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Bugnyar, T., & Kotrschal, K. (2004). Leading a conspecific away from food in ravens ( Corvus corax)? Anim. Cogn., 7(2), 69–76.
Abstract: Active misleading of conspecifics has been described as a social strategy mainly for primates. Here we report a raven leading a competitor away from food in a social foraging task. Four individuals had to search and compete for hidden food at color-marked clusters of artificial food caches. At the beginning of the experiment, a subordinate male found and exploited the majority of the food. As a result, the dominant male displaced him from the already opened boxes. The subordinate male then developed a pattern, when the loss of reward to the dominant got high, of moving to unrewarded clusters and opening boxes there. This diversion often led the dominant to approach those unrewarded clusters and the subordinate then had a head start for exploiting the rewarded boxes. Subsequently, however, the dominant male learned not to follow the subordinate to unrewarded clusters and eventually started searching for the reward himself. These interactions between the two males illustrate the ravens' potential for deceptively manipulating conspecifics. We discuss under which circumstances ravens might use this capacity.
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Cloutier, S., Newberry, R. C., & Honda, K. (2004). Comparison of social ranks based on worm-running and aggressive behaviour in young domestic fowl. Behav. Process., 65(1), 79–86.
Abstract: Worm-running is behaviour in which a chick runs carrying a worm-like object while flock mates follow and attempt to grab the object from its beak. We hypothesised that social ranks based on worm-running frequency are stable over time and are positively correlated with social ranks based on success in aggressive interactions when older. At 8-12 days of age, we scored worm-running in 17 groups of 12 female White Leghorn chicks during three 10-min tests. Based on instantaneous scans at 5-s intervals, the bird carrying the `worm' most often was placed in rank one and so on down the rank order. These tests were repeated at 68-70 days of age. An aggression index for each bird was calculated as the number of aggressive acts given, divided by the number given and received, during three 1-h observation periods when the birds were 68-70 days. Ranks obtained in worm-running tests were positively correlated over the two age periods (P<0.05) but were not correlated with ranks based on the aggression index (P>0.05). Our results indicate that worm-running ranks are not predictive of success in aggressive interactions. Instead, worm-running fits some criteria for play.
Keywords: Aggression; Social behaviour; Dominance; Play; Chickens; Animal welfare
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Jennings, D. J., Gammell, M. P., Carlin, C. M., & Hayden, T. J. (2004). Effect of body weight, antler length, resource value and experience on fight duration and intensity in fallow deer. Anim. Behav., 68(1), 213–221.
Abstract: We tested predictions of evolutionary game theory focusing on fight duration and intensity during contests between European fallow deer, Dama dama L. We examined the relation between contest duration and intensity and resource-holding potential (RHP; body weight and antler size), in an effort to reveal the assessment rules used by competing males. We examined other potential determinants of duration and intensity: resource value (the oestrous female) and experience of agonistic interactions. Asymmetry in body weight or antler length of contestants was not correlated with fight duration. Body weight and antler length of the fight winner or loser were also not correlated with fight duration. Neither were the body weight of the heavier or lighter animal or the antler length of the animal that had longer or shorter antlers. A measure of intensity (the jump clash) was positively related to the body weight of the losing animal and the lighter member of the dyad. These results are consistent with the hypothesis that opponents escalate contest intensity based on assessment of their own ability rather than through mutual assessment. There was no evidence that resource value is an important factor in either fight duration or intensity in this population. As the number of fights between pairs of males increased, there was a decrease in fight duration. Fights were longer when at least one member of a competing pair of males had previously experienced a victory.
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Langbein, J., & Puppe, B. (2004). Analysing dominance relationships by sociometric methods--a plea for a more standardised and precise approach in farm animals. Appl. Anim. Behav. Sci., 87(3-4), 293–315.
Abstract: Social dominance is a multidimensional phenomenon occurring in all gregarious farm animals and finds its reflection in a dominance hierarchy. Hence, numerous studies have tried to analyse dominance relationships as well as to correlate outcoming results (mostly individual ranks) with other behavioural and/or physiological features of the animals. Although the concept of dominance, once established, has been developed continuously and several sociometric measures were cumulatively introduced, a consistent analysing approach has not been achieved, especially in farm animals. Thus, considerable inconsistencies in the used methodology may impair obtained results and interpretations. The present paper is a plea for a more standardised and complex approach when analysing dominance relationships, not only in farm animals. First, derived from a structural definition of dominance, we suggest in detail the preferably consistent use of appropriate sociometric measures at all social levels of analysis: the dyad as the starting level, the group as the highest level, and the individual as the basic level. Second, we applied this procedures in a case study to analyse social dominance in a group of dwarf goats (n=12) and pigs (n=10), respectively, to comparatively demonstrate benefits and problems of such an approach in two different farm animal species. It is concluded that the use of individual ranks is actually only reasonable when fundamental sociometric measures both at the dyadic level (e.g. percentage of dyads which have a significant asymmetric outcome) and at the group level (e.g. the strength of hierarchy) are successfully tested by statistical methods as also presented in this paper. The calculated sociometric measures deliver not only a more comprehensive “picture” of the social relationships within a group as simple ranks do, but also indicate possible reasons of differences in the behavioural development. For instance, whereas the dwarf goats maintained a quasi-linear dominance hierarchy over time with a high rate of overt agonistic behaviour, pigs after the establishment of their hierarchy showed a reduced agonistic behaviour which makes it questionable to calculate reliable sociometric measures. These species-dependent variations may be primarily caused by different kinds of the fighting behaviour in goats (i.e. ritualised, low costs) and pigs (i.e. more seriously, high costs). Overall, a more consistent and standardised approach of analysing social dominance in (farm) animals may improve the scientific value of single studies and makes it easier to compare various studies within a species and between species.
