Cauls Pond (31359)
Anguilla (to UK), Caribbean
Site overview
KBA status: confirmed
Year of last assessment: 2013
National site name: Cauls Pond
Central coordinates: Latitude: 18.2232, Longitude: -63.0220
System: freshwater, terrestrial
Elevation (m): 0 to 7
Area of KBA (km2): 0.4778
KBA classification: Global/Regional TBD
Legacy site: Yes
Site details
Site description: 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.
Rationale for qualifying as KBA: This site qualifies as a Key Biodiversity Area of international significance because it meets one or more previously established criteria and thresholds for identifying sites of biodiversity importance (including Important Bird and Biodiversity Areas, Alliance for Zero Extinction sites, and Key Biodiversity Areas)
Additional 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.
Other site values: Private/State. None
Delineation rationale: The Anguillan IBA maps were sent to Gill Bunting.
Habitats
Summary of habitats in KBA: The main habitat at Cauls Pond is an expanse of open water which is especially favourable to ducks and pelicans. Within the western half of the pond, the mud flat island is a habitat for birds who feed, roost and congregate. Indeed the trees on this mud flat are utilised by roosting great, snowy, and cattle egrets as well as pelicans. A stand of dead mangrove with dried, exposed branches lies within the western half of the pond. This stand has been found to accommodate roosting groups of the three species of egrets as well as pelicans. The muddy shores along the western end of the pond are ideal for shore birds. This shoreline can extend for several feet when the pond dries. When the pond is full, the water can extend far behind the buttonwood mangroves that that surround the pond’s edge. The limestone pavement is made vibrant with a large population of pope’s head cacti, bromeliads, cedars, and grasses. The limestone shoreline is used mostly by shorebirds and ducks which hide under the vegetation. Current Usage: The vegetation surrounding the pond is used to provide food for livestock as they graze on the surrounding land. The pond is used for the biological control of pests and prevented from serving as a breeding ground for various vectors through the Department of Health Promotion’s Environmental Health Unit’s Vector Control Programme. Recreationally, the pond supports limited bird watching and hiking. It is included in wetlands education material used to educate individuals and groups about Anguilla’s wetlands. The pond also provides habitat for the Least tern, a species considered to be an endangered in the countries along its migration route. The pond is used for research into the population trends of this bird as well as all others observed during the Anguilla National Trust’s Monthly Bird Monitoring Programme. Results of monitoring activities are published in biennial status reports.
Land use: agriculture | nature conservation and research | tourism/recreation
| IUCN Habitat | Coverage % | Habitat detail |
|---|---|---|
| Forest | 48 | |
| Marine Coastal/Supratidal | 48 | |
| Shrubland | 5 |
Threats
Summary of threats to biodiversity at KBA: Plastic bottle caps from the now-abandoned Crystal Stream processing plant operation can still be sound littered across the northern shoreline of the pond. Invasive species around the pond have potential to compete with native species.
Additional information
References: Anguilla National Trust. ANT wetland bird count data (2007 – 2011). Unpublished. Daniels, Edsel B. 2011. Anguilla Wetlands Mapping Project Report: A component of the UK DFID/OTEP funded “Building a Foundation for Anguilla’s Wetland Future” Project. Unpublished Report. Holliday, S.H.; Hodge, K.V.D.; Hughes, D.E. 2007. A guide to the birds of Anguilla. Bedfordshire, England; Royal Society for the Protection of Birds. Lloyd C. and Mukhida, F. 2012. The state of Anguilla’s wetland birds 2007-2011. The Valley, Anguilla: Anguilla National Trust. Raffaele, H.; Wiley, J.;Garrido, O.; Keith, A. ; Raffaele, J. (2003) Birds of the West Indies. New Jersey, USA: Princeton University Press. Subin, E, Dudley, J, Crock, J, Bryan, JAS, Thomas, R, Christian, I, Vanterpool, V & Warner, B (1998) A Field Guide to Anguilla’s Wetlands. Anguilla National Trust, The Valley, Anguilla