Event Timers In The Natural World

The remainder of this review is devoted to understanding why animals need event timers. One might argue that there is no need; all ecologically relevant behaviors could just as easily be performed without this faculty. I recognize this argument not because it is helpful to understanding the behavior, but because it elucidates a very real constraint on our understanding of animal event timing. In the natural world, it is very difficult to tell by what cues an animal makes its decisions. Until we can isolate the event timer or show that its properties are consistent with behavioral predictions (see Bateson, this volume), any assumptions we make about the behavioral ecology of animals using event timers run the risk of oversight. On the other hand, without understanding the ecological context to which the event timer might be adapted, claims that an animal does or does not have an event timer based on laboratory tests assume a similar risk.

With respect to the argument of clock existence, however, we are at a slight advantage. From the psychophysics, we know the behavior exists. At this point we are merely in the business of knowing why. But how can we know why if we are not sure when the behavior really exists? Pigeons in cages can learn the difference between 2 and 8 sec. Does this mean that an osprey uses time to capture prey? It does not. Does this mean that squirrels make assumptions about how much time they would have to escape given the appearance of a predator in a particular location? It does not mean this either.

The first step toward understanding the adaptive contribution of event timers is to recognize the contribution they would make if they were being used. This will provide us with some sense of the situations that might have facilitated the evolution of event timers. The following tour through event timing in the natural world will focus primarily on the domains of animal behavior that would show a positive fitness relationship in the presence of a cost-free event timer that can associate nonover-lapping events in time. I will discuss the difficulties with assessing event timer cost in "Conclusions" (Section 4.6).

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