The Real Hunger Games: Prey Animals Weigh Their Options Before Fleeing Predators

SCIENCE

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Discussion Ideas

The Cosmos article describes a new study that upsets the “signal detection theory” used in most predator-prey research. What is signal detection theory?
- According to the good folks at U.C. Davis, signal detection theory in this context “is a popular and well-established idea that has influenced behavioral science for around 50 years. Essentially, the theory holds that in a predator-prey relationship, prey animals will show more wariness and be more prone to flee as predators become more common … so in what appears to be a threatening situation, animals are better off running than hanging around to see if a predator really does strike.”

The new model of predator-prey relationships is called “state-dependent detection theory” or SDDT. What is SDDT? How does it differ from signal detection theory?
- State-dependent detection theory considers a number of variables to determine the prey animal’s “state” at the time a predator is detected. In other words, “Any prey animal will have to weigh up multiple factors in making a possible life-or-death choice.” Some of these factors may include hunger, illness or injury, exhaustion, or confusion.
- This differs significantly from traditional signal detection theory, which “assumes that prey animals make one decision at a time—and that the choice between staying put or heading for the hills is the only thing on the agenda.”

How might hunger, one of the key variables described in state-dependent detection theory, influence a prey animal’s decision to flee or stay put?
- Researchers evaluate this variable by estimating an animal’s “energy reserves.” “If the potential prey is well stocked with food itself, it can afford to miss a meal and flee. If its reserves are low, it may choose to stay put.”
- How might other factors, such as injury or exhaustion, influence a prey animal’s decisions?

The research also indicates that increasing numbers of predators actually make prey less likely to run away. Why?
- “[I]f predators are very common, the organism cannot afford to flee every time it receives a signal of possible danger.” May the odds be ever in their favor.

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