“Most of the land birds pass by day, usually crossing the Straits in the morning. The waders are, as a rule, not seen on passage; so it may be concluded they pass by night, although I have occasionally observed Peewits, Golden Plover, Terns and Gulls, passing by day. “The autumnal or return migration is less conspicuous than the vernal; and whether the passage is performed by night, or whether the birds return by some other route, or whether they pass straight on, not lingering by the way as in spring, is an open question; but during the autumn months passed by me at Gibraltar, I failed to notice the passage as in spring, though more than once during the month of August, which I spent at Gibraltar, myself and others distinctly heard Bee-eaters passing south at night, and so conclude other birds, may do the same. “The best site for watching the departure of the vernal migration is at Tangier, where just outside the town the well-known plain called the Marshan, a high piece of ground that in England would be called a common, seems to be the starting-point of half the small birds that visit Europe. “Both the vernal and autumnal migrations are generally executed during an easterly wind, or Levanter. At one time I thought that this was essential to the passage; but it appears not to be the case, as whether it be an east or west wind, if it be the time for migration, birds will pass, though they linger longer on the African coast before starting if the wind be westerly; and all the very large flights of _Raptores_ (Kites, Neophrons, Honey-Buzzards, &c.), which I have seen, passed with a Levanter. After observing the passage for five springs, I am unable to come to any decided opinion; the truth being, that as an east wind is the prevalent one, the idea has been started that migration always takes place during that wind. Nevertheless, it is an undoubted fact, that during the autumnal or southern migration of the Quail in September, they collect in vast numbers on the European side, if there be a west wind, and seem not to be able to pass until it changes to the east; this is so much the case that, if the wind keeps in that quarter during the migration, none hardly are to be seen. “On some occasions the passage of the larger birds of prey is a most wonderful sight; but of all the remarkable flights of any single species, that of the common Crane has been the most noteworthy that has come under my own observation. “On the Andalusian side the number of birds seen even by the ordinary traveller appears strikingly large; this being, no doubt, in a great measure caused by the quantity which are, for ten months, at least, out of the year, more or less on migration; that is to say, with the exception of June and July, there is no month in which the passage of birds is not noticeable, June being the only one in which there may be said to be absolutely no migration, as during the month of July Cuckoos and some Bee-eaters return to the south.”