Page:The Migration of Birds - Thomas A Coward - 1912.pdf/55

Rh threes or scores, and at night in large numbers. The other is an observation of a "bird wave" by Mr P. Cox during a snow storm in 1885 at Newcastle, New Brunswick. The birds passed eastward in a column about twenty-five yards wide, some just above the trees, others hardly visible, but the bulk in a massed column directly over the margin of the shore, and not over the river or meadow on either side. The movement was continuous for about two hours.

Dr I. A. Palmén was the great upholder of routes in the Old World, but his routes were largely speculative; they were founded on a considerable knowledge of migratory birds, but not sufficient to cover the vast area mapped out (39). Until a very large band of workers, working on similar lines all the world over, accumulate a sufficient mass of evidence as to which birds do or do not pass their various stations, with the times at which they appear, accurate knowledge of the routes of birds is impossible.

Von Middendorf collected statistics of the passage of birds in the Russian Empire, and by reckoning the average date of arrival of a few species at certain points of observation, worked out a number of curves or lines which he calls isepipteses' or lines of simultaneous arrival (35). The result was, according to his argument, a general convergence northwards; the birds passing through Central Siberia travelled