Misplaced Pages

This is a collection of lists of mammal gestation period estimated by experts in their fields. The mammals included are only viviparous (marsupials and placentals) as some mammals, which are monotremes (including platypuses and echidnas) lay their eggs. A marsupial has a short gestation period, typically shorter than placental. For more information on how these estimates were ascertained, see Misplaced Pages's articles on gestational age.

The gestation figures given here are shown in days. They represent average values and should only be considered as approximations.

Factors affecting the gestation period in mammals

There are several factors affecting the length of the gestation period in mammals.

Animal size/mass

There is a positive relationship between mass at birth and length of gestation in eutherian mammals. Larger mammals are more likely to produce a well-developed neonate than small mammals. Large mammals develop at an absolute slower rate compared to small mammals. Thus, the large mammal tend have longer gestation periods than small mammal as they tend to produce larger neonate. Large mammals require a longer period of time to attain any proportion of adult mass compared to small mammals.

The level of development at birth

More developed infants will typically require a longer gestation period. Altricial mammals needs less time to gestate compare to the precocial (well-developed neonate) mammal. A typical precocial mammal has a gestation period almost four times longer than a typical altricial mammal of the same body size. Precocial mammal species generally have greater adult body weights than altricial mammals as precocial mammals have markedly longer gestation periods than altricial mammals. The neonatal of larger mammals develop relatively more quickly and thus making it more likely that a large mammal would produce a more well-developed neonate as a consequence of its longer gestation period. In some cases, some mammal species may have similar gestation periods despite having significantly different body masses.

Environmental factor

In response to the conditions of the environment, some mammals, such as bat delay the implantation due to the cold temperature in winter. Another factor is due to the shortage of food stocks during winter as the insects are being driven away and as the result, bat hibernate in pregnant condition.

In pinnipeds, the purpose of delayed implantation is in order to increase survival chance of the young animals as the mother ensure that the neonates are born at an optimal season.

See also

• Evolution of mammals - Timing of placental evolution
• Gestation

References

Citations

1. infoplease.com > Health and Science > Environment and Nature > Nature > Gestation, Incubation, and Longevity of Selected Animals By James G. Doherty, general curator, The Wildlife Conservation Society. Retrieved on April 9, 2010
2. ^ Langer, P. (2008). The phases of maternal investment in eutherian mammals. Zoology, 111(2), 148-162.
3. Paris Hill Farm. "Alpacas 101". Retrieved 2012-07-14.
4. Northwest Alpacas. "Alpaca Q&A". Archived from the original on 2012-07-21. Retrieved 2012-07-14.
5. ^ Sacher, G. A., & Staffeldt, E. F. (1974). Relation of gestation time to brain weight for placental mammals: implications for the theory of vertebrate growth. The American Naturalist, 108(963), 593-615.
6. Christian R. Abee; Keith Mansfield; Suzette D. Tardif; Timothy Morris, eds. (May 9, 2012). Nonhuman Primates in Biomedical Research: Biology and Management. Academic Press. p. 215. ISBN 978-0-12-397837-0.
7. University of Michigan. "Ursus Americanus". Retrieved 2013-01-16.
8. ^ Ardito, G. (1976). Check-list of the data on the gestation length of primates. Journal of human evolution, 5(2), 213-222.
9. "Pregnant cows, timing of pregnancy, open cows, pregnancy rate".
10. A.Rijnberk, F.J (2005). Anamnese en lichamelijk onderzoek bij gezelschapsdieren, A.Rijnberk, F.J.van Sluis, 2nd print, Bohn Stafleu van Loghum, 2005, (Current Dutch veterinary examination study book for small domestic mammals)
11. ^ Anamnese en lichamelijk onderzoek bij gezelschapsdieren, A.Rijnberk, F.J.van Sluis, 2nd print, Bohn Stafleu van Loghum, 2005, (Current Dutch veterinary examination study book for small domestic mammals)
12. ^ Kiltie, R. A. (1982). Intraspecific variation in the mammalian gestation period. Journal of Mammalogy, 63(4), 646-652.
13. Larry Vogelnest; Rupert Woods (August 18, 2008). Medicine of Australian Mammals. Csiro Publishing. p. 439. ISBN 978-0-643-09928-9.
14. Frances M.D. Gulland; Leslie A. Dierauf; Karyl L. Whitman (20 March 2018). CRC Handbook of Marine Mammal Medicine. CRC Press. p. 408. ISBN 978-1-351-38416-2.
15. The Laboratory Rat, 2nd Edition, Eds. Mark A. Sucklow, Steven H. Weisbroth, and Craig L. Franklin. Page 151.
16. . A timetable of embryonic development, and ovarian and uterine changes during pregnancy, in the stripe-faced dunnart, Sminthopsis macroura (Marsupialia: Dasyuridae). Journal of reproduction and fertility 91 1 (1991): 213-27. DOI 10.1530/jrf.0.0910213
17. Sacher, G. A., & Staffeldt, E. F. (1974).Relation of gestation time to brain weight for placental mammals: implications for the theory of vertebrate growth. The American Naturalist, 108(963), 593-615.
18. Martin, R. D., Genoud, M., & Hemelrijk, C. K. (2005). Problems of allometric scaling analysis: examples from mammalian reproductive biology. Journal of Experimental Biology, 208(9), 1731-1747.
19. Zullinger, E. M., Ricklefs, R. E., Redford, K. H., & Mace, G. M. (1984). Fitting sigmoidal equations to mammalian growth curves. Journal of Mammalogy, 65(4), 607-636.
20. Martin, R. D., & MacLarnon, A. M. (1985). Gestation period, neonatal size and maternal investment in placental mammals. Nature, 313(5999), 220-223.
21. Derrickson, E. M. (1992). Comparative reproductive strategies of altricial and precocial eutherian mammals. Functional Ecology, 57-65.
22. Isler, K., & van Schaik, C. P. (2009). The expensive brain: a framework for explaining evolutionary changes in brain size. Journal of human evolution, 57(4), 392-400.
23. Racey, P. A., & Swift, S. M. (1981). Variations in gestation length in a colony of pipistrelle bats (Pipistrellus pipistrellus) from year to year. Reproduction, 61(1), 123-129.
24. Bradley, S. (2006). The ecology of bat reproduction.
25. Scheffer, V. B., & York, A. E. (1997). Timing of implantation in the northern fur seal, Callorhinus ursinus. Journal of Mammalogy, 78(2), 675-683.

Sources

• Gestation, Incubation, and Longevity of Selected Animals
• David Crystal, The Cambridge Factfinder Cambridge: Cambridge University Press, 1998 (84).
• Online animal encyclopedia
• Study finds wide range in pregnancy length

• Fertility
• Midwifery