Abstract
Differing intensities of predation pressure can affect the evolution of life history traits in island and mainland populations. We found extremely low nesting success in an insular subspecies of the Varied Tit (Parus varius namiyei; Kozushima Island), and we compared certain life history traits among three subspecies of P. varius experiencing different predation pressures. The nesting success of P. v. namiyei was extremely low as a result of significant nest predation and nest abandonment; 83% of active nests failed due to snake predation. The proportion of depredated nests was significantly greater on Kozushima Island than on Miyakejima Island (P. v. owstoni) or on the mainland (P. v. varius). Of the three subspecies, P. v. namiyei had the longest incubation period, shortest nestling period, an intermediate clutch size, and a small brood size. There were no differences in the date of egg laying among the three populations. The short nestling period for P. v. namiyei may be an adaptive response, as the predation risk during the nestling period on Kozushima was extremely high.
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