to find food than they thought, but then if they keep finding food all day, by the evening they might have actually got fatter than they really need to be.

This is also what happens to my domestic cat, even if she is not a bird and she can’t sing. ;-D

But, in fact, it’s not wise to have too much extra fat, as it makes you less manoeuvrable and more vulnerable to predation, (my cat doesn’t know this or, most likely, she ignore it deliberately!), so you might want to sing a bit in the evening again: and this is exactly what we see.

These possibilities have been tested in a series of experiments by Rob Thomas.  In an experiment he fed some robins the same amount of food during the day, but some of them have been convinced that there was a regular and constant supply of food throughout the day, others have been persuaded that it was much more variable getting lots of food at one point, but much less later in the day, and then listening to how long they sang that evening or the following morning: more variable gives more song.

The general conclusion is that this theory is robust.

 

And this explains why the dawn chorus here in Kenya, where the weather is pretty predictable from day to day, is much shorter and less impressive than, for example, in a British woodland where it’s quite possible one day it will be warm and sunny and the next day it will be cold and snowy!

Even if brief, the dawn chorus here is still impressive in many parts of Kenya and well worth listening to when you’re out in the bush, maybe with us… the best way to start the day I think! And you?

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