VEIT, R.R., SANTORA, J.A. & OWEN, H. 2008. Using a video camcorder to quantify spatial association between seabirds and their prey. Marine Ornithology 36: 145–151.

 

Studies of marine predators that feed on krill and other plankton are often hampered by the difficulty of continuously sampling prey within the uppermost layers of the water column. Echo sounders, whether hull-mounted or towed, usually “miss” the uppermost two meters or so of the ocean’s surface. Many non-diving seabirds, such as petrels and albatrosses, can access only krill and other prey that are located within the uppermost two meters. Therefore, a clear need exists to sample plankton abundance at the ocean’s surface. We used a video camcorder to do this, aboard the National Science Foundation’s R/V Laurence M. Gould near Elephant Island in the Antarctic Peninsula during December 2003. We towed the camcorder on a cable that also supported a towed echo-sounding transducer. In the present paper, we compare plankton abundance estimated by echo sounder and camcorder simultaneously, and we correlate these two measures of plankton abundance with visual estimates of bird abundance and quantification of bird behavior. We ask whether (1) krill could be detected using video technology; (2) krill estimated by echo sounder could be corroborated by camcorder; (3) krill detected at the surface by camcorder had predatory birds associated with it. Our analysis shows that camcorder and echo sounder ought to be used simultaneously to sample seabird prey. The camcorder most faithfully records prey for surface-feeding birds, but acoustic methods are more suitable for sampling the prey of diving birds, especially penguins.

 

Key words: Seabird–prey interactions, video camcorder, acoustic plankton sampling, Antarctica, foraging behavior