The propensity to roost on high

My small brood of three young chickens, hatched on July 19th, have, to my surprise, done exactly what their predecessors did and taken voluntarily to roosting among the rafters under the roof of the barn, high above the henhouse where the adult birds spend the night.
(These are the cocks; the hen has wisely perched a few feet away.)

The celebrated amateur naturalist, the Hampshire curate Gilbert White of Selborne, noted in his journal on September 23rd 1792

My Bantam chickens, which have been kept in the scullery every night for fear of the rats, that carried away the first brood from the brew-house, went up last week to the beam over the stable. The earnest & early propensity of the Gallinae to roost on high is very observable; & discovers a strong dread impressed on their spirits respecting vermin that may annoy them on the ground during the hours of darkness. Hence poultry, if left to themselves & not housed, will perch, the winter through on yew-trees & fir-trees; & turkies & Guinea-fowls, heavy as the are, get up into apple trees; pheasants also in woods sleep on trees to avoid foxes: - while pea-fowls climb to the tops of the highest trees round their owner's house for security, let the weather be ever so cold or blowing. Partridges, it is true, roost on the ground, not having the faculty of perching; but then the same fear prevails in their minds; for through apprehensions from pole-cats, weasels, & stoats, they never trust themselves to coverts; but nestle together in the midst of large fields, far removed from hedges & coppices, which the love to haunt in the day; & where at that season they can skulk more secure from the ravages of rapacious birds. As to ducks, & geese, their aukward splay web-feet forbid them to settle on trees: they therefore, in the hours of darkness & danger, betake themselves to their own element the water, where amidst large lakes & pools, like ships riding at anchor, they float the whole night long in peace & security.

(Picture taken with flash after dark.)