VISIBLE MIGRATION THROUGH THE PYRENEES: AN AUTUMN RECONNAISSANCE.

SUMMARY.1 Our present findings are preliminary. 2 On the southwest corner of France round St. Jean de Luz four migratory streams were found: (i) Blue Tits and Tree Sparrows travelling west, (ii) Chaffinches travelling S.W. by W., (iii) cardueline finches, some Chaffinches, Motacillidae, Wood Pigeons and Cranes travelling S.S.W., and (iv) Skylarks and Motacillidae, also grey geese, arriving from the Bay of Biscay and continuing inland south. 3 The birds in the above groups (iii) and (iv) were seen crossing the low mountaiiis of the Basses Pyrenees in large numbers. With a cross wind the small passerincs selected the windward slopes, presumably because of the updraught. 4 Kaptors, pigeons, hirundines, finches and Motacillidae were seen migrating through the high mountains of the central Pyrenees. In certain conditions all these groups (as well as three orders of insects) could be found migrating through the Port de Gavarnie at 7500 feet. 5 In the high mountains, hirundines (nearly all of which were Swallows) flea high on a broad front with a following wind, when they ignored the contours, somewhat lower with a cross wind, when they selected the windward slopes, and very low with a head wind, or in rain, or in the early morning and late evening, when they followed the valleys. 6 Finches and Motacillidae likewise migrated well above the floor of the vallejs except in bad weather or in the early morning. Most passed through the Port de Gavarnie in the middle hours of the day, not (as on the coast) in the early morning. 7 Other published records also indicate that small passerine birds regularly cross the European mountain ranges on their migration.