Hurricane-associated population decrease in a Critically Endangered long-lived reptile

Catastrophic events, like hurricanes, bring lethal conditions that can
have population-altering effects. The threatened Caribbean dry forest
occurs in a region known for its high-intensity hurricane seasons and high
species endemism, highlighting the need to better understand hurricane
impacts in combination with habitat fragmentation and loss. However, such
studies remain rare, and for reptiles are mostly restricted
to Anolis. Here we used single-season occupancy modeling to infer
the impact of the intense 2017 Atlantic hurricane season on the critically
endangered Lesser Antillean Iguana, Iguana delicatissima. We
surveyed 30 transects across eight habitats on St. Eustatius during
2017–2019, which resulted in 344 individual surveys and 98 iguana
observations. Analyses of abundance and site occupancy indicated both
measures for 2018 and 2019 were strongly reduced compared to the
pre-hurricane 2017 state. Iguanas at higher elevations were affected more
profoundly, likely due to higher wind speeds, tree damage and extensive
defoliation. Overall, our results indicate a decrease in population
estimates (23.3-26.5%) and abundance (22-23.8%) for 2018 and 2019, and a
75% reduction in opportunistic sightings of tagged iguanas between
2017–2018. As only small and
isolated I. delicatissima populations remain,
our study further demonstrates their vulnerability to stochastic events.
Considering the frequency and intensity of hurricanes are projected to
increase, our results stress the urgent need for population-increasing
conservation actions in order to secure the long-term survival
of I. delicatissima throughout its range. Given
the projected increase and poleward shift of hurricanes, our study
provides important insights from a non-model species.