SHORT COMMUNICATION Rainfall predicts seasonal home range size variation in nyala Jeanrick Janse van Rensburg 1 | Michael McMillan 2,† | Aleksandra Gi _ zejewska 3 | Julien Fattebert 4 1 Kube Yini Private Game Reserve, Mkuze, South Africa 2 Department of Conservation Ecology and Entomology, Stellenbosch University, Stellenbosch, South Africa 3 unaffiliated 4 School of Life Sciences, University of KwaZulu-Natal, Durban, South Africa Correspondence Julien Fattebert Email: julien.fattebert@gmail.com 1 | INTRODUCTION Optimal foraging theory posits that animals should minimize the size of their home range—the area used to meet their require- ments (Burt, 1943)—around limiting resources (Ford, 1983). Hence individuals ranging in less productive habitats or exploiting patchy resources have larger home ranges (Ford, 1983), and spatio-tem- poral variations in resource availability can lead to changes in home range size (Fattebert, Baubet, Slotow, & Fischer, 2017; van Beest, Rivrud, Loe, Milner, & Mysterud, 2011). In nyala (Tragela- phus angasii), a mixed-feeder antelope, the effects of habitat vari- ability on ranging and space use patterns are poorly understood (Kirby, Shannon, Page, & Slotow, 2008; Lab^ ao-Tello & van Gelder, 1975). A better understanding of the drivers affecting ranging pat- terns in nyala would help the design of evidence-based habitat management strategies. In this highly dimorphic, polygynous species, males are expected to have larger home ranges than the females because of size-dependant metabolic rates (McNab, 1963). In polygynous spe- cies, females are expected to secure access to limiting resources through optimal foraging to successfully raise offspring, while males are expected to range more widely in order to increase mating opportunities with numerous females (Clutton-Brock, 1989; Fattebert et al., 2016). In the rain season, vegetation becomes more palatable with higher protein contents (Duncan & Poppi, 2008), and together with abundance of surface water, this should lead to a reduction of home range size (Bowers, Welch, & Carr, 1990). Alternatively, in the dry season, although food resources are more dispersed, scarcity of surface water could constrain rang- ing patterns around permanent surface water (Smit, Grant, & Whyte, 2007). We investigated seasonal variations of space use patterns in nyala, and tested the effects of sex, and rainfall as a metric of seasonal variability on home range size. 2 | MATERIALS AND METHODS 2.1 | Study area The study area was the northern section of the Mun-Ya-Wana Private Game Reserve (27°92 0 –27°68S, 32°44 0 –32°2 0 E, 265 km 2 ), South Africa. Climate is sub-tropical, with a hot, wet summer from mid-September to March (mean 31.5°C) and a mild, dry winter from April to mid-September (mean 23.5°C), with mean annual rainfall of 788 mm. Approximately 95% of the reserve lies below 100 m a. s. l. In the north, terrain is mostly flat with few gentle slopes, and vegetation consists mainly of open red sand bushveld, closed red sand bushveld and a small portion of sand forest (Mucina & Rutherford, 2006). The reserve has an extensive net- work of dirt roads for game viewing and management purposes (Figure 1). 2.2 | Data collection We immobilized nyala using Ethorphine hydrochlorine (M99). We fit- ted darts with a radio-transmitter for recovery. We outfitted nyala with VHF transmitters (Sirtrack â , New Zealand; 250 g; <1% body mass). We released all individuals at the capture site upon antago- nization with diprenorphine (M5050). We radio-tracked nyala from September 2013 to December 2014. We relocated nyala by hom- ing-in from a vehicle or on foot (Kernohan, Gitzen, & Millspaugh, 2001). Once the tracked animal was in sight, we recorded its reloca- tion to the nearest 50 m using a hand-held GPS receiver (Garmin, USA). We collected rainfall data using rain gauges in the reserve (Table 1). † In memoriam. Accepted: 7 July 2017 DOI: 10.1111/aje.12455 Afr J Ecol. 2017;1–6. wileyonlinelibrary.com/journal/aje © 2017 John Wiley & Sons Ltd | 1