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Martin Wolff's List: Birds
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A new study by researchers at Cardiff University reveals that wild birds foraging on invertebrates contaminated with environmental pollutants, show marked changes in both brain and behaviour: male birds exposed to this pollution develop more complex songs, which are actually preferred by the females, even though these same males usually show reduced immune function compared to controls.
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Dec 19, 09
Once upon a time, every tweet had an actual bird attached. If that bird happened to live in southern Brazil, a region whose rich avian life was long undocumented, chances are good that it was stalked repeatedly — and its tweets, coos and whistles recorded patiently — by William Belton.
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An internationally recognized ornithologist, Mr. Belton was almost single-handedly responsible for the current body of knowledge of the bird life of Rio Grande do Sul, the southernmost Brazilian state. His field recordings and specimens from the region are today in the collections of major research institutions. His two-volume study of the birds of the area is widely considered seminal.
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Mr. Belton’s accomplishments are all the more unusual in that as an ornithologist, he was completely self-taught.
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The Atlantic piping plover has been on the endangered species list for more than 20 years after dwindling to 722 nesting pairs. Scientists have gone through a difficult, and sometimes contentious, program to restore them, which involved shutting down parts of various beaches for weeks at a time and banning off-road vehicles. However, the efforts appear to have worked.
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By 2100, climate change could cause up to 30 percent of land-bird species to go extinct worldwide, if the worst-case scenario comes to pass. Land birds constitute the vast majority of all bird species. ''Of the land-bird species predicted to go extinct, 79 percent of them are not currently considered threatened with extinction, but many will be if we cannot stop climate change,'' said Cagan Sekercioglu, a senior research scientist at Stanford and the lead author of a paper detailing the research.
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An endangered species, condors cannot reproduce until they are 8 to 12 years old. Even if they manage to survive to that age, they can lay only one egg every three years. Many of those eggs turn out to be infertile. For the past decade, a team of scientists and volunteers at the Buenos Aires Zoo has been raising condor hatchlings and releasing them throughout South America, helping restore populations of the bird in places where it had long been considered extinct.
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Frown though we may on steroid-style supplementation as cheating, or as competitiveness taken to unsporting and unnatural extremes, in nature such pious niceties do not apply. In nature, as the saying has it, it’s not whether you win or lose, it’s whether you win — and animals will do or ingest the most outrageous, dangerous, blechy things in their quest for victory. Egyptian vultures consume large amounts of cow and goat dung to extract traces of plant pigments that will turn the birds’ pasty faces a sexually alluring shade of mustard. A male goat will demonstrate his ardor for a nanny by drinking her urine and soaking his beard and belly in his own.
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Some of the birds flew upside down or threw their heads back between their wings. Some fell out of the sky. Others tried to land a foot or more above the water, or swam in circles when they got there. And then they died.
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Ornithologists have long known that waterfowl migrate huge distances. But it is rarely possible to be sure where any flock’s route begins and ends — information useful to tracking the spread of avian flu. These pictures, from the Wildlife Conservation Society, which runs New York City’s zoos, are the first proof that bar-headed geese — one suspect in moving the flu around the world — can travel 3,000 miles from their breeding grounds.
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When a male Anna’s hummingbird swoops down over a female in an acrobatic mating display, it emits a loud and quick chirp, closely corresponding in tone to the highest C on a piano. For years, the source of the sound has been the subject of debate. Is it a vocal sound, or something else?
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Seven endangered California condors, about 20 percent of the population in Southern California, have been found to have lead poisoning. Officials do not yet know the source of the contamination, but a United States Fish and Wildlife Service official said the birds had probably been poisoned by eating the carcasses of animals shot by hunters. The California condor nearly became extinct in the 1980s, but a trapping and breeding program has helped restore the species. There are about three dozen of the endangered birds in Southern California and about 200 in the wild over all. Under a ban that takes effect July 1, 2008, it will be illegal for California hunters to possess or fire lead ammunition when they are in the birds’ habitat.
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Sexual signaling in animals is generally considered a one-way street. That is, a physical characteristic that conveys information about an animal’s desirability takes a physiological toll, and thus keeps things “honest†— if the animal isn’t up to it physiologically, it can’t produce the signal. But a study of barn swallows by Rebecca J. Safran of the University of Colorado and colleagues at Princeton and Arizona State universities suggests that the link between signaling and physiology may be more complicated.
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Did you sleep like a baby last night? You might think so, but actually you slept like a bird. Or rather, a bird slept like you. One bird, in particular — the zebra finch, which researchers say has a sleep structure very much like that of people and other mammals.
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Less than two years after the bald eagle was removed from the federal government’s endangered species list, an environmental organization in Maine has found an alarming accumulation of mercury in the blood and feathers of bald eagle chicks in the Catskill Park region of New York. Lynda White, eagle watch coordinator at the Audubon Center for Birds of Prey in Maitland, Fla., which monitors active eagle nest sites, said that because eagles are so sensitive to contamination — evidenced by their tragic link to DDT — they are good barometers of environmental health. “If mercury is affecting them, it eventually is going to affect us, as well,†Ms. White said. Eagle chicks elsewhere in New York also were tested for mercury. But levels were not as high as those in the Catskills, which is home to several huge reservoirs that store drinking water for New York City, 110 miles away.
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For the last eight years, Operation Migration has been one of several organizations collectively trying to bring whooping cranes back to the eastern part of the North American continent. The whooping crane is reclusive and headstrong — it demands a square mile around its nest to itself — and consequently was one of the first birds to suffer as humans crowded into North America. In a 1946 article in The New York Times, a spokesman for the U.S. Wildlife Service, which was then going through considerable trouble on the species’s behalf — much of it for naught — called the whooping crane “intolerant of civilization.†The article went on to blame the crane’s “lack of cooperation†for its looming extinction. But the birds’ uncompromising wildness “is part of their majesty,†Joe Duff, Operation Migration’s co-founder told me. Thus, re-establishing the species presents a challenge: how can humans intervene to breed and teach the birds what they’ll need to survive without also wearing away those birds’ natural apprehension of people? One way is to do it in disguise. From the time Operation Migration’s cranes hatch at the federal government’s Patuxent Wildlife Research Center in Maryland, and for the rest of their lives, every effort is made to keep them from acclimating to humans or encountering even the slightest sign of them. Workers never speak around the cranes, and they always wear the same white costumes. They use a small crane-head puppet slipped over one hand to teach the chicks how to peck and forage. Gradually, the cranes “imprint†on the costume, accepting whoever is wearing it as the dominant bird in their cohort. The chicks are then shipped to the Necedah National Wildlife Refuge in Wisconsin for “flight training.†Like many species, whooping cranes learn to migrate only by following their parents. They have no inborn understanding of where to go, and if no older birds are around to show them, they
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Why do we help out our relatives when one of them needs a buck or a meal, and who gains the most from such acts of generosity? It's a tough question to answer in human populations, where self-awareness and cultural expectation cloud the biological forces that underlie behavior. But there are hints of answers in other species.
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Bird brains produce patterns of electrical activity that look strikingly like human brains during sleep, a remarkable similarity considering that birds and their brains have been on a separate evolutionary course from mammals for 300 million years. But similarities reach just so far.
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