Simultaneous Watch for migrant Swifts, May 11th, 1947
01 May 1948
Main paper
IN the spring of 1947 the British Trust for Ornithology invited as many as possible of its members and others interested to undertake a simultaneous watch of the movements of Swifts (Apus a. apus) on a pre-selected day--May n t h , 1947.Five similar watch...
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