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Re: Carolina Wrens bunking together



Communal roosting by Winter Wrens is well known in Great Britain 
and large numbers of birds can cram themseleves into a very 
small space. Below is taken from the Birds of Britain website


"Wrens are not social during the day, but regularly pack into roosts 
soon after sunset during the winter. They may continue this habit 
until the last week in April. Most favoured sites include old house 
martins' nests, nest-boxes and holes in walls and under roofs.

It is on record that nests specially built in mid-winter have then 
been used for communal roosting, providing a warm refuge from 
frost and snow. One such nest constructed in a cotoneaster was 
quickly packed to capacity. It became so full that the tail and rear 
end of the last wren to enter protruded from the entrance.

During severe weather, one nestbox roost held 60 wrens. The 
occupants took between a quarter and a half hour to enter at night 
and twenty minutes to disperse in the morning. Some roost sites 
are traditional, drawing birds from more than a mile away. Once 
inside, roosting wrens squat up to two or three layers deep with 
heads facing inwards and tails towards the entrance or sides.

The largest roost of which I am aware was situated in the loft of an 
isolated house. The birds entered through a hole in the fascia just 
under overhanging roof slates. Accurate counting was difficult as 
birds continued arriving until almost dark.

On occasions they needed to line up before entering-running the 
gauntlet of a highly aggressive wren at the entrance forcing some 
to go elsewhere. Highest total of occupants was a remarkable 96."


Jim Bloor, Ph.D

Department of Biology
Developmental, Cell and Molecular Biology 
Group
B330 LSRC Building
Duke University
Research Drive
Durham, NC 27708-1000

Tel.      (919) 613-8150
Fax.     (919) 613-8177
email  jwbloor@duke.edu