Male songbirds undergo a suite of physiological changes during spring migration that prepare them to initiate breeding activities upon arrival at nesting sites. These physiological changes could result in the expression of sexual behaviors, such as singing, during the migratory period. Yet, mostly anecdotal observations of singing during stopovers exist in the literature. We explored singing by males of 20 species of New World warblers (Parulidae; hereinafter “warblers”) during stopovers on spring migration through southwest Michigan. To explore patterns of stopover singing by males, we used eBird data to determine the migratory timing of each species in our region, superimposed singing observations on these migration schedules, and calculated song rates of migrating birds. We compared song rates of species during stopovers with those from breeding populations and examined whether interspecific variation in song rates depended on the distance to be traveled to the closest potential breeding range. We observed singing by males in 19 of 20 warbler species. Stopover singing differed from breeding season singing, as males sang at lower rates on stopovers than when they were in northern breeding areas. Species breeding farther from our study region showed larger intraspecific differences in song rates between stopover and breeding populations than those breeding in closer proximity. Moreover, interspecific variation in song rate was explained in part by the distance between our stopover area and the closest breeding area. Our results suggest that male warblers commonly sing during stopovers, at least at this latitude, and variation in singing across species could reflect physiological readiness to breed. Understanding the prevalence and rate of singing on spring migration stopovers highlights the behavioral outcomes of physiological changes occurring in male birds. Our study contributes new data on migratory singing to a body of research that has historically focused solely on birdsong within a breeding framework.

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