SINT MAARTEN (GREAT BAY) - Sint Maarten's iconic Pope's head cactus (Melocactus intortus) is the focus of the first jointly developed conservation project between the Nature Foundation Sint Maarten and the managers of the Réserve Naturelle de Saint-Martin (AGRNSM).
Supported through funding from SPAW-RAC, the organizations have announced the completion of the Cactus MAP (Mapping, Assessment, and Protection) project, a transboundary initiative designed to assess the health, distribution, and conservation status of this unique native species across the island of Saint Martin.
The project represents the first comprehensive island-wide baseline assessment of the species and the first co-developed project between the two non-profit organizations since a Memorandum of Understanding (MoU) was signed in March 2025.
Locally known as the Pope's head cactus among English speakers and tête à l'anglais among French speakers, Melocactus intortus is one of the island's most recognizable native plants. The species is known for its melon-shaped body and tall red cephalium, or "crown," which develops when plants reach maturity.
Adapted to survive in harsh coastal environments, it grows on rocky slopes, cliff faces, and exposed shorelines where few other plant species can persist. Despite this resilience, the species faces increasing pressure from invasive pests, habitat loss, development, and human disturbance.
Working together under the coordination of project fellow Joshua Bruns from January to June 2026, teams from the Nature Foundation and AGRNSM surveyed six key sites across both the Dutch and French sides of the island.
Nearly 4,000 individual cacti were assessed for health, age structure, and evidence of threats. On the French side, surveys used AGRNSM’s established method, previously used in in 2021 and 2016. The resulting information was compiled into a shared ArcGIS database and transboundary distribution map.
Most notably, evidence of the invasive cactus moth (Cactoblastis cactorum) was recorded at every survey location. Mortality linked to the moth ranged from approximately 1% to 10% of individuals counted.
In addition, signs of active infestation were frequently more widespread than observed mortality, suggesting that the full impacts of recent outbreaks may not yet have been realized.
"Where infestation levels are high, but mortality remains relatively low, cactus deaths may simply not have caught up with the spread of the pest," explained Bruns. "Fort Amsterdam is a clear example of this pattern, with approximately 8% of cacti surveyed showing signs of attack despite limited recorded mortality."
The project also highlighted differences in legal protection for the species across the island. On the French side, disturbing or uprooting wild Melocactus is prohibited by law. On the Dutch side, no equivalent species-specific protection exists, despite the species' listing under the regional Specially Protected Wildlife (SPAW) Protocol, to which Sint Maarten is a Party.
To support future conservation action and legislation, Cactus MAP documented land ownership patterns at major cactus sites, creating future opportunities for direct engagement with private landowners.
Staff also visited plant nurseries to understand how cacti are traded, documenting which species are sold and where ornamental cacti are imported from. These findings will support future discussions on biosecurity measures and help reduce the risk of introducing invasive pests and plant diseases through the horticultural trade, and are particularly timely given the recent launch of a joint biosecurity program between the Nature Foundation and the Sint Maarten Ministry of Justice.
Finally, both education and outreach formed a core part of the project. The team developed bilingual classroom lesson plans in English and French that use Melocactus to explore basic ecological concepts and the importance of protecting native plants.
The Nature Foundation and AGRNSM intend to use the data and experience generated through Cactus MAP to support evidence-based conservation policy, strengthen terrestrial species monitoring programs, and bring more attention to the role Melocactus plays in dry coastal ecosystems. Future priorities include expanding surveys to additional sites, improving drone-based monitoring of difficult-to-access cliff populations, and exploring stronger legal protections for the species on the Dutch side.
Interested readers can learn more by visiting naturefoundationsxm.org/cactus-map and visiting the interactive ArcGIS Story Map at https://arcg.is/jWv1r1. The project is funded by the Regional Activity Center for the Protocol Concerning Specially Protected Areas and Wildlife (SPAW-RAC), which is primarily financed by the government of France.
It operates under the United Nations Environment Programme’s (UNEP) Regional Coordination Unit to implement the SPAW Protocol, focusing on the protection of marine and coastal biodiversity in the Caribbean region.
- Group at Cactus Place, Saint-Martin | Photo credit: AGRNSM
