I have observed humming birds visiting cardinal flowers in some of the wetlands that I frequent for nature photography. Thus I decided to plant the Virginia natiave cardinal flowers near my backyard pond anticipating Rubythroated Hummingbirds visiting them for nector and thus spreading their pollen. When the flowers were in bloom I set up my camera for photographing when the sun would shine on the subjects. After many hours over many days, I was rewarded with this female that shut her eyes as the pollen from another flower that she bumped dropped on her head. Thus I recorded a perfect textbook illustastration of mutualism.
Camera was a Nikon D7100 with Nikon f4 VR 200-400 VR lens mounted on a Bogen fiber tripod with Wimberly Head. The lens was set at the maximum, 400mm and f5.6. The shutter speeed was 1/2000 sec. I used the spot meter setting because I could follow the bird as it zoomed around in varied lighting and was dependent upon the single focus point that traveled with it.