Keywords: Dominance; Dyads; Social hierarchy; Sociometric measures; Pig; Dwarf goat
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Powell, F., & Banks, P. B. (2004). Do house mice modify their foraging behaviour in response to predator odours and habitat? Anim. Behav., 67(4), 753–759.
Abstract: Predator odours and habitat structure are thought to influence the behaviour of small mammalian prey, which use them as cues to reduce risks of predation. We tested this general hypothesis for house mice, Mus domesticus, by manipulating fox odour density via addition of fox scats and habitat via patchy mowing of vegetation, for populations in 15 x 15-m field enclosures. Using giving-up densities (GUDs), the density of food remaining when an animal quits harvesting a patch, we measured foraging behaviours in response to these treatments. Mice consistently avoided open areas, leaving GUDs two to four times greater in these areas than in densely vegetated patches. However, mouse GUDs did not change in response to the addition of fox scats, even immediately after fresh scats were added. There was no interaction between fox odour and habitat use. We then tested whether habituation to fox odours had occurred, by comparing the individual responses to scats of eight mice born into enclosures with fox scats to those of eight mice born into scat-free enclosures and five wild mice. In smaller enclosures, GUDs of trays with scats did not differ from GUDs of trays without scats for any treatment. We conclude that exposure to high levels of fox odours did not alter the foraging behaviour of mice, but that mice did reduce foraging in areas where habitat was removed, perceiving predation risk to be greater in these areas than controls. We suggest further that studies using the `scat-at-trap' technique, which have shown avoidance of predator odours by mice and other small mammals, may overestimate the general avoidance of predator odours by free-living prey, which must forage with a constant background of predator odours.
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Sih, A., Bell, A., & Johnson, J. C. (2004). Behavioral syndromes: an ecological and evolutionary overview. Trends. Ecol. Evol, 19(7), 372–378.
Abstract: Recent studies suggest that populations and species often exhibit behavioral syndromes; that is, suites of correlated behaviors across situations. An example is an aggression syndrome where some individuals are more aggressive, whereas others are less aggressive across a range of situations and contexts. The existence of behavioral syndromes focuses the attention of behavioral ecologists on limited (less than optimal) behavioral plasticity and behavioral carryovers across situations, rather than on optimal plasticity in each isolated situation. Behavioral syndromes can explain behaviors that appear strikingly non-adaptive in an isolated context (e.g. inappropriately high activity when predators are present, or excessive sexual cannibalism). Behavioral syndromes can also help to explain the maintenance of individual variation in behavioral types, a phenomenon that is ubiquitous, but often ignored. Recent studies suggest that the behavioral type of an individual, population or species can have important ecological and evolutionary implications, including major effects on species distributions, on the relative tendencies of species to be invasive or to respond well to environmental change, and on speciation rates. Although most studies of behavioral syndromes to date have focused on a few organisms, mainly in the laboratory, further work on other species, particularly in the field, should yield numerous new insights.
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Lamoot, I., Callebaut, J., Degezelle, T., Demeulenaere, E., Laquiere, J., Vandenberghe, C., et al. (2004). Eliminative behaviour of free-ranging horses: do they show latrine behaviour or do they defecate where they graze? Appl. Anim. Behav. Sci., 86(1-2), 105–121.
