When is it safe to go home? Post-predation assessment of risk and safety when personal information conflicts with social cues

Abstract

Navigating risk of predation is a major driver of behavioral decision-making in small fishes. Fish use personal information from olfactory and visual indicators of risk, and also rely upon social cues to inform behavioral trade-offs between risk avoidance and fitness-positive activities such as foraging. Here, fathead minnows (Pimephales promelas), were captured, clipped and released at 48 field sites chemically labeled with either fathead minnow alarm cue (high risk) or water (low risk). We removed the chemical label after 2 h, then monitored area use by clipped and non-clipped fish. In addition, a shoal was placed in traps in half of the risky and half of the safe locations as a visual social cue of safety. We caught 2919 fish in the first sample, of which 594 were fathead minnows. These were clipped and released. The second sample caught 1500 fish, of which 164 were fathead minnows including 11 bearing marks from the first sample. Non-clipped fathead minnows and northern redbelly dace in the general community, which lacked personal information about risk status associated with trap sites, avoided areas previously labeled with alarm cues for at least 2 h after the source of alarm cue was removed, unless an experimental shoal was present at the risky site, in which case they joined the shoal in the trap. Clipped fathead minnows with direct personal knowledge of risk showed a significant shift away from areas labeled with conspecific alarm cue and a significant attraction toward sites seeded with a shoal. Moreover, unlike non-clipped fish in the general community, clipped fathead minnows were not influenced by experimental shoals at sites previously labeled as risky. These data indicate that the influence of social cues of safety depend on whether individual minnows have access to recent personal information about risk.

Significance statement

Animals use information for making decisions about when and where it is safe. Information comes from direct personal experience and/or from observing the behavior of others (social cues). In this study minnows with different levels of personal knowledge about risk responded differently to social cues about safety. Naïve minnows relied on social cues while minnows with personal knowledge of risk associated with an area ignored social cues. This study, conducted on free-living fish in a natural population, show how fish use information about risk and safety when the risk of predation is highly variable in space and time.