So don't female birds sing? I mean, I don't know, I'm asking. Because if they do Dr Luis Baptista's reasons don't deal with that.

But even with males, words like "why" don't really feel right. These might well bethe advantages to a species of having male birds sing and so forth, and I suppose you canb call that "why". But I imagine a bird sitting up on a tree. He's going to start singing because that's what a bird sitting on a tree does. "A bird's got to do what a bird's got to do." It feels good singing, and there's no reason not to. And when you start singing, some bird in a tree over there is going to sing out too, and you can sing just as good as him, so you do.

I've got a cat likes to sing when she's happy. Purring isn't good enough sometimes, she starts chirruping.

There's a poem about that, by Stevie Smith.

The Singing Cat.

It was a little captive cat
Upon a crowded train.
His mistress takes him from his box
To ease his fretful pain.

She hiolds him tight upopn her knee
The graceful animal
And all the people look at him
He is so beautiful.

But oh he pricks and oh he prods
And turns upon her knee
Then lifteth up his innocent voice
In plaintive melody.

He lifteth up his innocent voice
He lifteth up, he singeth
And to each human countenance
A smile of grace he bringeth.

He lifteth up his innocent paw
Upon her breast he clingeth
And everybody cries, "Behold
The cat, the cat that singeth."

He lifteth up his innocent voice
He lifteth up, he singeth,
And all the people warm themselves
In the love his beauty bringeth.