Trait-mediated functional responses: predator behavioural type mediates prey consumption.

Area of Science:

• Ecology
• Behavioral Ecology
• Population Dynamics

Background:

• Predator functional response, crucial for population dynamics, depends on attack and handling rates.
• Individual behavioral differences (types) are common but their impact on functional responses is unknown.
• Predator-prey interactions are shaped by individual behaviors and environmental factors like predation risk.

Purpose of the Study:

• To investigate how crab (Panopeus herbstii) behavioral type (activity level) affects their functional response to mussels (Brachidontes exustus).
• To determine if predation threat (toadfish, Opsanus tau) modifies the relationship between crab activity level and functional response.
• To understand how individual behaviors scale up to influence predator-prey population dynamics.

Main Methods:

• Experimental manipulation of crab activity levels and predation threat (chemical cues).
• Quantification of mussel consumption rates by crabs across different activity levels, body sizes, and threat conditions.
• Analysis of the predator functional response (type II) parameters (slope and asymptote) in relation to behavioral types and predation risk.

Main Results:

• Crab activity level significantly impacted the functional response of small crabs, increasing its magnitude.
• Activity level had no effect on the functional response of large crabs.
• Predation threat reduced the functional response slope independently of crab activity level, but did not interact with it.

Conclusions:

• Individual behavioral types can have size-specific effects on predator-prey interactions.
• Behavioral plasticity in response to predation risk can modify predator functional responses.
• Understanding individual behavior is essential for predicting predator-prey population dynamics.