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| Author |
Richards, S.A.; de Roos, A.M. |
| Title |
When is habitat assessment an advantage when foraging? |
Type |
Journal Article |
| Year |
2001 |
Publication |
Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
| Volume |
61 |
Issue |
6 |
Pages |
1101-1112 |
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| Abstract |
Foragers can often show a broad range of strategies when searching for resources. The simplest foraging strategy is to search randomly within a habitat; however, foragers can often assess habitat quality over various spatial scales and use this information to keep themselves in, or direct themselves to, regions of high resource abundance or low predation risk. We investigated models that describe a population of consumers competing for a renewable resource that is distributed among discrete patches. Our aim was to identify what foraging strategy or strategies are expected to persist within a population, where strategies differ in the degree of habitat assessment (i.e. none, local, or global). We were interested in how the optimal strategies are dependent on the cost of assessment and habitat structure (i.e. the variation in renewal rates and predation risks among patches). The models showed that the simple random foraging strategy (i.e. make no habitat assessments) often persisted even when the cost of habitat assessment was low. Persistence could occur when habitat assessment and population dynamics generated an ideal free distribution because it could be exploited by the random foragers. Habitat assessment was more advantageous when consumers could not achieve ideal free distributions, which was more likely as patches became less productive. When productivity was low we sometimes observed the situation where different foraging strategies generated resource heterogeneities that promoted their coexistence, and this could occur even when all patches were intrinsically identical. |
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2153 |
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| Author |
Giulotto, E. |
| Title |
Will horse genetics create better champions? |
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Journal Article |
| Year |
2001 |
Publication |
Trends Genet. |
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17 |
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166 |
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Cited By (since 1996): 1; Export Date: 24 October 2008 |
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Admin @ knut @ |
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4589 |
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Seferta, A.; Guay, P.-J.; Marzinotto, E.; Lefebvre, L. |
| Title |
Learning Differences between Feral Pigeons and Zenaida Doves: The Role of Neophobia and Human Proximity |
Type |
Journal Article |
| Year |
2001 |
Publication |
Ethology |
Abbreviated Journal |
Ethology |
| Volume |
107 |
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Pages |
281-293 |
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Learning differences predicted from ecological variables can be confounded with differences in wariness of novel stimuli (neophobia). Previous work on feral pigeons (Columba livia), as well as on group-feeding and territorial zenaida doves (Zenaida aurita), reported individual and social learning differences predicted from social foraging mode. In the present study, we show that speed of learning a foraging task covaries with neophobia and latency to feed from a familiar dish in the three types of columbids. Pigeons were much faster than either territorial or group-feeding zenaida doves on all tests conducted in captivity, but showed unexpectedly strong neophobia in some urban flocks during field tests. Human proximity strongly affected performance in group-feeding doves both in the field and in captivity. They were slightly faster at learning than their territorial conspecifics in cage tests. In multiple regressions, species identity, but not social foraging mode, significantly predicted individual variation in learning, as did individual variation in neophobia. Wariness of novel stimuli and species differences associated with artificial selection appear to be more important than foraging mode and wariness of humans in accounting for learning differences between these columbids. |
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Equine Behaviour @ team @ |
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2184 |
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Stahl, J.; Tolsma, P.H.; Loonen, M.J.J.E.; Drent, R.H. |
| Title |
Subordinates explore but dominants profit: resource competition in high Arctic barnacle goose flocks |
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Journal Article |
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2001 |
Publication |
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61 |
Issue |
1 |
Pages |
257-264 |
