Exploring behavior of an unusual megaherbivore: a spatially explicit foraging model of the hippopotamus

Lewison, Rebecca L.; Carter, Jacoby

doi:10.1016/s0304-3800(03)00305-3

Cited by 44 publications

(31 citation statements)

References 40 publications

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“…with other evidence for CP foraging behaviour in terrestrial mammals (Jenkins 1980;Fryxell and Doucet 1991;Giraldeau et al 1994;Lewison and Carter 2004).…”

Section: Figsupporting

confidence: 67%

Central-place foraging in nursing, arthropod-gleaning bats

2008

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Central-place (CP) foraging theory predicts a positive correlation between the time a breeding CP forager spends in a patch and the distance of the patch to the CP. We found that nursing female Hemprich's long-eared bats (Otonycteris hemprichii Peters, 1859; Vespertilionidae) that forage around a lake in the Negev roost in only two areas: one 0.5-2 km (near) and one 9 km (far) from the foraging area. If these bats are CP foragers, then the strategies of the two groups should differ. We predicted that females roosting farther away would have longer but fewer foraging bouts. Using radiotelemetry, we measured the activity of six females from the near site and three from the far site. Without exception, females from the far site made a single, prolonged foraging bout each night, while females roosting nearby made several shorter bouts. Among the females from the near site, daily foraging time, mean daily foraging bout length, and first daily foraging bout length were all significantly and positively correlated with distance between the roost and the foraging site. Our data support the prediction that female O. hemprichii are CP foragers. We suggest that the females trade off using a safe roost site, distant from a choice foraging area, and lower nursing frequency against using a risky roost site close to the foraging area and greater nursing frequency.Résumé : La théorie de la quête alimentaire depuis un point central (CP) prédit qu'il y aura une corrélation positive entre le temps qu'un organisme reproducteur qui s'alimente depuis un CP passe dans une parcelle et la distance de cette parcelle du CP. Nous avons observé que des femelles allaitantes de l'oreillard d'Hemprich (Otonycteris hemprichii Peters, 1859; Vespertilionidae) qui s'alimentent autour d'un lac dans le Néguev se perchent seulement dans deux sites, l'un (proche) à 0,5-2 km et l'autre (éloigné) à 9 km de la région d'alimentation. Si ces chauves-souris s'alimentent depuis un CP, il devrait alors y avoir des différences de stratégie entre les deux groupes. Nous avons prédit que les femelles qui se perchent à une distance plus grande devraient avoir des épisodes alimentaires plus longs, mais moins nombreux. Nous avons mesuré par radiotélémétrie l'activité de six femelles du site rapproché et de trois du site éloigné. Sans exception, les femelles du site éloigné entreprennent une seule sortie alimentaire prolongée chaque nuit, alors que les femelles qui nichent tout près font plusieurs sorties plus courtes. Chez les femelles du site rapproché, la durée journalière de la quête alimentaire, la durée journalière moyenne des sorties alimentaires et la durée de la première sortie chaque jour sont toutes en corrélation significative et positive avec la distance entre le site de perchage et le site d'alimentation. Nos données appuient la prédiction que les femelles d'O. hemprichii s'alimentent depuis un CP. Nous croyons que les femelles font un compromis entre un site sécuritaire de perchage loin du site d'alimentation et une fréquence réduite d'allaitement, d'une...

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“…with other evidence for CP foraging behaviour in terrestrial mammals (Jenkins 1980;Fryxell and Doucet 1991;Giraldeau et al 1994;Lewison and Carter 2004).…”

Section: Figsupporting

confidence: 67%

Central-place foraging in nursing, arthropod-gleaning bats

2008

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“…Results from empirical studies often match these predictions (Pyke et al. , Andersson , Stephens and Krebs ), even for animals that do not meet the original definition of central‐place foragers (e.g., those that do not bring food resources back to a central site and/or do not always return to the same exact central site; Huntly , Chase , Lewison and Carter , Bakker et al. , van Gils and Tijsen , Bestley et al.…”

Section: Introductionmentioning

confidence: 83%

Central‐place foraging and ecological effects of an invasive predator across multiple habitats

