Actually, the main function of this blue tarpaulin serving as a makeshift roof is to keep the pen dry(ish) and stop the feed in the feeders from getting completely soaked. There are two at the back of the pen on opposite sides: we bought the green one after we spotted Pearl regularly shoving Ida out of the way when the others were troughing from the red one. The third feeder nearest the entrance supplies water. All three are currently full of bits of bark, but they don’t seem too bothered.
However, they were definitely bothered by the installation of the tarpaulin. There’s no way of telling what was going through their tiny chicken brains, but they clearly Were Not Happy – Vi in particular was running round the pen like a feathery maniac, though it’s easy to see why she specifically would feel most strongly about this new development.