Morning, I am a little confused (what's new)

I planted out some lettuce and broccoli yesterday evening, and covered each one with a cut up bottle, lid off.

Question is do I have to take these off in the day? We have a lot of birds (pigeons mainly) and the plants are quite small, about 5 inches high.

I am out all day today so don't want to get home to stalks, but also don't want them to die. They have all been watered and look still damp today. And not wilting (had to go and check on them first thing, lol how sad am I?)

Any advice?

Thanks janeyo