Tuesday, February 28, 2012

2012-02-28 "Woodpecker tapping spurs study, wonder" by Donna Beth Weilenman from "The Benicia Herald"
 Solano County has its share of woodpeckers, said Monique Liguori, executive director of the Suisun Marsh Natural History Association and its wildlife center.
Residents sometimes hear the birds tapping rapidly against the side of a tree. A few of the larger members of the avian clan, such as the pileated woodpecker — a large, crested bird — pound like a jackhammer.
Their tapping against tree trunks is called drumming, and a woodpecker can hit the bark as often as 20 times a second, Liguori said. Those drumming sessions can occur as often as 500 to 600 times a day.
The impact can reach a deceleration of 1,200g, she said. That means the bird’s beak collides with the tree at 1,200 times the strength of gravity. The birds have been known to drill into concrete to make burrows.
By comparison, commercial airline passengers experience up to 1.5g. Space Shuttle astronauts felt 3.5g, and professional pilots performing aerial acrobatics may train to survive up to 10g.
Roller coasters deliver about 4g, and a dragster can give its driver a horizontal g measurement of 5 or more when it accelerates.
But woodpeckers are taking direct hits to the head, on purpose. If a person is hit on the head at 4g to 6g, he or she may lose consciousness. That same person will have a concussion with a single deceleration hit of about 100g, Liguori said.
How woodpeckers can pound on trees without knocking themselves out has puzzled both birdwatchers and scientists, and in the past few years researchers have used computer simulations to learn how the birds survive their self-inflicted impacts.
Sang-Hee Yoon and Sungmin Park of the University of California-Berkeley studied video and other scans of the bird’s head and neck, and published a report Jan. 17, 2011. “They’ve found that there are a few factors that give the woodpecker this unique ability,” Liguori said.
For instance, the bird’s beak is hard, but elastic. It has a springy tongue-supported structure, called a hyoid, that is made of a sinewy substance and extends behind the skull.
The bird’s skull and cerebrospinal fluid work together to to suppress vibration, researchers have learned. And the birds hammer in a straight line, avoiding any rotation injury.
Scientists are using their findings to develop shock-absorbing systems, particularly for skulls, but with other applications as well, Liguori said.
Yoon and Park focused on suppressing damage to micromachined devices, and tested a woodpecker-inspired protection system using an airgun bullet fired into an aluminum wall, she said.
Their design prevented damage to some enclosed electronics, despite impacts reaching 60,000g.
According to their report, the failure rate of the shock-absorbing system inspired by woodpeckers was 0.7 percent. Conventional protection made of hard resin failed more than 26 percent of the time.
Flight recorders also have benefitted. They can withstand shocks of 1,000g.
But woodpeckers have other design features that intrigue scientists, Liguori said.
They have special feathers that cover their nostrils to filter out wood chips and other debris. Their tongues are three times the length of their beaks and extend to the back of their heads, and are either barbed or sticky so the birds can reach into their drilled holes to capture insects.
Liguori said local birdwatchers have a variety of woodpeckers and their relatives that they can observe as the birds drum away.
Not only can area residents find the crow-sized pileated woodpecker, but also the smaller acorn, Nuttall’s, hairy, downy and occasionally a Lewis’s woodpecker as they drill away into bark or other surfaces, hoping either to dine on insects or create a new home.
Also in Solano and Napa counties are northern flickers and red-breasted sapsuckers, she said; it’s uncommon to find a yellow-bellied sapsucker here, though they have been seen in the area.
Higher elevations are homes to white-headed, black-backed and three-toed woodpeckers, Liguori said.
The Suisun Marsh Natural History Association and its wildlife center is a recognized nonprofit volunteer organization dedicated to the rescue of native California wildlife and the preservation of the Suisun Marsh. It accepts donations.
In addition to wildlife rescue and release programs, the organization, 1171 Kellog St., Suisun, provides educational programs, field trips into the marsh and presentations at the wildlife center.
Anyone finding an injured or orphaned wild animal or bird in Solano County may call the center at 707-429-4295.
The wildlife center is open from 9 a.m. to 4 p.m. daily, which will expand to 9 a.m. to 6 p.m. in summer.
Its website is www.suisunwildlife.org.

ACORN WOODPECKER. Kim Cabrera photo

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