Furthermore, such studies are also limited to the few species that are regularly reported as victims of hunting or bycatch in fishing gear. 2008) and the uncertain origins of wintering birds because of their high dispersal outside the breeding season, make it difficult to assess how much weight individuals of any species add during the non-breeding season. However, the increase in body size with breeding latitude (Jones 1988, Barrett et al. Thus, the body mass of Common Guillemots Uria aalge taken as bycatch in fishing gear in the Skagerrak during late autumn and winter (950−1050 g), was much higher than that of breeding birds in nearby colonies in Scotland and South Norway (650−920 g Cramp 1985, Anker-Nilssen & Lorentsen 1995, Barrett et al. To increase their chances of surviving periods of poor food supply and, for the Atlantic species of auks, also reduced flight and diving abilities when they moult their main wing feathers more-or-less synchronously, seabirds are known to increase their body mass outside of the breeding season by storing fat in sub-cutaneous and visceral deposits (Camphuysen et al. Consequently, populations are potentially vulnerable to poor conditions outside the breeding season, when most adult mortality is expected to occur. Most pelagic seabirds are long-lived and invest more in survival than reproduction (Schreiber & Burger 2002). 2017, and results of SEATRACK at Results from these studies indicate that under normal conditions, many seabird species never come to land in autumn and winter. Over the last decades, the over-wintering behaviour of several species of seabirds breeding in the North Atlantic has been documented in detail through the use of various tracking devices, particularly light loggers (geolocators) (Frederiksen et al. Many seabirds, including most species of tubenoses (Procellariiformes) and auks (Alcidae) and a few species of gulls (Laridae), spend the entire non-breeding season at sea, often thousands of kilometres away from their breeding colonies (Schreiber & Burger 2002). Given the Atlantic Puffin’s deteriorating conservation status, improved information on seasonal changes in body condition should help determine the underlying causes of die-offs in major wreck incidents such as those reported in recent years. They indicate that gains in body mass between chick-rearing and winter are at least double the decline in mass previously recorded between incubation and chick-rearing. The very limited individual level data accorded well with the population level estimates.Ĭonclusions: Our results provide the first estimates of the order of magnitude in mass change between two key life history stages in this species. Results: On average, Atlantic Puffins breeding in Scotland and Norway increased their body mass by 20–30% between the chick-rearing period and winter. In three cases data were available for individuals weighed both at the colony and on the wintering grounds. These measurements were used to estimate seasonal changes in body mass for the two breeding populations. Methods: We took standardized measurements of wing length and body mass of Atlantic Puffins during the summer chick-rearing period and on the wintering grounds near the Faroe Islands. It does not store any personal data.Capsule: Atlantic Puffins Fratercula arctica from Scottish and Norwegian populations were significantly heavier in winter than when rearing chicks.Īims: To compare body masses of Atlantic Puffins on their wintering grounds off the Faroe Islands with those of birds rearing chicks at colonies in Scotland and Norway. The cookie is set by the GDPR Cookie Consent plugin and is used to store whether or not user has consented to the use of cookies. The cookie is used to store the user consent for the cookies in the category "Performance". This cookie is set by GDPR Cookie Consent plugin. The cookie is used to store the user consent for the cookies in the category "Other. The cookies is used to store the user consent for the cookies in the category "Necessary".
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