Effects of density on foraging success and aggression in age-structured groups of brown trout

Kaspersson, Rasmus; Höjesjö, Johan; Pedersen, Stig

doi:10.1016/j.anbehav.2009.12.025

Cited by 45 publications

(50 citation statements)

References 48 publications

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“…There is likely to be more competition for food in large groups and consequently interference between individuals, and the associated social vigilance are expected to increase with group size (Sansom et al 2008;Kaspersson et al 2010;Favreau et al 2010). The lack of any positive effect of group size on apprehensive foraging, and of any effect of distance to the nearest neighbor in our experiment, does not support social monitoring and scrambling competition hypotheses (Table 1, Hyp.…”

Section: Discussioncontrasting

confidence: 74%

Detecting predators and locating competitors while foraging: an experimental study of a medium-sized herbivore in an African savanna

et al. 2011

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Vigilance allows individuals to escape from predators, but it also reduces time for other activities which determine fitness, in particular resource acquisition. The principles determining how prey trade time between the detection of predators and food acquisition are not fully understood, particularly in herbivores because of many potential confounding factors (such as group size), and the ability of these animals to be vigilant while handling food. We designed a fertilization experiment to manipulate the quality of resources, and compared awareness (distinguishing apprehensive foraging and vigilance) of wild impalas (Aepyceros melampus) foraging on patches of different grass height and quality in a wilderness area with a full community of predators. While handling food, these animals can allocate time to other functions. The impalas were aware of their environment less often when on good food patches and when the grass was short. The animals spent more time in apprehensive foraging when grass was tall, and no other variable affected apprehensive behavior. The probability of exhibiting a vigilance posture decreased with group size. The interaction between grass height and patch enrichment also affected the time spent in vigilance, suggesting that resource quality was the main driver when visibility is good, and the risk of predation the main driver when the risk is high. We discuss various possible mechanisms underlying the perception of predation risk: foraging strategy, opportunities for scrounging, and inter-individual interference. Overall, this experiment shows that improving patch quality modifies the trade-off between vigilance and foraging in favor of feeding, but vigilance remains ultimately driven by the visibility of predators by foragers within their feeding patches.

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Section: Discussioncontrasting

confidence: 74%

Detecting predators and locating competitors while foraging: an experimental study of a medium-sized herbivore in an African savanna

et al. 2011

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“…For example, if it takes longer to find and consume prey due to increased resource depletion or interference while foraging at higher densities, some individuals may increase the amount of time spent foraging (Clark & Mangel 1986, Shaw et al 1995, Anholt & Werner 1995, Grand & Dill 1999, Bohlin & Johnsson 2004, White & Warner 2007, which may also be accom panied by an in crease in conspecific aggressive encounters (Pintor et al 2009, Kaspersson et al 2010. Species that differentially forage over a diel cycle can expand their foraging time by hunting for longer during their typical hunting hours and/or by hunting at more periods of the day (Lawton 1987, Kronfeld-Schor & Dayan 2003, Wasserberg et al 2006.…”

Section: Introductionmentioning

confidence: 99%

Invasive lionfish increase activity and foraging movements at greater local densities

Benkwitt¹

2016

Mar. Ecol. Prog. Ser.

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Density-dependent changes in predator foraging behavior due to intraspecific competition for food can have important implications for population dynamics of both the predator and its prey. The Indo-Pacific red lionfish Pterois volitans is an invasive predatory reef fish that has reached high population densities and can cause large reductions in small native fishes. To determine whether lionfish behavior or movement varies with local lionfish and/or prey densities, I conducted observations of lionfish on 16 coral patch reefs in The Bahamas. Lionfish foraging activity and movement varied significantly with lionfish density. At higher densities, lionfish exhibited greater activity levels, time away from shelter, and more short-term foraging movements between coral patch reefs and surrounding seagrass habitats. However, these changes were not uniform throughout the day, with differences in activity occurring only at dusk and differences in movement occurring at both dawn and dusk, but not midday. Although some lionfish foraging behaviors varied with prey density, overall lionfish density was more strongly related to differences in lionfish activity patterns. These temporal and spatial changes in lionfish foraging behaviors are consistent with the predicted effects of intraspecific competition and may have important consequences for lionfish removal efforts and native prey populations. Specifically, in areas with higher lionfish densities, prey fishes that are more active at dusk and/or inhabit seagrass beds near coral patch reefs may be more vulnerable to lionfish predation. By culling lionfish, managers may reduce the local foraging movements of lionfish and thus help maintain native fish communities in multiple habitats.

