The incubation and fledging-periods of the Razorbill

THE incubation-period of the British Razorbill (Alca tarda britannica) does not appear to have been accurately recorded. The Handbook of British Birds (Vol. v, p. 146), quotes the incubation-period as "25 days in incubator (F. G. Paynter), 26-30 (O. A. J. Lee), 30 in incubator (W. Evans), at least 35 (Miller)." The following observations were made at Skokholm Bird Observatory, where some 800 pairs o...