Techniques for shipboard surveys of marine birds

We describe shipboard and small boat techniques used by the US Fish and Wildlife Service in Alaska to survey marine birds at sea. The basis is a 10-min, 300-m-wide, strip transect taken from a platform moving at a constant speed in a constant direction. Special routines, such as instantaneous counts of traveling birds, are explained to help reduce biases caused by factors such as varying flight patterns, ship-following and avoidance, and patchy distributions. Data recording and coding techniques and formats, based on those developed for the National Oceanic Data Center, are described.