Diet of the European Shag Gulosus aristotelis during the non-breeding season at a roost within a tidal channel

Research output: Contribution to journalArticlepeer-review


The diet of the European Shag Gulosus aristotelis was assessed at one of their most northerly roosts in the UK; Bluemull Sound, Shetland. One pellet and 40 faecal samples were collected during the non-breeding season. The most frequent prey was Velvet Swimming Crab Necora puber, while the highest number of otoliths were from Saithe Pollachius virens and estimated mean (±sd) fish length was 143.9 ± 66.9 mm (range 81.4–223.6 mm).
The European Shag Gulosus aristotelis (hereafter Shag) is a Bird of Conservation Concern (BoCC) in the UK, added to the Red List due to steep declines in breeding populations (BoCC, Eaton et al. Citation2015). It is presumed that high winter mortality of adults and declines in prey (especially Lesser Sandeel Ammodytes marinus) availability and/or quality are some of the driving mechanisms behind this decline (Frederiksen et al. Citation2008, Heubeck et al. Citation2015). Therefore, studying the diet composition of Shags specifically during the non-breeding season is important if we are to increase our understanding of these mechanisms. Due to logistical constraints, however, most diet studies of Shags, like those of many seabirds, are conducted during the breeding season (Barrett et al. Citation2007). Such studies most often make use of regurgitated pellets that are examined for fish otoliths and other prey items (Johnstone et al. Citation1990, Howells et al. Citation2018). Fish otoliths can often be identified down to species level and the age class of the fish determined from the length of the otolith (Härkönen Citation1986). While less commonly used in diet studies than pellets, faecal matter (also called excreta) can also be examined for prey remains (Lumsden & Haddow Citation1946, Barrett et al. Citation2007, Radhakrishnan et al. Citation2010).
Original languageEnglish
Pages (from-to)1-5
JournalBird Study
Issue number1
Publication statusPublished - 21 Feb 2024


Dive into the research topics of 'Diet of the European Shag Gulosus aristotelis during the non-breeding season at a roost within a tidal channel'. Together they form a unique fingerprint.

Cite this