Every evening all the rooks of the neighbourhood gathered into vast flocks and returned to roost in the woods of the Chace. But one winter afternoon there came on the most dense fog that had been known for a length of time, and a flock of rooks on their way as usual to the Chace stopped all night in a clump of trees on the farm a mile from the roosting-place. This the oldest labourer had never known them do before. In the winter just past (1879-80) there were several very thick fogs during sharp frost. One afternoon I noticed a small flock of starlings which seemed unable to find their way home to the copse where I knew vast numbers of them roosted. This flock as it grew dusk settled in an elm by the roadside, then removed to another, shaking down the rime from the branches, and a third time wheeled round and perched in an oak. At that hour on ordinary days the starlings would all have been flying fast in a straight line for the copse, but these were evidently in doubt and did not know which direction to take. Hilary disliked to see the wood-pigeons in his wheat-fields: the wood-pigeon beats the grains out of a wheat-ear with the bill, striking it while on the ground. The sparrows, again, clear the standing wheat-ears, which at a little distance look thin and disarranged, and when handled are empty. There were many missel-thrushes about the Chace; they are fond of a wooded district. They pack together in summer and part in winter--just opposite in that respect to so many other birds, which separate in warm weather and congregate as it grows cold, so that the lower the temperature the larger the flock. In winter and spring the missel-thrushes fly alone or not more than two together. After their young have left the nest they go in small packs. I saw ten or twelve rise from an arable field on the 18th of June last year; there do not often seem to be more than a dozen together. I have counted ten in a pack on the 16th of September, and seven together as late as the 2nd of October. Soon after that they appear to separate and act on their individual wishes. Starlings in like manner pack after their young can fly, but then they do not separate in autumn.