A management experiment evaluating nest-site selection by beach-nesting birds

Abstract

It is important to understand nest-site selection in avian species to inform appropriate conservation management strategies. Studies of habitat selection alone, however, may be misleading unless the consequences for survival and reproduction are also documented. We conducted a management experiment for 2 conservation-dependent and managed species of beach-nesting birds, the California least tern (Sternula antillarum browni) and western snowy plover (Charadrius nivosus nivosus) at Marine Corp Base Camp Pendleton, southern California, 2012–2014. We conducted vegetation treatments targeting cover reduction to 5–15% cover in 90-m by 60-m management plots and documented how cover influenced nest-site selection and nest outcomes. At the microhabitat scale (9 × 6.5-m patch), we also compared habitat characteristics and nest outcomes with control patches. Our findings document no effects of vegetation cover at the management-plot scale but many effects at the microhabitat scale. Plovers and terns nested in relatively open areas but selected for areas with more cover (∼5% cover) than was available nearby. Nesting close to areas with more cover conferred benefits to both species. Terns and plovers experienced higher nest success in areas with more cover, a result explained in part by lower levels of predation for plovers. Other factors, such as vegetation height, woody debris, presence of sand mounds, and specific plant species also influenced nest-site selection and nest outcomes. Our results suggest that many aspects of tern and plover nesting ecology appear to be governed by the role of camouflage in reducing predation. These results also point to several simple management actions that can be taken, including managing vegetation cover to 5–10% with some heterogeneity, reducing certain plant species such as grasses and beach bur, creation of sand mounds, and provision of woody debris. With few exceptions, the same management actions should benefit both species. © 2017 The Wildlife Society.