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Wolf, M., van Doorn, G. S., Leimar, O., & Weissing, F. J. (2007). Life-history trade-offs favour the evolution of animal personalities. Nature, 447(7144), 581–584.
Abstract: In recent years evidence has been accumulating that personalities are not only found in humans but also in a wide range of other animal species. Individuals differ consistently in their behavioural tendencies and the behaviour in one context is correlated with the behaviour in multiple other contexts. From an adaptive perspective, the evolution of animal personalities is still a mystery, because a more flexible structure of behaviour should provide a selective advantage. Accordingly, many researchers view personalities as resulting from constraints imposed by the architecture of behaviour (but see ref. 12). In contrast, we show here that animal personalities can be given an adaptive explanation. Our argument is based on the insight that the trade-off between current and future reproduction often results in polymorphic populations in which some individuals put more emphasis on future fitness returns than others. Life-history theory predicts that such differences in fitness expectations should result in systematic differences in risk-taking behaviour. Individuals with high future expectations (who have much to lose) should be more risk-averse than individuals with low expectations. This applies to all kinds of risky situations, so individuals should consistently differ in their behaviour. By means of an evolutionary model we demonstrate that this basic principle results in the evolution of animal personalities. It simultaneously explains the coexistence of behavioural types, the consistency of behaviour through time and the structure of behavioural correlations across contexts. Moreover, it explains the common finding that explorative behaviour and risk-related traits like boldness and aggressiveness are common characteristics of animal personalities.
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Heinrich, B., & Bugnyar, T. (2007). Just how smart are ravens? Sci Am, 296(4), 64–71.
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Thornton, A., & McAuliffe, K. (2006). Teaching in wild meerkats. Science, 313(5784), 227–229.
Abstract: Despite the obvious benefits of directed mechanisms that facilitate the efficient transfer of skills, there is little critical evidence for teaching in nonhuman animals. Using observational and experimental data, we show that wild meerkats (Suricata suricatta) teach pups prey-handling skills by providing them with opportunities to interact with live prey. In response to changing pup begging calls, helpers alter their prey-provisioning methods as pups grow older, thus accelerating learning without the use of complex cognition. The lack of evidence for teaching in species other than humans may reflect problems in producing unequivocal support for the occurrence of teaching, rather than the absence of teaching.
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Burke, D., Cieplucha, C., Cass, J., Russell, F., & Fry, G. (2002). Win-shift and win-stay learning in the short-beaked echidna (Tachyglossus aculeatus). Anim. Cogn., 5(2), 79–84.
Abstract: Numerous previous investigators have explained species differences in spatial memory performance in terms of differences in foraging ecology. In three experiments we attempted to extend these findings by examining the extent to which the spatial memory performance of echidnas (or “spiny anteaters”) can be understood in terms of the spatio-temporal distribution of their prey (ants and termites). This is a species and a foraging situation that have not been examined in this way before. Echidnas were better able to learn to avoid a previously rewarding location (to “win-shift”) than to learn to return to a previously rewarding location (to “win-stay”), at short retention intervals, but were unable to learn either of these strategies at retention intervals of 90 min. The short retention interval results support the ecological hypothesis, but the long retention interval results do not.
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Fujita, K., Kuroshima, H., & Masuda, T. (2002). Do tufted capuchin monkeys (Cebus apella) spontaneously deceive opponents? A preliminary analysis of an experimental food-competition contest between monkeys. Anim. Cogn., 5(1), 19–25.
Abstract: A new laboratory procedure which allows the study of deceptive behavior in nonhuman primates is described. Pairs of tufted capuchin monkeys faced each other in a food-competition contest. Two feeder boxes were placed between the monkeys. A piece of food was placed in one of the boxes. The subordinate individual was able to see the food and to open the box to obtain the bait. A dominant male was unable to see the food or to open the box but was able to take the food once the box was opened by the subordinate. In experiment 1, two of four subordinate monkeys spontaneously started to open the unbaited box first with increasing frequency. Experiment 2 confirmed that this “deceptive” act was not due to a drop in the rate of reinforcement caused by the usurping dominant male, under the situation in which food sometimes automatically dropped from the opened box. In experiment 3, two subordinate monkeys were rerun in the same situation as experiment 1. One of them showed some recovery of the “deceptive” act but the other did not; instead the latter tended to position himself on the side where there was no food before he started to open the box. Although the results do not clearly indicate spontaneous deception, we suggest that operationally defined spontaneous deceptive behaviors in monkeys can be analyzed with experimental procedures such as those used here.
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Punzo, F., & Ludwig, L. (2002). Contact with maternal parent and siblings affects hunting behavior, learning, and central nervous system development in spiderlings of Hogna carolinensis (Araeneae: Lycosidae). Anim. Cogn., 5(2), 63–70.
