Seabird observations at a tidal mixing front in the Irish Sea

Seabird counts were carried out along six transects across a tidal mixing front in the western Irish Sea using, for the first time, a combination of conventional visual bird observation techniques and very high-resolution mapping of frontal structure using an undulating CTD. Four seabird species were clearly aggregated at a precisely defined frontal boundary. Flocks of seabirds were found to change location over short rime periods (hours), maintaining their position relative to the surface physical parameters and the subsurface thermocline. Results confirmed considerable anecdotal and limited documentary evidence that suggest fronts are important feeding areas for seabirds. (C) 1998 Academic Press.