Abstract: In contrast to horses in pastures, it is thought that free-ranging horses do not perform latrine behaviour, i.e. a behavioural pattern whereby the animals graze and defecate in separate areas. However, few studies deal with this particular subject, reporting contrasting conclusions. We hypothesize that horses free-ranging in large heterogeneous areas do not perform latrine behaviour. Thus, we believe that grazing and elimination behaviour are spatially related: where horses graze, they will also defecate. Behavioural data were collected from Konik horses, Haflinger horses, Shetland ponies and donkeys, grazing in different nature reserves (54-80 ha). Data for the different equids were analyzed separately, as well as data for mares and stallions (Konik and donkey stallions only). We investigated the proportion of the number of defecations/urinations while grazing on the total number of defecations/urinations; furthermore, we searched for the sequence of behaviours representing latrine behaviour in the strict sense. Additionally, we analyzed the correlation between grazing behaviour and eliminative behaviour on both vegetation type level and patch level. All the female equids often continued grazing while defecating. During urination, grazing ceases in the majority of instances. Cases where a mare terminated grazing in a certain vegetation type and sward height to eliminate in another vegetation type or in another sward height within the same vegetation type were rarely observed. On the vegetation type level as well as on the patch level, there was a highly significant (P<0.001) positive correlation between grazing time and number of eliminations (or eliminating time). The high values of the correlation coefficients (in case of the defecation variables r ranges between 0.553 and 0.955; in case of the urination variables r ranges between 0.370 and 0.839) illustrate that the spatial distribution of the eliminative behaviour can be explained to a high degree by the spatial distribution of the grazing behaviour. Results in the case of the stallions are preliminary, but indicate the same pattern. Horses, free-ranging in large heterogeneous areas, do not perform latrine behaviour, but defecate where they graze. Possibly, animal density is of major importance to explain this behavioural difference with horses in pastures. We suggest that also spatial vegetation heterogeneity and plant productivity of the grazed area, as well as parasite status of the grazing animals could play a role.
Keywords: Equids; Faeces avoidance; Grazing behaviour; Spatial differentiation; Urine; Horse marking
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Allcroft, D. J., Tolkamp, B. J., Glasbey, C. A., & Kyriazakis, I. (2004). The importance of `memory' in statistical models for animal feeding behaviour. Behav. Process., 67(1), 99–109.
Abstract: We investigate models for animal feeding behaviour, with the aim of improving understanding of how animals organise their behaviour in the short term. We consider three classes of model: hidden Markov, latent Gaussian and semi-Markov. Each can predict the typical `clustered' feeding behaviour that is generally observed, however they differ in the extent to which `memory' of previous behaviour is allowed to affect future behaviour. The hidden Markov model has `lack of memory', the current behavioural state being dependent on the previous state only. The latent Gaussian model assumes feeding/non-feeding periods to occur by the thresholding of an underlying continuous variable, thereby incorporating some `short-term memory'. The semi-Markov model, by taking into account the duration of time spent in the previous state, can be said to incorporate `longer-term memory'. We fit each of these models to a dataset of cow feeding behaviour. We find the semi-Markov model (longer-term memory) to have the best fit to the data and the hidden Markov model (lack of memory) the worst. We argue that in view of effects of satiety on short-term feeding behaviour of animal species in general, biologically suitable models should allow `memory' to play a role. We conclude that our findings are equally relevant for the analysis of other types of short-term behaviour that are governed by satiety-like principles.
Keywords: Cow; Feeding data; Bouts; Memory; Satiety; Latent structure; Model comparison
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Emery, N. J., & Clayton, N. S. (2004). The Mentality of Crows: Convergent Evolution of Intelligence in Corvids and Apes. Science, 306(5703), 1903–1907.
Abstract: Discussions of the evolution of intelligence have focused on monkeys and apes because of their close evolutionary relationship to humans. Other large-brained social animals, such as corvids, also understand their physical and social worlds. Here we review recent studies of tool manufacture, mental time travel, and social cognition in corvids, and suggest that complex cognition depends on a “tool kit” consisting of causal reasoning, flexibility, imagination, and prospection. Because corvids and apes share these cognitive tools, we argue that complex cognitive abilities evolved multiple times in distantly related species with vastly different brain structures in order to solve similar socioecological problems.
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Dukas, R. (2004). Evolutionary Biology Of Animal Cognition. Annual Review of Ecology, Evolution, and Systematics, 35(1), 347–374.
Abstract: This review focuses on five key evolutionary issues pertaining to animal cognition, defined as the neuronal processes concerned with the acquisition, retention, and use of information. Whereas the use of information, or decision making, has been relatively well examined by students of behavior, evolutionary aspects of other cognitive traits that affect behavior, including perception, learning, memory, and attention, are less well understood. First, there is ample evidence for genetically based individual variation in cognitive traits, although much of the information for some traits comes from humans. Second, several studies documented positive association between cognitive abilities and performance measures linked to fitness. Third, information on the evolution of cognitive traits is available primarily for color vision and decision making. Fourth, much of the data on plasticity of cognitive traits appears to reflect nonadaptive phenotypic plasticity, perhaps because few evolutionary analyses of cognitive plasticity have been carried out. Nonetheless, several studies suggest that cognitive traits show adaptive plasticity, and at least one study documented genetically based individual variation in plasticity. Fifth, whereas assertions that cognition has played a central role in animal evolution are not supported by currently available data, theoretical considerations indicate that cognition may either increase or decrease the rate of evolutionary change.
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