Abstract: Opportunities for social learning within a group of animals are likely to be influenced by the social dynamics of that group. Some individuals may be more influential demonstrators than others even when there are no differences in their skill level or performance. In this study of domestic hens,Gallus gallus domesticus, differences in demonstrator salience were examined. From 24 separate flocks we selected as demonstrators a dominant cockerel, a dominant hen, a mid-ranking hen or a subordinate hen. Demonstrators were pretrained to perform an operant discrimination task to obtain food. Six observers from each flock individually watched the demonstrator perform the task for four 5-min sessions held on consecutive days. On the fifth day observers were tested individually in the operant chamber. We analysed data from 19 flocks, where there were no quantitative differences in demonstrator performance. Observer hens of relatively high social status performed more correct operant pecks than observer hens of relatively low social status. Demonstrator category also had a significant effect on subsequent observer behaviour. Hens that had observed cockerels performed very few general pecks or operant pecks. Hens that had observed dominant hens performed more operant pecks, but hens that had observed sub-ordinate hens performed more general pecks in the chamber. The results suggested either that there was an interaction between dominance and gender in demonstrator salience or that dominant hens might have been influential because of some factor imperfectly associated with their dominance status. A possible candidate was the foraging ability of the dominant hens. In a second experiment using the same protocol, we manipulated the prior foraging success of dominant hens from four additional flocks but this had no significant effect on their subsequent influence as demonstrators.

Abstract: Behavioural tests using operant conditioning were conducted to examine how miniature pigs discriminate between people. During a 3-week handling period, six 8-week-old pigs were touched and fed raisins as a reward whenever they approached their handler. In subsequent training, the handler and a non-handler wearing dark blue and white coveralls, respectively, and wearing different eau de toilette fragrances sat at each end of a Y-maze. Pigs were rewarded with raisins when they chose the handler. Successful discrimination occurred when the pig chose the handler at least 15 times in 20 trials (P<0.05: by χ2 test). When all pigs exhibited successful discrimination under these standard conditions, they were exposed to Experiments 1 through 4. In Experiment 1, (1) handler and non-handler exchanged colours of coveralls; (2) handler and non-handler exchanged eau de toilette; (3) handler and non-handler exchanged both cues. The non-handler was chosen significantly more often following the exchange of coverall colours and the exchange of both coverall colours and eau de toilette. However, the handler was chosen significantly more frequently following exchange of eau de toilette only. In Experiment 2, when both handler and non-handler wore coveralls of the handler's original colour, the pigs had difficulty discriminating between them. In Experiment 3, both handler and non-handler wore coveralls of new colours. The pigs easily chose the handler wearing red or blue vs. white coveralls. In Experiment 4, (1) two novel people wore coveralls of the original colours of handler and non-handler; (2) the test with the original experimenters was conducted under the original conditions but in a novel place. Between novel people, the one wearing the handler's original colour of coveralls was preferentially chosen by the pigs. The pigs had difficulty discriminating the handler from the non-handler in a novel place. Pigs appear to discriminate between a familiar handler and a non-familiar person based primarily on visual cues, prominent of which is colour of clothing.

Abstract: Four Arabian horses and one Thoroughbred were presented with a series of two-choice color vs. gray discrimination problems. Testing was done in a stall containing a wall with two translucent panels that were illuminated from behind by light projected through color or gray filters to provide the discriminative stimuli. Horses first learned to push one of the panels in order to receive the food reward behind the positive stimulus in an achromatic light-dark discrimination task, and were then tested on their ability to discriminate between gray and four individual colors: red (617 nm), yellow (581 nm), green (538 nm), and blue (470 nm). The criterion for learning was set at 85% correct responses, and final testing for all color vs. gray discriminations involved grays of varying intensities, making brightness an irrelevant cue. Three subjects were tested with all four colors. Two of those subjects successfully reached the criterion for learning on all four color vs. gray discriminations, while the third reached criterion with red and blue, but performed at chance levels for yellow and green. A fourth horse was only tested with green and yellow, and a fifth only with blue, and both of those horses successfully reached criterion on the discriminations they attempted. With the exception of the one subject's poor performance with yellow and green, there was no significant difference between horses on any of the discrimination tasks, and no significant difference in their performance with different colors. The results suggest that horses have color vision that is at least dichromatic, although partial color-blindness may occur in some individuals.

Abstract: An important question in state-dependent behaviour is how multiple influences on state are integrated to determine current behaviour. Aggressive behaviour is known to be affected by a prior contest experience. Nevertheless, whether and how multiple prior fighting experiences are integrated into a fighting decision remain unexplored. In this study, individuals ofRivulus marmoratus(Cyprinodontidae), a hermaphroditic fish, were given different combinations of two prior fighting experiences to investigate: (1) the effect of penultimate experiences on the probability of winning a subsequent contest; (2) the relative effect of a recent win and loss; and (3) whether the effect of a winning experience was as short lived as observed in other species. Penultimate and recent fighting experiences were given to the test fish approximately 48 and 24 h prior to the dyadic contests, respectively. From the results of the five types of contests staged, we conclude that: (1) penultimate fighting experiences had a significant effect on the probability of winning a subsequent contest; (2) a more recent experience had a more pronounced effect than an earlier experience, which suggested that the effect of a fighting experience would decay and/or the effect of a recent experience would interfere with the effect of an earlier experience; (3) no asymmetric effect between a winning experience and a losing experience was detected; and (4) the effect of both a winning and a losing experience lasted for at least 48 h inR. marmoratuswhich was the maximum time tested in these experiments. The possible reasons for the differences in results among studies of experience effects on contest outcomes are discussed.

