Cooperative Foraging Research Articles

Small pack size imposes a trade-off between hunting and pup-guarding in the painted hunting dog Lycaon pictus

The painted hunting dog or African wild dog, Lycaon pictus, is one of the most endangered large carnivores in Africa, with extinction predicted within a few decades if their dramatic decline is not stopped. It has recently been hypothesized that because of their constraining need for helpers, group size was of major importance in obligate cooperative breeding species, and that the resulting likely existence of a threshold number of adults could create an Allee effect, increasing the group extinction risk. One example where the importance for a critical number of adults may have major repercussions for painted hunting dogs concerns baby-sitting, or pup-guarding, a behavior typical of obligate cooperative breeders. We propose that, as forgoing this behavior is costly because pup guards have the potential to decrease pup mortality, its use is costly too, especially in small packs, because helpers are strongly needed for their cooperative foraging (hunting, protecting the kill and bringing back food to the pups). We present a simple model showing how pup-guarding imposes a cost because it implies that less food per hunt is brought back to more individuals at the den. We complete these analyses with empirical tests of the effect of pack size on the probability of pup-guarding, from field data from the Hwange population in Zimbabwe. Our model, as well as our 5 years of empirical data, both suggest a critical threshold at a size of about five individuals. Key words: African wild dog conservation, Allee effect, cooperative hunting, inverse density dependence, Lycaon pictus, painted hunting dog, pup-guarding. [Behav Ecol 13:20–27 (2002)]

Advances in the Study of Feeding Behaviors, Mechanisms, and Mechanics of Sharks

Sharks as a group have a long history as highly successful predatory fishes. Although, the number of recent studies on their diet, feeding behavior, feeding mechanism, and mechanics have increased, many areas still require additional investigation. Dietary studies of sharks are generally more abundant than those on feeding activity patterns, and most of the studies are confined to relatively few species, many being carcharhiniform sharks. These studies reveal that sharks are generally asynchronous opportunistic feeders on the most abundant prey item, which are primarily other fishes. Studies of natural feeding behavior are few and many observations of feeding behavior are based on anecdotal reports. To capture their prey sharks either ram, suction, bite, filter, or use a combination of these behaviors. Foraging may be solitary or aggregate, and while cooperative foraging has been hypothesized it has not been conclusively demonstrated. Studies on the anatomy of the feeding mechanism are abundant and thorough, and far exceed the number of functional studies. Many of these studies have investigated the functional role of morphological features such as the protrusible upper jaw, but only recently have we begun to interpret the mechanics of the feeding apparatus and how it affects feeding behavior. Teeth are represented in the fossil record and are readily available in extant sharks. Therefore much is known about their morphology but again functional studies are primarily theoretical and await experimental analysis. Recent mechanistic approaches to the study of prey capture have revealed that kinematic and motor patterns are conserved in many species and that the ability to modulate feeding behavior varies greatly among taxa. In addition, the relationship of jaw suspension to feeding behavior is not as clear as was once believed, and contrary to previous interpretations upper jaw protrusibility appears to be related to the morphology of the upper jaw-chondrocranial articulation rather than the type of jaw suspension. Finally, we propose a set of specific hypotheses including: (1) The functional specialization for suction feeding hypothesis that morphological and functional specialization for suction feeding has repeatedly arisen in numerous elasmobranch lineages, (2) The aquatic suction feeding functional convergence hypothesis that similar hydrodynamic constraints in bony fishes and sharks result in convergent morphological and functional specializations for suction feeding in both groups, (3) The feeding modulation hypothesis that suction capture events in sharks are more stereotyped and therefore less modulated compared to ram and bite capture events, and (4) The independence of jaw suspension and feeding behavior hypothesis whereby the traditional categorization of jaw suspension types in sharks is not a good predictor of jaw mobility and prey capture behavior. Together with a set of questions these hypotheses help to guide future research on the feeding biology of sharks.

