Tracking and capture of a moving object in the pigeon (Columba livia)

• Main Author: Wilkinson, Anna
• Published: University of York 2007
• Subjects: 591.5
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485842

Tracking and interception is commonly seen in the natural environment and occurs in all predator-prey interactions, in mating displays and shoaling behaviour. Despite this prevalence, little experimental research has examined the mechanisms involved in tracking and capture in non-humans. The aim of this thesis was to experimentally assess tracking and capture abilities in pigeons, and establish the processes underlying this behaviour. The first experiment manipulated the speed and size of the stimulus over phases to examine the limits of the birds' tracking abilities. This identified two possible processes that controlled responding. The first being lag, this was a multiplicative factor that was controlled by the speed of the stimulus. It can be thought of as the time taken for the birds to fixate upon and peck the moving stimulus. The second factor was an anticipatory mechanism. This allowed the birds to anticipate ahead of the stimulus motion; it was an additive factor and appeared to be controlled by the onset of stimulus motion. The role of these mechanisms was tested through the manipulation of motion direction, the visual input and motion speed. The lag was extremely flexible and adapted easily to changes in direction, speed and sudden stops; however it could not predict the future position ofthe stimulus. The anticipatory mechanism was less flexible. It allowed the birds to anticipate the future position ofthe stimulus, but only when the motion was highly predictable. In circumstances when it was not, such as changes in direction or unexpected stops, it could not entirely adapt to the motion change. Furthermore, it could not reset while the visual input from the stimulus remained. This is quite different from the anticipatory tracking mechanism that has been proposed in humans. Further research with the pigeon should be conducted to ascertain the degree of similarity and the differences between these mechanisms.