Cauls Pond

Country/territory: Anguilla (to UK)

IBA criteria met: A2, B4i (2013)
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Area: 43 ha

Site description (2013 baseline)

Cauls’ Pond, is the second largest pond on the Anguilla mainland. It is a large, oblong shaped pond located within the south-eastern area of the island. The pond has a mostly limestone substrate with marl substrate on its western end. The limestone stretches up a slope on its northern, eastern and southern sides. Within the pond, there is a small mud flat ‘island’. There are two access points to the pond: one on the eastern end and one on its western end. 

The pond lies within a relatively undeveloped area. Lying under sea level, it is a water catchment for a large area of land surrounding it. The only development within the surrounding vegetation is the remnants of the Crystal Stream processing plant. An unpaved road that is overgrown by vegetation leads to the building’s ruins. The building was initially constructed by the Government of Anguilla to serve as a desalination plant but due to equipment failure, the plant was closed. 

Vegetation is evenly distributed around the pond. It is primarily scrub-like with a number of native plants lining the pond. Buttonwood mangrove and cacti grow close to the water’s edge, with trees, including mauby, tamarind and cedars, growing just behind the mangrove line.

Hydrological value: 

Cauls Pond is a brackish pond that has several springs. Over the years, some of the springs have closed naturally, some were deliberately blocked and others are still functional. The eastern, northern and southern sides of the pond are elevated above the pond which allows runoff after heavy rains to collect in the pond’s basin. 

Despite the pond’s distance from the sea, the pond is brackish. The source of salt water is believed to be attributed to the pond existing below sea level, the porosity of the base of the pond allows for the introduction of salt water. 

The pond has had no construction of dams or other water management measures.
Currently, monitoring of salinity, phosphates, nitrates, phosphates, pH, turbidity, dissolved oxygen and other gasses does not occur.

Key biodiversity

Overview of bird interests:

The average number of birds observed per month for each of the years studied gradually increased until 2010 where numbers dropped significantly. Bird numbers have continued to increase.

This pond is usually high in numbers of birds observed and has a moderate level of species diversity. An average of 25 different species of wetland birds were observed within the last five years.

IUCN redlisted species observed at this pond include Semipalmated sandpipers (near-threathened), and Caribbean Coot (near-threatened). . In addition, although listed as Least Concern on the IUCN’s Redlist, Least tern are considered endanged in the territories where they are observed, including Anguilla. They are protected within Appendix I of the Biodiversity and Heritage Conservation Act (2009).

Rare and scarce bird sightings at the pond include a group of Lesser Scaup which remained on the pond for three months in early 2011 as well as a few Black-bellied whistling ducks present for two months during mid-2009.

Overview of botanical interests:

The vegetation surrounding the pond’s edge consists primarily of buttonwood mangrove with Turks cap cacti interspersed around its circumference. Behind the perimeter layer of buttonwood mangrove and cacti, a thicker layer of scrub vegetation is present. White cedars, acacia, and mauby are some of the more dominant plants in the area around the pond. 

Within the water of the pond, an aquatic plant - wigeongass (ruppia maratima) - is also present.

Overview of other biodiversity interests:

The pond has a large population of the invasive Giant African snail (Achatina fulica). Their presence is indicated by their shells which have been abandoned which are now being claimed by the native Soldier Crabs (Coenobita clypeatus). 

The vegetation surrounding the pond provides habitat for a few species of spider.


Author: Clarissa Lloyd, Anguilla National Trust.

Edited by: Farah Mukhida, Anguilla National Trust.

Recommended citation
BirdLife International (2023) Important Bird Area factsheet: Cauls Pond. Downloaded from on 30/11/2023.