Argali lamb (Ovis ammon) morphometric measurements and survivorship in Mongolia

• Published in: Mammalia (Paris) Vol. 73; no. 2; pp. 98 - 104
• Main Authors: Reading, Richard P., Kenny, David, Amgalanbaatar, Sukh, DeNicola, Anthony, Wingard, Ganchimeg
• Format: Journal Article
• Language: English
• Published: Walter de Gruyter 01.06.2009
• Subjects: argali; lamb; Mongolia; morphometrics; Ovis ammon; survivorship
• ISSN: 0025-1461; 1864-1547
• DOI: 10.1515/MAMM.2009.021

We examined variables that might affect survivorship of neonatal argali sheep (Ovis ammon), including body weight, date of birth, gender, precipitation, and year affects, which often influence neonatal survivorship in other species of sheep. From 2003 to 2008 we hand-captured 75 argali lambs (38♂, 36♀, 1 undetermined) and attached expandable, drop-off radio collars in Ikh Nart Nature Reserve, Mongolia. We collected morphometric and physiological measurements and radio-tracked lambs to obtain data on survivorship and mortality. We found similar morphometric and physiological measurements for male and female lambs, with significant differences only in foreleg length (♀<♂) and respiration rates (♀>♂). Only 44.6% of argali lambs survive their first month of life, but thereafter their mortality rate decreases. Lambs not born in 2006, born in years following years with higher April precipitation, and born later in the year enjoyed significantly higher survival to one month. We found high mortality in the years with severe drought (2005–2006), which depressed overall survivorship. We found no significant effect of any physiological or morphometric variables on lamb survival. Argali lambs die from several causes, with predation (44.6%) and starvation (21.4%) being the most significant.