Spatial-concentration effects and the importance of local enhancement in the evolution of colonial breeding in seabirds

The information center hypothesis (ICH) suggests that birds breed in colonies because this behavior favors information exchange at the colony about the location of food patches. However, the complex suite of behaviors the ICH requires implies that information center following is more likely to evolve after colonial breeding has become established than to promote its initial development. A simpler hypothesis to explain the evolution of colonial breeding is that coloniality concentrates foragers in space, which leads to more rapid discovery of food patches and, by means of local enhancement, more efficient transfer of information about the location of patches than if foragers bred in a dispersed fashion. To assess the effects of breeding dispersion on foraging success, I simulated the foraging behavior of cliff-breeding seabirds (nesting either solitarily or colonially) searching for patchily distributed prey. Results show that colonial breeding is favored when food patches are sufficiently large or short-lived that competition for food is ameliorated. Conversely, dispersed nesting is favored when patches are small or long-lived. Individuals playing a colonial breeding strategy can invade a population of solitarily breeding birds, and once a colonial breeding strategy becomes established, it generally is resistant to invasion. These findings suggest that the spatial-concentration model is a plausible mechanism for the initial development of coloniality.     

Patterns of GPS tracks suggest nocturnal foraging by incubating Peruvian pelicans (Pelecanus thagus)

Most seabirds are diurnal foragers, but some species may also feed at night. In Peruvian pelicans (Pelecanus thagus), the evidence for nocturnal foraging is sparse and anecdotal. We used GPS-dataloggers on five incubating Peruvian pelicans from Isla Lobos de Tierra, Perú, to examine their nocturnality, foraging movements and activities patterns at sea. All instrumented pelicans undertook nocturnal trips during a 5–7 day tracking period. Eighty-seven percent of these trips (n = 13) were strictly nocturnal, whereas the remaining occurred during the day and night. Most birds departed from the island after sunset and returned a few hours after sunrise. Birds traveled south of the island for single-day trips at a maximum range of 82.8 km. Overall, 22% of the tracking period was spent at sea, whereas the remaining time was spent on the island. In the intermediate section of the trip (between inbound and outbound commutes), birds spent 77% of the trip time in floating bouts interspersed by short flying bouts, the former being on average three times longer than the latter. Taken together, the high sinuosity of the bird''s tracks during floating bouts, the exclusively nocturnal trips of most individuals, and the fact that all birds returned to the island within a few hours after sunrise suggest that pelicans were actively feeding at night. The nocturnal foraging strategy of Peruvian pelicans may reduce food competition with the sympatric and strictly diurnal Guanay cormorants (Phalacrocorax bougainvillii), Peruvian boobies (Sula variegata) and Blue-footed boobies (S. nebouxii), which were present on the island in large numbers. Likewise, plankton bioluminescence might be used by pelicans as indirect cues to locate anchovies during their upward migration at night. The foraging success of pelicans at night may be enhanced by seizing prey close to the sea surface using a sit-and-wait strategy.     

Deep inference of seabird dives from GPS-only records: Performance and generalization properties

At-sea behaviour of seabirds have received significant attention in ecology over the last decades as it is a key process in the ecology and fate of these populations. It is also, through the position of top predator that these species often occupy, a relevant and integrative indicator of the dynamics of the marine ecosystems they rely on. Seabird trajectories are recorded through the deployment of GPS, and a variety of statistical approaches have been tested to infer probable behaviours from these location data. Recently, deep learning tools have shown promising results for the segmentation and classification of animal behaviour from trajectory data. Yet, these approaches have not been widely used and investigation is still needed to identify optimal network architecture and to demonstrate their generalization properties. From a database of about 300 foraging trajectories derived from GPS data deployed simultaneously with pressure sensors for the identification of dives, this work has benchmarked deep neural network architectures trained in a supervised manner for the prediction of dives from trajectory data. It first confirms that deep learning allows better dive prediction than usual methods such as Hidden Markov Models. It also demonstrates the generalization properties of the trained networks for inferring dives distribution for seabirds from other colonies and ecosystems. In particular, convolutional networks trained on Peruvian boobies from a specific colony show great ability to predict dives of boobies from other colonies and from distinct ecosystems. We further investigate accross-species generalization using a transfer learning strategy known as ‘fine-tuning’. Starting from a convolutional network pre-trained on Guanay cormorant data reduced by two the size of the dataset needed to accurately predict dives in a tropical booby from Brazil. We believe that the networks trained in this study will provide relevant starting point for future fine-tuning works for seabird trajectory segmentation.     

