Impacts des mammifères allochtones sur quelques espèces autochtones de l’îlet Fajou (réserve naturelle du grand cul-de-sac marin, Guadeloupe), établis à l’issue d’une tentative d’éradication

Abstract

In March 2001, simultaneously by trapping and chemical baits an attempt was done to eradicate the Javanese Mongoose (Herpestes javanicus), the Ship Rat (Rattus rattus) and the House Mouse (Mus domesticus) from Fajou Island (104 ha of mangrove on peat, 11 ha of dry vegetation on sandy soil), part of a natural reserve managed by the Guadeloupe National Park (French West Indies). A control in December 2001 and January 2002 revealed the failure of the Ship Rat eradication. A second eradication operation was undertaken in March 2002 in order to test hypotheses explaining this failure and put right some technical defects. Its result will not be available before 2003. However it allowed to conclude to the success of the Mongoose eradication by trapping alone but the potential success of the House Mouse eradication by trapping and poisoning in March 2001 could not yet be properly evaluated. The spatial distribution of trapping specimens of the target species showed that statistically they concentrate on the dry part of the island. The Mongoose eradication and the sharp decline of the Ship Rat population induced the disappearance of the destruction of Hawksbill Turtle (Eretmochelys imbricata) nests and the colonization of the dry part of the island by the Clapper Rail (Rallus longirostris), strictly located in the mangrove before. The abundance indices of the Clapper Rail and the terrestrial crab Cardisoma guanhumi increased. To be tested, the eventual relationships between these increases and the drop of the alien mammal populations require more data. Such operations combining research and management have to be planned in the long term with good logistical, technical and qualified human supports. All these conditions were gathered here because of the protected area status of the Fajou Island. RÉSUMÉ L'éradication simultanée de la Petite Mangouste indienne (Herpestes javanicus auropunctatus), du Rat noir (Rattus rattus) et de la Souris domestique (Mus musculus) a été tentée en mars 2001 sur l'îlet Fajou (104 ha de mangrove sur tourbe, 11 ha de formation végétale xérophile sur sol sableux), partie d'une réserve naturelle gérée par le Parc National de la Guadeloupe (Antilles françaises). Elle a fait appel à l'utilisation successive du piégeage et de la lutte chimique. Un contrôle réalisé en décembre 2001 et janvier 2002 a démontré l'échec de l'éradication du Rat noir. Une seconde opération d'éradication a été conduite en mars 2002. Elle a permis de tester diverses hypothèses destinées à expliquer l'échec de l'élimination du

The Culprit behind the Mass Death of Mangroves: Egrets or Rats (Rattus losea)?

“…Additionally, rats also consume seabird eggs and sea turtle hatchlings as a food source [29,32]. In coastal areas, rats are widely distributed in mangrove forests [33,34]. Lesser rice-field rats prey on small birds [24], Sparsparia alterniflora [35], mangrove seedlings [36], and propagules [37][38][39].…”

Blanchard Cave 2: A historical period Audubon's shearwater (Puffinus lherminieri) nesting site in Marie-Galante (Guadeloupe islands, FWI)

“…Moreover, this carnivore is known regionally as the main predator of ground-breeding birds (Pinchon, 1976;Lescure, 1987), including sea birds (Lorvelec et al, 2004;Lewis et al, 2011). In this respect, the Blanchard 2 data are consistent with the mongoose having a decisive impact on the island's historical Audubon's shearwater populations.…”

“…Finally, gnawing marks observed on bones recovered from the surface of the cave and the summit of the fossil deposit further highlight the frequentation of the cave by a carnivore preying on Audubon's shearwater. Three carnivores have been identified in the mammalian faunal assemblages from sites on Marie-Galante; dogs (Canis familiaris), introduced during the Amerindian period (Grouard et al, 2013) alongside domestic cats (Felis catus) and the small Asian mongoose, both of which were first brought by European colonists (Lorvelec et al, 2004). While the island is not home to feral dogs and cats, the mongoose is frequent on the island and its traces around the site are easily visible, making it the most likely agent responsible for the traces on the bones.…”