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Author Shettleworth, S.J.; Plowright, C.M. openurl 
  Title How pigeons estimate rates of prey encounter Type Journal Article
  Year 1992 Publication Journal of experimental psychology. Animal behavior processes Abbreviated Journal J Exp Psychol Anim Behav Process  
  Volume 18 Issue 3 Pages 219-235  
  Keywords Analysis of Variance; Animals; *Appetitive Behavior; Columbidae; Conditioning, Operant; Food Preferences/*psychology; Motivation; *Predatory Behavior; *Probability Learning; *Reinforcement Schedule; Social Environment  
  Abstract (up) Pigeons were trained on operant schedules simulating successive encounters with prey items. When items were encountered on variable-interval schedules, birds were more likely to accept a poor item (long delay to food) the longer they had just searched, as if they were averaging prey density over a short memory window (Experiment 1). Responding as if the immediate future would be like the immediate past was reversed when a short search predicted a long search next time (Experiment 2). Experience with different degrees of environmental predictability appeared to change the length of the memory window (Experiment 3). The results may reflect linear waiting (Higa, Wynne, & Staddon, 1991), but they differ in some respects. The findings have implications for possible mechanisms of adjusting behavior to current reinforcement conditions.  
  Address Department of Psychology, University of Toronto, Ontario, Canada  
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  ISSN 0097-7403 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:1619391 Approved no  
  Call Number refbase @ user @ Serial 382  
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Author Kaiser, D.H.; Zentall, T.R.; Neiman, E. openurl 
  Title Timing in pigeons: effects of the similarity between intertrial interval and gap in a timing signal Type Journal Article
  Year 2002 Publication Journal of experimental psychology. Animal behavior processes Abbreviated Journal J Exp Psychol Anim Behav Process  
  Volume 28 Issue 4 Pages 416-422  
  Keywords Animals; *Attention; Columbidae; *Conditioning, Operant; Discrimination Learning; Mental Recall; Probability Learning; *Reinforcement (Psychology); *Reinforcement Schedule; Retention (Psychology); Time Factors; *Time Perception/physiology  
  Abstract (up) Previous research suggests that when a fixed interval is interrupted (known as the gap procedure), pigeons tend to reset memory and start timing from 0 after the gap. However, because the ambient conditions of the gap typically have been the same as during the intertrial interval (ITI), ambiguity may have resulted. In the present experiment, the authors found that when ambient conditions during the gap were similar to the ITI, pigeons tended to reset memory, but when ambient conditions during the gap were different from the ITI, pigeons tended to stop timing, retain the duration of the stimulus in memory, and add to that time when the stimulus reappeared. Thus, when the gap was unambiguous, pigeons timed accurately.  
  Address Department of Psychology, East Carolina University, Greenville, North Carolina 27858, USA. kaiserd@mail.ecu.edu  
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  Language English Summary Language Original Title  
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  ISSN 0097-7403 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:12395499 Approved no  
  Call Number refbase @ user @ Serial 238  
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Author Wallner, B.; Brem, G.; Muller, M.; Achmann, R. doi  openurl
  Title Fixed nucleotide differences on the Y chromosome indicate clear divergence between Equus przewalskii and Equus caballus Type Journal Article
  Year 2003 Publication Animal Genetics Abbreviated Journal Anim Genet  
  Volume 34 Issue 6 Pages 453-456  
  Keywords Animals; Base Sequence; DNA, Mitochondrial/genetics; Genetic Variation/*genetics; Horses/classification/*genetics; Male; Molecular Sequence Data; Phylogeny; Probability; Species Specificity; Y Chromosome/*genetics  
  Abstract (up) The phylogenetic relationship between Equus przewalskii and E. caballus is often a matter of debate. Although these taxa have different chromosome numbers, they do not form monophyletic clades in a phylogenetic tree based on mtDNA sequences. Here we report sequence variation from five newly identified Y chromosome regions of the horse. Two fixed nucleotide differences on the Y chromosome clearly display Przewalski's horse and domestic horse as sister taxa. At both positions the Przewalski's horse haplotype shows the ancestral state, in common with the members of the zebra/ass lineage. We discuss the factors that may have led to the differences in mtDNA and Y-chromosomal observations.  
  Address Institut fur Tierzucht und Genetik, Veterinarmedizinische Universitat Wien, Veterinarplatz, Wien, Austria. wallner@i122server.vu-wien.ac.at  
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  ISSN 0268-9146 ISBN Medium  
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  Notes PMID:14687077 Approved no  
  Call Number Equine Behaviour @ team @ Serial 5038  
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Author Hamilton, W.D. doi  openurl
  Title Geometry for the selfish herd Type Journal Article
  Year 1971 Publication Journal of theoretical biology Abbreviated Journal J. Theor. Biol.  
  Volume 31 Issue 2 Pages 295-311  
  Keywords Animals; Anura; *Behavior, Animal; Breeding; Communication; Evolution; Fear; Metallurgy; *Models, Biological; Probability; Snakes; *Spatial Behavior  
  Abstract (up) This paper presents an antithesis to the view that gregarious behaviour is evolved through benefits to the population or species. Following Galton (1871) and Williams (1964) gregarious behaviour is considered as a form of cover-seeking in which each animal tries to reduce its chance of being caught by a predator.

It is easy to see how pruning of marginal individuals can maintain centripetal instincts in already gregarious species; some evidence that marginal pruning actually occurs is summarized. Besides this, simply defined models are used to show that even in non-gregarious species selection is likely to favour individuals who stay close to others.

Although not universal or unipotent, cover-seeking is a widespread and important element in animal aggregation, as the literature shows. Neglect of the idea has probably followed from a general disbelief that evolution can be dysgenic for a species. Nevertheless, selection theory provides no support for such disbelief in the case of species with outbreeding or unsubdivided populations.

The model for two dimensions involves a complex problem in geometrical probability which has relevance also in metallurgy and communication science. Some empirical data on this, gathered from random number plots, is presented as of possible heuristic value.
 
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  ISSN 0022-5193 ISBN Medium  
  Area Expedition Conference  
  Notes PMID:5104951 Approved no  
  Call Number refbase @ user @ Serial 771  
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