The role of information transfer under different food patterns: a simulation study

The aim of this paper is to address the question of how informationtransfer affects foraging efficiency in a colonial breedingsituation. By creating computer simulations, we attempt to modelinformation transfer of food location by individuals withinthe colony. Three kinds of foraging strategy were modeled: searcher–noinformation transfer (solo foraging), watcher–limitedinformation transfer (local enhancement), and a mixture of watcherand follower–full information transfer (information center).The predictability of food was changed by varying patchiness(ratio of food patches) and duration of food patches. When thefood occurs in many randomly distributed patches and the fooddensity in each is low, the solitary searcher strategy givesthe best foraging efficiency. The significance of informationtransfer strategies and colonial breeding on foraging efficiencyincrease when food becomes more clumped. The solitary watcherstrategy is the best at intermediately clumped food distribution.Colonial breeding gives the best foraging efficiency when theinformation center operates and there are some high-densityfood patches.     

Hitting the buffers: conspecific aggression undermines benefits of colonial breeding under adverse conditions

Colonial breeding in birds is widely considered to benefit individuals through enhanced protection against predators or transfer of information about foraging sites. This view, however, is largely based on studies of seabirds carried out under favourable conditions. Recent breeding failures at many seabird colonies in the UK provide an opportunity to re-examine costs and benefits of coloniality under adverse conditions. Common guillemots Uria aalge are highly colonial cliff-nesting seabirds with very flexible parental care. Although the single chick is normally never left alone, more than 50 per cent of offspring were left unattended at a North Sea colony in 2007, apparently because poor conditions forced both parents to forage simultaneously. Contrary to expectation, unattended chicks were not killed by avian predators. Rather, although non-breeders and failed breeders sometimes provided alloparental care, unattended chicks were frequently attacked by breeding guillemots at neighbouring sites, often with fatal consequences. These results highlight a previously unsuspected trade-off between provisioning chicks and avoiding conspecific attacks, and indicate that understanding how environmental conditions affect social dynamics is crucial to interpreting costs and benefits of colonial breeding.     

Ecomorphology and foraging behaviour of Pacific boobies

Wing size and shape, expressed as wing loading and aspect ratio respectively, together with bill morphology are parameters that can reveal differences related to the foraging ecology of seabirds. Six species of booby (Sulidae) that inhabit the Pacific are the focus of this study: four mainly pelagic species, Masked Booby Sula dactylatra, Nazca Booby Sula granti, Red‐footed Booby Sula sula and Brown Booby Sula leucogaster, and two coastal species, Blue‐footed Booby Sula nebouxii and Peruvian Booby Sula variegata. Pelagic boobies showed segregation among species in body mass and relative bill size, and they differed in wing morphology (wing loading and aspect ratio) from the coastal boobies. The coastal Peruvian and Blue‐footed Boobies are largely allopatric but overlap in northern Peru. In their area of sympatry, they showed evidence of character displacement in body size and in wing and bill morphology, which suggests that competition plays an important role in sympatry. This study improves our understanding of ecological interactions among Pacific boobies and of how selective pressures have shaped their ecomorphology and foraging behaviours.     

Varying foraging patterns in response to competition? A multicolony approach in a generalist seabird

Reducing resource competition is a crucial requirement for colonial seabirds to ensure adequate self‐ and chick‐provisioning during breeding season. Spatial segregation is a common avoidance strategy among and within species from neighboring breeding colonies. We determined whether the foraging behaviors of incubating lesser black‐backed gulls (Larus fuscus) differed between six colonies varying in size and distance to mainland, and whether any differences could be related to the foraging habitats visited. Seventy‐nine incubating individuals from six study colonies along the German North Sea coast were equipped with GPS data loggers in multiple years. Dietary information was gained by sampling food pellets, and blood samples were taken for stable isotope analyses. Foraging patterns clearly differed among and within colonies. Foraging range increased with increasing colony size and decreased with increasing colony distance from the mainland, although the latter might be due to the inclusion of the only offshore colony. Gulls from larger colonies with consequently greater density‐dependent competition were more likely to forage at land instead of at sea. The diets of the gulls from the colonies furthest from each other differed, while the diets from the other colonies overlapped with each other. The spatial segregation and dietary similarities suggest that lesser black‐backed gulls foraged at different sites and utilized two main habitat types, although these were similar across foraging areas for all colonies except the single offshore island. The avoidance of intraspecific competition results in colony‐specific foraging patterns, potentially causing more intensive utilization of terrestrial foraging sites, which may offer more predictable and easily available foraging compared with the marine environment.     

