2.1 Study area and landscape characterization
The study was conducted on 11 islands of the Maldivian archipelago (a number of islands comparable to those investigated by Steibl, Franke & Laforsch, 2021), located in two adjacent atolls, namely the southern part of Faafu and the northern part of Dhaalu atolls, about 150 km from the capital Male (Fig. 1). The temperature in these islands is homogeneous throughout the year, with almost no seasonal variation and a mean of 28°C (Bailey, Khalil, & Chatikavanij, 2015). The natural vegetation is characterized by dense, unfragmented coastal forests, where association of Scaevola taccada, Pemphis acidula, andPandanus spp. are typically found together with coconut palm coastal plantations. Differently, the inner land of inhabited islands is characterized by scattered coconut palms along with large trees such asFicus benghalensis , Artocarpus altilis, and several cultivated fruit or ornamental species. Exotic plant species compose almost 60% of the vegetation of the islands (Sujanapal & Sankaran, 2016). The investigated islands were selected in order to cover a gradient of land-use intensification related to anthropic activities, intended as the proportion of buildings, such as houses or infrastructures devoted to human activities. The distances among adjacent islands range between 1110 m (between islands 8 and 9, Fig 1 ) and 12000 m (between islands 6 and 10, Fig 1). They also differ in terms of inhabitants (0-1600 people ca, Maldives population & housing census, 2014) that leads to a gradient of land-use and habitat fragmentation across islands (Supporting Information, Fig S1). Fragmentation was estimated through the edge density index (i.e. , green patches edge length divided by total area), specifically calculated for the inland green patches (i.e. , gardens, parks and semi-natural green covered patches excluding the usually continuous coastal forest). To estimate edge density, index polygons enclosing the inland green patches have been manually drawn for each island using QGIS 3.16 and Bing Aerial base map updated to 2019. The edge density of inland green patches was calculated through the LecoS QGIS plugin (Jung, 2013). In the five biggest islands (i.e. , those with a major axis greater than 500 m) two sampling sites were selected. Overall, 17 sampling sites were included in the survey (Supporting information -Table S1).
[Fig.1]