Predator exclosures, predator removal, and habitat improvement increase nest success of Snowy Plovers in Oregon, USA

Abstract

Management to increase reproductive success is commonly used to aid recovery of threatened and endangered species. The Western Snowy Plover (Charadrius nivosus nivosus) breeds from coastal Washington, USA, to Baja California, Mexico, and in disjunct interior sites. The Pacific coast population is federally listed as Threatened; habitat loss and nest loss to a suite of terrestrial and avian predators are thought to be primary factors limiting population growth in this species. In coastal Oregon, USA, a consortium of state and federal management agencies deployed nest exclosures on active Snowy Plover nests, initiated a lethal predator management program, and conducted local-scale habitat management in an effort to boost local productivity. During 1990-2009, we monitored 1,951 Snowy Plover nests at 9 sites with varying treatments. We examined the effectiveness of 3 types of nest exclosures (large, small, and outfitted with electric wire), predator removal, and habitat management on nest survival. Habitat management to remove invasive grasses and provide more suitable nesting substrate more than doubled nest survival. Predator management or use of any of the 3 types of exclosures also affected nest survival. There appeared to be no additional benefit to using both approaches, but the biological relevance of these findings is unclear because of site differences in treatments applied. Importantly, these management techniques only affected nesting success; their effect on other contributions to population viability (e.g., fledging success) was not correlated with nesting success. This long-term study illustrates the short-term benefits and tradeoffs of using nest exclosures, predator management, and habitat restoration to improve nesting success. Although we gained broader insight into the relative efficacy of common management techniques to improve avian nesting success, we cannot yet determine how improved nest success contributes to population growth. KeywordsCharadrius nivosus, exclosure, habitat management, nest exclosure, nest success, nest survival, Oregon, predator, Snowy Plover ABSTRACT Management to increase reproductive success is commonly used to aid recovery of threatened and endangered species. The Western Snowy Plover (Charadrius nivosus nivosus) breeds from coastal Washington, USA, to Baja California, Mexico, and in disjunct interior sites. The Pacific coast population is federally listed as Threatened; habitat loss and nest loss to a suite of terrestrial and avian predators are thought to be primary factors limiting population growth in this species. In coastal Oregon, USA, a consortium of state and federal management agencies deployed nest exclosures on active Snowy Plover nests, initiated a lethal predator management program, and conducted local-scale habitat management in an effort to boost local productivity. During 1990-2009, we monitored 1,951 Snowy Plover nests at 9 sites with varying treatments. We examined the effectiveness of 3 types of nest exclosures (large, small, and outfitted w...

To exclose nests or not: structured decision making for the conservation of a threatened species

“…Dinsmore et al. () found that nest survival rates for the closely related snowy plover ( C. nivosus ) benefited from exclosures or predator removal, but that using both provided little added value for nest survival. Mayer and Ryan () found that electric fencing of breeding areas greatly improved nest and chick survival at sites in the Great Plains.…”

“…, Maslo and Lockwood , Dinsmore et al. ). However, problems associated with exclosures included nest abandonment, adult mortalities, and depredation of multiple exclosed nests at a site within a very short period of time (Vaske et al.…”

Coastal protection and conservation on sandy beaches and dunes: context‐dependent tradeoffs in ecosystem service supply

“…In turn, beachgrass removal has recreated open nesting habitat and remains essential for plover productivity and recovery ( Fig. 9A; USFWS 1993, 2007, Muir and Colwell 2010, Zarnetske et al 2010, Dinsmore et al 2014, Pearson et al 2016.…”

Return of Beach-Nesting Snowy Plovers to Los Angeles County Following a 68-Year Absence

“…mini-exclosures are also used, even though at some sites they have increased depredation on incubating adults and fledglings (neuman et al 2004). These problems, however, have not arisen at other sites (Dinsmore et al 2014). Between 2005 and 2016 four of these enclosures were installed at malibu lagoon state Beach, santa monica Beach, and Dockweiler state Beach.…”