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Clement, T. S., Feltus, J. R., Kaiser, D. H., & Zentall, T. R. (2000). “Work ethic” in pigeons: reward value is directly related to the effort or time required to obtain the reward. Psychon Bull Rev, 7(1), 100–106.
Abstract: Stimuli associated with less effort or with shorter delays to reinforcement are generally preferred over those associated with greater effort or longer delays to reinforcement. However, the opposite appears to be true of stimuli that follow greater effort or longer delays. In training, a simple simultaneous discrimination followed a single peck to an initial stimulus (S+FR1 S-FR1) and a different simple simultaneous discrimination followed 20 pecks to the initial stimulus (S+FR20 S-FR20). On test trials, pigeons preferred S+FR20 over S+FR1 and S-FR20 over S-FR1. These data support the view that the state of the animal immediately prior to presentation of the discrimination affects the value of the reinforcement that follows it. This contrast effect is analogous to effects that when they occur in humans have been attributed to more complex cognitive and social factors.
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Clutton-Brock, T. H., Russell, A. F., Sharpe, L. L., Brotherton, P. N., McIlrath, G. M., White, S., et al. (2001). Effects of helpers on juvenile development and survival in meerkats. Science, 293(5539), 2446–2449.
Abstract: Although breeding success is known to increase with group size in several cooperative mammals, the mechanisms underlying these relationships are uncertain. We show that in wild groups of cooperative meerkats, Suricata suricatta, reductions in the ratio of helpers to pups depress the daily weight gain and growth of pups and the daily weight gain of helpers. Increases in the daily weight gain of pups are associated with heavier weights at independence and at 1 year of age, as well as with improved foraging success as juveniles and higher survival rates through the first year of life. These results suggest that the effects of helpers on the fitness of pups extend beyond weaning and that helpers may gain direct as well as indirect benefits by feeding pups.
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Eisenmann V, U. H. - P. (1986). Identification and discrimination of Equus metapodials. (pp. 118–163).
|
|
|
|
Fedak Ma, S. H. (1979). Reappraisal of energetics of locomotion shows identical cost in bipeds and quadrupeds including ostrich and horse. Nature, 282, 713–716.
|
|
|
|
Frerichs Wm, H. (1974). Treatment of equine piroplasmosis with imidocarb dipropionate. Vet Rec, 95, 188–189.
|
|
|
|
Green Nf, G. H. (1977). The wild horse population.... Proc National Wild Horse Forum, 1, 59–65.
|
|
|
|
LANG EM, L. E. H. M. A. N. N. E. von. (1972). Wildesel in Vergangenheit und Gegenwart. Zool. Garten., 41, 157–167.
|
|
|
|
Lloyd Ph, H. D. (1980). A case of adaptation and rejection of foals in Cape Mountain Zebra. S Afr Wildl Res, 10, 61–62.
|
|
|
|
Malcom Jr, L. H. (1975). Notes on wild dogs hunting zebras. Mammalia, 39, 231–240.
|
|
|
|
Meadow Rh, U. H. (1986). Equids in the ancient world. Beihefte z Tübinger Atlas d Vorderen Orients Reihe A, 19/1, P.
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