The uninhabited islands of the Grenadines are globally important for nesting seabirds and host regionally endemic and endangered reptile species, such as sea turtles – all of which are known to be especially vulnerable to invasive mammal species where they occur. EPIC is documenting invasive mammal species presence at offshore Grenadine islands using several tools, such as baited tracking tunnels and motion-activated cameras.
Invasive species are organisms that are purposefully or accidentally introduced to areas beyond their native ranges, where they establish and become harmful to the local environment, oftentimes with negative consequences for local economies and even human health. Their role in extirpations, when a species is no longer found in a certain area, and extinctions of native species is well documented worldwide.
Introductions of non-native mammal species to the Caribbean region coincides with arrivals of human inhabitants. Domestic animals were often brought along as a source of nutrition and companionship, while others such as rodents were unintentionally introduced. One of the more well-known invasive mammal species in the region is the mongoose, existing on many Caribbean islands, including mainland Grenada and Saint Vincent. While mongooses were purposefully introduced to control burgeoning rodent populations, they have been especially detrimental to native reptile and bird populations throughout the region, including the critically endangered Grenada Dove.
Introduced mammals known to exist on the uninhabited islands of the Grenadines consist of grazing and predatory animals, including goats, sheep, cows, dogs, cats, rats, mice and opossum. While predatory animals can directly injure or kill native species, livestock can trample nests, cause disturbance and significantly reduce plant cover, contributing to erosion and smothering of adjacent coral reef and fisheries habitat.
The “Grenadines Seabird Guardians” citizen scientist group visit offshore islands in Grenada and Saint Vincent and the Grenadines, conducting land and boat-based observations of wildlife, which included documenting the presence of non-native mammals.
Despite legislation prohibiting the release of domestic animals on Crown land and in protected areas in Grenada and Saint Vincent and the Grenadines, research has shown that they regularly occur in such areas with minimal to no intervention. Feral goat populations are prevalent in Wildlife Reserves, in Important Bird Areas (IBAs), on islands in the Tobago Cays Marine Park (TCMP), the Sandy Island Oyster Bed Marine Protected Area (SIOBMPA), and in several proposed marine protected areas. While landholders may graze animals on privately owned islands outside of protected areas, their negative effects on plants and animals at these sites remain uninvestigated and unregulated.
Efforts to remove or manage harmful invasive mammal species in other areas have proven to recover native biodiversity; however, without outreach and education on their negative effects, the likelihood of reintroductions to Grenadines islands is high. A Working Group of local stakeholders has been established to address the impacts of invasive mammals and other issues as part of the Grenadines Seabird Conservation Management Plan. With the support of communities and management agencies, reducing the negative impacts of invasive mammals is feasible.
Funding for this research was provided by the US Agency for International Development (USAID), US Fish and Wildlife Service (USFWS) and with partners Ocean Spirits, the Specially Protected Areas and Wildlife (SPAW-RAC).