Explanation: Species that rely on hummingbirds for pollination, instead of the insects their ancestors did, have acquired a number of ‘pro-bird’ and ‘anti-bee’ traits; nectar that is particularly sucrose rich, flowers that are brightly colored but unscented (smell is vital for insects to find flowers, but vision is the key for birds), and various adaptations to their flowers to allow easy access for hummingbirds.