Long-term trends of egg sizes of three seabirds and spatial variation of Great skua eggs

Activity: Talk or presentationOral presentation


Egg size may be a suitable ecological indicator as egg production is a demanding process. Some studies have shown long-term declines in seabird egg size for individual species and areas. What we are missing however are long-term studies of multiple species and on a wider geographical scale. With a compilation of egg measurements from field data and museum collections, this study investigates the long-term variation of over 10,000 Great Skua Stercorarius skua eggs across a wide spatial scale from 1809 to the present time as well as long-term trends in egg size of three seabird species breeding in the Faroe Islands. Great Skua egg size showed significant spatial and temporal variation. The temporal trend is apparent for Great Skuas eggs in the Faroes and similar trends were found in different areas suggesting either widespread environmental change, or feeding conditions have changed similarly over these areas. However, an examination of eggs of other seabird species such as Guillemot Uria aalge and Northern Fulmar Fulmarus glacialis eggs from the Faroes, showed different temporal trends from that in Great Skuas, suggesting not all species, respond similarly to changes in the marine ecosystem. Large-scale geographic differences of egg sizes at different colonies indicate a predictable latitudinal gradient in egg sizes, but trends at different colonies also suggest wide-ranging temporal changes, which are discussed in relation to changes in environmental conditions and fishing practices.
Period20 Mar 2018
Event titleResolving the Mysteries of the Avian Egg Conference
Event typeConference
LocationSheffield, United KingdomShow on map
Degree of RecognitionInternational