Mammal-exclusion fencing improves the nesting success of an endangered native Hawaiian waterbird

• DOI: 10.7717/peerj.10722
• Publication Date: 2021-03-01T09:21:36Z
• Authors: Dain L. Christensen; Kristen C. Harmon; Nathaniel H. Wehr; Melissa R. Price
• Keywords: Fencing; Fence (mathematics); Hatchling; Mongoose; Mammal; Netting

Invasive predator control is often critical to improving the nesting success of endangered birds, but methods vary in cost and effectiveness. Poison-baiting or trapping removal are relatively low-cost, may have secondary impacts on non-target species, not completely exclude mammals from areas. Mammal-exclusion fencing has a substantial up-front cost, due savings over lifetime structure complete exclusion mammalian predators, this option increasingly being utilized protect threatened species such as ground-nesting seabirds. However, non-mammalian predators excluded by these fences continue impact success, particularly cases where fence designed for protection waterbirds, open an estuary wetland one side. Thus, there remains research gap regarding potential gains waterbird implementation mammal-exclusion estuarine systems. In study, we compared Hawaiian Stilts (Ae‘o; Himantopus mexicanus knudseni ) within that breeding pairs nearby was sole means removing invasive mammals. We predicted would be greater inside hatchlings enclosure spend more time area than at unfenced site. During single season following construction fence, used motion-activated game cameras monitor nests two sites, site with without. Clutch sizes hatch rates were significantly fenced site, spent chicks did differ between sites. These results add mounting body evidence demonstrates effectiveness protecting birds suggests it can aid waterbirds toward recovery. also suggest greatest predatory threat Stilt mammals, despite host known including crabs, turtles, bullfrogs, resulted significant success. As additional built, future studies necessary compare among multiple sites across seasons determine fledging recruitment.