First island-wide assessment of Pope’s head cactus completed

GREAT BAY--The Nature Foundation St. Maarten and the Réserve Naturelle de Saint-Martin have completed the first comprehensive island-wide assessment of the Pope’s head cactus, creating a baseline for monitoring and protecting one of the island’s most recognisable native plants.

The Cactus MAP project, which stands for Mapping, Assessment and Protection, examined the health, distribution and conservation status of the species across both sides of the island. It was the first jointly developed project between the two organisations following the signing of a Memorandum of Understanding in March 2025.

From January to June 2026, teams surveyed six key locations and assessed nearly 4,000 cacti for their health, age structure and exposure to threats. The findings were compiled in a shared ArcGIS database and transboundary distribution map.

Evidence of the invasive cactus moth was found at every surveyed location. Mortality linked to the pest ranged from approximately one to 10 per cent of the cacti counted, while signs of active infestation were often more widespread than the recorded deaths. This suggests that the full effect of recent outbreaks may not yet be visible.

The Pope’s head cactus, scientifically known as Melocactus intortus, grows primarily on rocky slopes, cliff faces and exposed coastlines. Despite its ability to survive in harsh environments, the species faces increasing threats from invasive pests, development, habitat loss and human disturbance.

The assessment also identified differences in legal protection across the island. On the French side, disturbing or uprooting wild Melocactus is prohibited. St. Maarten currently has no equivalent species-specific protection, although the cactus is listed under the regional Specially Protected Areas and Wildlife Protocol.

As part of the project, the organisations documented land ownership at major cactus sites and visited plant nurseries to examine the importation and sale of ornamental cacti. The information is expected to support future discussions on biosecurity and reduce the risk of invasive pests and plant diseases entering through the horticultural trade.

Bilingual classroom materials were also developed in English and French to teach students about native plants, ecosystems and conservation.

The Nature Foundation and the Réserve Naturelle intend to use the findings to strengthen species monitoring, guide conservation policy and expand future surveys. Priorities include monitoring additional locations, improving the use of drones to assess cliffside populations and examining stronger legal protection for the species on St. Maarten.

The project was funded by the Regional Activity Centre for the Specially Protected Areas and Wildlife Protocol, SPAW-RAC.

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