Polly, I witnessed something similar many years ago at a feeder at our
house and at first also thought they were mating. I took some photos and
saw the male with its pecking had actually pulled feathers off of the
female's head. I am pretty sure that rather than mating, the male was
trying to drive the female off of "his" feeder. Hummingbirds are known to
aggressively protect a food source, and I suspect in cold weather when
there are fewer choices for food that some will endure the attack to get
some nourishment.
Andy Frank
