Greater Prairie Chickens Attract Predators to Their Nests

Abstract

Parental care theory incorporates the idea that ground-nesting parents behave to reduce nest predation. The alternative hypothesis is that parents attract predators to nests. Both hypotheses are supported by ambiguous data. This study shows that nocturnal, mammalian predators preyed upon nests of greater prairie chickens (Tympanuchus cupido) only during incubation when the females were on the nest all night long. No predation was observed during egg-laying when the females were away from their nests. Mortality was significantly greater during incubation than during egg-laying. The implication is that the females attract predators to the nests. An important function of parental care is to reduce the degree of predation on eggs or young. However, Skutch (1949) hypothesized that parental nesting activity attracts predators to nests. This idea has received wide acceptance (Hammond and Foreward, 1956; Klomp, 1970; Willis, 1973), but it is not well supported by evidence (Ricklefs, 1969). Wagner (1957) disagreed with the hypothesis and argued that it is unlikely that snakes, which are major nest predators, watch parent birds to find their nests. Gottfried and Thompson (1978) conducted nest experiments in a predator system dominated by snakes and blue jays (Cyanocitta cristata) and found that parent birds were not attracting these predators to their nests. Some evidence supporting the hypothesis comes from studies of colonial birds (Horn, 1968; Andersson and Wiklund, 1978) but the evidence is not completely clear because the colonies presumably function to reduce predation. Skutch's idea that parent birds attract predators is closely associated with another hypothesis that clutch size is reduced as a result of high predation. 1 Support for field work came from grants from the National Institutes of Health, National Science Foundation, and the Penrose Fund of the American Philosophical Society while the senior author was at Kansas State University. 2 Present address: Division of Science, College of Arts and Science, Widener University, Chester, Pennsylvania 19015. This content downloaded from 207.46.13.133 on Sat, 17 Dec 2016 05:24:46 UTC All use subject to http://about.jstor.org/terms 4 TRANSACTIONS OF THE KANSAS ACADEMY OF SCIENCE Table 1. The arrival and departure times of female Greater Prairie Chickens at the nest during egg laying. Arrival time Departure time Birds Average* Range Average Range 1 1146 1108-122