Saturday, August 19, 2017

Mammals in Saint Lucia

St Lucia’s native mammalian fauna consist of at least nine bat species: the frugivorous Jamaican Fruit Bat Artibeus jamaicensis jamaicensis (39% of captures), the nectarivorous Insular Long-tongued bat Monophyllys plethodon luciae (38%), the frugivorous Little Yellow-shouldered Bat Sturnira lilium luciae, (10%), the frugivorous Tree Bat (4%), the insectivorous Davy’s Naked-backed Bat Pteronotus davyi davyi (4%), the insectivorous Common Free-tailed Bat Molossus molossus molossus (2%), the insectivorous Brazilian Free-tailed Bat Tadarida brasiliensis antillularum (2%) and the piscivorous Greater Fishing Bat Noctilio leporinus mastivus (1%). A roost of a ninth species, the omnivorous Antillean Fruit Bat Brachyphylla cavernarum cavernarum , was located. The species diversity, composition and trophic structure of St Lucia’s bat community is comparable to that of other islands of similar size in the Lesser Antilles that also have a high floral diversity and significant tracts of wet forest. Bat species diversity and abundance were greater in wet and mesic forest than dry forest types, probably due to their greater habitat complexity, abundance of fruiting plants, and greater insect diversity and abundance.

Conserving St. Lucia’s bats is important to preserve the island’s natural heritage and because bats have key ecological roles and are economically important, notably in pollinating fruit crops. The Antillean Fruit Bat, Insular Long-tongued Bat and Tree Bat are regional endemics; that is they are not found anywhere else outside of the Antilles. Furthermore, the Tree Bat subspecies luciae only occurs on St Lucia and St Vincent, and the Little Yellow-shouldered Bat subspecies luciae is only found on St. Lucia, giving St Lucia a global responsibility for their stewardship. None of St Lucia’s bat species are listed as protected under the Wildlife Protection Act 1980 or the revised Wildlife Protection Act 2001, and it is proposed that all bats be added to Schedule 1 (fully protected wildlife), or at least Schedule 2,as part of the current review and amendment of this Act. Conservation actions for bats should focus largely on habitat protection because their continued survival may largely depend on conserving a full representative range of forest types, including existing forest reserves. Critical to several bat species is the protection of important cave roosts, especially those of the regional endemic Antillean Fruit Bat and Insular Long-tongued Bats. Roost protection should include routine monitoring of bat numbers and of threats to these roost sites. Research on the Tree Bat, Antillean Fruit Bat and the Insular Long-tongued Bat should be particularly encouraged as these bats are regional endemics and are not well known. Research should focus on habitat and roost requirements, diet (food preferences, pollination and seed dispersal studies), and movements of bats.

The distribution and abundance of the following introduced (alien) mammals were also determined: the Southern Opossum Didelphis marsupialis marsupialis, Small Asian Mongoose Herpestes  javanicus, Brazilian Agouti Dasyprocta leporina fulvus, the rats Rattus rattus and Rattus norvegicus, and feral pigs Sus scrofa. The Southern Opossum was found to commonly occur in most habitats in St. Lucia, from around sea level to at least 550m, but was more abundant in dry forests than wet and mesic forests. As a non-threatened, introduced species the Southern Opossum is a low conservation priority for St Lucia. Currently, the Southern Opossum is protected by law, but from a conservation standpoint, is not necessary to sustain the hunting ban on the opossum unless the FD perceives that opossum hunting practices could inadvertently and seriously endanger people or native wildlife. It is not clear what impact this abundant introduced mammal has on St Lucia’s endemic birds, reptiles, invertebrates and plants. Further research is needed to address this question, including dietary studies and experimental enclosure studies to measure the ecological impact of removing the opossum from selected areas. Reducing their numbers near key nesting iguana and marine turtles nesting sites could benefit St Lucia’s reptiles without endangering the overall opossum population. Neither subsistence hunting nor local eradication of opossums is likely to threaten this adaptable and fecund mammal.The Brazilian Agouti appears to be uncommon and largely restricted to wet and mesic forest in the interior of the island. Though listed as fully protected under Schedule 1 of the Wildlife Protection Act 1980, the agouti is not native and like the opossum, it is not necessary to sustain the hunting ban on the agouti from a conservation standpoint, unless the FD perceives that agouti hunting practices could inadvertently and seriously endanger people or native wildlife. It is recognised that some people regard the agouti as naturalised, and do not wish to risk losing the species entirely. There is potential to use this population sustainably, however, either

by hunting wild agouti or farming them for human consumption (“minilivestock farming”). A trade-off between protection and exploitation would be to down-list agouti to Schedule 2 of the Wildlife Protection Act (‘partially protected’), and prohibit hunting on all protected and state-owned forest lands, but allow agouti to be legally killed or captured for breeding stock on private land. Such measures would protect the ‘core’ agouti population that resides within state-owned wet forest lands and allow exploitation of agouti that are damaging crops. However, any new strategies for sustainable harvesting of agoutis and other wildlife using dogs or guns need to be considered in the context of FD’s policy on hunting since the 1980s, and should take into account the FD’s current capacity and resources to effectively regulate hunting. This report recommends specific hunting regulations and farming options.The Small Asian Mongoose was found to commonly occur in most habitats on St Lucia, from around sea level to at least 550m, but is more abundant in wet and mesic forests than dry forests. The Small Asian Mongoose is not native to St Lucia. As one of the world’s worst invasive species, the mongoose needs to be managed to mitigate its threat to native wildlife. St Lucia is too large and current control technologies too limited or labour intensive to attempt a total, permanent eradication of this widespread introduced species, but mongooses could be efficiently controlled in small, sensitive areas of high conservation value (e.g., sites where they present a critical threat to endangered birds, reptiles or other wildlife) using trapping, perhaps in combination with poisoning.

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