Abstract: The purpose of this study was to determine the effects of early experience (rearing conditions) on the central nervous system (CNS) and behavior of spiderlings of Hogna carolinensis (Lycosidae). We were interested in whether or not spiderlings that were allowed to remain in contact with their maternal parent and siblings (enriched condition, EC) would exhibit differences in CNS development or subsequent behavior when compared with those reared in isolation (improverished condition, IC). Spiderlings emerged from their egg sacs and climbed onto the dorsal surface of their mother's abdomen where they remained until their yolk supply was depleted (5 days). They dispersed on day 6 after emergence. We compared the ability of 16-day-old EC and IC spiderlings to capture prey in a linear runway and to learn a complex maze (spatial learning). We also compared certain aspects of CNS development (brain weight, total number of brain cells, volume of central body and protocerebral neuropil) in EC and IC spiderlings. Results indicated that EC subjects are more efficient at capturing moving prey (crickets) and exhibited improved performance (significantly fewer blind alley errors) in the maze. The volume of the protocerebral neuropil in 6-day-old EC animals increased 30% over a 5-day period after emergence as compared to IC animals of the same age. The volume of the central body of EC animals increased 34.8% over the same time period. On day 6 after emergence, the weight of the protocerebrum was significantly greater in EC versus IC subjects. There were no significant effects of rearing condition (EC vs IC) or age (1- and 6-day-old spiderlings) on the total number of nerve cells in the protocerebrum, suggesting that the difference in protocerebral weight was due primarily to differences in supporting glial tissues and neuropil matrix. In conclusion, the data suggest that early contact with the maternal parent and siblings is of vital importance to CNS development in lycosid spiderlings and can influence the capacity for spatial learning as well as the ability to capture prey.
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Jackson, R. R., Pollard, S. D., & Cerveira, A. M. (2002). Opportunistic use of cognitive smokescreens by araneophagic jumping spiders. Anim. Cogn., 5(3), 147–157.
Abstract: Little is known about how a prey species' cognitive limitations might shape a predator's prey-capture strategy. A specific hypothesis is investigated: predators take advantage of times when the prey's attention is focussed on its own prey. Portia fimbriata, an araneophagic jumping spider (Salticidae) from Queensland, is shown in a series of 11 experiments to exploit opportunistically a situation in which a web-building spider on which it preys, Zosis genicularis (Uloboridae), is preoccupied with wrapping up its own prey. Experimental evidence supports three conclusions: (1). while relying on optical cues alone, P. fimbriata perceives when Z. genicularis is wrapping up prey; (2). when busy wrapping up prey, the responsiveness of Z. genicularis to cues from potential predators is diminished; and (3). P. fimbriata moves primarily during intervals when Z. genicularis is busy wrapping up prey. P. fimbriata's strategy is effective partly because the wrapping behaviour of Z. genicularis masks the web signals generated by the advancing P. fimbriata's footsteps and also because, while wrapping, Z. genicularis' attention is diverted away from predator-revealing cues.
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Jackson, R. R., Pollard, S. D., Li, D., & Fijn, N. (2002). Interpopulation variation in the risk-related decisions of Portia labiata, an araneophagic jumping spider (Araneae, Salticidae), during predatory sequences with spitting spiders. Anim. Cogn., 5(4), 215–223.
Abstract: The extent to which decision-making processes are constrained in animals with small brains is poorly understood. Arthropods have brains much smaller and simpler than those of birds and mammals. This raises questions concerning limitations on how intricate the decision-making processes might be in arthropods. At Los Banos in the Philippines, Scytodes pallidus is a spitting spider that specialises in preying on jumping spiders, and Portia labiata is a jumping spider that preys on S. pallidus. Scytodid spit comes from the mouth, and egg-carrying females are less dangerous than eggless scytodids because the female uses her chelicerae to hold her eggs. Held eggs block her mouth, and she has to release them before she can spit. The Los Banos P. labiata sometimes adjusts its tactics depending on whether the scytodid encountered is carrying eggs or not. When pursuing eggless scytodids, the Los Banos P. labiata usually takes detour routes that enable it to close in from behind (away from the scytodid's line of fire). However, when pursuing egg-carrying scytodids, the Los Banos P. labiata sometimes takes faster direct routes to reach these safer prey. The Los Banos P. labiata apparently makes risk-related adjustments specific to whether scytodids are carrying eggs, but P. labiata from Sagada in the Philippines (allopatric to Scytodes) fails to make comparable risk-related adjustments.
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Watve, M., Thakar, J., Kale, A., Puntambekar, S., Shaikh, I., Vaze, K., et al. (2002). Bee-eaters ( Merops orientalis) respond to what a predator can see. Anim. Cogn., 5(4), 253–259.
Abstract: Two sets of experiments are reported that show that the small green bee-eater ( Merops orientalis, a small tropical bird) can appreciate what a predator can or cannot see. Bee-eaters avoid entering the nest in the presence of a potential nest predator. In the first set of experiments bee-eaters entered the nest more frequently when the predator was unable to see the nest from its position, as compared to an approximately equidistant position from which the nest could be seen. In the second set of experiments bee-eaters entered the nest more frequently when the predator was looking away from the nest. The angle of gaze from the nest was associated significantly positively with the probability of entering the nest whereas the angle from the bird was not. Birds showed considerable flexibility as well as individual variation in the possible methods of judging the predator's position and direction of gaze.
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Jackson, R. R., & Li, D. (2004). One-encounter search-image formation by araneophagic spiders. Anim. Cogn., 7(4), 247–254.
Abstract: An experimental study of search-image use by araneophagic jumping spiders (i.e., salticid spiders that prey routinely on other spiders) supports five conclusions. First, araneophagic salticids have an innate predisposition to form search images for specific prey from their preferred prey category (spiders) rather than for prey from a non-preferred category (insects). Second, single encounters are sufficient for forming search images. Third, search images are based on selective attention specifically to optical cues. Fourth, there are trade-offs in attention during search-image use (i.e., forming a search image for one type of spider diminishes the araneophagic salticid's attention to other spiders). Fifth, the araneophagic salticid's adoption of search images is costly to the prey (i.e., when the araneophagic salticid adopts a search, the prey's prospects for surviving encounters with the araneophagic salticid are diminished). Cognitive and ecological implications of search-image use are discussed.
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