Individual willingness to leave a safe refuge and the trade-off between food and safety: a test with social fish

Abstract

Refuges offer prey animals protection from predation, but increased time spent hiding can reduce foraging opportunities. Within social groups, individuals vary in their refuge use and willingness to forage in the presence of a predator. Here, we examine the relative foraging benefits and mortality costs associated with individual refuge use and foraging behaviour within groups of goldfish ( Carassius auratus ) under predation risk from an avian predator (little egret— Egretta garzetta ). We assessed individual order of emergence from the refuge and participation over 15 group foraging outings, and assigned each fish a daily outing index score. The individual fish that emerged from the refuge earlier than the other group members and that participated in more outings received high outing index scores and consumed more food compared with fish that tended to emerge in posterior positions and participate in fewer outings. However, individual fish that attained high outing index scores suffered a higher risk of predation. Furthermore, the amount of time the egret spent at the pool affected group foraging behaviour: as predation risk increased, groups of fish consumed significantly less food. Our results exemplify the trade-off between foraging success and safety from predation that prey species regularly experience.

Personality‐driven life history trade‐offs differ in two subpopulations of free‐ranging predators

“…The maintenance of inter‐individual differences in risk‐taking behaviour and growth rates in this subpopulation can be explained via the presence of a growth‐mortality trade‐off. In goldfish C. auratus risk‐prone individuals, grew faster and in cavies C. aperea exploration of a known environment predicted growth (Balaban‐Feld et al., 2019; Guenther, 2018). Similarly, juvenile lemon sharks who explore more, take more risks and profit from higher growth rates.…”

“…In turn, less explorative, risk‐averse individuals would likely conduct less extensive searches for resources, leading to lower growth and delayed reproduction but higher survival due to lower predator encounter probabilities (Lapiedra, Schoener, Leal, Losos, & Kolbe, 2018). In goldfish Carassius auratus , individuals that make more outings from a refuge acquire more food than their risk‐averse conspecifics but suffer higher risks from avian predation (Balaban‐Feld et al., 2019). In this way, individual behaviour is expected to play a critical role in mediating trade‐offs between important life‐history traits such as growth and mortality (Stamps, 2007).…”

Identifying reliable fitness proxies for growing animals responding to anthropogenic changes

“…Observations and experiments attempt to assess the impact of environmental changes on animals, such as disturbance, chronic noise, water turbidity, loss of vegetation, temperature, or reduced ability to capture food (Fletcher et al, 2012;Gurule-Small & Tinghitella, 2019;Sih et al, 2011). In deciding how to respond animals will follow rules for trading off the benefits against the costs (Balaban-Feld et al, 2019;Dmitriew, 2011;Zimmer et al, 2011). Their choices may not be intuitive, and so the assumptions about the relationships between easily observed responses and the viability of populations may be incorrect.…”

The ecological significance of time sense in animals

“…Animals often find themselves in vulnerable situations during foraging or reproductive activities as these tasks may be associated with exposure to predation (Sih, 1992; Hedrick, 2000). Consequently, animals must manage how much time they spend engaged in risky behaviours (Lima & Dill, 1990; Balaban‐Feld et al ., 2019). Interval‐timing ability is therefore assumed to be important in determining the duration of predator exposure, particularly in light of trade‐offs with foraging or other activities important for survival or reproduction.…”

“…Therefore, the decision to emerge was influenced by energetic considerations and opportunity cost of remaining in the burrow. Animals may also consider the perceived risk of remaining in the refuge (Jennions et al ., 2003), unique attributes of the refuge (Chavez‐Solis & Alcaraz, 2015), self‐conspicuousness within the environment (Hedrick, 2000), behaviours of group members (Balaban‐Feld et al ., 2019), or mating opportunity costs (Reaney, 2007) when deciding time to emerge.…”