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Adamo, S.A.; Ehgoetz, K.; Sangster, C.; Whitehorne, I. |
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Title |
Signaling to the Enemy? Body Pattern Expression and Its Response to External Cues During Hunting in the Cuttlefish Sepia officinalis (Cephalopoda) |
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2006 |
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Biol. Bull. |
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210 |
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3 |
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192-200 |
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Abstract. Cuttlefish can rapidly alter their appearance by using neurally controlled chromatophore organs. This ability may provide a window into their cognitive capacity. We test whether the changes in body pattern that occur during hunting depend on context. If they do, then it may be possible to use these changes to study cephalopod cognition while the animal is engaged in ecologically relevant tasks. We found consistent individual differences in the tendency of cuttlefish to hunt with the first two arms raised. We also found that cuttlefish usually darken their skin after they seize a prey item. This darkening is observed regardless of the identity of the prey (fish, crab, or shrimp), prey context (buried in sand, in a bare tank, or on top of a rock pile), or the presence of a sudden stimulus. The sudden stimulus was created by presenting an overhead model bird to the cuttlefish. The model induced components of the Deimatic Display, which is a form of antipredator behavior, suggesting that the model was perceived as a potential threat. Passing Cloud displays and the Darkening of the arms were significantly reduced after exposure to the model bird. The effect of a potential predator on body pattern expression during hunting suggests it may be possible to use these changes as a sensitive indicator of ecologically relevant learning. N1 - |
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Equine Behaviour @ team @ |
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2960 |
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Bobbert, M.F.; Alvarez, C.B.G.; van Weeren, P.R.; Roepstorff, L.; Weishaupt, M.A. |
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Validation of vertical ground reaction forces on individual limbs calculated from kinematics of horse locomotion |
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2007 |
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The Journal of Experimental Biology |
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J Exp Biol |
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210 |
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Pt 11 |
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1885-1896 |
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The purpose of this study was to determine whether individual limb forces could be calculated accurately from kinematics of trotting and walking horses. We collected kinematic data and measured vertical ground reaction forces on the individual limbs of seven Warmblood dressage horses, trotting at 3.4 m s(-1) and walking at 1.6 m s(-1) on a treadmill. First, using a segmental model, we calculated from kinematics the total ground reaction force vector and its moment arm relative to each of the hoofs. Second, for phases in which the body was supported by only two limbs, we calculated the individual reaction forces on these limbs. Third, we assumed that the distal limbs operated as linear springs, and determined their force-length relationships using calculated individual limb forces at trot. Finally, we calculated individual limb force-time histories from distal limb lengths. A good correspondence was obtained between calculated and measured individual limb forces. At trot, the average peak vertical reaction force on the forelimb was calculated to be 11.5+/-0.9 N kg(-1) and measured to be 11.7+/-0.9 N kg(-1), and for the hindlimb these values were 9.8+/-0.7 N kg(-1) and 10.0+/-0.6 N kg(-1), respectively. At walk, the average peak vertical reaction force on the forelimb was calculated to be 6.9+/-0.5 N kg(-1) and measured to be 7.1+/-0.3 N kg(-1), and for the hindlimb these values were 4.8+/-0.5 N kg(-1) and 4.7+/-0.3 N kg(-1), respectively. It was concluded that the proposed method of calculating individual limb reaction forces is sufficiently accurate to detect changes in loading reported in the literature for mild to moderate lameness at trot. |
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Institute for Fundamental and Clinical Human Movement Sciences, Vrije Universiteit, van der Boechorstraat 9, NL-1081 BT Amsterdam, The Netherlands |
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0022-0949 |
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PMID:17515415 |
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Equine Behaviour @ team @ |
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3700 |
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Roth, L.S.V.; Balkenius, A.; Kelber, A. |
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Title |
Colour perception in a dichromat |
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2007 |
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Journal of Experimental Biology |
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210 |
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16 |
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2795-2800 |
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Most mammals have dichromatic colour vision based on two different types of cones: a short-wavelength-sensitive cone and a long-wavelength-sensitive cone. Comparing the signal from two cone types gives rise to a one-dimensional chromatic space when brightness is excluded. The so-called `neutral point' refers to the wavelength that the animal cannot distinguish from achromatic light such as white or grey because it stimulates both cone types equally. The question is: how do dichromats perceive their chromatic space? Do they experience a continuous scale of colours or does the neutral point divide their chromatic space into two colour categories, i.e. into colours of either short or long wavelengths?We trained horses to different colour combinations in a two-choice behavioural experiment and tested their responses to the training and test colours. The horses chose colours according to their similarity/relationship to rewarded and unrewarded training colours. There was no evidence for a categorical boundary at the neutral point or elsewhere.This study suggests that dichromats perceive their chromatic space as a continuous scale of colours, treating the colour at the neutral point as any other colour they can distinguish. |
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Equine Behaviour @ team @ |
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5711 |
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Arnold, W.; Ruf, T.; Kuntz, R. |
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Title |
Seasonal adjustment of energy budget in a large wild mammal, the Przewalski horse (Equus ferus przewalskii) II. Energy expenditure |
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Journal Article |
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2006 |
