curious author

It's that simple? Presumably they would spend hours on the roof otherwise. Thanks very much for your very quick reply. Much appreciated.

I'm writing a book (not about pigeons) which includes a mention of a famous Sunderland pigeon cree at Ryhope Colliery. I'd like to know why lofts have short railings, like a low picket fence, on the roof. Is there a reason or is it just traditional design? Hope someone can help or guide me to somewhere I can find the answer. Many thanks.