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Lloyd P,. (1984). The Cape Mountain Zebra 1984. Afr Wildl, 38, 144–149.
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Mccort Wd,. (1984). Behavior of feral horses and ponies. J Anim Sci, 58, 493–499.
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Penzhorn Bl,. (1984). Dental abnormalities in free – ranging Cape mountain zebras. J Wildl Dis, 20, 161–166.
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Penzhorn Bl,. (1984). Observations on mortality of free – ranging Cape mountain zebras. S Afr Wildl Res, 14, 89–90.
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Reichholf J,. (1984). Funktion und evolution des Streifenmusters bei den zebras. Säugetierk Mitt, 32, 89–95.
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Vogt H,. (1984). Quagga: DNA konserviert. Naturwiss Rdsch, 37, 327–328.
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Keiper, R., & Houpt, K. (1984). Reproduction in feral horses: an eight-year study. Am J Vet Res, 45(5), 991–995.
Abstract: The reproductive rate and foal survival of the free-ranging ponies on Assateague Island National Seashore were studied for 8 years, 1975 to 1982. Most (52%) of the 86 foals were born in May, 13% were born in April, 22.6% in June, 10.4% in July, and less than 1% in August and September. The mean foaling rate was 57.1 +/- 3.9% and the survival rate was 88.3 +/- 3.6%. Forty-eight colts and 55 fillies were born (sex ratio 53% female). Mares less than 3 years old did not foal and the foaling rate of 3-year-old mares was only 23%, that of 4-year-old mares was 46%, that of 5-year-old mares was 53%, and 6-year-old mares was 69%. The relatively poor reproduction rate was believed to be a consequence of the stress of lactating while carrying a foal when forage quality on the island was low. The hypothesis was supported by the higher reproductive rate (74.4 +/- 2.4%) of the ponies in the Chincoteague National Wildlife Refuge on the southern part of the island. Their foals are weaned and sold in July each year. Despite the low reproductive rate on Assateague Island National Seashore , the number of ponies increased from 43 to 80, a 90% increase in the 8-year period or greater than 10%/yr. There were 24 deaths and 8 dispersals from the study area.
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DUNCAN P et al,. (1984). On lactation and associated behaviour in natural herd of horses. Hans Klingels Equine Reference List, 32, 255–263.
Abstract: Developmental changes in time spent suckling and related mother-foal behaviour are described in an unmanaged herd of Camargue horses. Male foals spent about 40% more time suckling than females during the first 8 weeks. Body weight did not differ between the sexes but time-budgets did: males grazed less and were more active. If pregnant, the typical multiparous mare nursed her foals for 35–40 weeks, males and females alike, and weaned them 15 weeks before the next foaling. Primiparae lactated longer and weaned closer to the next foaling by 5 weeks. The mares played an active role in regulating the time spent suckling in early, and particularly in late lactation.
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Sherry, D. F., & Galef Jr, B. G. (1984). Cultural transmission without imitation: Milk bottle opening by birds. Anim. Behav., 32(3), 937–938.
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Kacelnik, A., & Houston, A. I. (1984). Some effects of energy costs on foraging strategies. Anim. Behav., 32(2), 609–614.
Abstract: We consider the effect of including energy costs on the optimal strategy for animals exploiting a depleting food resource. In the context of central place foraging this leads to the problem of what load size should be brought back to the central place. Two strategies are discussed: (i) maximize gross rate of energy delivery and (ii) maximize net rate of energy delivery. The optimal load size (or optimal patch time) for net maximizers is not always larger than for gross maximizers, as has been claimed. Instead, the difference in optimal load size has the same sign as the difference between metabolic rates of travelling and foraging. We point out that the influence of costs has not always been correctly incorporated in experimental tests of the theory.
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