Antipredator Behavior and Breeding Success in Greater Golden-Plover and Eurasian Dotterel

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Abstract
Breeding success and antipredator of Greater Golden-Plovers (Pluvialis apricaria) and Eurasian Dotterels (Charadrius morinellus) were studied in Norway over seven summers in an area 1,200 to 1,350 m altitude. Behavior was recorded in a standardized manner on nest inspections, on approaching parent birds with chicks, and by observing reactions to overflying predators on scheduled observation bouts. Red foxes (Vulpes vulpes), Common Ravens (Corvus corax), and Mew Gulls (Larus cantus) were the most important nest and chick predators in the area. Nest predation was calculated from exposure time. During incubation both species either sneaked away from the nest when approached by a human (golden-plovers at a much larger distance dotterels) or sat tightly and flushed at a short distance giving distraction display. "Sneaking" had a positive effect on nest survival, and ground distraction displays had a better effect on nest survival than flight distraction displays. After hatching, golden plover parents exposed themselves to an approaching human at several hundred meters distance by loud alarm calls and by encountering the intruder, whereas dotterels kept unobtrusive until approached to about 40 m, and upon further approach finally gave distraction displays on the ground. Avian predators at a longer distance (> 300 m) from nest or chicks at most aroused alertness, while at close quarters (< 50 m) they induced golden-plovers to squat flat, while dotterels exposed themselves by "tail-flagging." Nest loss was greater for golden-plovers (78%) than for dotterels (47%), while chick loss was greater for dotterels (65%) than for golden-plovers (28%). The difference in nesting success and antipredator behaviors is discussed in terms of greater detectability in golden-plovers than dotterels, and of biparental (golden-plover) versus uniparental (dotterel) care.