arranged cabinet skins (National Museums of Scotland)

"Wrens regularly pack into roosts soon after sunset during the winter. During severe weather,
one nestbox roost held 60 wrens. Once inside roosting wrens squat two or three layers deep
with heads facing inwards and tails towards the entrance or sides."                                                                        (www.birdsofbritain.co.uk/bird-guide/wren.htm)