The African golden cat Caracal aurata in Tanzania: first record and vulnerability assessment

Abstract We report on the first population found in Tanzania of the Vulnerable African golden cat Caracal aurata, extending its documented range c. 200 km to the south and south-east. This is one of the least-known and truly forest-dependent felines in Africa, ranging across the Guinea–Congolian forest block. We recorded the new population in Minziro Nature Forest Reserve, north-west Tanzania, during a 3-month survey in 2018. We deployed 70 camera traps on a regular grid and obtained 33 detection events of the golden cat at 26% of sites, with a minimum of 10 individuals across 257 km2. We estimated occupancy and detection probability and modelled these in relation to the distance of sampling sites to the forest edge, which coincides with both the Reserve boundary and proximity to human settlements surrounding the Reserve. Mean estimated occupancy was 0.41 ± SE 0.12 (mean detectability = 0.13 ± SE 0.05), with occupancy increasing significantly with distance from the forest edge. Detectability did not vary significantly with distance from the forest edge, but was higher for camera models that had a shorter trigger time. Our findings add to the scant data available for this species. It appears threatened by human activity, which we recorded both outside and within the Reserve, and the presence of the species indicates Minziro Forest is an important site for its conservation.

T he African golden cat Caracal aurata is an elusive, medium-sized felid categorized as Vulnerable on the IUCN Red List, regarded as the least-known wildcat in Africa and one of the least-studied felines (Bahaa-El-Din et al., b). As the only truly forest-dwelling feline in Africa, it is threatened by deforestation, habitat destruction and snaring (Bahaa-El-Din et al., ). Although the population is believed to be decreasing (Bahaa-El-Din et al., a), robust knowledge of the species is scant. The golden cat occurs in West and Central Africa, with an easternmost population recently confirmed in Kenya from a roadkill in the Aberdare Mountains (Hatfield et al., ). Western Tanzania has been regarded as potentially suitable for the species (Butynski et al., ), but no records have previously been reported. Here, we present the first record and results of habitat association modelling for a population of golden cat found in Tanzania in the course of a biodiversity survey in Minziro Nature Forest Reserve. We used a cameratrap survey, and occupancy analysis, to determine the distribution of the golden cat and its association with habitat edges and human disturbance.
Camera trapping was conducted in Minziro Nature Forest Reserve, north-west Tanzania, during  October- December . Established in  and formerly a reserve with lower protection status, it comprises  km  of flat, moist forest at a mean altitude of , m (Rovero et al., ). The northern boundary is the country border, merging with the Sango Bay Forest Reserve in Uganda. All other boundaries adjoin human-modified areas with settlements, plantations and patches of drier woodland and grassland ( Fig. ), with Kagera river and seasonal flooding to the east, and a paved road and several villages to the west. The Reserve is the easternmost extension in Tanzania of the Congo-Guinea forest, with fauna typical of West and Central Africa. The Reserve is heavily disturbed by illegal logging, burning, livestock grazing and fishing occurring in the area (Rovero et al., ). We found evidence of bushmeat hunting: we encountered hunters with dogs on one occasion and found a number of snares, presumably set for ungulates but potentially a threat to the golden cat and other species.
We surveyed  sites across the Reserve using a regular grid of - km  cell size, firstly surveying  camera sites and then  (Fig. ), for a minimum of  days (mean  days) each. We used Browning (Morgan, USA), Cuddleback (Green Bay, USA) and UOVision (Shenzhen, China) cameras, with infrared flash and motion-activated sensor. The trigger speed was . s for Browning, and - s for Cuddleback and UOVision. Cameras were unbaited and attached to trees at c.  cm from the ground, facing a presumed animal trail.
