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Inferring the Properties of Predation and Other Injury‐Producing Agents from Injury Frequencies

Schoener, Thomas W.
Ecology 1979 v.60 no.6 pp. 1110-1115
animals, death, mortality, predation, tail
This paper analyzes how cumulative injury data in age—structured populations can be used to determine some properties of the injury—producing process, such as predation. If the injury—producing process is the only source of mortality or injury, raw frequencies of animals free from injury (e.g., tail breaks) are shown in a theoretical analysis to equal the efficiency of the injury—producing process (e.g., the fraction of predation attempts that result in death of the prey); they are not affected by the intensity of the injury—producing process. If alternate sources of mortality exist, this conclusion may still be approximately true unless those sources are large. If there exists alternative sources of injury that never result in death, raw frequencies of uninjured animals actually increase with increasing intensity of the process that produces both injury and death (e.g., predation). To estimate the intensity of the injury—producing and the per—unit—time rate of accumulating injuries in the simplest case, one needs both injury and survival frequencies. Formulae for these estimations are provided.