Benkwitt

2016

Ecology

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Cross-habitat foraging movements of predators can have widespread implications for predator and prey populations, community structure, nutrient transfer, and ecosystem function. Although central-place foraging models and other aspects of optimal foraging theory focus on individual predator behavior, they also provide useful frameworks for understanding the effects of predators on prey populations across multiple habitats. However, few studies have examined both the foraging behavior and ecological effects of nonnative predators across multiple habitats, and none has tested whether nonnative predators deplete prey in a manner predicted by these foraging models. I conducted behavioral observations of invasive lionfish (Pterois volitans) to determine whether they exhibit foraging movements similar to other central-place consumers. Then, I used a manipulative field experiment to test whether their effects on prey populations are consistent with three qualitative predictions from optimal foraging models. Specifically, I predicted that the effects of invasive lionfish on native prey will (1) occur at central sites first and then in surrounding habitats, (2) decrease with increasing distance away from their shelter site, and (3) extend to greater distances when prey patches are spaced closer together. Approximately 40% of lionfish exhibited short-term crepuscular foraging movements into surrounding habitats from the coral patch reefs where they shelter during daylight hours. Over the course of 7 weeks, lionfish depleted native fish populations on the coral patch reefs where they reside, and subsequently on small structures in the surrounding habitat. However, their effects did not decrease with increasing distance from the central shelter site and the influence of patch spacing was opposite the prediction. Instead, lionfish always had the greatest effects in areas with the highest prey densities. The differences between the predicted and observed effects of lionfish foraging are likely due to different constraints faced by invasive predators compared to native predators, namely that lionfish do not face increased predation risk with increased movement away from shelter sites. By foraging at greater distances from patch reefs than native predators, lionfish eliminated a spatial refuge from predation used by juveniles of many commercially and ecologically important reef fishes.

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“…This herbivorous semiaquatic mega-consumer forages widely on land at night consuming largely terrestrial C4 grasses and some browse (Eltringham 1999, Grey and Harper 2002, Cerling et al 2008. Individual H. amphibius consume approximately 40-50 kg (wet mass) of terrestrial organic matter per night (Lewison and Carter 2004) and then spend all or most of the daylight hours in aquatic refuges where a large proportion of this nutrient rich terrestrial intake is excreted ( Fig. 1; Appendix A; Subalusky et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Carbon stable isotopes suggest that hippopotamus‐vectored nutrients subsidize aquatic consumers in an East African river

et al. 2015

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The common hippopotamus, Hippopotamus amphibius, transports millions of tons of organic matter annually from its terrestrial feeding grounds into aquatic habitats. We evaluated whether carbon stable isotopes (δ13C) can be used as tracers for determining whether H. amphibius‐vectored allochthonous material is utilized by aquatic consumers. Two approaches were employed to make this determination: (1) lab‐based feeding trials where omnivorous river fish were fed a H. amphibius dung diet and (2) field sampling of fish and aquatic insects in pools with and without H. amphibius. Lab trials revealed that fish fed exclusively H. amphibius dung exhibited significantly more positive δ13C values than fish not fed dung. Fish and aquatic insects sampled in a river pool used for decades by H. amphibius also exhibited more positive δ13C values at the end of the dry season than fish and insects sampled from an upstream H. amphibius‐free reference pool. Fish sampled in these same pools at the end of the wet season (high flow) showed no significant differences in δ13C values, suggesting that higher flows reduced retention and use of H. amphibius subsidies. These data provide preliminary evidence that δ13C values may be useful, in certain contexts, for quantifying the importance H. amphibius organic matter.

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Exploring behavior of an unusual megaherbivore: a spatially explicit foraging model of the hippopotamus

Cited by 44 publications

References 40 publications

Central-place foraging in nursing, arthropod-gleaning bats

Central-place foraging in nursing, arthropod-gleaning bats

Central‐place foraging and ecological effects of an invasive predator across multiple habitats

Carbon stable isotopes suggest that hippopotamus‐vectored nutrients subsidize aquatic consumers in an East African river

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