Cooperative foraging by Steller Sea Lions, Eumetopias jubatus

Cooperative foraging by Steller Sea Lions, Eumetopias jubatus

Comparative patterns of philopatry and dispersal in two common mole‐rat populations: implications for the evolution of mole‐rat sociality

Summary 1. The aridity food‐distribution hypothesis (AFDH) maintains that ecological constraints and foraging risks in arid environments curtail dispersal and promote the evolution of cooperatively foraging social groups within African mole‐rat populations. To assess the influence of habitat constraints upon mole‐rat social behaviour and hence the validity of the AFDH, we investigated the differential patterns of dispersal and philopatry in two populations of the common mole‐rat, Cryptomys hottentotus hottentotus Lesson, one from a more ‘optimal’ habitat (mesic) and another from a ‘suboptimal’ habitat (arid). 2. Rates of immigration and emigration were markedly lower in the arid relative to the mesic site, reflecting divergence in the ecological constraints upon dispersal. 3. The rates of dispersal at both sites increased as a function of group size. However, for any given group size, colony attrition was significantly greater at the mesic site than at the arid site, probably reflecting the relaxation of constraints upon dispersal in mesic areas. 4. There was no sex bias in dispersal at either study site. 5. At the mesic sites dispersing and nondispersing individuals were of comparable mass, whilst at the arid site there was a trend for dispersing animals to be heavier than their nondispersing counterparts. 6. This investigation revealed marked differences between the study populations in the nature of dispersal. This reflects adaptive variation in social behaviour between the regions, and the results suggest that delayed dispersal and cooperation may be more crucial to individual survival in arid than in mesic areas. As such, these findings provide support for the underlying contention of the AFDH that ecological constraints on successful dispersal and colony formation in arid areas have promoted a greater degree of social cohesion in mole‐rats occurring in these regions, ultimately advancing the evolution of group‐living and cooperative foraging in the Bathyergidae.

Effects of hypoxia on an estuarine predator-prey interaction:foraging behavior and mutual interference in the blue crab Callinectes sapidus and the infaunal clam prey Mya arenaria

The effects of hypoxia on trophic interactions could vary dramatically depending on whether the benthos is experiencing the onset of a hypoxic event (decreasing dissolved oxygen concentrations from normoxia), or its dissipation (increasing dissolved oxygen concentrations from hypoxia). Predator-prey dynamics between the blue crab Callinectes sapidus and an infaunal clam prey Mya arenaria were examined to assess the impact of hypoxia upon predator foraging rates and prey mortality. Laboratory experiments quantified the behavioral response of M. arenaria to varying dissolved oxygen levels through the analyses of (1) sediment burial depth, and (2) siphon extension above the sediment surface. Moreover, the functional response (relationship between predator consumption rates and prey density) of single and 2 adult blue crabs to 2 densities of M. arenaria (6 and 24 clams tank -1 ) was examined across 3 dissolved oxygen treatments: (1) normoxia (≥6.0 mg DO l -1 ); (2) moderate hypoxia (3.0 to 4.0 mg DO l -1 ), subsequent to clam acclimation at high oxygen conditions (≥6.0 mg DO l -1 ); and (3) moderate hypoxia (3.0 to 4.0 mg DO l -1 ), subsequent to clam acclimation at low oxygen conditions (≤1.5 mg DO l -1 ). M. arenaria sediment burial depth decreased and siphon extension increased during exposure to severe hypoxia. Initiation of moderate hypoxia following normoxia altered blue crab foraging behavior from a destabilizing, type II functional response, to a partially stabilizing, type I functional response. Conversely, blue crabs exhibited a type II functional response under moderate hypoxia subsequent to clam exposure to severe hypoxia. Therefore, low dissolved oxygen concentrations appear to affect the predator-prey interaction between C. sapidus and M. arenaria by either hindering blue crab foraging, or alternatively, increasing clam vulnerability by altering their siphon extension and depth distribution within the sediment column. Moreover, the inclusion of a second blue crab in experimental trials further modified functional responses through both mutual interference and agonistic behavior or cooperative foraging between predators. The collective results indicate that fluctuations in dissolved oxygen concentrations, as well as both predator and prey density, must be examined jointly to understand their impact upon predator-prey dynamics in marine systems.