Could specialization to cold‐water upwelling systems influence gene flow and population differentiation in marine organisms? A case study using the blue‐footed booby,Sula nebouxii

Aim We assessed population differentiation and gene flow across the range of the blue‐footed booby (Sula nebouxii) (1) to test the generality of the hypothesis that tropical seabirds exhibit higher levels of population genetic differentiation than their northern temperate counterparts, and (2) to determine if specialization to cold‐water upwelling systems increases dispersal, and thus gene flow, in blue‐footed boobies compared with other tropical sulids. Location Work was carried out on islands in the eastern tropical Pacific Ocean from Mexico to northern Peru. Methods We collected samples from 173 juvenile blue‐footed boobies from nine colonies spanning their breeding distribution and used molecular markers (540 base pairs of the mitochondrial control region and seven microsatellite loci) to estimate population genetic differentiation and gene flow. Our analyses included classic population genetic estimation of pairwise population differentiation, population growth, isolation by distance, associations between haplotypes and geographic locations, and analysis of molecular variance, as well as Bayesian analyses of gene flow and population differentiation. We compared our results with those for other tropical seabirds that are not specialized to cold‐water upwellings, including brown (Sula leucogaster), red‐footed (S. sula) and masked (S. dactylatra) boobies. Results Blue‐footed boobies exhibited weak global population differentiation at both mitochondrial and nuclear loci compared with all other tropical sulids. We found evidence of high levels of gene flow between colonies within Mexico and between colonies within the southern portion of the range, but reduced gene flow between these regions. We also found evidence for population growth, isolation by distance and weak phylogeographic structure. Main conclusions Tropical seabirds can exhibit weak genetic differentiation across large geographic distances, and blue‐footed boobies exhibit the weakest population differentiation of any tropical sulid studied thus far. The weak population genetic structure that we detected in blue‐footed boobies may be caused by increased dispersal, and subsequently increased gene flow, compared with other sulids. Increased dispersal by blue‐footed boobies may be the result of the selective pressures associated with cold‐water upwelling systems, to which blue‐footed boobies appear specialized. Consideration of foraging environment may be particularly important in future studies of marine biogeography.     

Social interactions of juvenile brown boobies at sea as observed with animal-borne video cameras

While social interactions play a crucial role on the development of young individuals, those of highly mobile juvenile birds in inaccessible environments are difficult to observe. In this study, we deployed miniaturised video recorders on juvenile brown boobies Sula leucogaster, which had been hand-fed beginning a few days after hatching, to examine how social interactions between tagged juveniles and other birds affected their flight and foraging behaviour. Juveniles flew longer with congeners, especially with adult birds, than solitarily. In addition, approximately 40% of foraging occurred close to aggregations of congeners and other species. Young seabirds voluntarily followed other birds, which may directly enhance their foraging success and improve foraging and flying skills during their developmental stage, or both.     

Foraging and breeding performance of Japanese cormorants in relation to prey type

Seabirds are high trophic predators in marine ecosystems and are sensitive to change in food supply and thus seabirds can be used as monitors of the marine environment. In order to study the foraging responses of Japanese cormorants Phalacrocorax filamentosus breeding at Teuri Island, Hokkaido to changes in fish availability, the diet was assessed from the regurgitations of parents and chicks, and diving behavior was measured by using time-depth recorders. Breeding performance (brood size, chick growth, breeding success) was monitored using conventional methods to study their breeding responses. Japanese cormorants changed the diet and foraging behavior over four summers. The birds fed mainly on epipelagic schooling fish when they were available and on demersal fish when pelagic fish availability was low. They tended to dive deeper and longer in a year when they fed mainly on demersal fish than the other years, reflecting the change in the depth distribution of prey fish. Chick growth rate did not differ among years, but fledging success was lower in the years of demersal fish as their meal delivery rate was low. When epipelagic schooling fish were considered scare, parents maintained chick growth by reducing brood size. High variability and unpredictability in pelagic fish abundance are key factors affecting the foraging and breeding performance of Japanese cormorants, which could potentially be used to monitor fish resources.     

