Australian Field Ornithology 2015, 32, 100–107 Summary. Depredation of nests by native and introduced predators is contributing to the decline of beach-nesting shorebirds in many parts of Australia. Determining the relative importance of these predators is crucial for designing and implementing appropriate management strategies for shorebird conservation. We deployed and monitored 82 artiicial Red-capped Plover Charadrius ruicapillus nests, on six beaches within a 140-km stretch of the New South Wales Lower North Coast, to identify the main predators of beach-nesting shorebird nests and their relative importance. After 18 days, 53 (63%) artiicial nests were depredated. Australian Ravens Corvus coronoides and Forest Ravens C. tasmanicus were the chief nest-predators, and were responsible for depredating 40 (49%) nests collectively. Comparatively few nests were depredated by European Red Foxes Vulpes vulpes, which depredated 8 (10%) nests. The rate of depredation (nests depredated/2 days) by ravens was greater than the rate of depredation by foxes (P <0.05). Other predators preyed upon 5 (5%) nests. Introduction Nest-depredation is a major factor contributing to the decrease in populations of resident, beach-nesting shorebirds in many parts of Australia (Tomkovich & Weston 2007). A variety of nest-predators, both native and introduced, forage on Australian beaches (Rose 2001; Tomkovich & Weston 2007) and, in many areas, the abundance and diversity of predators have been elevated by human-mediated environmental change, and human disturbance has increased the vulnerability of shorebird nests to these predators (Recher & Serventy 1991; Coulson & Coulson 1998; Weston & Elgar 2007). Introduced European Red Foxes Vulpes vulpes are reputed to be proicient nest-raiders and are suspected to account for 17–27% of shorebird nest losses (Weston 2003), although, in one study, foxes may have accounted for up to 36% of depredations of artiicial Hooded Plover Thinornis rubricollis nests (Maguire et al. 2009). Accordingly, in mainland Australia, most predation-mitigation measures at shorebird nesting areas are directed towards foxes, with intensive 1080 baiting campaigns during the nesting season (Mahon 2009). Land managers rarely implement measures to control avian predators (Dunn & Harris 2009; Harris & Dunn 2010) because protective legislation for native Ravens are a key threat to beach-nesting birds James D. Rees 1, 4* , Jonathan K. Webb 2 , Mathew S. Crowther 3 and Mike Letnic 4 1 School of Biological Sciences, University of Sydney, Sydney NSW 2006, Australia Email: james.rees@live.com.au 2 School of Environmental Sciences, University of Technology Sydney, Sydney NSW 2007, Australia. Email: jonathan.webb@uts.edu.au 3 School of Biological Sciences, University of Sydney, Sydney NSW 2006, Australia Email: mathew.crowther@sydney.edu.au 4 School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney NSW 2052, Australia. Email: m.letnic@unsw.edu.au *Corresponding author