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A theoretical and empirical analysis of saltatory search
Abstract
There are two approaches to the study of adaptive hypotheses of behavior: a historical approach focused on determining the origins of behaviors, and a non-historical approach designed to analyze the maintenance of adaptive behaviors. I employ the latter approach that assumes behaviors are adaptive and examines the trade-offs that make them adaptive. Using optimality methods, I analyze search behavior while foraging. Many animals search in a saltatory fashion: they move forward, pause briefly, and move forward again. Although many optimal foraging models have been developed, most do not address how an animal searches for food. The key feature of the models I present is distinguishing between a body position and a scan position. I see the varying movement of saltatory search as a consequence of the curvature in the functions that relate body speed to benefits (Jensen's inequality). These functions are based on sensory and movement explanations for saltatory search. The models predict (1) As a forager's ability to detect prey in the distance degrades more rapidly, the forager should pause more often and not move as far between pauses. (2) As a forager's ability to detect prey at increasing speeds degrades more rapidly, a forager should move further, but less often, between pauses. (3) As movement costs increase more rapidly, a forager should move less often, but further when it does move. (4) As prey density increases, a forager should pause more, often but for only a short period of time. An empirical analysis of saltatory search in blue jays, Cyanocitta cristata, supports the first two predictions. The last two predictions assume movement is a relevant economic factor in determining search patterns, but my data suggest that movement costs are not important. Instead, the movement patterns are explained adequately by sensory degradation. Testing hypotheses involving sensory abilities in blue jays is problematic due to the different perceptual abilities of birds and humans. I explore some of those visual differences and promote the use of subjects to assess crypticity.
Subject Area
Ecology
Recommended Citation
Anderson, James Paul, "A theoretical and empirical analysis of saltatory search" (1997). ETD collection for University of Nebraska-Lincoln. AAI9815876.
https://digitalcommons.unl.edu/dissertations/AAI9815876