From banners to microhabitats: how common house geckos utilise illuminated advertisements

Abstract Artificial light at night (ALAN) is a pervasive driver of ecological change in urban ecosystems, yet little is known about how reptiles respond to illuminated structures. We investigated the use of internally lit advertising banners by the common house gecko Hemidactylus frenatus in five Cambodian cities. Field surveys showed an occupancy rate of 28% across all banners. Generalised linear models revealed that gecko presence was positively associated with banner light intensity, whereas gecko abundance increased significantly with banner surface area. Trends indicated slightly higher numbers shortly after dusk and at brighter banners. Other tested variables, including air temperature, ambient noise, mounting height and anchoring type, had no detectable effects. The explained variance of the models was modest, suggesting that additional unmeasured factors, such as insect availability or the possibility of geckos quickly retreating into the banner structure, may play important roles. These findings demonstrate that illuminated banners provide suitable microhabitats for geckos. By concentrating predators, such structures may influence urban trophic interactions and contribute not only to the success of H. frenatus in anthropogenic environments but also to its invasive potential and the displacement of native species.