Nonconsumptive effects in a multiple predator system reduce the foraging efficiency of a keystone predator

Area of Science:

• Ecology
• Predator-prey dynamics
• Behavioral ecology

Background:

• Non-consumptive effects (NCE) of predators significantly impact prey demographics, comparable to consumptive effects (CE).
• Interactions between NCE and CE of multiple predator species on shared prey are less understood.
• Predicting combined predator impacts on prey mortality requires understanding these complex interactions.

Purpose of the Study:

• To investigate how the NCE of one predator influences the CE of another predator on a shared prey.
• To evaluate if incorporating NCE-CE interactions improves predictions of combined predator effects on prey mortality.
• To assess the impact of predator interactions on the foraging success and keystone role of predators.

Main Methods:

• Experimental setup using larval dragonflies, adult newts, and tadpole prey.
• Quantification of consumptive effects (CE) and non-consumptive effects (NCE) for each predator.
• Measurement of how NCE from one predator altered the CE of the second predator.
• Comparison of observed combined predator effects with four predictive models.

Main Results:

• Dragonfly NCE (increased tadpole hiding) reduced newt CE (foraging success).
• Newt NCE altered tadpole behavior but did not affect dragonfly CE.
• The combined effect of both predators on tadpole mortality was better predicted when NCE-CE interactions were considered.

Conclusions:

• Interactions between predator consumptive and non-consumptive effects are crucial for accurate ecological predictions.
• The presence of other predators can compromise the foraging efficiency and keystone role of a predator.
• Incorporating NCE-CE interactions into models enhances the predictability of multi-predator impacts on prey populations.