MadSci Network: Zoology

Re: Why do Magpies like shiny objects?

Date: Fri Jul 23 12:37:42 1999
Posted By: June Wingert, MadSci Admin
Area of science: Zoology
ID: 929119422.Zo

Hi Kriss, You have brought up an interesting point in regards to behaviour in birds. What I think you might be referring to is the use of objects to attract females to the males nest.

The female Magpie builds a nest from sticks, wire, string and plastic and lines it with soft material and grass.These nests are often reused from year to year. Magpies will repair the old nests or even build a new nest on top of the old one. During spring courtship displays, male magpies strut before their potential mates flashing their wings before finally chasing them around. Once established, these pair bonds can last all year or even for a life time.

Magpies are actually members of the Crow family. This family of birds, which also includes ravens, jays, and nutcrackers, has evolved the highest degree of intelligence among birds. Members of this family have learned to count, can solve puzzles, and can quickly learn to associate certain noises and symbols with food.

The BBC aired a special on "LIFE OF BIRDS" which dealt with the amazing behavior patterns that birds go through in finding partners. You can go to

The Public Broadcasting System also had a great special devoted to the antics of the Bowerbird and how this bird goes to great lengths in building and decorating a fantastic nest to attract a female. Go to the following site and you will be able to get a glimpse of the elaborate nest built by this amusing bird.

There are three basic kinds of bowers: "maypoles,""mats," and "avenues." But only now are scientists beginning to discover the reasons behind the existence behind these different forms -- and behind that of the bowers themselves. Mat, or platform,bowers are among the simplest: thick pads of plant material ringed with ornaments.

One mat-builder, Australia's Tooth-billed catbird, builds what is known as a "circus ring" by arranging silvery leaves around the mat, like the petals of a disheveled flower. The bird constantly removes withered leaves in favor of fresh, shiny replacements. Maypole bowers, more ambitious, are twig towers built around one or a few saplings in a carefully groomed courtyard.

The Golden bowerbird even perches on a roofed bridge suspended between towers. And four other kinds of maypole builders surround their creations with lawns of moss.

Avenue bowers, such as the Satin bowerbird's, featured on NATURE, have two close-set parallel walls of sticks that sometimes arch over to create a tunnel. In a rare example of a bird using a tool, Satin and Regent bowerbirds may use a leaf or twig to paint the inner walls of their bowers with a stain made from chewed plants, charcoal, and saliva.

Each builds its own shape of bower and prefers a different decorating scheme. A few, for instance, surround their bowers with carefully planted lawns of moss. Others have been known to steal shiny coins, spoons, bits of aluminum foil -- even a glass eye -- in an effort to create the perfect romantic mood.

Gerald Borgia, a University of Maryland bowerbird expert, believes the different kinds of bowers all serve essentially the same function: to make visiting female bowerbirds feel comfortable by protecting them from overeager males. Courtship rituals, he notes, almost always involve males and females standing with the bower between them, like a fence. In the case of the maypole-building Macgregor's bowerbird, for instance, the courting pair warily circles the central tower. Only when the female chooses to stop and allow the male to approach can mating occur. "The bower probably started as a protective device," Borgia concludes. "It allows females to get close enough to get a good look without feeling threatened. The male that builds something that makes the females feel most comfortable is likely to see more females." Borgia has also detected a relationship between the kind of bower and the intensity of the male's display. The male Spotted bower bird, for instance, builds a wide straw wall and performs a relatively energetic display full of dance steps and dramatic poses. In contrast, species building smaller barriers have toned-down displays that are probably less threatening to females. Other researchers have noticed a link between the showiness of a bower bird's plumage and the intricacy of its bower: in general, the drabber the bird, the fancier the bower will be. Some believe this reflects an evolutionary choice: drab birds compensate for their dull appearances by building flashier nests.

I want to thanky you for taking the time to send in a question to the MadSci Network.

June Wingert
Baylor College of Medicine
Houston, Texas

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