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Author Dugatkin, L.A.; Godin, G.J. doi  openurl
  Title Predator inspection, shoaling and foraging under predation hazard in the Trinidadian guppy,Poecilia reticulata Type Journal Article
  Year 1992 Publication Environmental Biology of Fishes Abbreviated Journal  
  Volume 34 Issue 3 Pages 265-276  
  Keywords (up) Antipredation – Social group – Feeding – Predation risk – Trade-off – Fish  
  Abstract Guppies,Poecilia reticulata, living in stream pools in Trinidad, West Indies, approached a potential fish predator (a cichlid fish model) in a tentative, saltatory manner, mainly as singletons or in pairs. Such behavior is referred to as predator inspection behavior. Inspectors approached the trunk and tail of the predator model more frequently, more closely and in larger groups than they approached the predator's head, which is presumably the most dangerous area around the predator. However, guppies were not observed in significantly larger shoals in the stream when the predator model was present. In a stream enclosure, guppies inspected the predator model more frequently when it was stationary compared to when it was moving, and made closer inspections to the posterior regions of the predator than to its head. Therefore, the guppies apparently regarded the predator model as a potential threat and modified their behavior accordingly when inspecting it. Guppies exhibited a lower feeding rate in the presence of the predator, suggesting a trade-off between foraging gains and safety against predation. Our results further suggest that predator inspection behavior may account for some of this reduction in foraging. These findings are discussed in the context of the benefits and costs of predator inspection behavior.  
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  Call Number Equine Behaviour @ team @ Serial 2176  
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Author Timney, B.; Keil, K. url  doi
openurl 
  Title Visual acuity in the horse Type Journal Article
  Year 1992 Publication Vision Research Abbreviated Journal Vis. Res.  
  Volume 32 Issue 12 Pages 2289-2293  
  Keywords (up) Horse Visual acuity Visual discrimination  
  Abstract We assessed the ease with which horses could learn visual discriminations and measured their resolution acuity. We trained three horses to press their noses against one of two large wooden panels to receive a small food reward. Following training on a series of two-choice discrimination tasks, resolution acuity was measured. Although there was some variability between animals, the best acuity obtained was 23.3 c deg-1. Within the margin of error imposed by limited anatomical data, the obtained values are consistent with predictions based on retinal ganglion cell density estimates and posterior nodal distance/axial length ratios. They suggest that the resolution acuity of the horse is limited by ganglion cell density in the temporal portion of the narrow visual streak.  
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  Notes Approved no  
  Call Number refbase @ user @ Serial 851  
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Author Rubenstein, D. I.; Hack, M. A. doi  openurl
  Title Horse signals: The sounds and scents of fury Type Journal Article
  Year 1992 Publication Evolutionary Ecology Abbreviated Journal Evol. Ecol.  
  Volume 6 Issue 3 Pages 254-260  
  Keywords (up) ommunication – combat – fighting ability – individual identity – signals – information – assessment – displays  
  Abstract During contests animals typically exchange information about fighting ability. Among feral horses these signals involve olfactory or acoustical elements and each type can effectively terminate contests before physical contact becomes necessary. Dung transplant experiments show that for stallions, irrespective of rank, olfactory signals such as dung sniffing encode information about familiarity suggesting that such signals can be used as signatures. As such they can provide indirect information about fighting ability as long as opponents associate identity with past performance. Play-back experiments, however, show that vocalizations, such as squeals, directly provide information about status regardless of stallion familiarity. Sonographs reveal that squeals of dominants are longer than those of subordinates and that only those of dominants have at their onset high-frequency components.  
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  Notes Approved no  
  Call Number refbase @ user @ Serial 506  
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Author Anderson, J.R.; Fornasieri, I.; Ludes, E.; Roeder, J.-J. url  doi
openurl 
  Title Social processes and innovative behaviour in changing groups of lemur fulvus Type Journal Article
  Year 1992 Publication Behavioural Processes Abbreviated Journal Behav. Process.  
  Volume 27 Issue 2 Pages 101-112  
  Keywords (up) Social learning; Lemur fulvus; Dominance; Individual differences  
  Abstract A group of brown lemurs was presented with one or two baited food-boxes requiring a specific type of motor response in order to be opened. Subsequently, four groups containing different combinations of experienced individuals from the original group and naive individuals were tested. Solutions to the problem and access to the food were recorded and considered in relation to social factors. In the original group, two adult males learned to open the boxes, with one male increasingly preventing the other from approaching. In the second group, with the subordinate male and certain females removed, the dominant male tolerated successful performances by a juvenile female. Group 3 consisted of three passive female participants from the original group and a naive female; one of the three original females now became the sole box-opener. The introduction of the subordinate male from the original group into the all-female group led to a sharing of box-opening by this subject and the skilled female. In the final group, intense aggression toward the skilled female by a new, naive adult male resulted in two previously passive females succeeding on some occasions. In lemurs, at least some `scroungers' appear able to learn to perform a new act when the social context permits.  
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  Notes Approved no  
  Call Number refbase @ user @ Serial 576  
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