A male Allen’s hummingbird (Selasphorus sasin) near Santa Cruz, CA. Image credit: Shravans14 / CC BY-SA 4.0.
Since the 1830s, ornithologists have assumed that hummingbirds drink by capillary action (wicking), the passive process of a fluid rising into a narrow tube because of forces attracting the liquid to the tube’s solid internal surface.
A new study, led by Dr Alejandro Rico-Guevara from the University of Connecticut, debunks the ‘wicking theory’ and shows that the hummingbird’s tongue actually works as an elastic micropump.
Using high-speed cameras, Dr Rico-Guevara and co-authors filmed the tongue-nectar interaction in 18 hummingbird species, from seven of the nine main hummingbird groups throughout the Americas.
The results were published online today in the journal Proceedings of the Royal Society B: Biological Sciences.
“A hummingbird’s tongue, which can be stuck out about the same length as its beak, is tipped with two long skinny tubes, or grooves,” Dr Rico-Guevara explained.
“Rather than wicking, the nectar is drawn into the tongue by the elastic expansion of the grooves after they are squeezed flat by the beak.”
The tongue structure is collapsed during the time it crosses the space between the bill tip and the nectar pool, but once the tip contacts the nectar surface, the supply of fluid allows the collapsed groove to gradually recover to a relaxed cylindrical shape as the nectar fills it.
Europe’s biggest woodchipper, the black woodpecker, tosses out woodchips from the nest hole he has been fashioning. The hole is a major excavation, probably extending 60cm down into the trunk.
The woodpecker’s chisel-like beak has a high-strength inner layer of bone and a flexible outer layer that helps reduce the shock of the vibrations. If the female finds the nest chamber to her satisfaction, she will lay two to eight eggs, which the pair take turns to incubate.
WITH ITS CONVICT ruins and connections to the HMS Bounty saga, Norfolk Island is perfectly suited to ghost stories.
When I visited in 2009 shearwaters (see below) crooned over the ruined ramparts of the Norfolk Island prison; a reminder of times past, when this small 34.6 km² South Pacific island heaved with incredible numbers of seabirds and a rich endemic birdlife.
Since Cook first sighted the island in 1774, a total of four endemic bird species and five subspecies have become extinct. Among the losses were the Norfolk Island kaka and pigeon, which were so common when members of the First Fleet landed in 1788 that they described them as pests.
The kaka, a separate species to the New Zealand parrot, only survived until the early 1800s and the pigeon, a subspecies of the New Zealand pigeon, until 1901.
Norfolk and Lord Howe Islands have by far the worst record of bird extinctions in Australia, which continues to this day.
The kaka and pigeon were exterminated by hunting and forest loss, but the latest wave of extinctions has been largely from rats and cats.
The last island thrush (guavabird) was seen in the 1970s and the white-chested white-eye is on the verge of extinction.
A grey fantail captured mid-flight in Melbourne, Victoria.
The most restless of Australia’s fantails, Grey Fantails are almost continually on the move, constantly changing position when perched, the tail swished back and forth, fluttering about in the canopy of trees or darting out after flying insects.
They seem never to keep still. Despite their fluttering flight, they are nevertheless capable of relatively long-distance movements, with some regularly flying across Bass Strait.
Grey Fantails’ movements are particularly complex, with no general rule: birds in each different region have their own individual patterns of movement.
Image Credit: Photograph by ABC Open contributor honeycut