Intra-annual variations of microhabitat use and movements of a critically endangered arboreal day gecko endemic to Reunion Island: implications for conservation

Abstract

Habitat loss is the leading cause of reptile decline and therefore, habitat studies are crucial to implement conservation actions. We investigated the microhabitat use of the Manapany day gecko (Phelsuma inexpectata), a critically endangered species endemic to Reunion Island (Western Indian Ocean). Anthropogenic disturbances led to a severe fragmentation of the gecko population, and habitat requirements of this species are poorly known, impeding effective restoration work. We (i) investigated intra-annual variations in microhabitat use, (ii) investigated movement rate to better understand habitat use, and (iii) characterised egg-laying sites. We surveyed two gecko populations in remnant natural habitat annually during five years (2015-2019) and monthly in one of the populations during 18 consecutive months. A total of 2621 gecko detections were recorded and 25 egg-laying sites were characterised. Geckos used mainly native plant species, with a high preference for screw pine thickets. We observed seasonal variations in microhabitat preferences and movement rates. Geckos perched higher and thermoregulated motionless in the canopy during winter. In summer, geckos perched lower, spent less time thermoregulating and exhibited saxicolous behaviour, particularly in females. Egg-laying sites were mainly found in rock cavities surrounded by native plants and facing southwards. Our findings confirm the importance of native coastal vegetation for the conservation of this species. Seasonal shifts of microhabitat use indicate that P. inexpectata (i) need habitats with thermal heterogeneity to adapt to seasonal changes in their thermal environment, and (ii) adapt their microhabitat use according to their reproductive phenology, especially for egg-laying in rock cavities.