July 1958 – vol. 51, issue 7–268 (Department of Zoology, University College of Wales, Aberystwyth) In connection with the survey of winter wrecks of Kittiwakes (Rissa tridactyla) (see pp. 253-266) it is of interest to note that several instances of mass mortality have occurred in recent years during the weeks when the Kittiwakes are on the breeding cliffs. In May and June 1955 there was a heavy mortality in a breeding colony near... This article is only available to registered users.To read more, please log in or purchase a subscription.