Red-Winged Blackbird Migration Distance and Its Relationship with Reproduction

Abstract

Red-winged blackbirds (Agelaius phoeniceus) are one of the most commonly researched birds in North America. My study aims to build upon what is known about migration patterns and reproduction in this species. My first objective was to determine if individuals that breed together travel to similar overwinter locations and to investigate the similarities or differences in the timing of migratory movements. My second objective was to examine the relationship between spring migration distance and reproduction. In short, I found that female blackbirds travel to more southern overwinter locations than males. Males and females may be leaving the North Dakota region at similar times during the fall, but males return to the breeding grounds approximately one month before females. Within sexes, there was not a correlation between migration distance and reproduction in females; however, males that migrated a shorter distance returned to the breeding ground with higher levels of baseline testosterone.