Abstract: Description
From reviews of previous editions: “Professional naturalists will find [these volumes] invaluable as a handy reference, and amateurs at least those citizens alive to their earthly environment should delight in finding so much fascinating information made so available and palatable. Audubon ”What an amazing lot mammals are, seen here in all of their diversity! . . . Walker has made available a mine of information, for the specialist as well as for the casually interested . . . If you want to find out about a mammal, then, here is the place to look.“New York Times ”Every mammalogist must have [these books], and those who profess a broad interest in the fauna of the world will want them.“Natural History From aardwolves and bandicoots to yapoks and zorillas, Ernest P. Walker's Mammals of the World is the most comprehensive the pre-eminent reference work on mammals. Now, completely revised and updated, this fascinating guide is better than ever. Providing a complete account of every genus of mammal in all historical time, the sixth edition is 25 percent longer than its predecessor. Of the previous generic accounts, 95 percent have been substantively modified, and there are 80 new ones among them, three remarkable, large ungulates recently discovered in the forests of Indochina. New also is a full account of the woolly mammoth, now known to have survived until less than 4,000 years ago. Each section of the book describes one genus and includes facts such as scientific and common names, the number and distribution of species, measurements and physical traits, habitat, locomotion, daily and seasonal activity, population dynamics, home range, social life, reproduction, and longevity. Textual summaries present accurate, well-documented descriptions of the physical characteristics and living habits of mammals in every part of the world. As in the last two editions, the names and distributions of every species of every genus are listed in systematic order. These lists have now been cross-checked to ensure coverage of all species in the comprehensive new Smithsonian guide, Mammal Species of the World. Facts on the biology of mammals have been brought together from more than 2,700 newly cited references, nearly all published in the last decade. Also new are the latest data on reproduction, longevity, fur harvests, numbers in the wild and in captivity, and conservation status. The sixth edition also records all official classifications of every mammal species and subspecies in the massive 1996 IUCN Red List of Threatened Animals. The illustrations more than 1,700 include virtually every genus of mammal. Among them are pictures by such noted wildlife photographers as Leonard Lee Rue III, Bernhard Grzimek, David Pye, and Warren T. Houck. Mammals pictured here for the first time include the just-discovered giant muntjac deer of Viet Nam, a rodent known only from the Solomon Islands, a large fruit bat whose male suckles the young, and an extremely rare web-footed tenrec of Madagascar. Since its publication in 1964, Walker's Mammals of the World has become a favorite guide to the natural world for general readers as well as an invaluable resource for professionals. This sixth edition represents more than half a century of scholarship? Ernest P. Walker himself devoted more than thirty years to the original project and remains true to Walker's vision, smoothly combining thorough scholarship with a popular, readable style to preserve and enhance what the Washington Post called ”a landmark of zoological literature."
Reviews
“"An absolute treasure trove--a 'must' for the working naturalist as well as for any person who has curiosity about the world's mammals.”Roger Tory Peterson."?
“Unlike many academic reference works, all editions [Walker's Mammals], the new one included, are as accessible to amateurs as to professionals . . . For wildlife enthusiasts, this two-volume set is an indispensable resource. The new edition not only updates taxonomic information generated in the last 10 years, it pushes back the historical record, including all mammals known to have existed in the past 5,000 years. Twenty-one new genera also appear, animals that have recently been discovered. Either volume is hefty enough to kill a small mammal if dropped there's a total of 2,160 pages . . . And despite almost a decade between editions the last edition appeared in 1991 the price has remained virtually the same, despite an increase in book size of more than 20 percent. After being exposed to this kind of thorough, detailed information saturation, many readers may find it hard to go back to a plain old encyclopedia for their animal questions.”Bloomsbury Review
“For anyone who needs an up-to-date, comprehensive guide to every known species of mammal, Walker's Mammals of the World is an essential purchase.”Nicholas Gould, International Zoo News
“A massive compilation ideal for readers who want to have at their fingertips information on every mammal species.”International Zoo News
Author Information
Ernest P. Walker (1891-1969) began work on Mammals of the World in the early 1930s, when he became assistant director of the National Zoo in Washington. His work reflected an unequaled store of knowledge about the world's mammals. Ronald M. Nowak was senior author of the fourth edition and author of the fifth edition of Walker's Mammals of the World. His other works on mammalogy include North American Quaternary Canis and several parts of the National Geographic Society's Wild Animals of North America, for which he also was editorial consultant. He received a Ph.D. in biology from the University of Kansas in 1973 and was staff mammalogist at the former Office of Endangered Species, U.S. Fish and Wildlife Service, from 1974 to 1987. He served as an Air Force officer for four years and is a private pilot.