This study took place from March 2015 to April 2018. Field work took place in an urban ecological estate, Meyersdal, Johannesburg, South Africa (26°17′10.4″S 28°05′14.7″E). The climate in the area is warm and temperate, with an average annual temperature of 16 °C, and average precipitation of 723 mm. The warmest temperatures occur in December–February (average minimum of 14 °C and average maximum of 26 °C) and the coldest in July (average minimum of 3 °C and average maximum of 19 °C). The estate (480 ha) consists of residential development interspersed with natural areas dominated by grassland vegetation, with dispersed areas of tree cover and undulating rocky hills [ 25 ]. Numerous outdoor trails for recreational use are located throughout the entire estate, and wildlife also occur in close proximity to human residences and utilize gardens and corridors between residential houses. Several small to large sized mammal game species occur here, as well as numerous smaller mammals, such as rock hyraxesporcupinesand spotted genets. Potential competitors of yellow mongooses include feral and domestic cats, slender mongoosesand black backed jackals, although yellow mongooses are the most abundant carnivore (estimated at 30–40 individuals per 100 ha; pers. obs.). Predators of the yellow mongooses are mostly jackals and a breeding pair of black eagles. Yellow mongooses are also found in neighboring Johannesburg south twons, such as Rosettenville and Alberton, which surround Meyersdal.

The prevalence and relative importance of food categories in the diet were quantified by using two index methods: (1) frequency of occurrence (F.O.), calculated by dividing the total frequency of a food category by the total number of scats analyzed, and expressed as a percentage; and (2) percent occurrence (P.O.), calculated by dividing the occurrence of a food category by the total number of occurrences of all food categories, and expressed as a percentage [ 26 ]. F.O. and P.O. were used since both use the presence, rather than the volume, of diet items to compare items of varying levels of digestibility (e.g., bones versus soft human food; [ 9 ]). Moreover, these two methods have been used in previous studies, allowing for inter-study comparisons [ 24 ]. Plants present in scats were dominated by grasses and leaves. These items do not form part of the yellow mongooses’ diet, and their presence in the scat was attributed to indirect ingestion when consuming other food [ 17 ]. Therefore, plants were excluded from the calculation of percent occurrence to avoid overrepresentation of their importance in the yellow mongoose’s diet.

Yellow mongoose diet was assessed through scat sample analysis. Fresh scat samples were collected from 10 sampling sites ( Figure S1 ), once a month, from March 2015 to March 2016. Total sample size was 1300 scats collected over the entire study period (13 collection periods). Yellow mongoose scats were identified on the basis of their odor and appearance and were easily located at middens near denning sites, characterized by underground dens in the open grassland or in rock crevices above- and belowground. Scat samples were morphologically analyzed using the protocol described by Cronk and Pillay [ 24 ]. The contents of scats were categorized into five types: plants, invertebrates (insects), mammals, birds, and anthropogenic. Previous studies have reported that yellow mongooses feed on amphibians and reptiles, but none were identified in scat samples in this study. To identify common prey items, a sub-sample of 200 scat samples was further analyzed and remains of invertebrates, mammalian and avian prey taxa were morphologically identified to appropriate taxonomic levels (order and family) using reference catalogues, and the assistance of relevant specialists at the University of the Witwatersrand.

A total of 66 sites were sampled throughout the study period ( Figure S1 ). At each site, we recorded the GPS coordinates, the relative distance to human residences (in meters), and the vegetation cover (open: areas dominated by open fields of grasses; or closed: areas dominated by tree cover or dense bushes); these variables aided in identifying relative use of residential areas (as a proxy for access to and potential use of anthropogenic resources) as well as micro-habitat type use. From photographs obtained where a yellow mongoose was present, we recorded the date and time of occurrence; consecutive captures of yellow mongooses within a 10 min time frame were considered as a single occurrence (i.e., the same individual; [ 27 ]). Time stamp data were used to generate the yellow mongooses’ activity patterns.

We used camera trap surveillance to assess the spatial and temporal occurrence of yellow mongooses throughout the estate. Three motion triggered Bushnell Essential ® camera traps were used over the sampling period of May 2015 to March 2016. These were attached to rigid surfaces (rocks/trees/poles) and angled to maximize field of view of wildlife trails. Camera traps were active 24 h a day, and remained at a site for a 2-week period before being moved to a new site approximately 200 m away; no bait was used and camera traps were not placed at known mongoose dens. Camera traps were never placed in the same area in a season but were sometimes placed in close proximity to previous sites in different seasons. Cameras were checked once a week to change batteries and memory cards.

2.4. Home Range and Residential Overlap

Trapping, collaring, and tracking of two male and two female mongooses took place from March 2016 to May 2017. We used single door humane animal traps (80 × 29 × 33 cm galvanized wire mesh) placed at four different sites in different regions of the estate (at least 1 km apart), in an attempt to avoid capturing individuals that were likely to congregate in social groups (resulting in spatial correlation between individual mongooses). Traps were camouflaged, baited with off-cut deli meats, and set out in the early morning before mongoose activity was expected to start. Traps were checked every hour to reduce the stress caused by captivity. Trapped yellow mongoose were immobilized using a 0.06 mL/kg Medatomidine and 6 mg/kg Ketamine, which was administered intramuscularly by a registered veterinarian. We recorded standard weights and body measurements before fitting a GPS collar. Collars were manufactured by Africa Wildlife Tracking (HAWK-UHF device, AWT CC, Pretoria, South Africa), weighed between 65 and 85 g, and were designed with an easy release point that required minimal stress to break when snagged (i.e., repetitive pulling by mongoose would break the collar). To maximize battery life, collars were programmed to record GPS coordinates (hereafter referred to as fixes) every 3 h during daylight hours (between 5 a.m. and 7 p.m.), to coincide with yellow mongoose activity; the 3 h interval accounted for potential spatial auto-correlation between fixes. Once the collar was fitted, the mongoose was returned to the trap, and an anesthetic reversal of 0.3 mg/kg Atipamezole was administered. The veterinarian monitored when the mongoose was mobile again in order to assess whether there was any discomfort or distress from the collar. The collared mongoose was subsequently released at the site of capture.

To collect data from the collars, collared individuals were located by means of the triangulation method, using a hand-held H antenna (AWT CC, 433 MHz), and a portable VHF receiver (HAWK 433 MHz transceiver, AWT CC). Each collar had a reception range of ±1 km, and data could be downloaded from within a ±50 m range of a collared mongoose. Tracking took place on foot. All GPS locations were automatically stored on the collar which required a single download from the receiver every 2 weeks. The receiver was connected to a computer and GPS coordinates were then downloaded for later analysis.