Breeding and nonbreeding season mortality of territorial male red- winged blackbirds (Agelaius phoeniceus)

Abstract

Tests the hypothesis that sexual selection for characteristics that are advantageous in territory defense or mate acquisition, or both, occurs at the expense of survivorship. Mean annual mortality of territorial male red-wings was 52%. with 29% mortality occurring during the "nonbreeding' season (1 June-1 March) and 22% mortality occurring during the breeding season before 1 June. The correlation between wing length and survivorship was negative and statistically significant. Mortality during the breeding season is thus a potentially important selective force. Sexual selection may have occurred at the expense of survivorship. -from Author