But could dense hedges and trees be planted along them in some/most places too? They'd still provide benefits for hibernation/shelter etc. (even if they were abandoned and left to crumble) but the presence of woody species could massively benefit biodiversity and increase the connectivity value of the boundary for many more species. Maybe the walls are only popular with some wildlife because much of this kind of Yorkshire landscape is so devoid of any other more 'natural' shelter...
But could dense hedges and trees be planted along them in some/most places too? They'd still provide benefits for hibernation/shelter etc. (even if they were abandoned and left to crumble) but the presence of woody species could massively benefit biodiversity and increase the connectivity value of the boundary for many more species. Maybe the walls are only popular with some wildlife because much of this kind of Yorkshire landscape is so devoid of any other more 'natural' shelter...