Foraging methods can affect patch choice: an experimental study in Mallard (Anas platyrhynchos)
55
Citation
16
Reference
10
Related Paper
Citation Trend
Keywords:
Anas
Optimal foraging theory
Optimal foraging theory
Cite
Citations (1)
Optimal foraging theory
Cite
Citations (6)
Optimal foraging theory
Ecological stoichiometry
Cite
Citations (18)
Food-plant and foraging-site selection by semidomesticated female reindeer (Rangifer tarandus tarandus L.) was studied to shed light on the searching and foraging behaviour of this herbivore. The aims of the study were (i) to determine the role of food biomass and (or) plant nitrogen content in feeding-site selection and (ii) to analyse the extent to which movement patterns of reindeer are related to availability of food resources using several models of searching behaviour (fractal analysis, correlated random walks, and Lévy flights). The study was conducted in summer 1999 in a mountainous area of northern Sweden. Reindeer selected different plant communities during this period and changed search pattern in late summer. We found that reindeer selected feeding sites with higher green biomass of Betula spp. and Salix spp. However, there was no sharp threshold for foraging as suggested by some models. Contrary to qualitative predictions of optimal-foraging theory, we found no selection of feeding sites on the basis of the nitrogen content of food. The changed search pattern in late summer and the discrepancy between reindeer foraging paths and a correlated random walk model suggests that reindeer were responding to their environment by changing their searching behaviour.
Optimal foraging theory
Lévy flight
Cite
Citations (193)
Oligophagous and polyphagous predators are confronted with spatially and temporally varying distributions of prey. Their species‐specific foraging strategies should be able to cope with this variability. Using an individual based model, we explore how diet breath and the spatial scale at which predators respond to prey affects their capture efficiency in four heterogeneous prey landscapes, and combinations thereof. We interpret the spatial scale of the predator's response as perceptual range, and propose giving‐up density as a proxy for diet breadth. Foraging behaviour is evaluated for a total of 121 perceptual range/giving‐up density combinations, with four of them reflecting the strategies adopted by real ladybeetle species. Foraging rules of oligophagous ladybeetles were generally not very effective in terms of attained predation rate when foraging in a single prey landscape, but appear to be more effective when foraging in multiple prey landscapes. This finding is compatible with the notion that oligophagous predators do not adopt a foraging strategy that is especially adapted to a specific prey landscape, but to multiple prey landscapes. Simulations further indicated that there was not a ‘best’ foraging rule that resulted in the highest predation rates for a range of spatial prey distributions and prey densities. The findings thus suggest that strategies of four ladybeetle species are effective in generating sufficient prey capture under a broad range of spatial distributions, rather than maximum capture under a narrower set of distributions.
Optimal foraging theory
Cite
Citations (33)
Ground-foraging birds of temperate woodlands of southern Australia are prominent among bird species considered to be susceptible to population decline. We examined the foraging ecology, including foraging substrates, actions and heights, of 13 ground-foraging species at four woodland sites in northern Victoria. Nine species are regarded as declining in southern Australia and four are considered common. Ten foraging substrates were identified, of which leaf-litter (54% of observations) and bare ground (17%) were most frequently used. In all woodland sites, litter was used more frequently than expected from its proportional cover. Bare ground was frequently used as a substrate by individual species, and fallen timber and grass were important for some species. Most species were generalists in their use of substrates. Six foraging actions were observed, of which gleaning and pouncing were most frequently recorded. All species foraged close to the ground and four foraged almost entirely at ground level. For pouncing birds, dead branches and fallen timber were the most important launch substrates from which pouncing actions were initiated. Eight of the 13 species differed in some aspect of their foraging ecology between woodland sites, especially in relation to the use of substrates (seven species). Fewer species (four) displayed differences in foraging ecology between seasons, with the greatest seasonal variation being in use of foraging substrates (three species). Overall, no significant differences were evident in the foraging ecologies of common and declining species. Species in both groups encompassed a wide range of foraging behaviours. Owing to this range in foraging ecology, the conservation of diverse assemblages of ground-foraging birds requires the maintenance of heterogeneous ground layers and careful management of disturbance processes.
Cite
Citations (48)
Optimal foraging theory
Cite
Citations (98)
Optimality theory can be used to predict the responses of foragers to changes in prey density. Predator-prey theory is interested in whether predators cause density-dependent mortality of their prey. Following Abrams (1982), I blended these two bodies of thought by determining conditions under which optimal foraging results in density-dependent predation. The following predictions emerged: (1) Optimal foraging contributes to density-dependent predation if the optimal behavior (e.g., size of foraging area, length of foraging period, foraging speed, proportion of time spent in risky, rewarding areas) increases with increasing prey density. (2) If the forager's goal is to maximize net benefit, then for food-limited foragers or those with high foraging costs, the optimal behavior should generally increase with prey density. (3) If foragers are near satiation, however, or if costs also increase with prey density, then the optimal behavior can decrease with increasing prey density. (4) If the goal is to minimize foraging time while attaining a benefit threshold, then the predictions are identical to those for benefit maximizers. (5) If the goal is cost or activity minimization, then the optimal behavior should generally decrease with increasing prey density.
Optimal foraging theory
Density dependence
Cite
Citations (107)
The foraging decisions involved in acquiring a meal can have an impact on an animal’s spatial distribution, as well as affect other animal species and plant communities. Thus, understanding how the foraging process varies over space and time has broad ecological implications, and optimal foraging theory can be used to identify key factors controlling foraging decisions. Optimality models are based on currencies, options and constraints. Using examples from research on free-ranging bison (Bison bison), we show how variations in these model elements can yield strong spatio-temporal variation in expected foraging decisions. First, we present a simple optimal foraging model to investigate the temporal scale of foraging decisions. On the basis of this model, we identify the foraging currency and demonstrate that such a simple model can be successful at predicting animal distribution across ecosystems. We then modify the model by changing (1) the forager’s option, from the selection of individual plants to the selection of food bites that may include more than one plant species, (2) its constraints, from being omniscient to having incomplete information of resource quality and distribution and (3) its currency, from the maximisation of energy intake rate (E) to the maximisation of the ratio between E and mortality risk (u).We also show that, where the maximisation of E fails, the maximisation of E/u can explain the circadian rhythm in the diet and movements of bison. Simple optimal foraging-theory models thus can explain changes in dietary choice of bison within a foraging patch and during the course of a day.
Optimal foraging theory
Resource distribution
Temporal scales
Cite
Citations (21)
Most of the situations to which optimal foraging theory has been applied can be divided into the following four categories: (1) optimal food choice; (2) optimal food patch choice; (3) optimal time allocation to different food patches; (4) optimal patterns and speed of movements (Pyke et al., 1977). I have reviewed the ways in which the first three problems have been tackled thus far in primate feeding ecology. I have also reconsidered the foraging behaviour of the wild Japanese monkeys that inhabit Kinkazan Island, Miyagi Prefecture, in terms of net rate of energy intake which is usually employed as a measure in analyses of optimal foraging theory. I found that there was no significant tendency for the monkeys to spend more time in feeding on food items that are associated with more rapid energy intake. Furthermore, monkeys chose the higher-quality food patch (i. e., where the feeding speed was higher) and fed there, but showed no significant tendency to feed for a longer time in the higher-quality patch. I have discussed ecological factors other than the net rate of energy intake and social factors that influence these results. Finally, I have presented a summary of the general foraging strategies of Japanese monkeys that I have studied thus far.
Optimal foraging theory
Time allocation
Cite
Citations (6)