Ruby-throated hummingbirds observed following yellow-bellied sapsucker

The authors document an observed association between Yellow-bellied Sapsucker and Ruby-throated Hummingbird. They conclude that the hummingbirds’feeding at sapsucker wells may effect the timing of hummingbird migration. by David Flaspohler and David Grosshuesch Several species of hummingbirds are known to feed at the sap wells
created by Yellow-bellied Sapsuckers

Flaspohler, David; Grosshuesch, David, The passenger pigeon Vol. 58, No. 3 (Fall 1996)