Microhabitat Selection of the Tropical Rattlesnake Crotalus simus (Serpentes: Viperidae) at the Southernmost Extent of Its Distribution

Habitat selection is a key ecological process that influences resource acquisition, reproduction, survival, and therefore, fitness. Assessing this process also informs on species management and conservation. However, habitat selection has been understudied in tropical snakes, despite their great diversity and ecological importance. This omission stems from the inherent challenges of researching snakes in the field. We employed radiotelemetry to investigate the microhabitat selection patterns of the Mesoamerican rattlesnake ( Crotalus simus ), a tropical pit viper with a Nearctic origin, at its southernmost distribution. Throughout 2023 and 2024, we monitored 11 adult snakes in Nosara, Costa Rica. We compared environmental and structural features between snake‐selected sites and random sites to assess differences in habitat use between diel period (daytime/nighttime) and origin status (resident/translocated). Rattlesnakes preferred leaf litter as substrate while avoiding other substrate types. They selected higher temperatures, although the effect was stronger during daytime. Humidity preference was stronger in resident individuals and during daytime, while understory complexity was preferred by translocated individuals during the day and avoided by residents at night. All individuals preferred greater distances to water sources and semi‐open areas, favoring locations with lower canopy cover and farther from large trees. Finally, selection patterns for distances to the nearest small tree and fallen log depended on origin status. Our findings demonstrate that microhabitat selection in C. simus is non‐random and shaped by diel period and origin status. The novel insights provided here represent an important first step toward a deeper understanding of this species' ecology.