Brown, A.C.

Audubon’s Shearwater (Puffinus lherminieri), known locally as Wedrego on Saba and St. Eustatius, is a medium-sized seabird species that feeds at sea and nests on islands throughout the Caribbean and worldwide. The species is known to nest on Saba, however estimates vary widely on the island population. The shearwaters are active on-island at night when they fly in off the sea to their nests which consist of burrows or natural cavities. Globally and in the Caribbean, Audubon Shearwater populations are threatened by introduced predators such as cats, rats, and goats.

Researchers have traditionally noted the extreme limitations of using conventional aural and visual methods when surveying species such as shearwaters that visit breeding areas only at night. Work on individual vocalization patterns has been developed for other species (Fernandez and Delnevo 2009), and on-going efforts are being pursued for Wedrego. These techniques are being developed, and tested for future use. However, currently, and in general, population estimates for this species can be fraught with uncertainty, variable accuracy, and broad statistical and biological confidence limits.

Marine radar has proven effective as an observation tool, to obtain accurate, reliable counts of species, their daily timing and pattern of movements, that are otherwise difficult or impossible to observe directly, such as the Marbled Murrelet (Day and Cooper 1995), and the Black-capped Petrel (Brown 2012; Brown 2013). These studies demonstrated that radar is an effective observation and monitoring tool that far extends researchers’ ability to observe and monitor nocturnal seabirds, and enables accurate, consistent counts.

Little is known regarding the species on Saba, including how many individuals are present on the island, probable nesting areas, and flight paths the species use between at-sea foraging areas and on-island nest areas. Without a basic understanding of these parameters it is difficult to identify and prioritize conservation actions.

Herein, we describe a pilot study that used marine radar on Saba from 11-17 December 2014 to survey for Audubon’s Shearwaters. 

St Maarten’s IBAs—the country’s international site priorities for bird conservation—cover 815 ha (including marine areas), and about c.36% of the country’s land area. Of the five IBAs, Pelikan Rock (AN005) is protected within the St Maarten Marine Park, and Fort Amsterdam (AN004) is protected as a historical site. The IBAs have been identified on the basis of eight key bird species (listed in Table 1) that variously trigger the IBA criteria. They are centred on wetland and marine sites being primarily significant for their populations four congregatory waterbird and seabird species (including the Near Threatened Caribbean Coot Fulica caribeae. However, shrublands in three IBAs support populations of the four restricted-range species known to occur in the country. With further targeted field research, three additional restrictedrange birds that occur in the montane forest across the border in St Martin would be expected to be found in the semievergreen forest remnants on the St Maarten side. Such a discovery could warrant the identification of an additional IBA for these forest dependent species.

The wetland IBAs of Little Bay Pond, Fresh Pond and Great Salt Pond all face similar, multiple threats such as land reclamation for development, inappropriate development, use for landfill, pollution and contamination from runoff and sewage, inappropriate water management (e.g. maintaining water levels by pumping in sea water), alien invasive predators and disturbance. The Nature Foundation of St Maarten and Environmental Protection in the Caribbean (EPIC) have variously planted mangroves, constructed bird observation towers and installed educational signage at Little Bay Pond and Fresh Pond IBAs, but it is clear that enforced legislation is critical if the biological integrity of these wetlands is to be maintained in the long term.

The protection afforded Fort Amsterdam (Historical Site) and Pelikan Rock (Marine Park) IBAs appears to be preventing site-based threats although factors outside of these areas are having negative impacts such as disturbance to the mainland pelican nesting colony from jet skis, dive boats, and parasail boats. Over-fishing, oil spills, and plastics entanglement are constant threats to the marine-based seabirds and waterbirds. The regular monitoring of the waterbirds at St Maarten’s IBAs (e.g. as has been undertaken by EPIC) and the monitoring of the other key bird species should be used to inform the assessment of state, pressure and response variables at each IBA in order to provide objective status assessments and inform management decisions (should the necessary legislation be enacted) that might be required to maintain these internationally important biodiversity sites.

Retrieved from Birdlife International

The Saba coastline IBA (AN006)—the island’s site priority for bird conservation—has been identified on the basis of nine key bird species (listed in Table 1) that variously trigger the IBA criteria. The IBA covers 2,000 ha of critical terrestrial and marine habitats that support the entire island’s population of breeding seabirds, and also the full complement of the restricted-range birds that still occur on the island. The lack of any legal protection for terrestrial areas is a concern that must be addressed to facilitate pro-active conservation of Saba’s terrestrial biodiversity (including breeding seabirds).

At present, it seems that the globally significant populations of Audubon’s Shearwater P. lherminieri, Redbilled Tropicbird P. aethereus and the restricted-range Bridled Quail-dove G. mystacea in the IBA are declining (or are at least limited) as a result of predation from cats and rats (exacerbated by trampling and grazing from goats). Saba is small enough that complete eradication of some invasive species may be feasible, given sufficient funding, time and local support. In anticipation of both formal protection of terrestrial habitats within the IBA, and a possible eradication program, there is an urgent need to determine the population of P. lherminieri and G. mystacea, and to continue monitoring the population of P. aethereus. Monitoring these populations within the IBA should be used to inform the assessment of state, pressure and response variables at each IBA in order to provide objective status assessments and inform management decisions (such as the necessity for invasive species control) that might be required to maintain this internationally important biodiversity site.

Retrieved from Birdlife International

Statia’s two IBAs—the island’s international priority sites for bird conservation—cover 41% of the island’s land area. Both IBAs are formally designated as protected areas—the terrestrial components are covered within the Quill–Boven National Park, and the marine component within the St Eustatius Marine Park. The IBAs have been identified on the basis of nine species that variously trigger the IBA criteria for restricted-range birds and congregatory birds. The Quill IBA (AN008) embraces the island’s forest-dependent species (the restricted-range species), while Boven IBA (AN007) supports nesting habitat for P. aethereus.

Resolving the land dispute within Boven IBA appears to be critical to enabling effective management of grazing and thus the successful recovery of vegetation within the park. It would also facilitate the potential control of goats, cats and rats that almost certainly represent limiting factors for the breeding population of P. aethereus. Enforcement of an animal registry program within the Quill IBA should decrease the incidence of grazing in the park, but both goats and chickens are often present around and within the volcano and presumably impact the native fauna. Surveys to assess the population of each of the IBA trigger species should be a priority. Such surveys should be combined with annual monitoring of state, pressure and response variables at each IBA to provide an objective status assessment and highlight management interventions that might be required to maintain these internationally important biodiversity sites.

Retrieved from Birdlife International

Abstract:

Recent surveys for the Snowy Plover (Charadrius alexandrinus) on St. Martin reveal that the species is no longer a resident on the island. Following surveys from 1997–2005, when the species was annually detected and observed breeding, plovers were no longer observed on the island. Both human disturbance to nesting birds and predation by invasive species are potential causes of the extirpation. 

Abstract:

The introduction of mammals to islands is one of the leading causes of extirpation of native biota worldwide. Data gaps in the introduction of mammals to islands have led to inadequate management practices which do not take into consideration the potential destruction caused by those mammals. Herein, we report the current status of introduced mammals on the island of St. Martin within the Lesser Antilles region of the Caribbean. We surveyed the island for introduced mammals and interviewed residents on their observations, from 2000 - 2007. In addition to recording domesticated mammals (i.e. dogs, Canis familiaris), we recorded six species of feral introduced mammals including raccoons (Procyon lotor) and African green vervet monkeys (Cercopithecus aethiops).