Guiana dolphins (Sotalia guianensis) displaying beach hunting behavior in the Cananéia Estuary, Brazil: social context and conservation issues

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

To be or not to be . . . a flower? A test of possible cues influencing hunting site selection in subadult females of the crab spider Epicadus heterogaster (Guerin 1812) (Araneae: Thomisidae)

Females of some Thomisidae species are known to use visual and olfactory stimuli to select high quality hunting sites. However, because studies about foraging behavior in this family are concentrated on a few species, the comprehension of the process related to hunting behavior evolution in crab spiders may be biased. In this study we investigated the hunting site selection of a previously unstudied crab spider, Epicadus heterogaster. We performed three experiments to evaluate the hypothesis that subadult females are able to use visual and olfactory stimuli to select hunting sites. In the first experiment, females did not preferentially select flower paper models that matched their body coloration. However, after choosing a model that had the same body color as the spider, they remained on it for longer periods than on models with different colors. In the second experiment, females did not discriminate between flower paper models, natural flower models and crumpled paper models. Females did also not discriminate among different olfactory stimuli in the third experiment. It is possible that subadult females of E. heterogaster need to establish and experience a given hunting site before evaluating its quality. However, it remains to be investigated if they use UV cues to select a foraging area before experiencing it.

Hunting and social behaviour of leopard seals (Hydrurga leptonyx) at Seal Island, South Shetland Islands, Antarctica

The hunting behavior of leopard seals Hydrurga leptonyx was monitored opportunistically at Seal Island, South Shetland Islands, during the austral summers from 1986/87 to 1994/95. Leopard seals used several methods to catch Antarctic fur seal pups Arctocephalus gazella and chinstrap penguins Pygoscelis antarctica, and individuals showed different hunting styles and hunting success. One to two leopard seals per year were responsible for an average of 60% of observed captures of fur seal pups. Leopard seals preyed on penguins throughout the summer, but preyed on fur seal pups only between late December and mid-February. Hunting behavior differed significantly between different locations on the island; fur seals were hunted only at one colony, and penguins were hunted in several areas. The relative abundance of prey types, size of prey in relation to predator, and specialization of individual leopard seals to hunt fur seal prey probably influence individual prey preferences among leopard seals. On five occasions, two leopard seals were seen together on Seal Island. Possible interpretations of the relationship between the interacting leopard seals included a mother-offspring relationship, a consorting male-female pair, and an adult leopard seal followed by an unrelated juvenile. In two incidents at Seal Island, two leopard seals were observed interacting while hunting: one seal captured fur seal pups and appeared to release them to the other seal. Observations of leopard seals interacting during hunting sessions were difficult to confirm as co-operative hunting, but they strongly implied that the two seals were not agonistic toward one another. The hunting success of individual leopard seals pursuing penguins or fur seals is probably high enough for co-operative hunting not to become a common hunting strategy; however, it may occur infrequently when it increases the hunting productivity of the seals.

The role of the ventrolateral caudoputamen in predatory hunting

The ventrolateral caudoputamen (VLCP) is well known to participate in the control of orofacial movements and forepaw usage accompanying feeding behavior. Previous studies from our laboratory have shown that insect hunting is associated with a distinct Fos up-regulation in the VLCP at intermediate rostro-caudal levels. Moreover, using the reversible blockade with lidocaine, we have previously suggested that the VLCP implements the stereotyped actions seen during prey capture and handling, and may influence the motivational drive to start attacking the roaches, as well. However, considering that (1) lidocaine suppresses action potentials not only in neurons, but also in fibers-of-passage, rendering the observed behavioral effect not specific to the ventrolateral caudoputamen; (2) the short lidocaine-induced inactivation period had left a relatively narrow window to observe the behavioral changes; and (3) that the restriction stress to inject the drug could have also disturbed hunting behavior, in the present study, we have examined the role of the VLCP in predatory hunting by placing bilateral NMDA lesions three weeks previous to the behavior testing. We were able to confirm that the VLCP serves to implement the stereotyped sequence of actions seen during prey capture and handling, but the study did not confirm its role in influencing the motivational drive to hunt. Together with other studies from our group, the present work serves as an important piece of information that helps to reveal the neural systems underlying predatory hunting. (C) 2011 Elsevier Inc. All rights reserved.

