Ibis (2008), 150 (Suppl. 1), 54–73 © 2008 The Authors Journal compilation © 2008 British Ornithologists’ Union Blackwell Publishing Ltd Predation on wader nests in Europe MICHAEL A. MACDONALD* & MARK BOLTON Royal Society for the Protection of Birds, UK Headquarters, The Lodge, Sandy, Beds. SG19 2DL, UK The population declines of waders in Europe are widely considered to have resulted from habitat loss and degradation due to agricultural changes. However, recent empirical evidence suggests that levels of predation on wader nests are unsustainably high in many cases, even in some situations where breeding habitat is otherwise favourable. We review the published and ‘grey’ literature on nest predation on waders in Europe and quantify the relative impor- tance of the major predators. Nest cameras offer the least biased method of identifying and quantifying nest predators. A small number of camera studies, in combination with others utilizing nest temperature loggers, indicate that nocturnal/mammalian predators make the largest contribution to wader nest predation. More than half of site-years or studies reviewed reported clutch failure rates of over 50% attributable to predation alone, a rate that is likely to be associated with declining populations, although parameters such as chick and adult survival will also affect population trends. Correlates of wader nest predation are docu- mented, with time of season, field type and management, distance to habitat/field edge, wader nest density, and abundance of mammalian predators being most consistently iden- tified. Future directions of research into wader productivity are discussed, and we suggest that studies quantify additional life-history parameters such as chick survival, as well as examining the predator community, wherever possible. Keywords: daily predation rate, deterministic model, habitat variables, nest cameras, nest density, predator abundance, predator identity. Europe holds internationally important populations of breeding waders. The populations and distribu- tions of several wader species have declined in Europe over recent decades (Heath et al. 2000, Tho- rup 2006). Of 68 populations of waders breeding in Europe examined by Thorup (2006), 18 were declining. Surveys restricted by habitat or geography have also documented declines in wader popula- tions, although not all species have declined (Jackson & Green 2000, SOVON 2002, Sim et al. 2005, Wil- son et al. 2005a, Ottvall & Smith 2006, Rönkä et al. 2006, Hötker et al. 2007). These declines in wader populations have been attributed to alterations of habitat associated with agricultural intensification, notably drainage and the use of inorganic fertilizers, that have rendered habi- tat less suitable (Shrubb 1990, Donald et al. 2001, Wilson et al. 2004). There has been an emphasis on the restoration and creation of habitat, such as exten- sively managed lowland wet grassland, in an effort to increase populations or to stem their declines, and there is mixed evidence that these are effective in increasing wader populations (Verhulst et al. 2007, Wilson et al. 2007). It is undeniable that appropriate habitat manage- ment is necessary to maintain or increase popula- tions of waders; however, increased nest predation has been suggested as a possible additional cause of wader population declines (Bellebaum 2002b, Chamberlain & Crick 2003, Milsom 2005). Preda- tors may cause prey populations to decline to extinc- tion, or to stabilize at lower levels, where they may be more susceptible to extinction from other causes. Alternatively, populations that have declined due to other causes may be more likely to suffer increased rates of predation. There are several possible mecha- nisms whereby agricultural intensification may itself lead to increased rates of predation on wader nests: smaller and more dispersed wader populations may be less effective at deterring predators by mobbing; anti-predator vigilance may be compromised in *Corresponding author. Email: michael.macdonald@rspb.org.uk Conflict of interests: The authors declare no conflict of interests.