February 1967 – vol. 60, issue 2–89 (Tubbs 1963) it was shown that the Dartford Warbler Sylvia undata is subject to periodic population 'crashes' which are correlated with severe winters and normally follow a build-up in numbers over several years. Such a build-up was demonstrated for the New Forest in Hampshire over the period 1955-61, terminating in a population crash as a result of severe weather early in 1962. It was considered un... This article is only available to registered users.To read more, please log in or purchase a subscription.