The patch distributed producer-scrounger game

Grouping in animals is ubiquitous and thought to provide group members antipredatory advantages and foraging efficiency. However, parasitic foraging strategy often emerges in a group. The optimal parasitic policy has given rise to the producer-scrounger (PS) game model, in which producers search for food patches, and scroungers parasitize the discovered patches. The N-persons PS game model constructed by Vickery et al. (1991. Producers, scroungers, and group foraging. American Naturalist 137, 847-863) predicts the evolutionarily stable strategy (ESS) of frequency of producers that depends on the advantage of producers and the number of foragers in a group. However, the model assumes that the number of discovered patches in one time unit never exceeds one. In reality, multiple patches could be found in one time unit. In the present study, we relax this assumption and assumed that the number of discovered patches depends on the producers’ variable encounter rate with patches (λ). We show that strongly depends on λ within a feasible range, although it still depends on the advantage of producer and the number of foragers in a group. The basic idea of PS game is the same as the information sharing (parasitism), because scroungers are also thought to parasitize informations of locations of food patches. Horn (1968) indicated the role of information-parasitism in animal aggregation (Horn, H.S., 1968. The adaptive significance of colonial nesting in the Brewer's blackbird (euphagus cyanocephalus). Ecology 49, 682-646). Our modified PS game model shows the same prediction as the Horn's graphical animal aggregation model; the proportion of scroungers will increase or animals should adopt colonial foraging when resource is spatiotemporally clumped, but scroungers will decrease or animals should adopt territorial foraging if the resource is evenly distributed.     

An energetic correlate between colony size and foraging effort in seabirds, an example of the Adélie penguin Pygoscelis adeliae

Central-place foraging seabirds alter the availability of their prey around colonies, forming a "halo" of reduced prey access that ultimately constrains population size. This has been indicated indirectly by an inverse correlation between colony size and reproductive success, numbers of conspecifics at other colonies within foraging range, foraging effort (i.e. trip duration), diet quality and colony growth rate. Although ultimately mediated by density dependence relative to food through intraspecific exploitative or interference competition, the proximate mechanism involved has yet to be elucidated. Herein, we show that Adélie penguin Pygoscelis adeliae colony size positively correlates to foraging trip duration and metabolic rate, that the metabolic rate while foraging may be approaching an energetic ceiling for birds at the largest colonies, and that total energy expended increases with trip duration although uncompensated by increased mass gain. We propose that a competition-induced reduction in prey availability results in higher energy expenditure for birds foraging in the halo around large colonies, and that to escape the halo a bird must increase its foraging distance. Ultimately, the total energetic cost of a trip determines the maximum successful trip distance, as on longer trips food acquired is used more for self maintenance than for chick provisioning. When the net cost of foraging trips becomes too high, with chicks receiving insufficient food, chick survival suffers and subsequent colony growth is limited. Though the existence of energetic studies of the same species at multiple colonies is rare, because foraging metabolic rate increases with colony size in at least two other seabird species, we suggest that an energetic constraint to colony size may generally apply to other seabirds.     

Use of Social and Ecological Information in Tamarin Foraging Decisions

A major consequence of group living is that foragers may rely on social information in addition to ecological information to locate feeding sites. Although conspecifics can provide cues as to the spatial location of food patches, individual foraging decisions also must include some assessment of the likelihood of obtaining access to a resource other group members seek. This likelihood differs in the 2 models generally proposed to explain intragroup social foraging: the information-sharing model and the producer-scrounger model. We conducted an experimental field study on wild groups of emperor (Saguinus imperator) and saddleback (S. fuscicollis) tamarins to determine the foraging strategies adopted by individual group members and their relationship to social rank, food intake, and the ability to use ecological and social information in making intra-patch foraging decisions. Individual tamarins applied different behavioral strategies compatible with a finder-joiner paradigm to solve foraging problems. About half of the individuals in each study group initiated 74%–90% of all food searches and acted as finders. Most alpha individuals adopted a joiner strategy by monitoring the activities of others' to obtain a reward. The individual arriving first at a reward platform enjoyed a finder's advantage. Despite differences in search effort, both finders and joiners presented similar abilities in learning to associate ecological cues with the presence of food rewards at our experimental feeding stations. We conclude that within a group foraging context, tamarins integrate social and ecological information in decision-making.     

