worst winters, relatively habitable inlands? Again, naturalists have observed a like movement hitherward in winter from Central Europe. There may be observed in the early spring as regular an emigration as, on a perhaps not vaster scale, an incalculable immigration. Apparently, most if not all of the myriads of skylarks which are undoubtedly with us throughout the winter are these immigrants from Northern and Central Europe. Those who come in February and in still greater numbers in March and April (and the later the arrivals the further north the goal, it is said) are the ‘strayed revellers’ from the South, the home-bred birds home again. In our remote Hebrides the nesting season is hardly over before the island-bred skylarks, so late in coming, are on the Great South Road once more. What with the habitual two and the not infrequent three broods raised in a single season, particularly in Southern England, South-West Scotland, and Ireland, and the enormous influx of aliens from Northern and Central Europe, our skylark population is at its highest, not, as most people might think, in May, or even about the season of the autumnal equinox, but at the beginning of November, when already the great tides of migration have ebbed. Another puzzling problem is the rhythmic regularity of the arrivals and departures of the incomers and the outgoers. For, while the latter will not take the high-road of the upper air till nightfall or at least until dusk, the former travel by day: and the goings and comings are so timed, or to observation appear so timed, that about four o’clock on a late October day the first cohort of the invaders may in the wide lonely desert overhead pass the first caravans of the exiles. In March, again, the two currents may once more meet: the home-bred birds are on their return, the aliens are on the wing for the hill-pastures and the vales and uplands of their native countries. This will account for how, say in the Hebrides, one observer will chronicle the departure of the skylarks before Summer-end, at the early close there of the nesting season, and how another, not less accurate, will note the presence weeks later of larks in apparently as great a number as ever. The islanders have gone, to seek the south: the newcomers from Scandinavia have taken their place. But here also, as elsewhere, the conditions of the weather will be more potent than even the summons of the spirit of migration: a severe frost will for a time clear a whole region of the tufted birdeens, a prolonged frost will drive them away from that region for the winter.