Triple Brooding by Southern Ontario Wood Thrushes

Abstract

Wood Thrushes (Hylocichla mustelina) typically are double brooded, and triple brooding is rare, even in the southern portions of their breeding range. We discovered one instance of triple brooding by a pair of Wood Thrushes in southern Ontario near the northern edge of their continental breeding range. Each of the three nesting attempts successfully fledged young. Females may spend only a short time (less than a week) with just-fledged broods before initiating another nest; in this circumstance, the survival of young birds from the earlier brood depends on the attentiveness of males. The rearing of three broods is an uncommon event among Wood Thrushes in our study; from 1998–2000, only one of 73 color-banded females (1.3%) with early season nesting success has been triple brooded.