Surveys took place in the Sahamalaza Peninsula, in the province of Mahajanga, Northwest Madagascar (Figure 1). The peninsula covers approximately 26,000 hectares and is defined by the Sahamalaza Bay to the east, the Mozambique Channel to the west and the Loza River to the south (Volampeno, 2009). Parts of the peninsula were designated a UNESCO Biosphere Reserve in 2001, followed by the creation of the Sahamalaza-Îles Radama National Park in July 2007 (Schwitzer et al., 2007).
Figure 1. The Sahamalaza Peninsula in northwestern Madagascar, indicating the study sites of (A) Ankarafa Forest, (B) Antafiabe village, (C) Berara (Anabohazo Forest), (D) Anketsakely (Anabohazo Forest) and (E) Betsimipoaka village.
The area has a sub-humid climate with two distinct seasons: a hotter, wetter season from December to April and a cooler, drier season from May to November. Monthly mean maximum temperature ranges from 28.5 ± 3.61 °C in July to 39.1 ± 2.11 °C in February; while monthly mean minimum temperature ranges from 13.2 ± 0.81 °C in October to 21.8 ± 0.81 °C in January (Volampeno et al., 2011). The mean annual precipitation rate is around 1600 mm (Schwitzer et al., 2007). This climate supports a unique type of hybrid forest, consisting of plant species from both the wetter Sambirano domain and drier Western domain (Birkenshaw, 2004; Schwitzer et al., 2006). The forest consists of a matrix of small fragments isolated by savannah, all subjected to high levels of human disturbance (Schwitzer et al., 2007).
Prior herpetological survey efforts were focused on Analavory Forest (14°23.30’ S, 47°56.15’ E; Raselimanana, 2008), since destroyed by fire in 2004 (Volampeno, 2009), and the Berara Forest fragment in Anabohazo (14°18.6’ S, 47°54.9’ E; Andreone et al., 2001). The present survey revisited Anabohazo, including the fragment of Anketsakely in addition to Berara, and surveyed the Ankarafa Forest (14°22.8’ S, 47°45.5’ E) for the first time. The surroundings of Antafiabe (14°21.3’ S, 47°52.1’ E), and Betsimipoaka (14°19.8’ S, 47°57.8’ E) villages were also surveyed. Surveys were conducted between October 2011 and January 2012, and between January and February 2013. This ensured coverage of the entire wet season, when individuals are expected to be more active, and the end of the dry season.