The Janthiel lagoon conservation area consists of about 80 hectares of hypersaline lagoons surrounded by some 228 hectares of woodlands. There is also one spring and several abandoned water catchment dams which harbor freshwater during the rainy season.
This site was one of the key breeding areas for the southern Caribbean population of the Sandwich tern (1200 pairs pre-1962) =12%, but tern breeding is down to less than 100 pairs (Common Tern and Least Tern) due to disturbance. With adequate protection, seabird breeding and flamingo abundance will certainly recover. Caribbean flamingo abundance on Curaçao has steadily increased over the last decades and at present the island has upwards of 200 resident flamingos year-round. These are principally concentrated in the three largest saline lagoons of the island namely Janthiel, Sint Michiel and Rif-Sint Marie. Flamingo abundance is highest during the dry season as freshwater habitats in Venezuela dry up. Curaçao hence appears to be playing an every greater role as a foraging area for the flamingo during certain parts of the year. Compared to the other two large lagoons frequented by flamingos (Sint Michiel and Rif-Sint Marie), the densities of principal flamingo food species (Ephydra cinerea and Artemia salina) were found to be highest and most stable in the Janthiel lagoon (Smelter 2005). This makes the Janthiel lagoon the single most important foraging area for the 200-300 flamingos that are typically present on the island throughout the year (Cuppens and Vogels 2004). Observations have been made of up to 400 birds in a single lagoon (Rif-Sint Marie lagoon). On a typical day, flamingo counts will surpass 75 birds in the Janthiel lagoon and regularly exceed 100 birds. Common Tern nesting is at about 75 pairs on a little island which is somewhat isolated from most recreational disturbance ( >1% Caribbean population). Least Tern number fluctuate from less than 10 to >60 pairs (45 birds is 1% Caribbean population) depending on disturbance levels, which continue to rise. Sandwich Tern (previously 1,200 pairs – will likely recover with less disturbance). Laughing Gull: 3 pairs breeding 2002. Aside from foraging flamingos and nesting terns, the lagoon is visited by flocks of migratory shore birds during the winter months. Hatching brine flies form a boon to swarms of insectivorous fall migrants (swallows and warblers) at the end of the dry season (August and September). During the peak of the dry season the pupfish Cyprinodon dearborni aggregate at the seaward mouth of the lagoon and form an important food source for the breeding terns and large numbers of aquatic birds such as herons, sandpipers, and plovers.
Non-bird biodiversity: The Janthiel conservation area is home to at least ten of the eleven Leeward Dutch Antilles endemic subspecies of birds that breed on Curaçao. An impressive bird list has been assembled for the area, including such rare and endangered raptors as the White-Tailed Hawk and Crested Caracara. Other endemics of the Leeward Dutch Antilles are well represented amongst the reptiles and land snails.
BirdLife International (2020) Important Bird Areas factsheet: Jan Thiel Lagoon, Curaçao. Downloaded from http://www.birdlife.org on 24/01/2020.