Abstract
Abstract. Understanding distribution patterns, activities, and foraging behaviours of seabirds requires interdisciplinary approaches. In this paper, we provide examples of the data and analytical procedures from a new study in the German Bight (North Sea) tracking northern gannets (Morus bassanus) at their breeding colony on the island of Heligoland. Individual adult northern gannets were equipped with different types of data loggers for several weeks, measuring geographic positions and other parameters mostly at 3–5 min intervals. Birds flew in all directions from the island to search for food, but most flights targeted areas to the (N)NW (north–northwest) of Heligoland. Foraging trips were remarkably variable in duration and distance; most trips lasted 1–15 h and extended from 3 to 80 km from the breeding colony on Heligoland. Dives of gannets were generally shallow, with more than half of the dives only reaching depths of 1–3 m. The maximum dive depth was 11.4 m. Gannets showed a clear diurnal rhythm in their diving activity, with dives being almost completely restricted to the daylight period. Most flight activity at sea occurred at an altitude between the sea surface and 40 m. Gannets mostly stayed away from the wind farms and passed around them much more frequently than flying through them. Detailed information on individual animals may provide important insights into processes that are not detectable at a community level.
Highlights
Seabirds are marine animals that live mostly at or near the air–water interface
We provide examples of the data and analytical procedures from a new study in the German Bight (North Sea) tracking northern gannets (Morus bassanus) at their breeding colony on the island of Heligoland
Individual adult northern gannets were equipped with different types of data loggers for several weeks, measuring geographic positions and other parameters mostly at 3–5 min intervals
Summary
Seabirds are marine animals that live mostly at or near the air–water interface. The dynamics of both these media may have a strong influence on the ecology of seabirds (Schneider, 1991). Two subsequent approaches focusing on the behaviours of seabirds at sea have allowed significant progress in our understanding of seabird ecology. One such approach involved studying seabird distributions at sea from boats. Brown, 1986; Tasker et al, 1987), later studies concentrated on improving our understanding of the underlying factors, including habitat parameters, mainly hydrographic features measured synoptically at sea or by remote techniques, and food availability, assessed by detecting and possibly quantifying prey at sea (e.g. Hunt Jr. et al, 1998; Davoren et al, 2003; Jahncke et al, 2005). We provide examples of the data and analytical procedures based on selected data sets from 2015, and explain the value and perspectives of such studies, especially in relation to coastal observation systems such as COSYNA
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