Information use in colonial living

Despite the fact that many animals live in groups, there is still no clear consensus about the ecological or evolutionary mechanisms underlying colonial living. Recently, research has suggested that colonies may be important as sources of social information. The ready availability of information from conspecifics allows animals to make better decisions about avoiding predators, reducing brood parasitism, migratory phenology, mate choice, habitat choice and foraging. These choices can play a large part in the development and maintenance of colonies. Here we review the types of information provided by colonial animals and examine the different ways in which decision‐making in colonies can be enhanced by social information. We discuss what roles information might take in the evolution, formation and maintenance of colonies. In the process, we illustrate that information use permeates all aspects of colonial living.     

Influence of density‐dependent competition on foraging and migratory behavior of a subtropical colonial seabird

Density‐dependent competition for food resources influences both foraging ecology and reproduction in a variety of animals. The relationship between colony size, local prey depletion, and reproductive output in colonial central‐place foragers has been extensively studied in seabirds; however, most studies have focused on effects of intraspecific competition during the breeding season, while little is known about whether density‐dependent resource depletion influences individual migratory behavior outside the breeding season. Using breeding colony size as a surrogate for intraspecific resource competition, we tested for effects of colony size on breeding home range, nestling health, and migratory patterns of a nearshore colonial seabird, the brown pelican (Pelecanus occidentalis), originating from seven breeding colonies of varying sizes in the subtropical northern Gulf of Mexico. We found evidence for density‐dependent effects on foraging behavior during the breeding season, as individual foraging areas increased linearly with the number of breeding pairs per colony. Contrary to our predictions, however, nestlings from more numerous colonies with larger foraging ranges did not experience either decreased condition or increased stress. During nonbreeding, individuals from larger colonies were more likely to migrate, and traveled longer distances, than individuals from smaller colonies, indicating that the influence of density‐dependent effects on distribution persists into the nonbreeding period. We also found significant effects of individual physical condition, particularly body size, on migratory behavior, which in combination with colony size suggesting that dominant individuals remain closer to breeding sites during winter. We conclude that density‐dependent competition may be an important driver of both the extent of foraging ranges and the degree of migration exhibited by brown pelicans. However, the effects of density‐dependent competition on breeding success and population regulation remain uncertain in this system.     

Foraging in honeybees--when does it pay to dance?

Honeybees are unique in that they are the only social insectsthat are known to recruit nest mates using the waggle dance.This waggle dance is used by successful foragers to convey informationabout both the direction and distance to food sources. Nestmates can use this spatial information, increasing their chancesof locating the food source. But how effective is the bees'dance communication? Previous work has shown that dancing doesnot benefit a honeybee colony under all foraging conditionsand that the benefits of dancing are small. We used an individual-basedsimulation model to investigate under which foraging conditionsit pays to dance. We compared the net nectar intake of 3 typesof colonies: 1) colonies that use dance communication; 2) coloniesthat did dance but could not use the dance's spatial information;and 3) colonies that did not dance. Our results show that dancingis beneficial when the probability of independent discoveryof food sources is low. Low independent discovery rates occurwhen patches are very small or very far away. Under these conditions,dancing is beneficial as only a single individual needs to finda patch for the whole colony to benefit. The main benefit ofthe honeybee's dance communication, however, seems to be thatit enables the colony to forage at the most profitable patchesonly, ignoring forage patches that are of low quality. Thus,dancing allows the colony to rapidly exploit high-quality patches,thereby preventing both intra- and interspecific competitorsfrom using that same patch.     

Social networks predict patch discovery in a wild population of songbirds

Animals use social information in a wide variety of contexts. Its extensive use by individuals to locate food patches has been documented in a number of species, and various mechanisms of discovery have been identified. However, less is known about whether individuals differ in their access to, and use of, social information to find food. We measured the social network of a wild population of three sympatric tit species (family Paridae) and then recorded individual discovery of novel food patches. By using recently developed methods for network-based diffusion analysis, we show that order of arrival at new food patches was predicted by social associations. Models based only on group searching did not explain this relationship. Furthermore, network position was correlated with likelihood of patch discovery, with central individuals more likely to locate and use novel foraging patches than those with limited social connections. These results demonstrate the utility of social network analysis as a method to investigate social information use, and suggest that the greater probability of receiving social information about new foraging patches confers a benefit on more socially connected individuals.     