Foraging by Polybia (Trichothorax) ignobilis (Hymenoptera, Vespidae) on flies at animal carcasses

Proteins for brood nutrition of social wasps are obtained from many prey, including insects (even bees and other wasps), spiders and bits of decaying meat. After being captured and killed, prey are reduced to a shapeless mass and distributed to the brood. Little is known about the foraging activity, especially on this group. Herein we describe the sequence of foraging behaviours of the social wasp Polybia (Trichothorax) ignobilis for hunting flies (Diptera: Calliphoridae and Muscidae) over pig carcasses. To our knowledge, there are few scientific descriptions of prey foraging behaviour on this species.

Influence of Prey Size on the Capture of Social Wasps (Hymenoptera: Vespidae) by the Orb-Web Spider Nephilengys cruentata

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Foraging by Polybia (Trichothorax) ignobilis (Hymenoptera, Vespidae) on flies at animal carcasses

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Patógenos bacterianos isolados de fezes de felinos domésticos, sem sinais entéricos, de ambiente urbano e rural

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of Prey Size on the Capture of Social Wasps (Hymenoptera: Vespidae) by the Orb-Web Spider Nephilengys cruentata

The objective of the present study was to evaluate the plasticity of the hunting behavior of the spider Nephilengys cruentata (Araneae: Nephilidae) facing different species of social wasps. Considering that wasps can consume various species of spiders and that their poison can be used as defense against many predators, the effect of the corporal size of the prey was evaluated in the behavior of N. cruentata. Predation experiments were conducted using three species of social wasps of different sizes and the data registered in this research were compiled through annotations and filming of the hunting behavior of each spider, in relation to the offered prey. The results revealed that the size of the wasp and the sequential offer of prey change the hunting behavior of the spider, and prey of large size have high influence on this behavior.

Swarm Intelligence applied in synthesis of hunting strategies in a three-dimensional environment

Systems of distributed artificial intelligence can be powerful tools in a wide variety of practical applications. Its most surprising characteristic, the emergent behavior, is also the most answerable for the difficulty in. projecting these systems. This work proposes a tool capable to beget individual strategies for the elements of a multi-agent system and thereof providing to the group means on obtaining wanted results, working in a coordinated and cooperative manner as well. As an application example, a problem was taken as a basis where a predators` group must catch a prey in a three-dimensional continuous ambient. A synthesis of system strategies was implemented of which internal mechanism involves the integration between simulators by Particle Swarm Optimization algorithm (PSO), a Swarm Intelligence technique. The system had been tested in several simulation settings and it was capable to synthesize automatically successful hunting strategies, substantiating that the developed tool can provide, as long as it works with well-elaborated patterns, satisfactory solutions for problems of complex nature, of difficult resolution starting from analytical approaches. (c) 2007 Elsevier Ltd. All rights reserved.

Chaos and crises in a model for cooperative hunting: A symbolic dynamics approach

In this work we investigate the population dynamics of cooperative hunting extending the McCann and Yodzis model for a three-species food chain system with a predator, a prey, and a resource species. The new model considers that a given fraction sigma of predators cooperates in prey's hunting, while the rest of the population 1-sigma hunts without cooperation. We use the theory of symbolic dynamics to study the topological entropy and the parameter space ordering of the kneading sequences associated with one-dimensional maps that reproduce significant aspects of the dynamics of the species under several degrees of cooperative hunting. Our model also allows us to investigate the so-called deterministic extinction via chaotic crisis and transient chaos in the framework of cooperative hunting. The symbolic sequences allow us to identify a critical boundary in the parameter spaces (K, C-0) and (K, sigma) which separates two scenarios: (i) all-species coexistence and (ii) predator's extinction via chaotic crisis. We show that the crisis value of the carrying capacity K-c decreases at increasing sigma, indicating that predator's populations with high degree of cooperative hunting are more sensitive to the chaotic crises. We also show that the control method of Dhamala and Lai [Phys. Rev. E 59, 1646 (1999)] can sustain the chaotic behavior after the crisis for systems with cooperative hunting. We finally analyze and quantify the inner structure of the target regions obtained with this control method for wider parameter values beyond the crisis, showing a power law dependence of the extinction transients on such critical parameters.

