Fine Scale Baleen Whale Behavior Observed Via Tagging Over Daily Time Scales.

摘要

Tagging studies of cetaceans have focused primarily on two disparate time scales: short (hours) or long (weeks to months). Studies using sensor-rich suction-cup tags, focal follows, and proximate environmental sampling provide highly detailed observations of behavior that can be interpreted in the context of conspecific behavior, oceanographic conditions and prey distribution; however, tag attachment durations are typically short (hours) and sustained tracking and environmental sampling from small vessels is logistically challenging. Longer-term tagging studies using implanted satellite tags can provide location data over periods of weeks to months; however, inferences about behavior at time scales of hours to days are difficult to make with the limited sensor data returned by the tags and the low rate at which location data are provided (typically only 1-2 locations per day). While studies at both short and long time scales are enormously beneficial, there is also a critical need to understand cetacean behavior at intermediate daily time scales. Recent efforts to assess the impacts of sound on marine mammals and to estimate foraging efficiency have called for the need to measure daily activity budgets to quantify how much of each day an individual devotes to foraging, resting, traveling, or socializing. Moreover, many conservation issues require an understanding of daily diving activity (e.g., how much time each day does an individual spend near the bottom, at depth, in a sound channel, or at the surface?). Finally, several studies have observed diel trends in calling behavior or prey distribution that suggest diel variability in cetacean behavior; hypotheses about diel patterns in behavior can only be addressed definitively with tagging studies over daily time scales.