Range use by an adult male caracal in the southern Kalahari

1. What they did

The size of a wild cat’s home range depends mostly on hunting success, especially the number of hunting places, cover and how much prey there is. In dry areas, where prey varies and cover is sparse, the authors expected caracal ranges to be larger than elsewhere. They tested this with one adult male caracal in the south-western Kalahari Gemsbok National Park, South Africa.

• Capture and collaring. The caracal was caught on 26 January 1990 in the red dunes south-west of Hakskeenpan, on the park boundary with the Mier farming area. They were fitted with a radio collar and released at Kamqua in the Auob riverbed.
• Aerial tracking. From 26 January 1990 to 12 August 1991, the authors located the caracal at irregular intervals from a light aircraft (a Cessna 206), using a left-right antenna switch and circling over the spot.
• Mapping. They plotted 18 locations on computer mapping software and measured the observed range as a minimum convex polygon (the smallest outline that encloses all the locations). The core area was the part of the range where locations were clearly clumped.
• Comparing. They compared this range with the only published range sizes for caracals in South Africa at the time.

2. What they found

• The observed range was 308.4 km² and the core area 93.2 km². Thirteen of the 18 locations fell in the core area.
• The range was significantly larger than the mean range of four adult males in Mountain Zebra National Park (15.2 km²). It was also far larger than the ranges reported in the south-western Cape (a young male settled into a range of 65 km² after moving widely over 483 km²) and West Coast National Park (two males averaged 26.97 km², the largest 32.87 km²).
• 61.4 km² of the range (19.9%) lay on the neighbouring Mier farms, outside the park.
• The range held four known waterholes, although caracals do not need to drink. Its northern edge roughly followed the Auob riverbed.
• The caracal used the whole range during the study. Their last two locations, at opposite ends of the range (2 km east of Hakskeenpan and 5 km east of Groot Skrij), were visited within 22 days.
• After release at Kamqua, the caracal returned to near their capture site, about 25 km in a straight line.

3. What they concluded

• These are the first range data for caracals in the extremely arid south-western Kalahari.
• The caracal’s return from the release site to near the capture site points to homing behaviour and a stable range.
• Although minimum convex polygons can be biased with fewer than 25 locations, the authors consider 18 locations probably a fair estimate of an adult male caracal’s movements in the area.
• Home ranges of carnivores grow when food is limited, and food is limited in arid areas. This study gives a first idea of the range and core area an adult male caracal needs in the arid Kalahari, much larger than any caracal home range then known in the Cape Province.

4. How tracking was or was not used

Tracks and signs were not used. The authors’ keywords say “aerial tracking”, but this means locating the caracal’s radio collar from an aircraft.

6. Other technologies, skills or innovations

• Telonics radio collar working at 148 to 150 MHz (very high frequency, VHF).
• Aerial radio-tracking from a Cessna 206 with a cabin-mounted left-right switch.
• Locations plotted with Microstation PC mapping software, and areas measured with a Geographic Information System (GIS).