Invasive rat establishment and changes in small mammal populations on Caribbean Islands following two hurricanes

• Published in: Global Ecology and Conservation
• Main Authors: Aaron B. Shiels, Claudia D. Lombard, Laura Shiels, Zandy Hillis-Starr
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2020
• Subjects: Biodiversity; Cyclone; Non-native mongoose; Pest rodent biosecurity; Rapid wildlife surveillance; Tracking tunnels; Ecology; QH540-549.5; Buck Island; Croix Island; St. Croix Island; Rattus rattus
• Online Access: https://doi.org/10.1016/j.gecco.2020.e00986; https://doaj.org/article/1a368eda1f5e4e8d9c94d7b56761b24c

Invasive mammals, particularly black rats (Rattus rattus), house mice (Mus musculus), and mongoose (Herpestes auropunctatus) are established on many tropical islands and threaten natural resources such as native birds, sea turtles, lizards, invertebrates, and plants. St. Croix (U.S. Virgin Islands, Caribbean) has a diversity of natural resources being protected from invasive mammals by U.S. conservation agencies. Sandy Point National Wildlife Refuge and Buck Island Reef National Monument receive among the highest density of nesting sea turtles in the region, including annual nesting populations of 50–250 leatherbacks (Dermochelys coriacea), 25–80 hawksbills (Eretmochelys imbricata), and 100–250 green turtles (Chelonia mydas). Buck Island Reef National Monument and Green Cay National Wildlife Refuge are small islands near St. Croix Island that have endangered St. Croix ground lizards (Ameiva polops) established. Rodents and mongoose threaten each of these natural resources. The goal of our study was to determine the types of small mammals (i.e., mongoose, rats, and/or house mice) that are established in each of the three hotspot locations mentioned, and to determine how two severe hurricanes (Irma and Maria) affected the small mammal populations. We used traps and tracking tunnels, which are baited ink cards placed in tunnels so that animal foot prints can be identified, to determine presence and relative abundances of small mammal species. We found that: 1) black rats invaded and established, possibly by rafting and/or swimming, Green Cay following the hurricanes, 2) house mice, rats, and mongoose were present before and after the hurricanes at Sandy Point (mice had not been documented prior to our sampling), and house mouse abundance significantly increased (>2.5 times pre-hurricane levels) 9-months after the hurricanes, and 3) the house mouse population more than doubled 15-months after the hurricanes on Buck Island. Land and resource managers benefit from knowing the composition and relative abundances of ...