Sitting swallow standing!

Well, I had thought that today I would grab a shot of Mrs Swallow sitting on her eggs, but Mr Swallow swung by and warned her I was watching. She didn't leave the nest, but she did decide to stand instead of sit, just in case she needed to make a swift swallow exit!

I wonder how long it will be now before her eggs hatch! Anyone know the gestation period? Here are her beautiful eggs!