What Should a Clever Ungulate Eat?

Owen‐Smith, Norman; Novellie, Peter

doi:10.1086/283902

Cited by 353 publications

(209 citation statements)

References 21 publications

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“…food resources versus shelter from environmental extremes). As noted above, the activity state can be identified from the movement mode if the time step between GPS-based locations is sufficiently short (less than or equal to 1 h), otherwise it can be inferred from the time of day when particular activities More precise estimates of food benefits derived by herbivores require records of the vegetation components consumed and nutritional contents thereof, as well as the rates of food intake achieved (Owen-Smith & Novellie 1982). The close-range observations required for such estimates are possible for free-ranging animals tracked by VHF telemetry only if these animals have been habituated to the close approach of a human observer (e.g.…”

Section: Optimality Assessmentsmentioning

confidence: 99%

Foraging theory upscaled: the behavioural ecology of herbivore movement

Owen‐Smith

Fryxell

Merrill

2010

Phil. Trans. R. Soc. B

303

289

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We outline how principles of optimal foraging developed for diet and food patch selection might be applied to movement behaviour expressed over larger spatial and temporal scales. Our focus is on large mammalian herbivores, capable of carrying global positioning system (GPS) collars operating through the seasonal cycle and dependent on vegetation resources that are fixed in space but seasonally variable in availability and nutritional value. The concept of intermittent movement leads to the recognition of distinct movement modes over a hierarchy of spatio-temporal scales. Over larger scales, periods with relatively low displacement may indicate settlement within foraging areas, habitat units or seasonal ranges. Directed movements connect these patches or places used for other activities. Selection is expressed by switches in movement mode and the intensity of utilization by the settlement period relative to the area covered. The type of benefit obtained during settlement periods may be inferred from movement patterns, local environmental features, or the diel activity schedule. Rates of movement indicate changing costs in time and energy over the seasonal cycle, between years and among regions. GPS telemetry potentially enables large-scale movement responses to changing environmental conditions to be linked to population performance.

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Section: Optimality Assessmentsmentioning

confidence: 99%

Foraging theory upscaled: the behavioural ecology of herbivore movement

Owen‐Smith

Fryxell

Merrill

2010

Phil. Trans. R. Soc. B

303

289

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“…Two explanations are available for the absence of a correlation between diet composition and forage quality. Firstly, forage quality was good overall, with a mean crude protein concentration for leaves of the principal forage species of 15.8, well above the minimum required concentration of 7% (Owen-Smith and Novellie 1982;Prins 1996;Hadjigeorgiou et al 2003). The concentration of the other macro-elements (P, K, Ca, Mg and Na) are also well above maintenance requirements for cattle (Bokdam and Wallis de Vries 1992) and fit the suggested maintenance requirements for horses for P, Na and Mg, but are slightly below requirements for Ca (0.4-0.5%) and K (0.3-0.6%;National Research Council 1989;Meyer and Coenen 2002).…”

Section: Euclea Undulatamentioning

confidence: 99%

A comparison of faecal analysis with backtracking to determine the diet composition and species preference of the black rhinoceros (Diceros bicornis minor)

et al. 2009

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The diet of black rhinoceros (Diceros bicornis minor) was studied using backtracking and faecal analysis in South Africa. Both methods yielded different results, with a large bias for dominant species. Results of backtracking showed that the rhinos browsed on 80 plant species. Grasses comprised 4.5% of the diet in the faecal analysis, but were not recorded during the backtracking. The backtracking method, along with a measure of forage availability, was used to identify two groups of plant species, those species taken in a higher proportion than available in the field and those taken in a lower proportion. Chemical analyses showed that these two species groups were similar in in vitro digestibility, macro-elements and fibre constituents. Mean bite size and species contribution to the diet were not correlated with any of the forage quality parameters, indicating that rhinos were not maximising nutrient intake or minimising fibre intake of these consumed plant species.

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“…Most extensions to OFT have involved the constraints animals face while trying to either maximize the intake rate of a resource or minimize the time needed to acquire a specific amount of this resource (Pulliam 1974(Pulliam , 1975Westoby 1974;Belovsky 1978;Owen-Smith and Novellie 1983;Stephens and Krebs 1986;Illius and Gordon 1991;Owen-Smith 1993;Wilmshurst et al 2000;Bergman et al 2001;Fryxell et al 2004). However, animals need to acquire more than one type of resource during foraging; many (macro)nutrients (e.g., proteins or nitrogen and phosphorus) are consumed and needed (Westoby 1974(Westoby , 1978Belovsky 1978;Prins and Beekman 1989;Prins 1996;Forbes 1999;Raubenheimer and Simpson 2004;Simpson et al 2004;Anderson et al 2005;Prins and van Langevelde 2008).…”

Section: Introductionmentioning

confidence: 99%

“…These decisions involve choosing in which areas to search for food, which food species to include in their foraging path or diet, and how long to stay in a given patch (Schoener 1971;Owen-Smith and Novellie 1983;Pyke 1984;Senft et al 1987;Bailey et al 1989;Skarpe et al 2007). Most studies on optimal foraging focus on one of those decisions.…”

Section: Introductionmentioning

confidence: 99%

Optimal Foraging for Multiple Resources in Several Food Species

Hengeveld¹,

Langevelde²,

Groen³

et al. 2009

The American Naturalist

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The concentrations of resources in forage are not perfectly balanced to the needs of an animal, and food species differ in these concentrations. Under many circumstances, animals should thus forage on multiple food species to attain the maximum and most balanced intake of several resources. In this article we present a model to extend optimal foraging theory to incorporate concurrent foraging for multiple resources from several food species. A balancing of resources is achieved by representing the amount of a resource as the time during which it is used. Optimization is considered at two hierarchical levels: the time spent in a patch and the proportion of patches of each food species included in the foraging path. Our model results show that the balancing of resource intake can be achieved at the level of the foraging path, while the maximization of intake can be realized at the nested patch level. The choice for a food species should be dependent on the differences in intake and resource ratios between the food species. Under free choice of food species, the optimal patch residence time is subject not to differences between patches but to the local intake rate.

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What Should a Clever Ungulate Eat?

Cited by 353 publications

References 21 publications

Foraging theory upscaled: the behavioural ecology of herbivore movement

Foraging theory upscaled: the behavioural ecology of herbivore movement

A comparison of faecal analysis with backtracking to determine the diet composition and species preference of the black rhinoceros (Diceros bicornis minor)

Optimal Foraging for Multiple Resources in Several Food Species

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