Morand-Ferron, J., & Quinn, J. L. (2011). Larger groups of passerines are more efficient problem solvers in the wild. Proc Natl Acad Sci USA, 108(38), 15898–15903.
Abstract: Group living commonly helps organisms face challenging environmental conditions. Although a known phenomenon in humans, recent findings suggest that a benefit of group living in animals generally might be increased innovative problem-solving efficiency. This benefit has never been demonstrated in a natural context, however, and the mechanisms underlying improved efficiency are largely unknown. We examined the problem-solving performance of great and blue tits at automated devices and found that efficiency increased with flock size. This relationship held when restricting the analysis to naive individuals, demonstrating that larger groups increased innovation efficiency. In addition to this effect of naive flock size, the presence of at least one experienced bird increased the frequency of solving, and larger flocks were more likely to contain experienced birds. These findings provide empirical evidence for the “pool of competence” hypothesis in nonhuman animals. The probability of success also differed consistently between individuals, a necessary condition for the pool of competence hypothesis. Solvers had a higher probability of success when foraging with a larger number of companions and when using devices located near rather than further from protective tree cover, suggesting a role for reduced predation risk on problem-solving efficiency. In contrast to traditional group living theory, individuals joining larger flocks benefited from a higher seed intake, suggesting that group living facilitated exploitation of a novel food source through improved problem-solving efficiency. Together our results suggest that both ecological and social factors, through reduced predation risk and increased pool of competence, mediate innovation in natural populations.
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Miyata, H., Gajdon, G. K., Huber, L., & Fujita, K. (2011). How do keas (Nestor notabilis) solve artificial-fruit problems with multiple locks? Anim. Cogn., 14(1), 45–58.
Abstract: Keas, a species of parrots from New Zealand, are an interesting species for comparative studies of problem solving and cognition because they are known not only for efficient capacities for object manipulation but also for explorative and playful behaviors. To what extent are they efficient or explorative, and what cognitive abilities do they use? We examined how keas would solve several versions of artificial-fruit box problems having multiple locks. After training keas to remove a metal rod from over a Plexiglas lid that had to be opened, we exposed the birds to a variety of tasks having two or more locks. We also introduced a preview phase during which the keas had extended opportunity to look at the tasks before the experimenter allowed the birds to solve them, to examine whether the preview phase would facilitate the birds' performance on the tasks. In a large number of tests, the keas showed a strong trend to solve the tasks with no positive effect of previewing the tasks. When the tasks became complex, however, the keas corrected inappropriate responses more quickly when they had had chance to preview the problems than when they had not. The results suggest that the keas primarily used explorative strategies in solving the lock problems but might have obtained some information about the tasks before starting to solve them. This may reflect a good compromise of keas' trial-and-error tendency and their good cognitive ability that result from a selection pressure they have faced in their natural habitat.
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Hendriksen, P., Elmgreen, K., & Ladewig, J. (2011). Trailer-loading of horses: Is there a difference between positive and negative reinforcement concerning effectiveness and stress-related signs? J. Vet. Behav., 6(5), 261–266.
Abstract: The traditional way to train horses is by the application of negative reinforcement (NR). In the past few years, however, the use of positive reinforcement (PR) has become more common. To evaluate the effectiveness and the possible stressor effect of the 2 training methods, 12 horses showing severe trailer-loading problems were selected and exposed to trailer-loading. They were randomly assigned to one of the 2 methods. NR consisted of various degrees of pressure (lead rope pulling, whip tapping). Pressure was removed as soon as the horse complied. PR horses were exposed to clicker training and taught to follow a target into the trailer. Heart rate (HR) was recorded every 5 seconds and behavior denoting discomfort was observed using one-zero sampling with 10 seconds sampling intervals. Training was completed when the horse could enter the trailer upon a signal, or was terminated after a maximum of 15 sessions. Of the 12 horses, 10 reached the criterion within the 15 sessions. One horse was eliminated from the study because of illness and 1 PR horse failed to enter the trailer. A Mann-Whitney U-test indicated that the horses trained with NR displayed significantly more discomfort behavior per training session than horses trained with PR (NR: 13.26 ± 3.25; PR: 3.17 ± 8.93, P < 0.0001) and that horses in the PR group spent less time (second) per session to complete the training criterion (NR: 672.9 ± 247.12; PR: 539.81 ± 166.37, P < 0.01). A Mann-Whitney U-test showed that no difference existed in mean HR (bpm) between the 2 groups (NR: 53.06 ± 11.73 bpm; PR: 55.54 ± 6.7 bpm, P > 0.05), but a Wilcoxon test showed a difference in the PR group between the baseline of HR and mean HR obtained during training sessions (baseline PR: 43 ± 8.83 bpm; PR: 55.54 ± 6.7 bpm, P < 0.05). In conclusion, the PR group provided the fastest training solution and expressed less stress response. Thus, the PR procedure could provide a preferable training solution when training horses in potentially stressing situations.
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Jørgensen, G. H. M., Liestøl, S. H. - O., & Bøe, K. E. (2011). Effects of enrichment items on activity and social interactions in domestic horses (Equus caballus). Appl. Anim. Behav. Sci., 129(2), 100–110.
