Camera Trapping Table Mountain and Constantiaberg - Larger Terrestrial Mammals Approaching Metropolitan Cape Town, South Africa

Table Mountain and Silvermine-Tokai are the two mountain ranges and distinct sections of Table Mountain National Park in closest proximity to the metropolitan megacity of Cape Town, SA. This study used unbaited motion-triggered digital remote camera traps to determine species richness, relative abundance, occupancy, and spatial distribution of medium- to large-sized terrestrial mammals in the 60 km² study range to assist future decisions of conservation stakeholders by providing unprecedented biodiversity baseline datasets.

During 2038 trapping days, 410 individual visits by wild mammals, 1795 individual visits by humans, and 351 individual visits by domestic dogs (Canis lupus familiaris) were evident on the 35 sampling stations. To assess the internal distribution of mammalian wildlife, trapping stations were attributed with covariates like altitude, steepness of slope, mountain aspect, vegetation type, and distance to permanent freshwater sources. The anthropogenic impact on mammalian wildlife was estimated by attributing covariates to the trapping stations such as distance to settlement, distance to public hiking trails, and habitat transformation. The timestamps of capturing events were used to obtain hourly and weekday activity patterns, which were then overlapped to gain insights into the likelihood of interaction between two species.

Humans (Homo sapiens sapiens) were by far the most abundant species. Domestic dogs, the second-most abundant species, accompanied 20.5% of humans. The occurrence of wild or stray dogs was found to be highly unlikely. Humans and dogs were active exclusively diurnally and remained on the hiking paths in over 92% of the cases (p<0.001).

Of all wild species, the Cape Porcupine (Hystrix africaeaustralis, LC) was the most highly abundant, being present in approximately 5% of the trap nights and venturing quite far into suburban spaces. The Large Spotted Genet (Genetta tigrina, LC) was similarly abundant but showed stronger avoidance towards human activity. The Small Spotted Genet (Genetta genetta, LC) was not recorded. The diurnally active Cape Grey Mongoose (Galerella pulverulenta, LC) avoids human activity by retreating to higher altitudes. The Water Mongoose (Atilax paludinosus, LC) was regularly found along riverbeds of lowland streams close to urban settlements. It shares its ecological niche competitively with the Cape Clawless Otter (Aonyx capensis, LC), which was only found in Fish Hoek Valley.

An estimated maximum of 12 individual Caracals (Caracal caracal, LC) roam the study area as the only remaining top predator, preying on rodents, birds, genets, and small antelopes such as the Grysbok (Raphicerus melanotis, LC), which was less abundant but occurred throughout the study area. The recently reintroduced Klipspringer (Oreotragus oreotragus, LC) was the only other antelope found, though it occurred rarely. Three alien species were found in small numbers: the Grey Squirrel (Sciurus carolinensis, LC), the Himalayan Tahr (Hemitragus jemlahicus, NT), and the Sambar Deer (Rusa unicolor, VU). The two latter were previously thought to be exterminated. None of the once ubiquitous rock hyraxes (Procavia capensis, LC) were detected, indicating a dearth of the population.

Three biodiversity hotspots were identified, accumulating 77% of the observed mammal wildlife within just 40% of the surface area: Orange Kloof (a valley south of Table Mountain), Silvermine (a nature reserve at Constantiaberg), and the Tokai pine plantation, which is inhabited by the Northern Cape Peninsula's last Chacma Baboon troops (Papio ursinus, LC).

In summary, the study area offers a stable ecosystem for a small range of terrestrial medium- to large-sized mammal species. However, further conservation efforts are necessary to enhance connectivity between the sampled subsections.