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Author Wilson, A.M.; McGuigan, M.P.; Su, A.; van Den Bogert, A.J.
Title Horses damp the spring in their step Type Journal Article
Year 2001 Publication Nature Abbreviated Journal Nature
Volume (down) 414 Issue 6866 Pages 895-899
Keywords Animals; Biomechanics; Elasticity; Forelimb; Gait; Horses/anatomy & histology/*physiology; Leg Bones/*physiology; Locomotion; Models, Biological; Muscle Fibers/physiology; Muscle, Skeletal/anatomy & histology/*physiology; Tendons/anatomy & histology/*physiology; Vibration
Abstract The muscular work of galloping in horses is halved by storing and returning elastic strain energy in spring-like muscle-tendon units.These make the legs act like a child's pogo stick that is tuned to stretch and recoil at 2.5 strides per second. This mechanism is optimized by unique musculoskeletal adaptations: the digital flexor muscles have extremely short fibres and significant passive properties, whereas the tendons are very long and span several joints. Length change occurs by a stretching of the spring-like digital flexor tendons rather than through energetically expensive length changes in the muscle. Despite being apparently redundant for such a mechanism, the muscle fibres in the digital flexors are well developed. Here we show that the mechanical arrangement of the elastic leg permits it to vibrate at a higher frequency of 30-40 Hz that could cause fatigue damage to tendon and bone. Furthermore, we show that the digital flexor muscles have minimal ability to contribute to or regulate significantly the 2.5-Hz cycle of movement, but are ideally arranged to damp these high-frequency oscillations in the limb.
Address Department of Veterinary Basic Sciences, The Royal Veterinary College, Hatfield, Herts AL9 7TA, UK. awilson@rvc.ac.uk
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ISSN 0028-0836 ISBN Medium
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Notes PMID:11780059 Approved no
Call Number Equine Behaviour @ team @ Serial 2300
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Author Whiten, A.; McGrew, W.C.
Title Is this the first portrayal of tool use by a chimp? Type
Year 2001 Publication Nature Abbreviated Journal Nature
Volume (down) 409 Issue 6816 Pages 12
Keywords Animals; *Behavior, Animal; Pan troglodytes/*physiology; Philately
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ISSN 0028-0836 ISBN Medium
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Notes PMID:11343083 Approved no
Call Number refbase @ user @ Serial 739
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Author Clayton NS; Griffiths DP; Emery NJ; Dickinson A
Title Elements of episodic-like memory in animals Type Journal Article
Year 2001 Publication Philos. Trans. R. Soc. Lond. B Biol. Sci. Abbreviated Journal
Volume (down) 356 Issue Pages 1483
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Call Number Equine Behaviour @ team @ Serial 3062
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Author Clutton-Brock, T.H.; Russell, A.F.; Sharpe, L.L.; Brotherton, P.N.; McIlrath, G.M.; White, S.; Cameron, E.Z.
Title Effects of helpers on juvenile development and survival in meerkats Type Journal Article
Year 2001 Publication Science (New York, N.Y.) Abbreviated Journal Science
Volume (down) 293 Issue 5539 Pages 2446-2449
Keywords Animals; Breeding; Carnivora/growth & development/*physiology; *Cooperative Behavior; Feeding Behavior; Female; Male; Survival Rate; *Weight Gain
Abstract Although breeding success is known to increase with group size in several cooperative mammals, the mechanisms underlying these relationships are uncertain. We show that in wild groups of cooperative meerkats, Suricata suricatta, reductions in the ratio of helpers to pups depress the daily weight gain and growth of pups and the daily weight gain of helpers. Increases in the daily weight gain of pups are associated with heavier weights at independence and at 1 year of age, as well as with improved foraging success as juveniles and higher survival rates through the first year of life. These results suggest that the effects of helpers on the fitness of pups extend beyond weaning and that helpers may gain direct as well as indirect benefits by feeding pups.
Address Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. thcb@hermes.cam.ac.uk
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ISSN 0036-8075 ISBN Medium
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Notes PMID:11577235 Approved no
Call Number refbase @ user @ Serial 414
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Author Whiten, A.; Boesch, C.
