Population growth of mountain gazelles Gazella gazella reintroduced to central Arabia

Abstract

Captive-born mountain gazelles were reintroduced to Hawtah Reserve in central Saudi Arabia from 1991 to 1995. This study describes the survival, reproduction and changing number of gazelles within the population during the first four years of the programme. The mortality rate was highest during the first month after release, but 69–73% of gazelles survived for ⩾ 1 year and 58–59% survived for ⩾ 2 years. Weaned gazelles < 2 years-of-age had the highest survival rate during the first year after release. The mean annual survival rate for gazelles which survived their first month of freedom was 78%. Predation was a major mortality factor and older gazelles were particularly vulnerable. Rainfall was seasonal, but calves were born throughout the year, with peaks in the number of births during spring and autumn. Females often produced two calves annually. All calves were singletons. The exponential rate of increase (r) of a subpopulation during two years after the last release was 0·275 on a yearly basis. In a wadi protected from domestic livestock, the density of gazelles remained constant after reaching ca. 15 gazelles km−2. By the end of 1994, the estimated number of gazelles in the reserve was 165, more than twice the number released during the previous four years. An important lesson for all reintroductions is that predators can be a major problem even when uncommon. Recommendations are given for selecting gazelles for release during future reintroductions.