Calling the birds

I remember quite well when I was small, my grandfather used to rub a wet cork on a glass bottle to call the birds. At least a couple would appear. This is in a backyard, full of hortenses, in the middle of Coimbra. You wouldn't expect it to be so easy. But then again it was my grandfather doing it.
When the birds got close enough António would catch them with a white sheet. Flying trough the air, as a single wing of a huge bird, it would softly fall on the top of the birds.
The bird's cage were beautiful! All made of wood, just like the ones you imagine as the perfect bird cages. The ones you see in the movies!

At the time that seemed like a truly act of nature. Like one of the most pure thing one could ever do. But then again, it was my grandfather doing it...