ScienceDaily (Nov. 21, 2012) — How flowers have evolved particular colours, shapes and scents to attract pollinators has long fascinated ecologists. Now, using artificial flowers and high-speed video, researchers have gained intriguing insights into the intimate relationship between hummingbirds and the flowers they pollinate. The study, published in the British Ecological Society's journal Functional Ecology, is the first to measure how much energy hummingbirds use while hovering to feed from flowers of different orientation.
Hummingbirds are among the smallest and most brightly-coloured birds on Earth, and one of the only types of bird capable of hovering for long periods. They are also crucial pollinators of flowering plants across the Americas. Hummingbird-pollinated flowers are usually red, tubular-shaped and have no smell, characteristics that have been well-studied by ecologists. Why most hummingbird-pollinated flowers hang down vertically, however, has remained a mystery.
Working with Anna's hummingbirds (Calypte anna) – the most common hummingbird species on their university campus – Dr Nir Sapir and Dr Robert Dudley of the University of California, Berkeley built a series of artificial “flowers”. The artificial flowers, which pointed horizontally, vertically-downwards or were tilted 45 degrees downward, supplied nectar to the birds.