Prey aggregation is an effective olfactory predator avoidance strategy

Abstract

2Predator-prey interactions have a major effect on species abundance and diversity and 3 aggregation is a well-known anti-predator behavior. For immobile prey, the effectiveness of 4 aggregation depends on two conditions: (a) the inability of the predator to consume all prey 5 in a group and (b) detection of a single large group not being proportionally easier than that 6 of several small groups. While the benefits of grouping to avoid visually hunting predators 7 are well understood, the potential costs and benefits of aggregation when visual cues are not 8 available are not well understood. We carried out foraging (predation) experiments using a 9 fish predator and (dead) chironomid larvae as prey in both laboratory and field settings. In the 10 laboratory, a reduction in visual cue availability (in turbid water) led to a delay in the location 11 of aggregated prey compared to when visual cues were available, but aggregated prey 12 suffered high mortality once discovered, leading to better survival of dispersed prey in the 13 longer term (this was likely due to their inability to take evasive action and due to prey 14 groups being small). In the field (where prey were placed in feeding stations that allowed 15 transmission of olfactory but not visual cues), aggregated (large groups) and semi-dispersed 16 prey survived for longer than dispersed prey -including long term survival. Together, our 17 results indicate that like in systems where predators hunt using vision, aggregation is an 18 effective anti-predator behavior for prey avoiding olfactory predators. Prey detection is likely to be dependent on a predator's sensory acuity and modality 51 (Cain 1985). Theory predicts that as a group of prey grows, the ability of a visual predator to 52 detect the group will increase at a slower rate; that is, a group of N individuals should be less 53 than N times more detectable than a single individual (Brock and Riffenburgh 1960; 54 Treisman 1975;Turner and Pitcher 1986). This is supported by empirical evidence for visual

A trait‐based approach reveals the feeding selectivity of a small endangered Mediterranean fish

“…Although aggregate assemblages make the group more conspicuous to predators, aggregation may be an antipredator adaptation to dilute the predation impact among neighbors (Wrona and Dixon ) and to respond faster to detecting danger (Johannesen et al. ). Regarding prey feeding habits, shredders were the most vulnerable to predation, suggesting that fish preferred to forage on leaf litter substrates.…”

Structure of the Main Olfactory Bulb and Immunolocalisation of Brain-Derived Neurotrophic Factor in the Olfactory Layers of the African Grasscutter (Thryonomys swinderianus - Temminck, 1827)

“…Thus, to test the acuity of olfaction in the different postnatal periods in the African grasscutter, spatial distribution of brain-derived neurotrophic factor in the different layers was accessed by immunohistochemistry. The functional significance of the adult olfactory system in reproduction (Polese et al, 2015), emotional response (Mouly and Sullivan, 2010), mate recognition (Keller et al, 2010), predator and prey detection (Johannesen et al, 2014), flavour perception (Trelea et al, 2008), cancer diagnosis (Amundsen et al, 2014) and salmonelosis diagnosis (Mahoney et al, 2014a) has been established. Conversely, the variability in the acuity of olfaction due to age in animal models is yet to be fully investigated.…”

Investigation of cue-based aggregation in static and dynamic environments with a mobile robot swarm

“…Aggregation behavior can be observed from amoeba (Rappel, Nicol, Sarkissian, Levine, & Loomis, 1999) to insects and to other animals (Camazine et al, 2001). Animals in an aggregate gain additional capabilities such as forming a spore-bearing structure by slime mold (Bonner, 1944), building a nest by termites (Parrish & Edelstein-Keshet, 1999) or protection against predators (Johannesen, Dunn, & Morrell, 2014; Morrell & James, 2008).…”