Trail marking by the larva of the Madrone butterfly Eucheira socialis and the role of the trail pheromone in communal foraging behavior

The larva of the Madrone butterfly Eucheira socialis (Lepidoptera: Pieridae) secretes a trail pheromone from the ventral surface of the posterior tip of its abdomen. Caterpillars mark trails by bringing the secretory site into brief contact with the substrate during a locomotive cycle. Foragers mark most heavily when they move onto new branches and little, if at all, when they move over established trails or when they return to the communal shelter after feeding. The caterpillars make careful comparisons of alternative pathways at choice points and select newer and stronger trails over older and weaker trails. Differential marking of new and established trails during nightly forays, coupled with sensory discrimination of trails by strength and age, leads colonies to abandon old trails in favor of new trails. When applied at a rate as low as 2.5 × 10 −10 g/mm, caterpillars followed synthetic trails prepared from 5β-cholestane-3-one, a trail pheromone previously reported from the tent caterpillars (Malacosoma spp.). Although both Eucheira and Malacosoma mark with the tip of the abdomen and have near-identical sensitivites to 5β-cholestane-3-one, our study shows that Eucheira employs a relatively unsophisticated system of trail-based communication and does not recruit to food. The trail-based communication system of Eucheira appears to represent an early stage in the evolution of cooperative foraging that is derived from, and motivationally linked to, conflict behavior.

Comment on "Phase Transitions in Instigated Collective Decision Making"

The aim of this comment is to highlight the clear correspondence between some existing experimental data on cooperative foraging in ants, where it is known that mass recruitment is less flexible than combinations of group and mass recruitment, and the idea of "instigated" decision making (Numaoka, 1995). A simple model accounting for the experimental observations is introduced, and its phase diagram is presented briefly.

Cooperation among unrelated individuals: reciprocal altruism, by-product mutualism and group selection in fishes

Cooperation among unrelated individuals can evolve not only via reciprocal altruism but also via trait-group selection or by-product mutualism (or some combination of all three categories). Therefore the (iterated) prisoner's dilemma is an insufficient paradigm for studying the evolution of cooperation. We replace this game by the cooperator's dilemma, which is more versatile because it enables all three categories of cooperative behavior to be examined within the framework of a single theory. Controlled studies of cooperation among fish provide examples of each category of cooperation. Specifically, we describe reciprocal altruism among simultaneous hermaphrodites that swap egg parcels, group-selected cooperation among fish that inspect dangerous predators and by-product mutualism in the cooperative foraging of coral-reef fish.

Attraction Toward Feeding Conspecifics when Food Patches are Exhaustible

Animals that forage in groups commonly share patches of food discovered by one or a few individuals.

Cooperative foraging by North American River Otters, Lontra canadensis

Cooperative foraging by North American River Otters, Lontra canadensis

Spatial Model of Movement and Foraging in Harvester Ants ( Pogonomyrmex) (II): The Roles of Environment and Seed Dispersion

Individual-based models provide a framework for understanding individual and collective behavior of a complex system, such as social insects. We applied an individual-based simulation model of foraging of the western harvester ant ( Pogonomyrmex occidentalis) to two environments, shrub-steppe and shortgrass-steppe, in which the movement characteristics of individual ants differed according to vegetation structure. Using regular, clumped, and fractal seed dispersions, we simulated the influence of environment and foraging speed on rates of seed harvest by a colony of ants. The relative importance of individual and co-operative foraging behavior, where ants use spatial memory or chemical recruitment, was also explored in conjunction with environment and seed dispersion. Our replicated modeling "experiment" permitted us to study the three-way interaction among environment, seed dispersion, and behavior in the rates of seed harvest by ants. When foraging individually or co-operatively at observed movement rates, ants had similar harvest rates of seeds in a regular dispersion. In contrast, ants rapidly removed seeds from a fractal dispersion of seeds when foraging co-operatively. This suggests that differences in ant behavior were less important to the rate of food intake when foraging in a homogeneous resource dispersion, whereas co-operative foraging was most responsive to food resources that were spatially correlated over a range of scales. A slight difference was found between observed and modeled distributions of ant foraging distances in the shrub-steppe environment, while observed and modeled distributions were not significantly different in the shortgrass-steppe. Thus, our simulation model captured many of the foraging properties of individual ants, although it did not always accurately describe the spatial distribution of foraging ants. Our application to P. occidentalis shows that processes operating in a social unit, such as the rate of food intake by an ant colony, are strongly influenced by the interplay of the environment, resource dispersion, and the behavioral responses of individuals to food resources. This interaction arises because of the spatial properties of both foraging ants and seed resources, which suggest that spatially explicit modeling approaches may yield different insights into foraging than those based on energetic criteria.