THE ROLE OF THE SUPERIOR COLLICULUS IN PREDATORY HUNTING

Combining the results of behavioral, neuronal immediate early gene activation, lesion and neuroanatomical experiments, we have presently investigated the role of the superior colliculus (SC) in predatory hunting. First, we have shown that insect hunting is associated with a characteristic large increase in Fos expression in the lateral part of the intermediate gray layer of the SC (Wig). Next, we have shown that animals with bilateral NMDA lesions of the lateral parts of the SC presented a significant delay in starting to chase the prey and longer periods engaged in other activities than predatory hunting. They also showed a clear deficit to orient themselves toward the moving prey and lost the stereotyped sequence of actions seen for capturing, holding and killing the prey. Our Phaseolus vulgaris-leucoagglutinin analysis revealed that the lateral SCig, besides providing the well-documented descending crossed pathway to premotor sites in brainstem and spinal cord, projects to a number of midbrain and diencephalic sites likely to influence key functions in the context of the predatory behavior, such as general levels of arousal, motivational level to hunt or forage, behavioral planning, appropriate selection of the basal ganglia motor plan to hunt, and motor output of the primary motor cortex. In contrast to the lateral SC lesions, medial SC lesions produced a small deficit in predatory hunting, and compared to what we have seen for the lateral SCig, the medial SCig has a very limited set of projections to thalamic sites related to the control of motor planning or motor output, and provides conspicuous inputs to brainstem sites involved in organizing a wide range of anti-predatory defensive responses. Overall, the present results served to clarify how the different functional domains in the SC may mediate the decision to pursue and hunt a prey or escape from a predator. (C) 2010 IBRO. Published by Elsevier Ltd. All rights reserved.

Individual Specialization in the Hunting-wasp Trypoxylon (Trypargilum) agamemnon Richards (Hymenoptera: Crabronidae)

Renan B. Pitilin, Marcio S. Araujo, and Maria L.T. Buschini (2012) Individual specialization in the hunting-wasp Trypoxylon (Trypargilum) agamemnon Richards (Hymenoptera: Crabronidae). Zoological Studies 51(5): 655-662. Individuals of a population may differ with respect to resource use. This among-individual variation in resource utilization is called 'individual specialization' and may substantially impact the ecological and evolutionary dynamics of a population. The aim of this study was to evaluate whether females of 1 population of the hunting-wasp Trypoxylon agamemnon differed in their preferences for spider size and/or taxa. To observe the behavior of wasps, trap-nests were installed in an araucaria forest fragment in the Parque Municipal das Araucarias, Guarapuava (PR), southern Brazil. The indices within-individual component (WIC)/total niche width of a population (TNW) and average of values of the proportional similarity index (IS) were used to measure the degree of individual specialization. We found evidence of strong, significant individual specialization in T agamemnon in terms of both prey size (WIC/TNW = 0.43) and taxa (IS = 0.45). We hypothesized that individual specialization in this species resulted from cognitive tradeoffs that limit individuals to exploring a small subset of available resources. http://zoolstud.sinica.edu.tw/Journals/51.5/655.pdf

Ahead of the Game: Middle and Upper Palaeolithic Hunting Behaviors in the Southern Caucasus

Over the past several decades a variety of models have been proposed to explain perceived behavioral and cognitive differences between Neanderthals and modern humans. A key element in many of these models and one often used as a proxy for behavioral “modernity” is the frequency and nature of hunting among Palaeolithic populations. Here new archaeological data from Ortvale Klde, a late Middle–early Upper Palaeolithic rockshelter in the Georgian Republic, are considered, and zooarchaeological methods are applied to the study of faunal acquisition patterns to test whether they changed significantly from the Middle to the Upper Palaeolithic. The analyses demonstrate that Neanderthals and modern humans practiced largely identical hunting tactics and that the two populations were equally and independently capable of acquiring and exploiting critical biogeographical information pertaining to resource availability and animal behavior. Like lithic techno-typological traditions, hunting behaviors are poor proxies for major behavioral differences between Neanderthals and modern humans, a conclusion that has important implications for debates surrounding the Middle–Upper Palaeolithic transition and what features constitute “modern” behavior. The proposition is advanced that developments in the social realm of Upper Palaeolithic societies allowed the replacement of Neanderthals in the Caucasus with little temporal or spatial overlap and that this process was widespread beyond traditional topographic and biogeographical barriers to Neanderthal mobility.