The three-dimensional flight of red-footed boobies: adaptations to foraging in a tropical environment?

In seabirds a broad variety of morphologies, flight styles and feeding methods exist as an adaptation to optimal foraging in contrasted marine environments for a wide variety of prey types. Because of the low productivity of tropical waters it is expected that specific flight and foraging techniques have been selected there, but very few data are available. By using five different types of high-precision miniaturized logger (global positioning systems, accelerometers, time depth recorders, activity recorders, altimeters) we studied the way a seabird is foraging over tropical waters. Red-footed boobies are foraging in the day, never foraging at night, probably as a result of predation risks. They make extensive use of wind conditions, flying preferentially with crosswinds at median speed of 38 km h(-1), reaching highest speeds with tail winds. They spent 66% of the foraging trip in flight, using a flap-glide flight, and gliding 68% of the flight. Travelling at low costs was regularly interrupted by extremely active foraging periods where birds are very frequently touching water for landing, plunge diving or surface diving (30 landings h(-1)). Dives were shallow (maximum 2.4 m) but frequent (4.5 dives h(-1)), most being plunge dives. While chasing for very mobile prey like flying fishes, boobies have adopted a very active and specific hunting behaviour, but the use of wind allows them to reduce travelling cost by their extensive use of gliding. During the foraging and travelling phases birds climb regularly to altitudes of 20-50 m to spot prey or congeners. During the final phase of the flight, they climb to high altitudes, up to 500 m, probably to avoid attacks by frigatebirds along the coasts. This study demonstrates the use by boobies of a series of very specific flight and activity patterns that have probably been selected as adaptations to the conditions of tropical waters.     

Comparative phylogeography of brown (Sula leucogaster) and red-footed boobies (S. sula): The influence of physical barriers and habitat preference on gene flow in pelagic seabirds

To test the hypothesis that both physical and ecological barriers to gene flow drive population differentiation in tropical seabirds, we surveyed mitochondrial control region variation in 242 brown boobies (Sula leucogaster), which prefer inshore habitat, and 271 red-footed boobies (S. sula), which prefer pelagic habitat. To determine the relative influence of isolation and gene flow on population structure, we used both traditional methods and a recently developed statistical method based on coalescent theory and Bayesian inference (Isolation with Migration). We found that global population genetic structure was high in both species, and that female-mediated gene flow among ocean basins apparently has been restricted by major physical barriers including the Isthmus of Panama, and the periodic emergence of the Sunda and Sahul Shelves in Southeast Asia. In contrast, the evolutionary history of populations within ocean basins differed markedly between the two species. In brown boobies, we found high levels of population genetic differentiation and limited gene flow among colonies, even at spatial scales as small as 500 km. Although red-footed booby colonies were also genetically differentiated within ocean basins, coalescent analyses indicated that populations have either diverged in the face of ongoing gene flow, or diverged without gene flow but recently made secondary contact. Regardless, gene flow among red-footed booby populations was higher than among brown booby populations. We suggest that these contrasting patterns of gene flow within ocean basins may be explained by the different habitat preferences of brown and red-footed boobies.     

Social tactics of pigs in a competitive foraging task: the 'informed forager' paradigm

Studies of the social dynamics in foraging groups have focused primarily on birds, rodents and nonhuman primates. We extended the study of animal social tactics to the domestic pig, Sus scrofa, by using an experimental analogue of natural foraging skills, the 'informed forager' paradigm. We investigated the behaviour of 16 pigs foraging in pairs in an arena in which food had been hidden in one of eight monopolizable buckets. Before each pair trial, one of the pigs, the 'informed' pig, was given privileged knowledge about the location of the food during a solitary search trial. The 'noninformed' pig was na?ve about the location of the food during pair trials, but heavier than its informed partner and thus able to displace the latter from the baited bucket. By first focusing on the informed pigs' behaviour, we show that pigs are able to remember and relocate the food site. They found the food in relocation trials, using fewer bucket investigations than expected of a random searcher. Second, by focusing on the noninformed pigs, we show that pigs are able to exploit the knowledge of others by following them to a food source. They investigated more buckets immediately after their informed partners significantly more often than expected by chance and required fewer bucket investigations to find the food in pair trials than expected from a random searcher, but not in solitary search trials. We discuss these latter findings with reference to social foraging tactics. Copyright 2000 The Association for the Study of Animal Behaviour.