Foraging Strategies of American White Pelicans

AbstractForaging strategies employed by American white pelicans were studied at a riverine site in Manitoba, Canada, during the breeding season in 1985 and 1986. Six strategies were identified during both diurnal and nocturnal foraging periods. Sit-and-wait was the least common strategy (four instances). Mobile individuals were common but had low rates of bill dipping and prey capture, as did relatively rare and uncoordinated aggregations. A degree of flock coordination occurred in following flocks, characterized by foragers following one after the other, with occasional synchronization of bill dipping among flock members. The largest number of pelicans foraged within more or less circular groups called nuclei. Synchronous bill dipping and apparent herding of prey towards shore were common within nuclei. The most highly coordinated strategy, semicircles, involved small numbers of foragers (2 to 30 birds) that maintained their positions relative to one another, usually in a semicircle but sometimes moving to a closed circular pattern. The greatest degree of synchronized bill dipping occurred in semicircles. Small inter-bird distances and synchronized bill dipping in nuclei and semicircles may enhance their effectiveness in driving or herding clumped fish prey. Foraging strategies could be arranged along a continuum based on degree of coordination, ranging from mobile individuals, then uncoordinated aggregations, through increasing degrees of coordination in following, nuclei, and semicircles. Along this continuum, prey size and capture rats were greatest for the more highly coordinated strategies, while less coordinated strategies appeared to be involved primarily in searching. Switching among strategies fit along the same continuum, with a tendency to switch from less to more coordinated strategies when prey were located and to return to less coordinated search when capture rates declined. Video analysis of captures within large nuclei and observations of positional shifts among foragers in nuclei and following flocks indicated that all individuals within a coordinated group potentially benefited from the presence of others, supporting the view that coordinated foraging strategies in this species are examples of true cooperative foraging. The range of strategies, and interplay among them, appear to provide the American white pelican with a highly effective group foraging system for harvesting mobile, clumped fish prey.

Cooperative foraging, productivity, and the central limit theorem.

The central limit theorem is applied to group foraging to show an automatic and universal benefit to group living. This may explain the paradoxical inverse correlation between group size and per capita brood production in primitively eusocial insects and why only one of the five major lineages of social insects contains species that revert to solitary habit.

Cooperative Foraging and Communication in Caterpillars

Journal Article Cooperative Foraging and Communication in Caterpillars: Silk and chemical markers may catalyze social evolution Get access T. D. Fitzgerald, T. D. Fitzgerald Search for other works by this author on: Oxford Academic Google Scholar S. C. Peterson S. C. Peterson Search for other works by this author on: Oxford Academic Google Scholar BioScience, Volume 38, Issue 1, January 1988, Pages 20–25, https://doi.org/10.2307/1310642 Published: 01 January 1988

Comparative foraging ecology of north temperate ants: The role of worker size and cooperative foraging in prey selection

The common North Temperate open-field antsLasius neoniger, Formica schaufussi, Myrmica americana, andMonomorium minimum overlap temporally in foraging activity as well as in the sizes of arthropod prey in their diets. Arthropod prey were taken by both individual workers and cooperative worker groups, and species differed in the proportion of prey in the diet retrieved by each method. Although prey size was significantly correlated with worker size for individually retrieved prey, when cooperative foraging was considered worker size did not serve as a consistent predictor of prey choice. Contrasting social strategies of foraging and the evolution of worker body size differences are discussed.

Graded recruitment in a ponerine ant

(1) The giant tropical ant, Paraponera clavata, exhibits graded recruitment responses, depending on the type, quantity, and quality of a food source. More ants are initially recruited to a large prey or scavenge item than to a large quantity of sugar water. (2) Individual ants encountering prey items gauge the size and/or unwieldiness of the item, regardless of the weight, when determining whether to recruit. (3) The trail pheromone of this species is often used as an orientation device by individual ants, independent of recruitment of nestmates. (4) It is proposed that the foraging behavior of P. clavata represents one of the evolutionary transitions from the independent foraging activities of the primitive ants to the highly coordinated cooperative foraging activities of many “higher” ants.

