Exceptionally large foraging ranges in provisioning Manx Shearwaters (Puffinus puffinus)

24 Oct 2016

Saskia Wischnewski presented her work at the International Seabird Group Conference in Edinburgh, and at the International Albatross and Petrel Conference in Barcelona last month. See Saskia's poster and a summary of her presentation below.  

Exceptionally large foraging ranges in provisioning Manx Shearwaters (Puffinus puffinus): A triple foraging strategy facilitated by environmental variables?

Saskia Wischnewski¹, Mark J. Jessopp² and John L. Quinn¹

 ¹ School of Biological, Earth and Environmental Sciences, University College Cork, Distillery Fields, North Mall, Cork, Ireland ² MaRei, University College Cork, Beaufort Building, Ringaskiddy, Ireland Trip strategies of central place foraging seabirds are dependent on breeding stage. While incubating birds are not constraint by provisioning needs, chick rearing adults have to ensure regular returns to the nest causing a smaller foraging range. It has been suggested that alternating between short provisioning and longer (self-)foraging trips aids balancing their own and their offspring’s energy requirements. This dual foraging strategy is highly variable across species and colonies. First GPS tracking of dual foraging Manx Shearwaters from the Irish West coast (2014 -15, N=57) shows a surprisingly high proportion of exceptionally long provisioning trips to the Mid-Atlantic ridge (range=1459km). These cause a larger range during chick rearing than during incubation.  Model based clustering of all chick rearing trips proposes three rather than two distinct strategies: 1.) Short distance and duration (N=96.). 2.) Short to medium distance and long duration (N=22). 3.) Long duration and distance trips (N=10). However, models including intrinsic drivers such as adult or chick body condition were not able to sufficiently predict trip choice. We therefore suggest that the third trip strategy is driven by a combination of increased offshore productivity and wind conditions facilitating energy efficient travel to such sites later in the season.