Interesting the bowerbird research undertaken by US academics ...
http://www.inform.umd.edu/CampusInfo/Departments/InstAdv/newsdesk/releases/2002/02002.html
Sensitive Guys Get The Girls In The Bowerbird World
COLLEGE PARK, Md. - Courtship displays of male satin bowerbirds on
stages they build and decorate in the Australian forest rate as the
flashiest in the animal world. But University of Maryland researchers
have discovered that it's not enough for a courting male to have great
taste in decor and some showy dance steps to wow the ladies. It turns
out it's the sensitive guy who gets the girls.
Using a robot female bird dressed in alluring feathers, a research team
from the University of Maryland discovered that the most attractive
satin bowerbird males are not the guys who just put on the most intense
display of masculinity in the mating ritual, but those who also can
respond to female moods. In a paper to be published in the Jan. 17
edition of the journal Nature, Gail L.Patricelli and Gerald Borgia show
that the fellows who have the most conquests are the ones who can adjust
the intensity of their mating dance if the female signals that she is
Uncomfortable.
"The male satin bowerbird puts on a very intense mating display, which
is important for wooing the female," said Patricelli, who designed the
experiment for her doctoral dissertation with Borgia, a biology
professor at Maryland. "But if it gets too aggressive and threatening,
it also can startle her. Our experiment showed that the preferred males
were those who could give a highly intense display but who could tone
down the intensity to avoid startling the female.
"The less successful males either didn't pick up on the female's signals
and were scaring her, or they were not displaying intensely enough."
The team's discovery reveals a new characteristic in understanding how
males in polygamous species attract females. "In pair-bonded species,
males and females collaborate to rear young, so it's been expected and
demonstrated that courtship involves reciprocal communication,"
Patricelli said, "but in species such as the bowerbird, in which the
male has many mates and no role in raising the young, it's been assumed
that communication during display was essentially one way - the male
saying 'Mate with me.'
"Our observations of bowerbirds, that male display is very aggressive
and that females are often startled, started us thinking in a different
way -- that females might be threatened during display, and, for the
benefit of both, females should signal their level of comfort with the
males' display. Our experiments supported this view."
To determine the finer points of bowerbird sexual prowess, the Maryland
team built a remote-controlled, realistic femme fatale that could mimic
the movements of a real female satin bowerbird. Called a fembot, the
remote-controlled flirt gives off all the subtle signals a male needs to
figure out if the lady is interested. The fembot turns her head, fluffs
her wings, tilts her beak and can assume the mating stance, a slow
crouch with a tip.
"We wanted to control the signals given by females during courtship,"
said Borgia, who has been studying the bowerbird for 22 years. "Females
have fewer moves than the male in courtship, so we could realistically
duplicate the female's behavior with a mechanical bird."
Gregory Walsh, the University of Maryland mechanical engineering
professor who, with his students, designed and built the robotic beauty
after watching videotapes of the birds in their Australian habitat said
"It was tricky but not terribly difficult. Robotics takes a lot of
inspiration from nature. We built a sheet metal skeleton, and a
taxidermist did the bird's exterior. We inserted a small computer to
control the bird. Of course we called that the 'bird brain.'"
The bowerbird courtship ritual is well suited for introducing a robotic
love interest, because, for one thing, it's easy to tell where mating
will take place. Males in almost all of the 19 bowerbird species, found
in Australia and New Guinea, begin the mating season by constructing
elaborate bowers, or courting areas, to attract females.
The satin bowerbird female, a gray-green bird about the size of a turtle
dove, cruises the neighborhood, checking out the bowers, and when she
sees one that interests her, she steps inside. The iridescent purple
male architect of the love nest then launches into a raucous song and
dance, jumping, ruffling his feathers and singing, even imitating the
calls of other birds. If he gets the crouch from the female, he knows
he's scored, and mating takes place. Sometimes a female will visit the
bower several times before she consents.
The actual consummation is as quick as a ruffle of feathers, and the
female is off to lay her eggs and hatch her young. Once she has found a
good man, the female may return to his bower each year as long as he is
sexually active.
Patricelli carefully snuck a fembot into bowers scattered along Wallaby
Creek in northern New South Wales, Australia when the males were away
from the sites, hid the remote control wires under leaves and waited for
the Casanovas to appear. From a hidden blind, Patricelli operated the
controls to send four different courtship signals, including consent. A
video camera recorded the action.
The feathered robot was so accurate in its movements that more than one
lothario attempted to mate with the fembot, but it took several years to
refine the fembot into her current svelte size. "Our prototype was a
big, healthy girl, because she was radio-controlled and had a lot of
machinery hidden in her gut, " Patricelli said. "We switched to wires,
which slimmed her down a lot." The debut bird was a hit in the bower,
however, said Gregory Walsh, "In the trials, two males were fighting
over her and knocked her head off."
The bowerbird is the only male bird in the world known to use interior
decorating and landscaping to prove his manhood to the female, according
to Borgia. Different species construct different styles of bowers, from
the satin's upswept 2-walled stick construction to a 6-foot wide
dome-style bower built by a New Guinea species.
Borgia's research has shown that the more refined and decorated the
bower, the more successful the builder is in the mating game. The top
male satin bowerbirds are even clever with landscaping. Many of the
species lay out colorful lawn ornaments of seeds, feathers and bright
plastic baubles, such as clothespins, in neat arrays around the bower.
"The males can't wander far from their bowers," said Borgia, "because
other males will steal their gear. The satins especially like to steal
the blue parrot feathers."
The 36 cameras that Borgia and his team of graduate students maintain in
Wallaby Creek through the mating season have shown that attention to
detail in the construction of a bower pays off for the satin bowerbird.
"One very successful male who had a good bower mated with 25 females
over one 2-month mating period," said Borgia. "He mated with nine
females in one day. But that's the exception. Most of them don't land a
female mate at all. The sexiest guys get all the mates.
"Like humans, bowerbirds have evolved a high level of intelligence, but
each species has come to this point with a very different set of
ancestors," said Borgia. "The example of bowerbirds has led some to
suggest that in humans and bowerbirds, intelligence may have been driven
by competition to show off to the opposite sex."
View video of the fembot and the satin bowerbirds on the web.
Contact Ellen Ternes, 301-405-4627, for the
website address.
For more information, contact Gerald Borgia 301-405-6943
; Gail Patricelli, 425-392-2251 until January 27th,
or 301-585-9301 after January 27th, ; Gregory
Walsh
#0202, Ternes, 1/15/02
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