29 August 2008
Vol 321, Issue 5893

About The Cover

Cover image expansion

COVER A black-chinned hummingbird (Archilochus alexandri) drinks nectar from a flower of wild tobacco (Nicotiana attenuata). Nicotine in the nectar moderates its consumption by the hummingbird and protects against predators; the flower lip produces benzyl acetone, which attracts pollinators. Together, the repellent and attractant maximize the plant's reproductive fitness. See page 1200. Photo: Danny Kessler