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Social dominance plays an important role in assessing and obtaining access to patchy or scarce food sources in group-foraging herbivores. We investigated the foraging strategies of individuals with respect to their social position in the group in a flock of nonbreeding, moulting barnacle geese, Branta leucopsis, on high Arctic Spitsbergen. We first determined the dominance rank of individually marked birds. The dominance of an individual was best described by its age and its sex-specific body mass. Mating status explained the large variation in dominance among younger birds, as unpaired yearlings ranked lowest. In an artificially created, competitive situation, subordinate individuals occupied explorative front positions in the flock and were the first to find sites with experimentally enriched vegetation. Nevertheless, they were displaced quickly from these favourable sites by more dominant geese which were able to monopolize them. The enhanced sites were subsequently visited preferentially by individuals that succeeded in feeding there when the exclosures were first opened. Data on walking speed of foraging individuals and nearest-neighbour distances in the group suggest that subordinates try to compensate for a lower energy intake by exploring and by lengthening the foraging bout. Observations of our focal birds during the following breeding season revealed that females that returned to the study area were significantly more dominant in the previous year than those not seen in the area again. |
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Equine Behaviour @ team @ |
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2186 |
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McCreery, E.K.; Robbins, R.L. |
| Title |
Proximate Explanations For Failed Pack Formation In Lycaon Pictus |
Type |
Journal Article |
| Year |
2001 |
Publication |
Behaviour |
Abbreviated Journal |
Behaviour |
| Volume |
138 |
Issue |
11 |
Pages |
1467-1479 |
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Among the most social of all canids, the endangered African wild dog lives in packs in which the alpha pair typically monopolizes breeding while nonreproductive members help care for the offspring. Consequently, the size of the breeding population is directly related to the number of packs in the population. Although the formation of new packs affects both individual fitness and population dynamics, little is known about the process of pack formation and the proximate factors that influence the outcome. In this paper, seven cases of attempted pack formation are documented, of which four failed. Three possible explanations for pack annulment are considered: group size, mate competition, and mate choice (i.e. group compatibility). Our observations suggest that group compatibility can influence whether stable reproductive units form. The influence of individual behavior, via the process of pack formation, on population dynamics is discussed. The potential conservation application of the theoretical study of wild dog pack formation is highlighted. |
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Equine Behaviour @ team @ |
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2199 |
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Feh, C.; Munkhtuya, B.; Enkhbold, S.; Sukhbaatar, T. |
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Ecology and social structure of the Gobi khulan Equus hemionus subsp. in the Gobi B National Park, Mongolia |
Type |
Journal Article |
| Year |
2001 |
Publication |
Biological Conservation |
Abbreviated Journal |
Biol. Conserva. |
| Volume |
101 |
Issue |
1 |
Pages |
51-61 |
| Keywords |
Equus hemionus; Ecology and social structure; Gobi National Park; Mongolia |
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The status of the Gobi khulan Equus hemionus subsp. is recorded as “insufficiently known” in the Species Survival Commission's Equid Action Plan. Recent counts confirm that Mongolia holds the most important population of the whole species. Since 1953, the animals have benefited from a protected status, but this is now challenged. A 5-year study in the B part of the Gobi National Park on one subpopulation showed that it has remained stable over the past 15 years with an adequate mean reproductive rate of 15% and a 50% survival rate over the first year. Age/sex related mortality and prey analysis indicate that wolf predation probably has some impact on the population, in particular for 4-6-year-olds of both sexes at the start of reproduction. Desert and mountain steppes are the khulan's year-round preferred habitat, but `oases', play an important role at the beginning of lactation. Anthropogenic factors affect both home range and habitat use through direct intervention or permanent occupation of the scarce water sources. Khulans of this subpopulation, unlike other Asian and African wild asses, form year-round stable, non-territorial families. These families and all-male groups join together into “bands” in winter, and herds of several hundred animals, where reproductive rate is highest, form throughout the year. The existence of such herds may thus be critical for the breeding success of the population. Our study provides the first detailed quantitative data for this subspecies, which will help to monitor changes in the future. |
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Equine Behaviour @ team @ |
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2289 |
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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 |
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 |
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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. |
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Department of Veterinary Basic Sciences, The Royal Veterinary College, Hatfield, Herts AL9 7TA, UK. awilson@rvc.ac.uk |
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0028-0836 |
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PMID:11780059 |
