Islands are dynamic places that are often vulnerable to rapid disturbances, which could have detrimental effects on local habitats. This can lead to loss of wildlife communities where species endemism is often high. Hurricanes Irma and Maria of 2017 provided an opportunity to study the effects of disturbances on herpetofauna communities in Virgin Islands National Park (VINP), on St. John, US Virgin Islands. St. John lies in the Lesser Antillean chain in the Caribbean Sea, with VINP comprising 60% of the island’s landmass. Eleven species of reptiles and eight species of amphibians are predicted by historic literature and previous surveys to inhabit the island. Standardized survey methods were used first in 2016, and again in 2018, following the 2017 hurricane season, to determine changes in herpetofauna community composition and habitat occupancy. We used visual encounter surveys, vocalization surveys, and recorded any opportunistic encounters to observe herpetofauna species throughout VINP. Surveys took place along trails within VINP and were classified into one of five habitat types. Non-metric multidimensional scaling was used to determine differences in community composition of habitats between 2016 and 2018.
Results/Conclusions
Thirteen species were encountered during visual encounter surveys; eleven in 2016, and nine in 2018. Our results showed no significant changes from 2016 to 2018 in species’ associations with one another and distributions across habitat types (Habitat Type: p=0.06, Year: p=0.8). Species richness only changed in estuarine habitats from 2016 to 2018. Two species of frog were heard vocalizing during our 2016 vocalization surveys, and three species were heard during our 2018 surveys. Five predicted species were not observed at all either during VES or opportunistic encounters. Several species were found to have expanded their range in VINP, including introduced species of lizard and frogs, though we did not record significantly higher number of these species in 2018 compared to 2016.
The lack of change in herpetofauna community composition suggests that the ecosystems of VINP show resilience to high-intensity, low-frequency disturbances. However, increased threats of invasive predators and habitat modification concurrent with increased hurricane intensity due to climate change could prove harmful to herpetofauna populations in VINP. In the future, we would like to initiate a longer-term program to contribute to the monitoring of native herpetofauna, while carefully monitoring the presence of non-native species.