The survey yielded , camera-days from  camera traps (two were stolen). We annotated images using Wild.ID and ran analyses using R . (R Core Team, ). We calculated the number of golden cat detections per day, and used them to derive a relative abundance index. We plotted the species' daily activity pattern using hourly events. We then used single-season occupancy modelling (MacKenzie et al., ) to estimate golden cat occupancy (ψ) and detection probability (p) and their association with presumed covariates. We arranged golden cat detections/non-detections into a site-by-sampling occasion matrix; we chose  days as the resolution of the occasions as with poorly detected species this provides the best estimation of detectability, and hence occupancy (Rovero & Spitale, ). We built parsimonious models using the distance from each site to the closest Reserve border (i.e. forest edge) as a covariate. We derived these distances using QGIS (QGIS Development Team, ) and a :, scale map. Based on our survey of human disturbance, we considered greater distance to the border as a proxy for increasing habitat quality and decreasing human disturbance. We assumed that both ψ and p increase with distance to border. For detection probability we also considered that camera-trap model could potentially influence detection. Using unmarked (Fiske & Chandler, ), we built all model combinations and ranked them according to the Akaike information criterion (AIC). We considered statistically supported models with ΔAIC , . and used AICcmodavg (Mazerolle, ) to average parameter estimates.
After discarding , blank and set-up images, camera trapping yielded , photographs of  species of medium to large wild mammals (Supplementary Table ), including  images of golden cats. These corresponded to  independent detection events of the species within -hour intervals at  sites (naïve occupancy = .; Fig. ). Based on individual pelage marks, we identified a minimum of  individuals. Pelage colouration varied from dark brown to sandy and golden (Plate ). Animals were mainly active at night, with activity peaking at ., . and ., but were also detected in daylight ( Supplementary Fig. ). Based on occupancy model ranking (Table ), we averaged the two most supported models, and the resultant mean estimated occupancy was . ± SE .. Occupancy increased significantly with distance to the Reserve border (. ± SE .; Table , Fig. ). Mean detection probability was . ± SE . and did not vary significantly with distance to the Reserve border but did vary between camera models, with Browning cameras having significantly higher values (Supplementary Table ).
Our findings suggest that habitat intactness and human disturbance affect golden cat occurrence, with increased occupancy with increasing distance from the Reserve border and human settlements. This matches the feline's known sensitivity to anthropogenic disturbance and its vulnerability in human-disturbed areas (Martinez Marti, ; Bahaa-El-Din et al., ). We documented a high incidence of human activities around and within the Reserve, potentially explaining the species' relatively higher occurrence in areas with dense, closed-canopy, continuous forests. A similar pattern has also been reported in Uganda (Mugerwa et al., ). Detection probability was greater with faster cameras, highlighting the importance of standardizing camera models in wildlife surveys: the best performing devices increase the probability of detecting elusive species. Although not exclusively nocturnal, the golden cat activity pattern showed peaks at night, mirroring the cathemeral behaviour reported by Bahaa-El-Din et al. (a). Peaks of golden cat activity may overlap with periods of low human presence and higher prey activity. The minimum number of  individual cats detected gives a naïve density of  per  km  , suggesting that this population may not be as abundant as in other areas. Densities of  individuals per  km  have been reported in pristine habitats in Gabon, and densities similar to our estimates have been reported in highly disturbed and hunted areas (Bahaa-El-Din et al., ). It is possible that the presence of seasonally flooded forest and swamps, mainly on the eastern side of Minziro Nature Forest Reserve, make this habitat type suboptimal for the golden cat. This is the first record of the little-known golden cat in Tanzania, c.  km east-south-east from the closest known populations in Uganda and Rwanda, potentially confirming anecdotal reports of the species in the contiguous Sango Bay Forest in Uganda in the mid s (T. Davenport, pers. comm., ). Pelage pattern suggests the population in Tanzania may be the subspecies Caracal aurata aurata, with spots only on the abdomen and limbs (Bahaa-El-Din et al., a). Given its isolation and the heavily modified habitat, we assume this population is genetically isolated, and thus Minziro Nature Forest Reserve may be an important site for the species' conservation. We also recorded the tree pangolin Phataginus tricuspis and giant pangolin Smutsia gigantea, both Endangered, and the first record in Tanzania of the fire-footed rope squirrel Funisciurus pyrropus. Considering the human encroachment we detected, and ineffective law enforcement, these findings indicate the need for appropriate protection of this forest.