“…-GPS (e.g., Valdés-Pizzini et al, 1997;Sidi Cheikh et al, 2009;Daw et al, 2011), -observations and counts made from a fixed point on land or through overhead flights (e.g., Léauté, 1998;Dalton et al, 2010), -individual or collective interviews, sometimes supported by participatory GIS (e.g., Close and Hall, 2006;Hall and Close, 2007;des Clers et al, 2008;St Martin and Hall-Arber, 2008b;De Freitas and Tagliani, 2009;Hall et al, 2009;Lieberknecht et al, 2011;Maes et al, 2012;Moreno-Báez, 2010;Pascual et al, 2013;Leite and Gasalla, 2013;Yates and Schoeman, 2013;Kafas et al, 2014a;Purroy et al, 2014;Léopold et al, 2014;Sullivan et al, 2015;Kafas et al, 2017) feasible combinations which are sometimes tested, namely by Daw et al (2011).…”