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Equine Behaviour @ team @ |
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2300 |
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Kimura, R. |
| Title |
Volatile substances in feces, urine and urine-marked feces of feral horses |
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Journal Article |
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2001 |
Publication |
Canadian Journal of Animal Science |
Abbreviated Journal |
Can. J. Anim. Sci. |
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81 |
Issue |
3 |
Pages |
411-420 |
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Odors (volatile), excrement, scent-marking, masking, horse (feral), (releaser) pheromone |
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The identity and amount of volatile substances in the feces, urine and feces scent-marked with urine (i.e., feces mixed with urine) of feral horses was determined by acid/steam distillation and gas chromatography-mass spectrometry. The frequency of excretion and scent marking, as evaluated in the breeding and non-breeding seasons, showed clear evidence of seasonal behavioral differences. The concentration of each substance (fatty acids, alcohols, aldehydes, phenols, amines and alkanes) in the feces differed according to maturity, sex and stage in the reproductive process. They had a characteristic chemical fingerprint. Although the levels of tetradecanoic and hexadecanoic acids in the feces of estrous mares were significantly higher than the respective levels in the feces of non-estrous mares, in the case of scent-marked feces by stallions, the levels of them in the feces from estrous mares had decreased to levels similar to those in non-estrous mares. The concentration of these substances in mares were not significantly different. The presence of a high concentration of cresols in the urine of stallions in the breeding season suggests that one role of scent marking by stallions is masking the odor of the feces produced by mares. |
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0008-3984 |
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Equine Museum of Japan, 1-3 Negishidai, Nakaku, Yokohama 231, Japan (hidousch@alles.or.jp) |
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Equine Behaviour @ team @ |
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2314 |
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Gosling, L.M.; Roberts, S.C. |
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Testing ideas about the function of scent marks in territories from spatial patterns |
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Journal Article |
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2001 |
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Animal Behaviour. |
Abbreviated Journal |
Anim. Behav. |
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62 |
Issue |
3 |
Pages |
F7-F10 |
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Equine Behaviour @ team @ |
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2317 |
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Barros, A.T. |
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Seasonality and relative abundance of Tabanidae (Diptera) captured on horses in the Pantanal, Brazil |
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Journal Article |
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2001 |
Publication |
Memorias do Instituto Oswaldo Cruz |
Abbreviated Journal |
Mem Inst Oswaldo Cruz |
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96 |
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7 |
Pages |
917-923 |
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Animals; Brazil; Climate; Diptera/classification/*physiology; Ecology; Horses/*parasitology; Population Dynamics; Seasons; Species Specificity |
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Once a month, from June 1992 to May 1993, collections of tabanids on horse were conducted in the Nhecolandia, Pantanal State of Mato Grosso do Sul, Brazil. Tabanid catches using hand nets were conducted from sunrise to sunset at grassland and cerradao (dense savanna) habitats. A total of 3,442 tabanids from 21 species,12 genera, and 3 subfamilies were collected. Although species abundance varied seasonally depending on habitat, no habitat specificity was observed for the most abundant species. In the grassland, 1,625 (47.2%) tabanids belonging to 19 species were collected, while 1,817 (52.8%) tabanids from 17 species were caught in the cerradao. The number of tabanid species varied from 7 during winter (July/August) to 15 in the spring (October). Tabanus importunus (56%) was the most abundant species, followed by T. occidentalis (8.2%), and T. claripennis (8.1%). The tabanid peak, in October, coincided with the beginning of the rainy season. The population peak of most species, including those with higher vector potential, suggests that the rainy season can be considered as the period of potentially higher risk of mechanical transmission of pathogens by tabanids to horses in the region. |
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Embrapa Pantanal, 79320-900 Corumba, MS, Brasil. thadeu@cpap.embrapa.br |
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0074-0276 |
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PMID:11685255 |
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Equine Behaviour @ team @ |
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2644 |
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