Biodiversity
Monitoring and surveys
Studying tropical terns on Aruba
Waardenburg Ecology’s long-running research on breeding terns has built internationally recognised expertise in tern ecology, monitoring and spatial behaviour. Water- en Energiebedrijf Aruba N.V. (WEB) drew on this expertise to gain insights into tern populations and their habitat use on Aruba.
20.000 breeding terns
Aruba supports an estimated 20,000 breeding terns, including 15-30% of the global breeding population of Cayenne Terns. The island also hosts breeding Cabot’s, Royal, Sooty, Bridled, Common, Roseate and Least Terns, as well as Brown and Black Noddies. Because the most recent population estimates and assessments date back to 2016, Waardenburg Ecology was invited to assess the current status of breeding colonies and begin research into tern spatial ecology. This work builds on monitoring and training programmes carried out on Aruba between 1998 and 2016 by Dr Adrian Delnevo.
Mapping breeding colonies and tern movements
During an initial visit in May 2026, certified drone pilot and geo-ecological data expert Job de Jong and ornithologist Mark Collier surveyed the offshore San Nicolas Bay Reef Islands and mainland coast. The drone imagery collected during these surveys will be processed using Waardenburg Ecology’s internally developed AI software to identify and count breeding Cayenne and Cabot’s Terns. The imagery will also provide unique insights into the offshore areas used by foraging terns and their breeding status.
Estimates for species that breed in or under vegetation, including Sooty and Bridled Terns and Brown Noddy, were supported by ground counts during colony visits. These visits also provided essential insight into breeding status, potential predation issues and the feasibility of GPS-tracking studies. Such tracking studies will help identify key foraging areas and assess whether terns fly over Aruba’s wind farm, where they may be exposed to collision risk from turbine blades.
A broader understanding of the spatial and breeding ecology of terns on Aruba will help support the long-term protection of these species and their breeding habitats. Additional visits to Parke Nacional Arikok, supported by Aruba Conservation Foundation (ACF), also provided opportunities to identify Least Tern breeding areas in this windswept and rugged coastal landscape.
We are grateful for the support and contributions of all stakeholders including Aruba Conservation Foundation (ACF), Aruba BirdLife Conservation, Utilities Aruba N.V., Vogelbescherming Nederland en Water- en Energiebedrijf Aruba N.V. (WEB), without whom this fieldwork would not have been possible.
Estimates for species that breed in or under vegetation, including Sooty and Bridled Terns and Brown Noddy, were supported by ground counts during colony visits. These visits also provided essential insight into breeding status, potential predation issues and the feasibility of GPS-tracking studies. Such tracking studies will help identify key foraging areas and assess whether terns fly over Aruba’s wind farm, where they may be exposed to collision risk from turbine blades.
A broader understanding of the spatial and breeding ecology of terns on Aruba will help support the long-term protection of these species and their breeding habitats. Additional visits to Parke Nacional Arikok, supported by Aruba Conservation Foundation (ACF), also provided opportunities to identify Least Tern breeding areas in this windswept and rugged coastal landscape.
We are grateful for the support and contributions of all stakeholders including Aruba Conservation Foundation (ACF), Aruba BirdLife Conservation, Utilities Aruba N.V., Vogelbescherming Nederland en Water- en Energiebedrijf Aruba N.V. (WEB), without whom this fieldwork would not have been possible.