As regular CFZ-watchers will know, for some time Corinna has been doing a column for Animals & Men and a regular segment on On The Track... particularly about out-of-place birds and rare vagrants. There seem to be more and more bird stories from all over the world hitting the news these days so, to make room for them all - and to give them all equal and worthy coverage - she has set up this new blog to cover all things feathery and Fortean.

Thursday, 20 October 2016

Invasive plants dye woodpeckers red

Central Ornithology Publication Office

An ornithological mystery has been solved! Puzzling red feathers have been popping up in eastern North America's "yellow-shafted" population of Northern Flickers, but they aren't due to genes borrowed from their "red-shafted" cousins to the west, according to a new study in The Auk: Ornithological Advances. Instead, the culprit is a pigment that the birds are ingesting in the berries of exotic honeysuckle plants.

The Northern Flicker comes in two varieties--the birds of the west have a salmon pink or orange tinge to the undersides of their wings, while the eastern birds are yellow. Where the two populations meet in the middle, they frequently hybridize, producing birds with a blend of both colors. For years, however, flickers far to the east of the hybrid zone have been popping up with red-orange wing feathers. The prevailing explanation has been that they must somehow have genes from the western population, but Jocelyn Hudon of the Royal Alberta Museum and his colleagues have determined that the eastern birds' unusual color actually has a different source: a pigment called rhodoxanthin, which comes from the berries of two species of invasive honeysuckle plants.

Hudon and his colleagues used spectrophotometry and chromatography to show that rhodoxanthin, rather than the type of carotenoid pigment that colors western red-shafted birds, was present in the feathers of yellow-shafted flicker specimens with the aberrant red coloration. Data from a bird-banding station helped confirm that the birds acquire the red pigment during their fall molt about early August, which coincides with the availability of ripe honeysuckle berries. The honeysuckles have also been implicated as the source of unusual orange feathers in Cedar Waxwings.

How do birds dive safely at high speeds? New research explains

Date: October 5, 2016
Source: Virginia Tech

To surprise their prey, some species of seabirds dive into the water at speeds greater than 50 miles per hour. A human diver entering the water that fast would likely sustain serious injuries, but birds, such as gannets and boobies, pull off these dives safely in spite of their slender necks.

New research from Virginia Tech helps explain how the birds manage these high-speed dives.

"We were interested in what happens when objects plunge into water, so we looked for examples in nature; the gannets are incredible," said Sunny Jung, an associate professor of biomedical engineering and mechanics in the College of Engineering and an expert in fluid biomechanics; he has also studied dogs' unusual drinking technique and how shrimp use microscopic bubbles to hunt.

In a new study published in the Proceedings of the National Academy of Sciences, Jung and his coworkers investigate the biomechanics of gannets' dives. They found that the birds' head shape, neck length and musculature, and diving speeds work in concert to ensure that the force of the water doesn't buckle their slim necks.

Previous studies of the diving birds have focused on ecological aspects of this hunting behavior, called "plunge diving." Jung's is the first paper to explore the underlying physics and biomechanical engineering that allow the birds to plunge beneath the water without injury.

To analyze the bird's body shape and neck musculature, the team used a salvaged gannet provided by the North Carolina Museum of Natural Sciences. They also created 3-D printed replicas of gannet skulls from the collection at the Smithsonian Institution, which helped them measure the forces on the skull as it enters the water.

The primary force acting on the gannet's head as it plunges beneath the water is drag, which increases with speed. To analyze what other parameters affect the force the bird experiences, the researchers created a simplified model from a 3-D printed cone on a flexible rubber "neck," and plunged this system into a basin of water, varying the cone angle, neck length, and impact speed. High-speed video showed whether the neck buckled.

Some birds behave like human musicians

Date: October 6, 2016
Source: New Jersey Institute of Technology

The tuneful behavior of some songbirds parallels that of human musicians. That's the conclusion presented in a recent paper published by an international team of researchers, among them David Rothenberg, distinguished professor of philosophy and music in NJIT's Department of Humanities. Other members of the team are from the City University of New York (CUNY), the Freie Universit├Ąt Berlin and Macquarie University in Australia.

"Temporal regularity increases with repertoire complexity in the Australian pied butcherbird's song" was published online in Royal Society Open Science.

A Very Musical Species
The pied butcherbird, a very musical species, provided a wealth of intriguing data for analysis by co-author Eathan Janney, a Ph.D. candidate in the Department of Psychology at CUNY's Hunter College. Janney based his analysis upon years of data collected and also analyzed by violinist and biomusicologist Hollis Taylor of Macquarie University, who has previously published extremely detailed analyses of butcherbird songs. "Since pied butcherbird songs share so many commonalities with human music," Taylor writes, "this species could possibly revolutionize the way we think about the core values of music."

In the past, claims that musical principles are integral to birdsong were largely met with skepticism and dismissed as wishful thinking. However, the extensive statistical and objective analysis of the new paper demonstrates that the more complex a bird's repertoire, the better he or she is at singing in time, rhythmically interacting with other birds much more skillfully than those who know fewer songs. The accompanying video includes a sample of a butcherbird's solo song, as well as the song of another butcherbird and an Australian magpie.