Dynamic social system in Nubian ibex: can a second mating season develop in response to arid climate

We studied a population of Nubian ibex Capra ibex nubiana in the eastern extreme of its range, the hyper-arid central desert of the Sultanate of Oman. Long-term data were collected from January 1983 to December 1997 by direct observation, as well as VHF telemetry on 12 animals (eight from 1987 to 19...

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Bibliographic Details
Published in:	Journal of zoology (1987) Vol. 274; no. 3; pp. 216 - 225
Main Authors:	Massolo, A, Spalton, J.A, Tear, T.H, Lawrence, M.W, Said al Harsusi, L, Lovari, S
Format:	Journal Article
Language:	English
Published:	Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01-03-2008 Blackwell Publishing Ltd
Subjects:	Animal populations Animal reproduction arid environment Arid zones Capra ibex nubiana Climate Goats group size group structure Oman secondary reproductive season Spring Zoology Oman
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Summary:	We studied a population of Nubian ibex Capra ibex nubiana in the eastern extreme of its range, the hyper-arid central desert of the Sultanate of Oman. Long-term data were collected from January 1983 to December 1997 by direct observation, as well as VHF telemetry on 12 animals (eight from 1987 to 1990; four from 1994 to 1996). We recorded 884 sightings: 40.4% of single animals and 59.6% of groups. Although no significant monthly variation of group size (Jarman's Typical Group Size) was found, there were distinct peaks in March (4.0 ind. group⁻¹) and September (5.1 ind. group⁻¹). Groups of males and females formed especially in March and November, and female-kid groups in February and July-August. Our data may suggest two mating periods: the first one in autumn (similar to the rut of ibex in temperate mountain areas), with kids born in spring/early summer, after winter-spring rainfall, and the second one in spring, with kids born in late summer/autumn, before winter-spring rainfalls. We suggest that the second rutting period may have evolved as a micro-evolutionary process, with the local population adapting to hyper-arid environment constraints. The spring mating season may favour only females in prime conditions, who can afford a pregnancy in the local severe summers and will deliver kids when plant greening begins, in the autumn, whereas the autumn (original) mating season may be afforded by any female, but kids will be born in an unfavourable period, before the summer drought.
Bibliography:	http://dx.doi.org/10.1111/j.1469-7998.2007.00373.x ArticleID:JZO373 ark:/67375/WNG-X1MZ11C6-F istex:321135F7EA324760936F27094D3699EBABDF1618 * Current address: Department of Animal Biology and Genetics, Florence University, Viale delle Cascine 18, I‐50144, Florence, Italy.
ISSN:	0952-8369 1469-7998
DOI:	10.1111/j.1469-7998.2007.00373.x