See other Science/Tech Articles
Title: Friend or foe, crows never forget a face
Source:
[None]
URL Source: http://seattlepi.nwsource.com/local/376433_crows26.html?source=mypi
Published: Aug 27, 2008
Author: MICHELLE NIJHUIS
Post Date: 2008-08-27 19:41:22 by angle
Keywords: None
Views: 149
Comments: 6
Scientist finds birds can recognize individuals, helping to identify threats Crows and their relatives -- among them ravens, magpies and jays -- are renowned for their intelligence and for their ability to flourish in human-dominated landscapes. That ability may have to do with cross-species social skills. In the Seattle area, where rapid suburban growth has attracted a thriving crow population, researchers have found that the birds can recognize individual human faces. John Marzluff, a wildlife biologist at the University of Washington, has studied crows and ravens for more than 20 years and has long wondered whether the birds could identify individual researchers. Previously trapped birds seemed more wary of particular scientists and often were harder to catch. "I thought, 'Well, it's an annoyance, but it's not really hampering our work,' " Marzluff said. "But then I thought we should test it directly." To test the birds' recognition of faces separately from that of clothing, gait and other individual human characteristics, Marzluff and two students wore rubber masks. He designated a caveman mask as "dangerous" and, in a deliberate gesture of civic generosity, a Dick Cheney mask as "neutral." Researchers in the dangerous mask then trapped and banded seven crows on the university's campus in Seattle. In the months that followed, the researchers and volunteers donned the masks on campus, this time walking prescribed routes and not bothering crows. The crows had not forgotten. They scolded people in the dangerous mask significantly more than they did before they were trapped, even when the mask was disguised with a hat or worn upside down. The neutral mask provoked little reaction. The effect has not only persisted, but also multiplied over the past two years. Wearing the dangerous mask on one recent walk through campus, Marzluff said, he was scolded by 47 of the 53 crows he encountered, many more than had experienced or witnessed the initial trapping. The researchers hypothesize that crows learn to recognize threatening humans from both parents and others in their flock. After their experiments on campus, Marzluff and his students tested the effect with more realistic masks. Using a half-dozen students as models, they enlisted a professional mask maker, then wore the new masks while trapping crows at several sites in and around Seattle. The researchers then gave a mix of neutral and dangerous masks to volunteer observers who, unaware of the masks' histories, wore them at the trapping sites and recorded the crows' responses. The reaction to one of the dangerous masks was "quite spectacular," said one volunteer, Bill Pochmerski, a retired telephone company manager who lives near Snohomish. "The birds were really raucous, screaming persistently," he said, "and it was clear they weren't upset about something in general. They were upset with me." Again, crows were significantly more likely to scold observers with a dangerous mask, and when confronted simultaneously by observers in dangerous and neutral masks, the birds almost unerringly chose to persecute the dangerous face. In downtown Seattle, where most passers-by ignore crows, angry birds nearly touched their human foes. In rural areas, where crows are more likely to be viewed as noisy "flying rats" and shot, the birds expressed their displeasure from a distance. Although Marzluff's is the first formal study of human face recognition in wild birds, his preliminary findings confirm the suspicions of many researchers who have observed similar abilities in crows, ravens, gulls and other species. The pioneering animal behaviorist Konrad Lorenz was so convinced of the perceptive capacities of crows and their relatives that he wore a devil costume when handling jackdaws. Stacia Backensto at the University of Alaska-Fairbanks who studies ravens in the oil fields on the North Slope has assembled an elaborate costume, including a fake beard and a potbelly made of pillows, because she believes her face and body are familiar to previously captured birds. Kevin McGowan, an ornithologist at the Cornell Laboratory of Ornithology who has trapped and banded crows in Upstate New York for 20 years, said he was regularly followed by birds that have benefited from his handouts of peanuts -- and harassed by others he has trapped in the past. Why crows and similar species are so closely attuned to humans is a matter of debate. Bernd Heinrich, a professor emeritus at the University of Vermont known for his books on raven behavior, suggested that crows' apparent ability to distinguish among human faces is a "byproduct of their acuity," an outgrowth of their unusually keen ability to recognize one another, even after many months of separation. McGowan and Marzluff believe that this ability gives crows and their brethren an evolutionary edge. "If you can learn who to avoid and who to seek out, that's a lot easier than continually getting hurt," Marzluff said. "I think it allows these animals to survive with us -- and take advantage of us -- in a much safer, more effective way." Nevermore.
Post Comment Private Reply Ignore Thread
Top • Page Up • Full Thread • Page Down • Bottom/Latest
Begin Trace Mode for Comment # 3.
#2. To: angle (#0)
So enthusiastic a crow hunter was I that my hunting buddy swore that the crows would leave the county when they spotted my car! I was so well camo'ed when crow hunting that a 3 ft tall great blue heron once fed in the marsh three feet in front of me. (I was sitting on a folding stool at the water's edge) They are known for their wariness and are used as "confidence decoys" when waterfowling because dux believe that if a blue heron (decoy among the duck dekes) is present then all is well. That feeding heron kept eyeballing me because it didn't recognize my outline. They have the ability to control the focus of their eyes like telescopes and it kept checking me out with wide shots and zoom ins! So, just to reward its vigilance and curiosity I finally moved, and it went APE! It was close enough to touch with my shotgun barrel but, I didn't want to give the critter a heart attack! (Also, they're protected, and they don't taste any better than eagles or any other fish eating fowl...)
There's one of those that hunts gophers at Golden Gate Park. A while back a few of us were out there waving the coils and he was scoping gopher mounds. We saw it spear one, take it over to a puddle formed by a leaky sprinkler head and wet it and then swallow it whole. Pretty cool, except we like the gophers 'cause they'll bring up old coins from the deeps when they're burrowing :-)
#4. To: Axenolith (#3)
How kewl! A gopher could put you over the top someday! "Look Ma! I found the ring that the Queen gave Cortez!"
Top • Page Up • Full Thread • Page Down • Bottom/Latest
#3. To: HOUNDDAWG (#2)
Replies to Comment # 3.
End Trace Mode for Comment # 3.