Parental behavior, anti-predatory behavior, reproductive success, and management of piping plovers breeding on Cape Hatteras and Cape Lookout National Seashores, North Carolina

I monitored reproductive success and observed breeding behaviors of piping plovers (Charadrius melodus) on Cape Hatteras and Cape Lookout National Seashores, North Carolina during the 1992--1994 breeding seasons. Behavioral observations consisted of scan and focal samples of adult and chick behaviors and all-events samples of intrusions in the vicinity of breeding pairs. Population numbers varied little (11 to 12 pairs at Cape Hatteras; 33 to 39 pairs at Cape Lookout) and productivity averaged 0.47 fledglings per pair, well below mean productivity (1.33 fledglings/pair) along the Atlantic coast during the same time. Nest losses were primarily due to predation and flooding. Exclosures were effective at reducing predation. Human disturbance rate was low (0.13 human intrusions evoking responses per hour). Because of significant influence of weather effects on reproductive success on my study sites, North Carolina breeding populations may be a sink, and it is unlikely that reproductive success could reach goals set in the recovery plan for piping plovers on the Atlantic coast.; I tested hypotheses regarding change in intensity of anti-predatory behavior over the breeding season utilizing all-events samples of natural intrusions by various species on piping plover breeding grounds. Intensity did not significantly change over the incubation period, yet decreased significantly over the chick dependency period. These results are contrary to the age-investment and renesting ability hypotheses and supportive of the vulnerability hypothesis. Intensity of defense did not change with brood size. Piping plovers demonstrate ability to discriminate between predatory and non-predatory species.; There are four hypotheses proposed explaining the limitation of clutch size in shorebirds to a maximum of four eggs. I tested a key prediction of the parental behavior hypothesis by examining parental behaviors of adults tending different brood sizes. Percent time devoted to parental care, foraging or resting was not influenced significantly by brood size. Percent time adults were in the role of tending chicks did significantly change with brood size, yet it appears unlikely that this effect is strong enough to influence evolution of clutch size in piping plovers. This represents the first time the parental behavior hypothesis has been tested since its formulation.