Adult Kittiwake expelling chick from nesting ledge

On 17th June 2021, we witnessed an adult Kittiwake Rissa tridactyla expel a chick from its nesting ledge. The chick fell to its death. We made the observation during our annual monitoring of this species on Lundy. A scan of the colony at 12.13 hrs detected unusual movement in a two-chick nest. One chick, which we designated as the beta chick given its smaller size, was unusually positioned outside the nest away from the alpha chick and the adult, which both remained in the nest. We estimate that the beta chick was about 1–2 days old. The site was such that the floor of the ledge extended well behind the nest to a slightly overhanging back wall, and the chick was scrabbling against this back wall. At 12.25 hrs, in a rapid sequence of movements lasting only seconds, the beta chick turned and moved back in the direction of the nest. As it approached, it came between the adult and a side wall and was then grasped in the adult’s beak and expelled in an upward arc, falling into the sea below. No interactions between the alpha and beta were observed.

The full text is a publisher version, reproduced here with permission. The final version published in British Birds, vol. 114, issue 12, pp 766 and is available via https://britishbirds.co.uk/content/adult-kittiwake-expelling-chick-n...