Species Density of Galago Moholi at Loskop Dam Nature Reserve, South Africa

African Primates 12: 1-8 (2017)/ 1 Species Density of Galago moholi at Loskop Dam Nature Reserve, South Africa Ian S. Ray1,2,3, Brandi T. Wren2,4, and Evelyn J. Bowers1 1Department of Anthropology, Ball State University, Muncie, IN USA; 2Applied Behavioural Ecology and Ecosystem Research Unit, University of South Africa; 3Department of Social Sciences, Community College of Aurora, Aurora, Colorado USA;4Department of Anthropology, Purdue University, West Lafayette, IN USA Abstract: Galagos are a poorly studied group of nocturnal primates endemic to sub-Saharan Africa, particularly in regard to distribution in southern Africa. We conducted a population survey of Galago moholi along the road system of Loskop Dam Nature Reserve in Mpumalanga, South Africa, during the winter months of June and July, 2011. Results from 151 km of transects that were driven over 23 survey hours indicate that the population density of G. moholi is several times lower than previously reported in similar areas. We estimate the population density at Loskop Dam to be between 1.4 and 5.1 animals/km2, suggesting a population estimate for the entire reserve of 296-1029 animals. This number is substantially lower than the expected density of 95 animals/km2 and total population of 20,000 animals based on previously published density estimates. Low population density may be due to an unknown environmental condition that, in addition, excludes other Galago species from the reserve. Key words: Galago, population density, strepsirrhine, bushbaby INTRODUCTION Bushbabies, or galagos, are small nocturnal Galago moholi averages 158 g and 438 mm in primates endemic to sub-Saharan Africa. Many total length, with a 288 mm tail and a 150 mm head species of galago inhabit overlapping geographical and body (Nash et al. 1989). Previous reports have ranges, though most have differing habitat listed primary food sources of G. moholi to consist preferences when found sympatrically (Nash et al. exclusively of tree gums and small arthropods 1989; Pozzi 2016). The only member of the genus (Bearder & Martin 1980; Harcourt 1986), though Galago endemic to this study’s research site in recent findings have noted the inclusion of plant Mpumalanga, South Africa, is the southern lesser parts in the diet (Scheun et al. 2014; Ray et al. 2016). bushbaby (Galago moholi A. Smith 1836). Based No observations of heterothermy during the winter on current published distribution data (Bearder months of June and July, when insects are scarce, et al. 2008), the thick-tailed bushbaby (Otolemur have been recorded in natural settings (Mzilikazi et crassicaudatus É. Geoffroy Saint-Hilaire 1812) is al. 2006; Nowack et al. 2010, 2013). not found within this study’s locality, although Bearder & Doyle (1974) reported population greater galagos have been observed nearby. There densities of G. moholi that ranged from a low is a significant lack of published field studies on of 95 animals/km2 in escarpment riparian bush galago behavior and ecology, particularly recent and scrub habitat to a high of 500 animals/km2 in studies. This makes it difficult to establish a baseline Vachellia karoo (previously Acacia karoo) thickets. understanding of galago ecology and distribution in That research, however, commenced in 1968 and is southern Africa. now approaching 50 years old. It is likely that those Correspondence to: Ian S. Ray, Department of Social Sciencs, Community College of Aurora, 16000 East CentreTech Parkway, Aurora, Colorado 80011 USA; Email: [email protected]. 2 / Ray et al. numbers are no longer representative due to human 2007). Daily temperatures within the reserve ranged encroachment, habitat changes, anthropogenic from 7°C to 21°C during the study period, and climate change, and changes in land-use patterns from 7°C to 29°C during 2011 (National Center across southern Africa (Hoffman & Ashwell 2001; for Environmental Information 2016). Monthly Thomas et al. 2004; McCusker & Carr 2006). precipitation in 2011 ranged from 0 cm (July) to Further, those estimates vary greatly from 95-500 19 cm (January), with no rainfall occurring during animals/km2 and later studies using radio tracking the study period. The reserve is managed by the found significantly lower densities of 31 animals/ Mpumalanga Tourism and Parks Agency, and the km2 (Bearder 1987). University of South Africa’s Applied Behavioural The goal of this study was to survey the Ecology and Ecosystem Research Unit maintains population of G. moholi at Loskop Dam Nature a research camp within its boundaries. To our Reserve in South Africa to assess its abundance and knowledge, no other research has been conducted distribution. Specifically, our objectives were to: 1) on galagos in LDNR. record sightings of G. moholi; and 2) calculate an estimated population density of G. moholi at the Survey Methods study site. Transects were driven throughout LDNR’s tourist road system between the hours of 1800 and 2200 