Song has a clear territorial function in many birds, and certainly in Great Tits. A male Great Tit’s territory is the area which he defends from other, neighbouring Great Tits, it is the area within which his mate will lay her eggs and it is the area most used for much of the nesting season. It is his patch – his home.
Great Tit territories are a bit like the line of houses and gardens in my street: we all live in a particular portion of the street and we don’t encroach on our neighbours’ land very much. But we have fences and walls, there are no such things in the Great Tit world but Great Tits seem to have a good idea of where the boundaries lie.
If you watch Great Tits in a wood during the breeding season and accurately map all the places that each of the males goes then you soon build up a picture of a woodland full of territories. Every square inch of the wood ‘belongs’ to one Great Tit or another, and the edges of those territories are pretty well defined. It’s as though each Great Tit has a map of their own territory in their head and their map is pretty similar to their neighbour’s map.
And you can see that when two male Great Tits meet on the edges of their respective territories, all pumped up with testosterone, they sing at each other, display at each other and occasionally have a brief skirmish.
We can examine where these territory boundaries are by using recorded Great Tit songs in playback experiments. Take your sound recordings into a wood and play a Great Tit song on the edge of the territory of a particular Great Tit and he will soon turn up (often within just a few seconds) and sing back at the ‘intruder’ just as he would if his neighbour were pushing his luck. If you play the same song in the centre of the territory of a Great Tit he goes wild with fury (or so it appears) – rushing in and singing away at a very high rate. Border disputes are one thing, incursions into one’s home territory are quite another.
At the flick of a switch, by turning on the song of a real but not-present or visible Great Tit, one can alter and examine the behaviour of a real Great Tit. The territory holder’s reaction, measured in time spent responding to the broadcast recorded song, is a measure of something which looks very much to us to be related to how angry the bird is, and how ready to fight the intruder. I know that’s anthropomorphic but that is certainly how it looks.
And measuring those reactions can be useful in investigating other aspects of Great Tit’s songs – but those are stories for later (not much later).
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Surely the Great tit’s territory is the most researched in ornithology! Living not far from the University of Oxford research wood at Wytham, I reckon that every Great tit must have it’s own PhD student, its own daemon.
I’m sure Richard that there must have been or may be still are some Great Tits there that have been so involved in the research they are probably entitled to research assistant remuneration or even some sort of qualification. Imagine the headlines “Great Tit gets PhD for research into own song!”
Actually I find this sort of stuff fascinating although I’m sure it cannot all apply to all birds or even all songbirds.
When I first started birding and trying to learn birdsong, I remember being told that if I didn’t recognise something it would be a Great Tit. Surprising how often that still works out (LOL)
And if it’s not a Great Tit it’s a Chaffinch.
Tim – yes, usually
Chaffinch vocals are very infrequent so far this spring. Is that concerning? But Greenfinch songs and calls are well up compared to the last few years – a tiny bit of good news.