1. School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg 2050, South Africa
2. South African Environmental Observation Network (SAEON), Pretoria 0001, South Africa
3. Department of Geography, Geoinformatics and Meteorology, University of Pretoria, Pretoria 0028, South Africa
4. Department of Biological Sciences, University of Cape Town, Rondebosch 7700, South Africa