Population ecology Earlier colony arrival but no trend in hatching timing in two congeneric seabirds (Uria spp.) across the North Atlantic

• Published in: Biology letters (2005)
• Main Authors: Merkel, Benjamin, Descamps, Sébastien, Yoccoz, Nigel G, Danielsen, Jóhannis, Daunt, Francis, Erikstad, Kjell E, Ezhov, Aleksey V, Grémillet, David, Gavrilo, Maria, Lorentsen, Svein-Håkon, Reiertsen, Tone K, Steen, Harald, Systad, Geir H, Lindberg Þórarinsson, Þorkell, Wanless, Sarah, Strøm, Hallvard
• Format: Journal Article
• Language: English
• Published: Royal Society, The 23.10.2019
• Subjects: Environmental Sciences; ecology Keywords: guillemots; murres; timing of egg-laying; pre-laying period; Uria lomvia; Subject Areas: behaviour; Uria aalge
• ISSN: 1744-9561
• DOI: 10.1098/rsbl.2019.0634

A global analysis recently showed that seabird breeding phenology (as the timing of egg-laying and hatching) does not, on average, respond to temperature changes or advance with time (Keogan et al. 2018 Nat. Clim. Change 8, 313-318). This group, the most threatened of all birds, is therefore prone to spatio-temporal mismatches with their food resources. Yet, other aspects of the breeding phenology may also have a marked influence on breeding success , such as the arrival date of adults at the breeding site following winter migration. Here, we used a large tracking dataset of two congeneric seabirds breeding in 14 colonies across 18°latitudes, to show that arrival date at the colony was highly variable between colonies and species (ranging 80 days) and advanced 1.4 days/year while timing of egg-laying remained unchanged, resulting in an increasing pre-laying duration between 2009 and 2018. Thus, we demonstrate that potentially not all components of seabird breeding phenology are insensitive to changing environmental conditions.