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“…In addition, the abundance of Rhino gobius cliffordpopei was highest in the littoral habitat (water depth < 6 m), followed by sub-littoral habitat (water depth ranging from 6 to 12 m) and lowest in profundal habitat (water depth ranging from 12 to 20 m), whereas the abundance of R. giurinus were highest in the profundal habitat, followed by sub-littoral habitat and lowest in littoral habitat (Guo et al 2012). Density of competitors (the 2 goby species) is also an important factor that influences foraging behavior and competitive processes (Kim & Grant 2007, Kaspersson et al 2010. Therefore, further investigations are needed to elucidate the specific effects of those factors on the patterns of competition and food partitioning be tween the 2 invasive species.…”

Section: Discussionmentioning

confidence: 99%

“…Trophic resource use among competing fishes may vary with environmental factors in - cluding habitat conditions (e.g. stable versus highly variable ecosystem, Davis et al 2012), prey availability (Shimose et al 2010), or density of competitors (Kim & Grant 2007, Kaspersson et al 2010. In Lake Erhai, the 2 studied habitats are characterized by strong differences in depth, submerged macrophytes, food abundances, and density of predators (Guo et al 2012).…”

Section: Discussionmentioning

confidence: 99%

“…In fish, for instance, some closely related species co-existing in the same ecosystem display strong food resource differentiation and trophic niche specialization (Colloca et al 2010, Davis et al 2012. Since the diet and foraging behavior of fishes are often strongly driven by environmental conditions such as prey availability (Shimose et al 2010), competition (Kaspersson et al 2010), and predation (Hammerschlag et al 2010), the patterns of food use among potentially competing fishes might therefore also vary between habitats with different environmental characteristics (Davis et al 2012). However, few studies have focused on the potential effects of habitat characteristics on trophic resource use among competing and closely related fish species.…”

Section: Introductionmentioning

confidence: 99%

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Trophic niche differences between two congeneric goby species: evidence for ontogenetic diet shift and habitat use

Liu¹,

Lek²,

Li³

et al. 2014

Aquat. Biol.

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Food partitioning is one of the primary mechanisms facilitating the stable cooccurrence of competing species, but very few studies have investigated how food resource use of competing and closely related species varies with life-history stages and habitats. In Lake Erhai (China), the trophic niche of 2 congeneric and co-occurring invasive goby species (Rhinogobius cliffordpopei and R. giurinus) was examined to test the existence of an ontogenetic diet shift and to determine potential differences in trophic niche between species within a habitat and between habitats (i.e. littoral and profundal) within species. Results obtained from gut content and stable isotope analyses revealed a strong trophic niche shift during ontogeny, whereby juveniles mainly consumed macrozooplankton while sub-adults and adults increasingly consumed aquatic insects and Tubificidae. The trophic niche of juveniles was similar between species in each of the 2 habitats but significantly different for sub-adults and adults, notably in littoral habitat. Moreover, the trophic niche was similar between habitats for juveniles of each species, whereas it differed significantly between habitats for sub-adults and adults. This study demonstrates the importance of ontogeny and shows that habitat use can significantly affect food resource use and trophic relationships between 2 co-occurring fish species.KEY WORDS: Species co-occurrence · Niche differentiation · Ontogenetic niche shift · Stable isotope analyses · Rhinogobius · Gut content analysis Resale or republication not permitted without written consent of the publisher

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Effects of density on foraging success and aggression in age-structured groups of brown trout

Cited by 45 publications

References 48 publications

Detecting predators and locating competitors while foraging: an experimental study of a medium-sized herbivore in an African savanna

Detecting predators and locating competitors while foraging: an experimental study of a medium-sized herbivore in an African savanna

Invasive lionfish increase activity and foraging movements at greater local densities

Trophic niche differences between two congeneric goby species: evidence for ontogenetic diet shift and habitat use

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