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The Journal of experimental biology |
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J Exp Biol |
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209 |
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Pt 22 |
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4566-4573 |
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Animals; Animals, Wild/*physiology; Body Temperature; Body Temperature Regulation; Eating; *Energy Metabolism; Female; Heart Rate; Horses/*physiology; Male; Motor Activity; Pregnancy; Reproduction; *Seasons |
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Many large mammals show pronounced seasonal fluctuations of metabolic rate (MR). It has been argued, based on studies in ruminants, that this variation merely results from different levels of locomotor activity (LA), and heat increment of feeding (HI). However, a recent study in red deer (Cervus elaphus) identified a previously unknown mechanism in ungulates--nocturnal hypometabolism--that contributed significantly to reduced energy expenditure, mainly during late winter. The relative contribution of these different mechanisms to seasonal adjustments of MR is still unknown, however. Therefore, in the study presented here we quantified for the first time the independent contribution of thermoregulation, LA and HI to heart rate (f(H)) as a measure of MR in a free-roaming large ungulate, the Przewalski horse or Takhi (Equus ferus przewalskii Poljakow). f(H) varied periodically throughout the year with a twofold increase from a mean of 44 beats min(-1) during December and January to a spring peak of 89 beats min(-1) at the beginning of May. LA increased from 23% per day during December and January to a mean level of 53% per day during May, and declined again thereafter. Daily mean subcutaneous body temperature (T(s)) declined continuously during winter and reached a nadir at the beginning of April (annual range was 5.8 degrees C), well after the annual low of air temperature and LA. Lower T(s) during winter contributed considerably to the reduction in f(H). In addition to thermoregulation, f(H) was affected by reproduction, LA, HI and unexplained seasonal variation, presumably reflecting to some degree changes in organ mass. The observed phase relations of seasonal changes indicate that energy expenditure was not a consequence of energy uptake but is under endogenous control, preparing the organism well in advance of seasonal energetic demands. |
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Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna, Savoyenstrasse 1, 1160 Vienna, Austria. walter.arnold@vu-wien.ac.at |
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0022-0949 |
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PMID:17079726 |
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1782 |
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Skedros, J.G.; Dayton, M.R.; Sybrowsky, C.L.; Bloebaum, R.D.; Bachus, K.N. |
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The influence of collagen fiber orientation and other histocompositional characteristics on the mechanical properties of equine cortical bone |
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Journal Article |
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2006 |
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The Journal of Experimental Biology |
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J Exp Biol |
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209 |
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Pt 15 |
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3025-3042 |
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Animals; Biomechanics; Bone and Bones/*physiology; Collagen/*physiology; Forelimb; Horses/*physiology |
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This study examined relative influences of predominant collagen fiber orientation (CFO), mineralization (% ash), and other microstructural characteristics on the mechanical properties of equine cortical bone. Using strain-mode-specific (S-M-S) testing (compression testing of bone habitually loaded in compression; tension testing of bone habitually loaded in tension), the relative mechanical importance of CFO and other material characteristics were examined in equine third metacarpals (MC3s). This model was chosen since it had a consistent non-uniform strain distribution estimated by finite element analysis (FEA) near mid-diaphysis of a thoroughbred horse, net tension in the dorsal/lateral cortices and net compression in the palmar/medial cortices. Bone specimens from regions habitually loaded in tension or compression were: (1) tested to failure in both axial compression and tension in order to contrast S-M-S vs non-S-M-S behavior, and (2) analyzed for CFO, % ash, porosity, fractional area of secondary osteonal bone, osteon cross-sectional area, and population densities of secondary osteons and osteocyte lacunae. Multivariate multiple regression analyses revealed that in S-M-S compression testing, CFO most strongly influenced total energy (pre-yield elastic energy plus post-yield plastic energy); in S-M-S tension testing CFO most strongly influenced post-yield energy and total energy. CFO was less important in explaining S-M-S elastic modulus, and yield and ultimate stress. Therefore, in S-M-S loading CFO appears to be important in influencing energy absorption, whereas the other characteristics have a more dominant influence in elastic modulus, pre-yield behavior and strength. These data generally support the hypothesis that differentially affecting S-M-S energy absorption may be an important consequence of regional histocompositional heterogeneity in the equine MC3. Data inconsistent with the hypothesis, including the lack of highly longitudinal collagen in the dorsal-lateral ;tension' region, paradoxical histologic organization in some locations, and lack of significantly improved S-M-S properties in some locations, might reflect the absence of a similar habitual strain distribution in all bones. An alternative strain distribution based on in vivo strain measurements, without FEA, on non-Thoroughbreds showing net compression along the dorsal-palmar axis might be more characteristic of the habitual loading of some of the bones that we examined. In turn, some inconsistencies might also reflect the complex torsion/bending loading regime that the MC3 sustains when the animal undergoes a variety of gaits and activities, which may be representative of only a portion of our animals, again reflecting the possibility that not all of the bones examined had similar habitual loading histories. |
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Utah Bone and Joint Center, 5323 S. Woodrow Street #202, Salt Lake City, UT 84107, USA. jskedros@utahboneandjoint.com |
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0022-0949 |
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PMID:16857886 |
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1868 |
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Gilbert, B.K.; Hailman, J.P. |
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Uncertainty of leadership-rank in fallow deer |
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1966 |
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Nature |
