Abstract and Summary

Observations on lapwing foraging on estuarine mudflats showed that:

  • 1
    They detected prey during stationary scanning pauses.
  • 2
    The majority of prey items were taken within three paces of the scanning position; the polychaete Nereis diversicolor was taken at greater distances than the amphipod Corophium volutator.
  • 3
    Pecks that proved abortive occurred after a greater number of paces than successful pecks, and their proportionate incidence increased with distance from the pause position; it is argued that aborted pecks are due to misidentification of prey cues rather than escape of the prey.
  • 4
    After failing to detect prey from one position, birds gave up and moved to a new scanning position; the median distance moved corresponded to the radius of an area within which 99% of prey items were located.
  • 5
    The total distance moved while taking prey (including steps taken after capture but before the next scanning pause) rarely took birds beyond the boundary of the previously scanned area; birds that chose to remain in the previous scanning position had higher subsequent probabilities of taking prey than those that moved to scan a fresh area.
  • 6
    There was a negative correlation between success rate (proportion of pauses that resulted in prey capture) and rate of movement (steps per min); this was caused by increased distances moved between pauses in low quality foraging areas, and not by handling times interfering with searching, as there was a positive correlation between the number of prey handled per min and searching rate (number of pauses per min).