Abstract
Age-specific fertility is an essential parameter of life history. Here we report age-specific fertility rates, measured as the number of foals per mare per year, for Jeju ponies aged 2–28 years. The total sample consisted of 545 foals produced by 178 mares from 1988 to 2002. The mean fertility rate across all ages of the mares was 0.65 foals/mare per year (±0.24 SD). The fertility rates were above average for the 7- to 8- and 19- to 20-year-old mares, whereas they were relatively low for mares under 4 years old. The fertility rates tended to increase with the age of the stallion, but the relationship was not significant (n =15, P =0.09). The incidence of inter-birth interval was not associated with the age that the mare first reproduced (n =64 mares, P =0.99). However, mares that reproduced later in life tended to have a reduced fertility rate due to an increase in the duration of inter-birth intervals relative to mares that reproduced earlier (n =4 years of first reproduction, P =0.068). The fertility rates of Jeju ponies were lower than for other horses, perhaps because only one stallion was introduced to a relatively large herd every year. We suggest that the introduction of more stallions to the herd each year would increase fertility rates.
References
Berger J (1986) Wild horses of the great basin. Social competition and population size. The University of Chicago Press, Chicago
Côté S, Festa-Bianchet M (2001) Reproductive success in female mountain goats: the influence of age and social rank. Anim Behav 62:173–181
Davies Morel MCG, Gunnarsson V (2000) A survey of the fertility of Icelandic stallions. Anim Reprod Sci 64:49–64
Duncan P (1992) Horses and grasses: the nutritional ecology of equids and their impact on the Camargue. Springer, Berlin Heidelberg New York
Hugason KM, Arnason TH, Jonmundsson JV (1985) A note on the fertility and some demographical parameters of Icelandic toelter horses. Livest Prod Sci 12:161–167
Keiper RK, Houpt KV (1984) Reproduction in feral horses: an eight-year study. Am J Vet Res 45:991–995
Levine MA (1999) Botai and the origins of horse domestication. J Anthropol Archaeol 18:29–78
Magistrini M, Vidament M, Clement F, Palmer E (1996) Fertility prediction in stallions. Anim Reprod Sci 42:181–188
Ropstad E (2000) Reproduction in female reindeer. Anim Reprod Sci 60–61:561–570
Rubenstein DI (1986) Ecology and sociality in horses and zebras. In: Rubenstein DI, Wrangham RW (ed) Ecological aspects of social evolution. Princeton University Press, Princeton, N.J., pp 282–302
Stearns SC (1992) The evolution of life histories. Oxford University Press, New York
Author information
Authors and Affiliations
Corresponding author
About this article
Cite this article
Rho, J.R., Srygley, R.B. & Choe, J.C. Age-specific fertility rates of the Jeju pony ( Equus caballus). J Ethol 22, 113–117 (2004). https://doi.org/10.1007/s10164-003-0104-0
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10164-003-0104-0