Cooperative Hunting and its Relationship to Foraging Success and Prey Size in an Avian Predator

AbstractAplomado falcons (Falco femoralis) often hunt in pairs when chasing birds; 29% of 349 hunts observed in eastern Mexico involved mated pairs of falcons simultaneously chasing the same prey animal; and 66% of 100 hunts of birds were tandem pursuits. Although true cooperative hunting is uncommon in birds of prey, hunts by pairs of Aplomado falcons consistently showed signs of cooperative behavior such as use of a simple coordinative signal, and some division of labor between participating individuals. Pairs were more than twice as successful as solo falcons hunting birds (44% vs. 19%), however, there was no evidence that cooperative hunting increased the range of feasible prey sizes. The frequent use of cooperative foraging in this and similar species may relate to necessities of efficient nest defense, and food and nest procurement in savannas inhabited by a diversity of nest‐site predators.

Optimal Foraging and Hominid Evolution: Labor and Reciprocity

We argue that cooperative foraging incorporating information exchange may have preceded tool use during the course of hominid evolution. In moving to the savanna, early hominids must have faced increasingly dispersed but sometimes more profitable food sources. The problem is finding such foods. Search costs can be reduced for each individual if a number of foragers cooperate by ranging over different parts of the habitat and by exchanging information about encountered food items. Given the probability of encountering a given food item and the return per individual for that item, it is possible to specify the optimal group size. Thus, in the patchy savanna environment, selection would have favored increased gregariousness and cooperation on the part of early hominids, setting the stage for the emergence of reciprocal exchanges of information and resources. However, such a system of reciprocity is open to manipulation. Outside the foraging context, the tension between reciprocity and manipulation would shape other social interactions. Communication and information exchange may have been more critical than labor and technology in evolving hominids from hominoids. Human sociality may find its origins in a shift in primate foraging tactics.

Inuit foraging groups: some simple models incorporating conflicts of interest, relatedness, and central-place sharing

Theory and research in evolutionary ecology and sociobiology have developed rather independently of each other. The mutual relevance of these two fields for understanding the adaptive significance of social interactions is exemplified by a consideration of cooperative foraging. Several simple models of optimal foraging group size are developed to explore the effect of the following factors: (1) conflicts of interest between group members and prospective joiners; (2) genealogical relatedness and kin-directed altruism; and (3) the scope of the sharing rule governing division of the harvest. Where the alternative is low-return solitary foraging, “joiners” are shown to prefer group sizes that are often suboptimal (in per capita efficiency) for “members.” Predicted group sizes are also above per-capita optima where kin-directed altruism is important and/or where groups and individuals pool their catch at a central place. The effect of kin-directed altruism is incorporated by defining “inclusive efficiency” measures based on genealogical relatedness and group membership options. Expansion of the harvest-sharing network to include all foragers based at a central place is shown to eliminate conflicts of interest between members and joiners, as well as cancel the role of relatedness in shaping optimal group size or composition. Predictions from the models are tested quantitatively with data on Inuit (Canadian Eskimo) foraging groups. Some models offer an improvement in accounting for variation in Inuit foraging group size, but others do not; empirical and theoretical gaps in our understanding are revealed that call for further research.

Social organization and foraging success in Lasius neoniger (Hymenoptera: Formicidae): behavioral and ecological aspects of recruitment communication.

Live, moribund, or dead arthropods are gathered by Lasius neoniger through individual and social retrieval. 85% of the total biomass of prey (fresh weight) in the diet is cooperatively retrieved by groups of workers. Short-and long-range chemical recruitment signals coordinate cooperative foraging. Stort-range recruitment of workers to assist in the retrieval or defense of prey is achieved by simultaneous discharge of hindgut material and poison gland secretion. In long-range recruitment, workers discovering prey deposit a trail of hindgut material while returning to the nest. Hindgut pheromone both stimulates nestmates to leave the nest and orients them to the food source. Colony response is adjusted according to prey weight. Group retrieval of prey follows after a sufficient number of foragers have been recruited to move the prey. Rapid prey movement decreases the exposure of food sources to neighboring conspecific and interspecific competitors. The ability to move prey rapidly is limited to prey on the order of 130 mg or less in weight. The probability of interference during foraging and resource loss to competitors increases with increasing prey size, but the probability of loss is significantly less than the probability of interference for intermediate size prey (∼20 mg), which can be moved quickly. The foraging and recruitment behaviors of Lasius neoniger appear to have a prey size-dependent effectiveness which results in greater foraging success on prey of a relatively narrow size range above those prey that can be retrieved by solitary foragers.