Title The cultures of chimpanzees Type Journal Article
Year 2001 Publication Scientific American Abbreviated Journal Sci Am
Volume (down) 284 Issue 1 Pages 60-67
Keywords Animals; *Behavior, Animal; Culture; Feeding Behavior; Grooming; Hominidae; Humans; Pan troglodytes/*physiology
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Address University of St. Andrews
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ISSN 0036-8733 ISBN Medium
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Notes PMID:11132425 Approved no
Call Number refbase @ user @ Serial 740
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Author Peake, T.M.; Terry, A.M.; McGregor, P.K.; Dabelsteen, T.
Title Male great tits eavesdrop on simulated male-to-male vocal interactions Type Journal Article
Year 2001 Publication Proceedings. Biological sciences / The Royal Society Abbreviated Journal Proc Biol Sci
Volume (down) 268 Issue 1472 Pages 1183-1187
Keywords Animals; Male; Songbirds/*physiology; *Vocalization, Animal
Abstract Animal communication generally occurs in the environment of a network of several potential signallers and receivers. Within a network environment, it is possible to gain relative information about conspecifics by eavesdropping on signalling interactions. We presented male great tits with the opportunity to gain such information by simulating singing interactions using two loudspeakers. Interactions were presented so that relevant information was not available in the absolute singing behaviour of either individual, only in the relative timing of their songs in the interaction as a whole. We then assayed the information extracted by focal males by subsequently introducing one of the 'interactants' (i.e. loudspeakers) into the territory of the focal male. Focal males responded with a reduced song output to males that had just 'lost' an interaction. Focal males did not respond significantly differently to 'winners' as compared with intruders recently involved in an interaction that contained no consistent information. Focal males also responded by switching song types more often when encountering males that had recently been involved in a low-intensity interaction. These results provide the clearest evidence yet that male songbirds extract information from signal interactions between conspecifics in the field.
Address Department of Animal Behaviour, Zoological Institute, Tagensvej 16, University of Copenhagen, 2200 Copenhagen N, Denmark. tmpeake@zi.ku.dk
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ISSN 0962-8452 ISBN Medium
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Notes PMID:11375107 Approved no
Call Number refbase @ user @ Serial 712
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Author Tebbich, S.; Taborsky, M.; Fessl, B.; Blomqvist, D.
Title Do woodpecker finches acquire tool-use by social learning? Type Journal Article
Year 2001 Publication Proceedings of the Royal Society of London B: Biological Sciences Abbreviated Journal Proc. Roy. Soc. Lond. B Biol. Sci.
Volume (down) 268 Issue 1482 Pages 2189-2193
Keywords
Abstract Tool–use is widespread among animals, but except in primates the development of this behaviour is poorly known. Here, we report on the first experimental study to our knowledge of the mechanisms underlying the acquisition of tool–use in a bird species. The woodpecker finch Cactospiza pallida, endemic to the Galápagos Islands, is a famous textbook example of tool–use in animals. This species uses modified twigs or cactus spines to pry arthropods out of tree holes. Using nestlings and adult birds from the field, we tested experimentally whether woodpecker finches learn tool–use socially. We show that social learning is not essential for the development of tool–use: all juveniles developed tool–use regardless of whether or not they had a tool–using model. However, we found that not all adult woodpecker finches used tools in our experiments. These non–tool–using individuals also did not learn this task by observing tool–using conspecifics. Our results suggest that tool–use behaviour depends on a very specific learning disposition that involves trial–and–error learning during a sensitive phase early in ontogeny.
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Call Number Equine Behaviour @ team @ Serial 5914
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Author Madigan, J.E.; Bell, S.A.
