Regional drivers of clutch loss reveal important trade-offs for beach-nesting birds.
Coastal birds are critical ecosystem constituents on sandy shores, yet are threatened by depressed reproductive success resulting from direct and indirect anthropogenic and natural pressures. Few studies examine clutch fate across the wide range of environments experienced by birds; instead, most focus at the small site scale. We examine survival of model shorebird clutches as an index of true clutch survival at a regional scale (∼200 km), encompassing a variety of geomorphologies, predator communities, and human use regimes in southeast Queensland, Australia. Of the 132 model nests deployed and monitored with cameras, 45 (34%) survived the experimental exposure period. Thirty-five (27%) were lost to flooding, 32 (24%) were depredated, nine (7%) buried by sand, seven (5%) destroyed by people, three (2%) failed by unknown causes, and one (1%) was destroyed by a dog. Clutch fate differed substantially among regions, particularly with respect to losses from flooding and predation. 'Topographic' exposure was the main driver of mortality of nests placed close to the drift line near the base of dunes, which were lost to waves (particularly during storms) and to a lesser extent depredation. Predators determined the fate of clutches not lost to waves, with the depredation probability largely influenced by region. Depredation probability declined as nests were backed by higher dunes and were placed closer to vegetation. This study emphasizes the scale at which clutch fate and survival varies within a regional context, the prominence of corvids as egg predators, the significant role of flooding as a source of nest loss, and the multiple trade-offs faced by beach-nesting birds and those that manage them.
Ecology, Evolution and Natural Resources, Rutgers, The State University of New Jersey , New Brunswick , NJ , United States.
Brooke
B
Maslo
School of Science and Engineering, University of the Sunshine Coast , Maroochydore , Australia.
Thomas A
TA
Schlacher
Centre for Integrative Ecology, Deakin University , Geelong , Australia.
Michael A
MA
Weston
School of Science and Engineering, University of the Sunshine Coast , Maroochydore , Australia.
Chantal M
CM
Huijbers
School of Science and Engineering, University of the Sunshine Coast , Maroochydore , Australia.
Chris
C
Anderson
School of Science and Engineering, University of the Sunshine Coast , Maroochydore , Australia.
Ben L
BL
Gilby
School of Science and Engineering, University of the Sunshine Coast , Maroochydore , Australia.
Andrew D
AD
Olds
Australian Rivers Institute - Coast & Estuaries, and School of Environment, Griffith University , Gold Coast , Queensland , Australia.
Rod M
RM
Connolly
School of Science and Engineering, University of the Sunshine Coast , Maroochydore , Australia.
David S
DS
Schoeman
Egg loss; Flood; Predators; Sandy shore; Seascape; Shorebirds
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