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Nature |
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209 |
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5027 |
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1041-1042 |
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Animals; Artiodactyla; *Behavior, Animal; Female; *Leadership; Pregnancy |
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0028-0836 |
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PMID:5927524 |
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2057 |
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Stich, K.P.; Winter, Y. |
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Lack of generalization of object discrimination between spatial contexts by a bat |
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2006 |
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J. Exp. Biol. |
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209 |
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23 |
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4802-4808 |
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Discrimination and generalization are important elements of cognition in the daily lives of animals. Nectar-feeding bats detect flowers by olfaction and probably vision, but also use echolocation and echo-perception of flowers in immediate target surroundings. The echo received from an interference-rich flower corolla is a function of a bat's own relative position in space. This raises the question how easily a free-flying bat will generalize an echo stimulus from a learning situation to a new spatial context where differences in relative flight approach trajectories may lead to an unfamiliar spectral composition of the self-generated echoes. We trained free-flying Glossophaga soricina in echoacoustic discrimination in a two-alternative forced-choice (2-AFC) paradigm at location A. We then tested at location B for spontaneous transfer of discrimination ability. Bats did not spontaneously transfer the discrimination ability acquired at A to location B. This lack of spontaneous generalization may have been caused by factors of the underlying learning mechanisms. 2-AFC tasks may not be representative of the natural foraging behaviour of flower-visiting bats. In contrast to insect-eating bats that constantly evaluate the environment to detect unpredictable prey, the spatial stability of flowers may allow flower visitors to rely on spatial memory to guide foraging. The 2-AFC task requires the disregard (learned irrelevance) of salient spatial location cues that are different at each new location. In Glossophaga, a conjunction between spatial context and 2-AFC discrimination learning may have inhibited the transfer of learned irrelevance of spatial location in the 2-AFC task to new spatial locations. Alternatively, the bats may have learnt the second discrimination task completely anew, and were faster only because of an acquired learning set. We suggest a dissociation between 2-AFC task acquisition and novel object discrimination learning to resolve the issue. |
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10.1242/jeb.02574 |
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Equine Behaviour @ team @ |
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2962 |
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Kuntz, R.; Kubalek, C.; Ruf, T.; Tataruch, F.; Arnold, W. |
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Seasonal adjustment of energy budget in a large wild mammal, the Przewalski horse (Equus ferus przewalskii) I. Energy intake |
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2006 |
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The Journal of experimental biology |
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J Exp Biol |
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209 |
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22 |
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4557-4565 |
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Large ruminants respond to changing plant phenology during winter by decreasing voluntary food intake, increasing gut passage time and utilizing body fat reserves. It is uncertain, however, how other large mammals with a non-ruminant digestive physiology cope with winter forage conditions. Therefore, we investigated seasonality of energy intake in a large herbivorous wild mammal, the Przewalski horse (Equus ferus przewalskii). Throughout all seasons we used the n-alkane method to measure daily dry matter intake (DMI), diet composition and digestion, and determined an index of gut passage time in horses living under close to natural conditions. DMI correlated positively with its content of crude protein and nitrogen-free extract. Independent of these effects, DMI further varied seasonally with a peak in autumn and a nadir in late winter. Fluctuations of DMI corresponded to the annual change in body condition, which decreased during winter while energy reserves were depleted, and increased during the fattening period. Gut passage time varied in the course of the year and was longer during winter when the diet was high in crude fibre. Nevertheless, changes in gut passage time occurred rather independently of changes in forage composition and DMI, suggesting endogenous control for timely adaption of the digestive strategy to meet predictable changes in forage quality. |
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10.1242/jeb.02535 |
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Equine Behaviour @ team @ |
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4729 |
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Viscido, S.V.; Miller, M.; Wethey, D.S. |
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The response of a selfish herd to an attack from outside the group perimeter |
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2001 |
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Journal of theoretical biology |
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J. Theor. Biol. |
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208 |
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3 |
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315-328 |
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Animals; *Behavior, Animal; *Computer Simulation; Models, Biological; *Movement; Predatory Behavior |
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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. |
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Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, U.S.A. viscido@u.washington.edu |
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0022-5193 |
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PMID:11207093 |
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refbase @ user @ |
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Krumbiegel I, |
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Einhufer |
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1958 |
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Die Neue Brehm – Bücherei |
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208 |
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from Professor Hans Klingels Equine Reference List |
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1330 |
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