Introduction

The island of Grenada is home to only two endemic terrestrial vertebrates, the Grenada Dove (Leptotila wellsi) and the Grenada Frog (Pristimantis euphronides, P.e. hereafter). Both are Critically Endangered (IUCN Red List).  The Grenada Dove is featured on the national emblem and is considered to be a national treasure. By contrast, the Grenada Frog is virtually unknown. Strategic and innovative outreach efforts to increase awareness for the Grenada frog and engage citizens would amplify the impacts of conservation actions. A lack of basic demographic information and awareness for Grenada frog drives the overall aims of our research project: 1) to assess species range, demography, and population connectivity for this endemic montane frog, 2) to understand the impact of the disease chytridiomycosis caused by the fungal pathogen Batrachochytrium dendrobaditis (Bd), and 3) to increase awareness of this unique species through targeted, long-term education and outreach activities.

Previous research has focused on assessing the relationship between the Grenada frog and the introduced Johnstone’s Whistling frog (Eleutherodactylus johnstonei) in three populations in different habitat types. While the Johnstone’s Whistling frog does negatively impact the Grenada frog in these three populations, this impact was only detected when the data were pooled. When analyzed separately, the populations showed that the two species were positively correlated. These findings suggest that fluctuations in numbers for both species were caused by other factors (Harrison, B. C. 2021. Habitat and Conservation of the Endemic Grenada Frog (Pristimantis euphronides) (Master’s thesis, University of Wisconsin–Stout).

We worked with the IUCN in 2021 on the Lesser Antillean amphibian assessment to develop extant range data based on mapping and quantitative analysis to update the status of the Grenada frog. to “Red List, Critically Endangered”. The status change was warranted because the Grenada frogmet requirements such as habitat fragmentation significantly limiting dispersal and gene flow, reduced global footprint, threats from development, climate change, invasive species, and disease, among others (Harrison, B. C. 2021. Habitat and Conservation of the Endemic Grenada Frog (Pristimantis euphronides) (Master’s thesis, University of Wisconsin–Stout). The 2021 project mapped the current, known Grenada frog range for the IUCN as well as habitat suitability across the island based on elevation limitations, long-term surveys, scouting and current land-use maps.

All ten amphibians native to the Lesser Antilles have now been assessed by the IUCN and among them only the Mountain chicken (Leptodactyllus fallax) and the Grenada frog are listed as Critically Endangered.

Current Focus

Our previous work led to the IUCN updating the status for the Grenada frog from “Endangered” to “Critically Endangered”. There are only ten amphibians native to the Lesser Antilles and many among them are limited to rapidly shrinking regions of remaining habitat (Heatwole, H. & Rios-Lopez, N. 2023. The Conservation and Biogeography of Amphibians in the Caribbean. Pelagic publishing). Because the Grenada frog is limited to upper elevation areas of pristine habitat, significant fragmentation is likely limiting connectivity among populations. Small and isolated populations are not only less demographically stable than large populations, but also are more susceptible to erosion of genetic variation through genetic drift. A lack of genetic variation in turn makes populations more vulnerable to inbreeding depression and less able to adapt to changing environmental conditions.  For these reasons, data on genetic diversity and population connectivity will be essential for identifying populations with the highest conservation priority to maintain long-term viability for this species.