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Accueil du site → Master → Etats Unis → 2014 → Desert bighorn sheep adult female and lamb survival, cause-specific mortality, and parturient female habitat selection in the Peloncillo Mountains, New Mexico, USA

New Mexico State University (2014)

Desert bighorn sheep adult female and lamb survival, cause-specific mortality, and parturient female habitat selection in the Peloncillo Mountains, New Mexico, USA

Karsch, Rebekah Catherine

Titre : Desert bighorn sheep adult female and lamb survival, cause-specific mortality, and parturient female habitat selection in the Peloncillo Mountains, New Mexico, USA

Auteur : Karsch, Rebekah Catherine

Université de soutenance : New Mexico State University

Grade : Master of Sciences (MS) Wildlife Sciences 2014

Résumé
When adult female survival is high and relatively constant from year to year, juvenile survival is the primary demographic rate affecting population growth. Juvenile recruitment in desert bighorn sheep is highly variable from year to year, yet influencing factors are not well understood. The objective of this study was to estimate lamb survival rates. I captures and radiocollared 12 neonatal desert bighorn in 2012 and 14 in 2013 in the Peloncillo Mountains, New Mexico. There were 14 mortalities ; 12 of which were due to predation, which was the leading proximate cause of mortality. I used the nest survival model in program MARK to estimate survival to 6 months of age. Model S₁[subscript wk,]>₁[subscript wk] performed the best in 2012, indicating that a 2-stage age interval (1 week and > 1 week) best explained survival. Survival estimate in 2012 for 1 week was 0.92 (SE = 0.08) and average weekly survival for >1 week was 0.99 (SE = 0.006). Survival in 2013 was best explained by a 3-stage age interval model S₁[subscript wk, 2-8 wks, and > 8 wks]. Survival estimate for 1 week, and average weekly survival for 2-8 weeks and >8weeks were 0.77 (SE = 0.11), 0.89 (SE = 0.04) and 0.89 (SE = 0.016), respectively. Precipitation patterns directly affect plant growth in desert environments, thus influencing forage quality ; which past studies have shown effects female condition and survival of young. Precipitation and forage conditions alone, however, do not fully explain the high annual variability in recruitment during this study. The indirect effect of long-term drought on lamb survival may be compounded by the cumulative negative effects of a multi-predator system. Past studies have shown that in multi-predator systems, ungulates may select or avoid particular resources in an attempt to minimize predation risk. Furthermore, prey switching may be especially pronounced in arid systems where drought lowers the abundance of primary prey, and pulses of resources vary dramatically with seasonal fluctuations. Thus, predation should be considered an additive source of mortality, not as a wholly separate factor from forage conditions during periods of drought.

Sujets : Desert bighorn sheep— Mortality— Peloncillo Mountains (Ariz. and N.M.) Desert bighorn sheep— Habitat. Habitat selection.

Présentation (NMSU Library)

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