Feeding associations between Grey Phalaropes Phalaropus fulicarius and Basking Sharks Cetorhinus maximus over a tidal-topographic front off southwest Cornwall

This paper documents a previously unreported feeding association between Grey Phalaropes Phalaropus fulicarius and Basking Sharks Cetorhinus maximus . The observations were made during effort-based visual monitoring from Gwennap Head in southwest Cornwall, in October 2008. Flocks of up to 50 Grey Phalaropes were seen to follow and aggregate around surface-feeding Basking Sharks, mostly in an area characterised by a prominent tidal-topographic front. It is proposed that Grey Phalaropes were initially attracted to visual manifestations of upwellings and convergence zones over and adjacent to this front (with enhanced surficial prey availability), and then opportunistically used the tall dorsal fins of foraging Basking Sharks as a visual cue to home in on particularly dense prey patches.