Disentangle contextual and permanent individual motivations:an application to shopping behavior

Past studies resulted in conflicting definitions of consumer motivation. On the one hand, motivations are seen as the consumer’s characteristics that shape her general behavior (motivational trait). On the other hand, they are seen as contextual variables representing the reason why the individual is behaving specific to today’s context (motivational state). The objective of this research is to stress the difference between these two concepts and to understand the impact of each on consumer behavior. We applied our empirical study to shopping motivations; our results show a strong interaction between motivational trait and motivational state. Problem and Hypothesis On the one hand, Westbrook and Black (1985) consider shopping motivations as individual permanent characteristics. This concept is shared by other researchers (Rohm and Swaminathan 2004), which show that some shoppers are functional (they shop for convenience, information seeking, and time saving) while some others are hedonic (they shop for social interaction, bargain hunting and browsing). On the other hand, Kaltcheva and Weitz (2006) define motivations as a contextual orientation changing over time, depending on the situation, and show that contextual shopping motivations have a strong impact on shopping behavior. From our knowledge, no research specifically examined the respective impact of both these shopping motivation types. To deal with this issue, we used the notions of “traits” and “states” that have been largely used in marketing research to designate respectively a permanent characteristic of the individual and a temporary orientation of the consumer (Mowen 2000). The reversal theory (Apter 2001) suggests that two opposite states exist: the telic and the paratelic states. In the telic state, individuals set goals for themselves, must be disciplined to reach these goals, and do not behave in accordance with their personal trait. In the paratelic state, individuals are seeking arousal and enjoyment, do not set rules, and one could postulate that they act in accordance with their natural tendencies. Based on these considerations, we hypothesize the following process: in situations involving paratelic states, hedonic as well as functional individuals should behave according to their natural traits, whereas in situations involving telic states, hedonic people should inhibit their natural propensity to enjoy shopping and behave similarly to functional people. Hence, we postulate the following: Hypothesis: Compared to shoppers with functional motivational trait, shoppers with hedonic motivational trait will a) significantly display more hedonic shopping behavior intentions in a condition of paratelic motivational state, and b) not display more hedonic shopping behavior intentions in a condition a telic motivational state Empirical Research First, 108 participants were asked to fill a multi-items scale about their shopping habits, which actually measured their shopping motivational traits. This questionnaire allowed us to highlight four different dimensions in shopping motivational traits: social interaction, novelty/utility seeking, bargain hunting, and browsing. According to their scores on different items, participants were classified as functional or as hedonic on each of these four dimensions (a single individual may be hedonic on some dimensions and functional on others). Then, participants were then induced to adopt either a telic or a paratelic shopping motivational state while reading an appropriate scenario. Finally, participants were asked for their shopping behavior intentions in response to the shopping context. Four items were developed, corresponding to the four shopping motivational trait dimensions we found with our factor analysis. Results As we found four dimensions in shopping motivational trait, we set up four quasi-experimental designs to capture the entire phenomenon: for each dimension, a 2 (motivational trait) x 2 (motivational state) design was built, where the dependant variable was the shopping behavior element corresponding to the studied dimension. Four 2 x 2 Anovas were performed to assess the interaction between motivational trait and motivational state. Concerning the three dimensions - browsing, novelty/utility seeking, and bargain hunting- , in the paratelic state scenario participants with hedonic motivational trait displayed significantly more hedonic shopping behavior intentions than participants with a functional motivational trait (resp. F = 9.701, p = .003; F = 4.979, p = .03; F = 5.757, p = .02); and in the telic state scenario, there was no significant difference in behavior intentions between participants with hedonic or functional motivation trait. Each time, the interaction effect between motivational state and motivational trait was significant (resp. F = 4.859, p = .03; F = 3.314, p = .07; F = 2.98, p = .08). Concerning the fourth dimension, social interaction, shopping behavior intentions of participants with hedonic and with functional motivational traits were significantly different in the paratelic state scenario (F = 29.898, p <.000) as well as in the telic state scenario (F = 9.559, p = .003). However, the interaction effect showed that this behavioral difference was significantly stronger in the paratelic scenario. All these results support our research hypothesis. Discussion and Implications Our study provides consistent support for our hypotheses saying that there is an interaction effect between shopping motivational states and shopping motivational traits. The generalization of the results is strengthened by the study of four different shopping traits: social interaction, novelty/utility seeking, bargain hunting and browsing. As we proposed, when shopping in a goal-oriented state (telic state), behaviors of hedonic and functional shoppers do not differ significantly. Conversely, when shopping for a recreational reason (paratelic state), hedonic and functional shoppers behave significantly different. These results could explain why some previous studies concluded that shopping motivational traits had no impact on shopping behavior: they did not take into consideration the interaction between motivational trait and motivational state. Moreover, our study shows that marketing surveys performed by store managers to draw the personal profile of their customers must be crossed with contextual motivations in order to accurately forecast shopper behavior. Future Developments Our results can be explained by the self-control process, which pushes hedonic-trait shoppers to behave in a rather functional way in utilitarian situations. However, to be certain that this is the very process that occurs, we plan to add self-control perception scales to our existing measures. This is obviously the next step of this research.