on MATERIALS AND METHODS 12 nights between June 29 and July 12, 2011 (winter Research Site at the study site). We surveyed a total of 151 km over This project was conducted between June and 23 hours. Transects were driven, not walked, due to July, 2011 at Loskop Dam Nature Reserve (LDNR). safety concerns expressed by reserve management LDNR is located in northern Mpumalanga province, owing to the presence of predators (e.g., leopard) South Africa, with a portion of the reserve extending and large dangerous game (e.g., rhinoceros and into Limpopo province (25°259’ S, 29°189’ E). The buffalo). Transects were selected based on major reserve measures 22,000 ha in size including the road landmarks and driven for approximately three reservoir created by Loskop Dam (Ferrar & Lotter hours per night (Figure 1). Fifteen minute breaks Figure 1. Map of driven transects and sightings in Loskop Dam Nature Reserve, Mpumalanga, South Africa Species Density of Galago moholi in Loskop Dam Nature Reserve / 3 were taken after each transect to avoid observer by selecting cutoff distances, as it was unlikely that fatigue. Transects were between 2.4 km and 7.5 km. all individuals were sighted beyond this distance. All roads were driven at the beginning, middle, and Maximum reliable perpendicular distance was end of a night and in each direction, resulting in a determined by: 1) constructing a histogram of all total of six separate surveys of each transect. Surveys perpendicular distances at which a subject was were scheduled to ensure each segment had not been sighted (Figure 2) and, 2) selecting any low points driven for at least two hours before collecting data. in sighting frequency as cutoffs. In this study, these The following habitat types are present within low points occurred at 15 m and 30 m. Maximum the survey area of this study: Senegalia caffra–Setaria observer-to-animal distance assumes that all sphacelata var. sphacelata woodland, Vachellia individuals within the distance to the farthest karoo–Dichrostachys cinerea shrubland, Vachellia sighting were observed. Maximum reliable observer- nilotica–Senegalia caffra woodland, Heteropogon to-animal distance was determined by constructing contortus–Sclerocarya birrea woodland, Hyperthelia a histogram of all observer-to-animal distances and dissoluta grassland, Lippia javanica–Loudetia simplex selecting any low points in sighting frequency as shrubland, and Olea europea subsp. africana–Rhus cutoffs. In this study, these low points occurred at leptodictya woodland (Barrett et al. 2010). Although 30 m and 50 m. a comprehensive vegetation survey of LDNR has not For all analytical methods, perpendicular been conducted, these habitat types appear to be distance was calculated using the degrees off transect representative of the areas of the reserve that were of the farthest sighting with the formula (sighting surveyed in this study (Barrett et al. 2010; Filmalter distance) sinθ. Observer-to-animal distance was 2010; Nkosi et al. 2016). determined using a laser rangefinder, and thus A Nissan pick-up truck with an open bed (i.e., needed no mathematical adjustment. We used Excel bakkie) was used for surveys. One member of the for all statistical analyses. research team was chosen as the driver and two team members knelt in the bed of the truck behind the RESULTS cab. This provided 360° visibility for the observers above the cab of the truck. Speed varied from 4-13 We recorded a total of 29 individual encounters km per hour with a target speed of 10 km per hour, of G. moholi (Appendix 1). Observer to animal consistent with the methodologies of other vehicle distance ranged from 5 m to 95 m. Calculated surveys (Nekaris & Jayewardene 2004; Off et al. 2008; perpendicular distances ranged from 0 m to 65 Leca et al. 2013; Acharya et al. 2015). Galago moholi m. The various methods used yielded a range of were spotted by the distinctive red tapetal reflections estimates from 0.96 ± 0.02 animals/km2 to 5.02 ± using 600 lumen LED torches with an illumination 0.11 animals/km2 (Table 1). Due to the low number distance of 412 m. We recorded measurements for of sightings, it was possible to determine only a each of the following variables for every sighting: maximum reliable sighting distance for the entire distance to the individual using a laser rangefinder, a survey area and not for each individual transect. compass bearing to the individual from the transect, The mean perpendicular distance method resulted and GPS coordinates of the vehicle. in the highest density estimate of 5.02 animals/km2, while the mean observer to animal distance method Analysis resulted in a more conservative estimate of 2.97 Transect data were analyzed using six animals/km2. The maximum perpendicular distance methods presented by the (National Research method yielded a density estimate of 1.58 animals/ Council Subcommittee on Conservation of km2, while the maximum observer to animal Natural Populations 1981).

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