Abstract: The aim of this study was to investigate the use of items intended to provide enrichment during turnout, both for individual and group kept horses in an attempt to reduce the amount of passive behaviours. The study was divided into two parts, where study 1 involved eight horses rotated through eight individual paddocks, each containing one of seven enrichment items and one paddock being kept without item, functioning as a control. The horses' item-directed behaviours; passive behaviours or other non-item related activities were scored using instantaneous sampling, every minute for 1h at the beginning and the end of the turnout period. Study 2 involved six horse groups (3-6 horses) and the same scoring methods and ethogram as in study 1. The four items that the horses interacted the most with during study 1 (straw STRA, ball filled with concentrates CBALL, branches BRAN and scratching pole POLE) are investigated in study 2. In addition, the amount of social interactions was recorded. Both horses kept individually (P<0.05) and in groups (P<0.0001) performed significantly more item-directed behaviours towards edible items like STRA and CBALL than other objects. There was, however, no overall relation between the numbers of item-directed behaviours and the number of passive behaviours observed, indicating that the enrichment items did not alone reduce the amount of passive behaviours during turnout periods. Such a reduction was, however, only apparent when horses spent more time eating green leaves growing on the paddock surface (R=-0.97 study 1, R=-0.67 study 2, P<0.0001). Access to STRA in group kept horses also seemed to reduce the amount of agonistic behaviours (P<0.0001). In conclusion, if grass is not available in paddocks, the provision of roughage reduces the amount of passive behaviours in singly kept horses and it also reduces the risk of agonistic interactions between horses kept in group.
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Christensen, J. W., Søndergaard, E., Thodberg, K., & Halekoh, U. (2011). Effects of repeated regrouping on horse behaviour and injuries. Appl. Anim. Behav. Sci., 133(3), 199–206.
Abstract: Domestic horses are faced with social challenges throughout their lives due to limitations in social contact, space restrictions and frequent changes in social companionship. This is in contrast to natural conditions where horses live in relatively stable harem bands. Currently, little is known about how repeated regrouping affect horse behaviour and welfare, and it is unknown whether horses may adapt to regrouping. In this study, we aimed to investigate the effects of an unstable group structure, caused by weekly regroupings, on behaviour and frequency of injuries in young horses. Forty-five horses were included in the study and were randomly assigned to the treatments; Stable (S; seven groups of three horses) or Unstable (U; eight groups of three horses). The experimental period lasted 7 weeks, during which horses in Stable groups remained in the same group, whereas one horse was exchanged between Unstable groups every week. The groups were kept in 80m×80m grass-covered enclosures and were fed additional roughage on the ground daily. Social interactions were recorded in Unstable groups immediately after each regrouping (30min), and in both Stable and Unstable groups on day 1, 3 and 6 after each regrouping (2×20min/group/day). Injuries were scored by the end of the experimental period. The level of aggression shown by horses in Unstable groups immediately after regrouping was not affected by week (F5,35=0.42, P=0.83), indicating that horses neither habituated, nor sensitized, to repeated regrouping. Compared to horses in Stable groups, more agonistic behaviour was shown by horses in Unstable groups (i.e. non-contact agonistic; F1,65=5.60, P=0.02), whereas there was no treatment effect on other variables. The level of play behaviour appeared, however, to be more variable in Unstable groups. There was a significant effect of week on the level of contact agonistic interactions as well as greeting behaviour, due to a high occurrence in weeks 4-6. Non-contact agonistic interactions constituted the major part of agonistic interactions (66%). Possibly as consequence, no serious injuries were registered and there was no treatment effect (U=184; P=0.11). We conclude that the behaviour of young horses is affected by group management, and that horses appear not to adapt to weekly regroupings.
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Piro, M., Benjouad, A., Karom, A., Nabich, A., Benbihi, N., El Allali, K., et al. (2011). Genetic Structure of Severe Combined Immunodeficiency Carrier Horses in Morocco Inferred by Microsatellite Data. J. Equine Vet. Sci., 31(11), 618–624.
Abstract: A total of 17 microsatellite deoxyribonucleic acid loci used routinely for horse parentage control were used to evaluate genetic diversity among normal Arabian horses and severe combined immunodeficiency (SCID) carrier Arabian horses (ArS) and normal Arab-Barb horses and SCID carrier Arab-Barb horses (ArbeS). On the basis of the genotype of 186 horses, mean allelic diversity was estimated as 6.82, 5.53, and 6.7059 in normal Arabian horses, ArS, and for both groups of Arab-Barb horses, respectively. Five specific alleles were observed in ArS and ArbeS, with one common with ArS at HMS6, whereas five alleles common between ArS and ArbeS had a high frequency. Expected and observed heterozygosity showed great heterogeneity in the population studied and were similar or higher when compared with other studies on Arabian horses. Coefficient of gene differentiation Gst of Nei associated with Nei's genetic distance and multivariate correspondence analysis indicated a possible differentiation between the studied populations when analyzed separately according to breed. Probability of assignment of a horse to a specific group was assessed using a full and partial Bayesian approach. In all, 80.6% of Arab horses and 78.2% of Arab-Barb horses were assigned properly with a partial Bayesian test, which provided better results than the full one. These findings will be useful for identification of SCID carrier horses by using the microsatellite deoxyribonucleic acid loci used routinely for horse parentage control in our laboratory.
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Holzapfel, M., Wagner, C., & Kluth, G. et al. (2011). Zur Nahrungsökologie der Wölfe (Canis lupus) in Deutschland. Beiträge zur Jagd- und Wildforschung, 36, 117–128.
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Heyes, C. (2012). What's social about social learning? J Comp Psychol, 120.
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Smaers, J. B., Dechmann, D. K. N., Goswami, A., Soligo, C., & Safi, K. (2012). Comparative analyses of evolutionary rates reveal different pathways to encephalization in bats, carnivorans, and primates. Proc Natl Acad Sci U S A, 109.
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Benson-Amram, S., & Holekamp, K. E. (2012). Innovative problem solving by wild spotted hyenas. Proc R Soc B, 279, 4087–4095.
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