Perception of predation risk under unpredictable conditions: chemosensory cues and the indirect effects of predation.

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Prey are continually faced with the conflicting demands of predator avoidance and other fitness related activities such as foraging, territorial defence and courtship. Key to balancing these trade-offs is the ability to reliably assess local predation threats. However, predation risk is seldom spatially and temporally predictable, increasing the costs associated with risk assessment. The effects of unpredictable predation and the resulting uncertainty of risk are only now beginning to be examined. A growing body of research argues that uncertainty about local conditions (i.e. foraging opportunities; predation threats) will increase the value (i.e. reliability as a risk assessment cue) of acquired public information and that such information should allow prey to predict risk with greater certainty. However, learning to recognize novel cues as sources of public information is in itself costly (i.e. risk of predation during initial encounters with novel threats). Recently, we have demonstrated that under unpredictable risk conditions, prey may benefit from responding any novel cues as a risk (neophobia). By doing so, prey could reduce the cost of the initial encounter). Here, we test the hypothesis that responding to novel predator cues is an adaptive response to unpredictability in local predation threats and that neophobia allows prey to reduce their overall costs associated with balancing predator avoidance trade-offs. We also propose to apply our neophobia model to test the hypothesis that inducible neophobic predator avoidance can enhance the post-stocking survival of hatchery-reared salmonids. Each year, millions of hatchery-reared juvenile salmonids are stocked into natural waterways as part of ongoing efforts to re-establish or maintain natural populations. However, the combined effects of lack of learning opportunities within a hatchery setting and reduced phenotypic variance leads to poor post-stocking survival. We will test the feasibility of applying inducible neophobia and ecologically relevant learning to current life-skills training programs in an effort to enhance reintroduction programs. Combined, these results will advance our knowledge of risk assessment among prey populations and potentially provide a valuable tool to enhance salmon conservation programs.