2009 年 8 巻 1 号 p. 37-42
I investigated nest-site characteristics affecting the risk of nest predation in the Madagascar Paradise Flycatcher Terpsiphone mutata. Several nest predators have been identified in the study area, and the time of nest predation has also been determined. Two variables, the distance from the nest to the nearest tree and nest visibility, were revealed to have effects on nesting success/failure in this species: nests further from other trees and better concealed by vegetation had higher probabilities of fledging success. Distance from the nearest tree may be a factor affecting predation by a nocturnal, arboreal snake species. On the other hand, nest visibility may affect the probability of being found by diurnal, visually oriented predators. Nest-site characteristics are expected to differ between the nests preyed upon by diurnal and nocturnal predators. Contrary to expectation, no significant difference was observed between the characteristics of nest sites preyed upon in two time categories. The existence of unidentified nest predators, especially diurnal, non-visually oriented species, may conceal the apparent difference in the measurements of nest-site characteristics preyed upon in the two time categories. I suggest that when several predators co-exist in the environment identification of those predators and the time of nest predation are important factors when examining the nest-site characteristics affecting the risk of nest predation.
