USING EGGSHELL EVIDENCE TO DETERMINE NEST FATE OF SHOREBIRDS

摘要: I collected eggshell evidence at nest sites of Piping Plover (Charadrius mel- odus), Snowy (C. alexandrinus), and Killdeer vociferus) in southeastern Colorado during 1994-1995, determined fate independently. Successful nests all three species generally contained fragments (ca 1-4 mm) the scrape membranes separated from eggshell. In comparison, "tops" or "bottoms" were found only near successful Plovers Plovers. used discriminant function analysis to predict probability correctly classifying a nest's given dif- ferent types evidence. The use fragment resulted correct classification 90% 96% cases, respectively. Eggshell can be future studies determine shorebirds increase precision estimates reproductive success. Received 14 April 1996, accepted 1 March 1997. Assessing precocial such as is problem- atic because chicks leave soon after hatching shortly there- their parents may move them considerable distance feeding areas. Consequently, establishing rigorous standards for determining critical understanding biology these species. Several cri- teria exist shorebirds, pres- ence least one chick (Haig Oring 1988), small produced (Hill 1985, Page et al. Paton 1995), absence predator sign whose clutches old enough have hatched. Conversely, failed been classified by presence too early incubation hatched (Page 1995). Hill (1985) above criteria except fragments. lack standard basis bias success make comparisons among difficult. Two meth- ods are commonly estimate success, pre- cision depends on accurate determination fate. Observed (the proportion total number nests) util- izes known-fate and, therefore, its accuracy sensitive unknown-fate removed analysis. By contrast, Mayfield method (Mayfield 1961, 1975) utilizes unknown- but estimated daily survival rate inflated ' Dept. Biology, State Univ., Fort Collins, 80523.