Spatial organization of mountain gazelles Gazella gazella reintroduced to central Arabia

Abstract

Captive-born mountain gazelles (Gazella gazella), including 28 radio-collared and 54 tagged animals, were freed in Hawtah Reserve, Saudi Arabia, during 1991–95. The size (as minimum-area convex polygons) and spatial distribution of their individual ranges were determined from daytime radiotracking and sightings. Some adult males were territorial and territorial fidelity was >94%. Territories were maintained year-round and were arranged linearly along the wadi floor. Initially, the size of territories decreased as their density increased, but after density stabilized, median territory area was 0.6 km2. The ranges of up to four released females were centred on each territory and female core areas were arranged in clusters along the wadi. Female ranges became smaller as the density of territories increased. After females had dispersed, their annual range averaged about 1 km2 during both 1993 and 1994 in wadis without domestic livestock and where, consequently, plant standing crop was high. Where camels foraged and plant standing crop was low, female ranges averaged 4.6 and 1.6 km2 during these two years. Some females shifted their core area, and their annual range was twice as large. The range area of non-territorial males averaged 6.7 km2 and extensively overlapped the ranges of other bachelors. Bachelor males occasionally passed through territories, but some wadi sections were used often by bachelors and seldom by females. The size and spatial distribution of gazelle ranges did not change seasonally, despite the temporal variation in rainfall. Runoff concentrated in wadis and the consistent food supply there allowed gazelles to occupy small ranges, even though annual rainfall was low (<150 mm).