Two consecutive years of field work on Ruby-throated Hummingbird ecology in northern Michigan gave evidence that nest sites are selected in close proximity to sapsucker trees. The hummingbirds were found to utilize as a food source the sap made available by sapsucker drillings. Because of the climate in this northernmost fringe of the hummingbirds’ breeding range, flowers did not consistently blossom and produce nectar before the spring arrival of migrants. The early arrivals were forced to find other sources of food and depend on active sapsucker trees. The sap was also preferred by brooding females over nectar available in blossoming flowers throughout the nesting season. It is suggested that selection of nest sites, and thus hummingbird distribution, is closely associated with sapsucker feeding trees.