Title Owner survey of headshaking in horses Type Journal Article
Year 2001 Publication Journal of the American Veterinary Medical Association Abbreviated Journal J Am Vet Med Assoc
Volume (down) 219 Issue 3 Pages 334-337
Keywords Animals; Anti-Allergic Agents/*therapeutic use; *Behavior, Animal/drug effects; Cyproheptadine/*therapeutic use; Data Collection; Diagnosis, Differential; Female; Horse Diseases/diagnosis/drug therapy/*etiology; Horses; Humans; Male; Questionnaires; Seasons
Abstract OBJECTIVE: To determine signalment, history, clinical signs, duration, seasonality, and response to various treatments reported by owners for headshaking in horses. DESIGN: Owner survey. ANIMALS: 109 horses with headshaking. PROCEDURE: Owners of affected horses completed a survey questionnaire. RESULTS: 78 affected horses were geldings, 29 were mares, and 2 were stallions. Mean age of onset was 9 years. Headshaking in 64 horses had a seasonal component, and for most horses, headshaking began in spring and ceased in late summer or fall. The most common clinical signs were shaking the head in a vertical plane, acting like an insect was flying up the nostril, snorting excessively, rubbing the muzzle on objects, having an anxious expression while headshaking, worsening of clinical signs with exposure to sunlight, and improvement of clinical signs at night. Treatment with antihistamines, nonsteroidal anti-inflammatory drugs, corticosteroids, antimicrobials, fly control, chiropractic, and acupuncture had limited success. Sixty-one horses had been treated with cyproheptadine; 43 had moderate to substantial improvement. CONCLUSIONS AND CLINICAL RELEVANCE: Headshaking may have many causes. A large subset of horses have similar clinical signs including shaking the head in a vertical plane, acting as if an insect were flying up the nostrils, and rubbing the muzzle on objects. Seasonality and worsening of clinical signs with exposure to light are also common features of this syndrome. Geldings and Thoroughbreds appear to be overrepresented. Cyproheptadine treatment was beneficial in more than two thirds of treated horses.
Address Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis 95616, USA
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ISSN 0003-1488 ISBN Medium
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Notes PMID:11497047 Approved no
Call Number refbase @ user @ Serial 1916
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Author Timney, B.; Macuda, T.
Title Vision and hearing in horses Type Journal Article
Year 2001 Publication Journal of the American Veterinary Medical Association Abbreviated Journal J Am Vet Med Assoc
Volume (down) 218 Issue 10 Pages 1567-1574
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Call Number Equine Behaviour @ team @ room B 3.029 Serial 2278
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Author Viscido, S.V.; Miller, M.; Wethey, D.S.
Title The response of a selfish herd to an attack from outside the group perimeter Type Journal Article
Year 2001 Publication Journal of theoretical biology Abbreviated Journal J. Theor. Biol.
Volume (down) 208 Issue 3 Pages 315-328
Keywords Animals; *Behavior, Animal; *Computer Simulation; Models, Biological; *Movement; Predatory Behavior
Abstract According to the selfish herd hypothesis, animals can decrease predation risk by moving toward one another if the predator can appear anywhere and will attack the nearest target. Previous studies have shown that aggregations can form using simple movement rules designed to decrease each animal's Domain of Danger. However, if the predator attacks from outside the group's perimeter, these simple movement rules might not lead to aggregation. To test whether simple selfish movement rules would decrease predation risk for those situations when the predator attacks from outside the flock perimeter, we constructed a computer model that allowed flocks of 75 simulated fiddler crabs to react to one another, and to a predator attacking from 7 m away. We attacked simulated crab flocks with predators of different sizes and attack speeds, and computed relative predation risk after 120 time steps. Final trajectories showed flight toward the center of the flock, but curving away from the predator. Path curvature depended on the predator's size and approach speed. The average crab experienced a greater decrease in predation risk when the predator was small or slow moving. Regardless of the predator's size and speed, however, predation risk always decreased as long as crabs took their flock-mates into account. We conclude that, even when flight away from an external predator occurs, the selfish avoidance of danger can lead to aggregation.
Address Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, U.S.A. viscido@u.washington.edu
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ISSN 0022-5193 ISBN Medium
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Notes PMID:11207093 Approved no
Call Number refbase @ user @ Serial 555
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