Metal in diet harms Colorado birds.Cadmium, the white metal used in rechargeable batteries, is poisoning the white ptarmigan ptarmigan (tär`məgən): see grouse. ptarmigan Any of three or four species of grouse (genus Lagopus) of cold regions. Ptarmigan plumage changes from white in winter to gray or brown, with barring, in spring and summer. , a species of grouse grouse, common name for a game bird of the colder parts of the Northern Hemisphere. There are about 18 species. Grouse are henlike terrestrial birds, protectively plumaged in shades of red, brown, and gray. , in Colorado. Stretching from Denver to Durango, the state's ore belt is rich in the toxic metal toxic metal Environment Any metal known to be toxic to humans–eg, antimony, arsenic, beryllium, bismuth, cadmium, lead, mercury, nickel. Cf Nontoxic metal. . Although cadmium concentrations in soil and water are highest downstream from commercial mining operations, it's not mining activities in this region that endanger the birds, researchers say. Seeking to discover why the Colorado Lagopus leucurus has fragile bones, a team of ecologists led by James R. Larison of Oregon State University Oregon State University, at Corvallis; land-grant and state supported; coeducational; chartered 1858 as Corvallis College, opened 1865. In 1868 it was designated Oregon's land-grant agricultural college and was taken over completely by the state in 1885. in Corvallis undertook a 2-year study of the foods that the ptarmigan consumes. The researchers also analyzed tissues from 39 birds. "The studies that took us through the food web clearly indicated that we were dealing with cadmium problems," Larison says. The willow is a major food source for ptarmigan in winter. All species of willow, the team discovered, take in and concentrate whatever cadmium is available in the soil and water. The trees funnel the metal into their buds and shoots, resulting in significantly higher concentrations than are found in neighboring neigh·bor n. 1. One who lives near or next to another. 2. A person, place, or thing adjacent to or located near another. 3. A fellow human. 4. Used as a form of familiar address. v. plants. Cadmium accumulates in the birds' kidneys and liver, say Larison and his colleagues. Concentrations above a threshold cause irreversible renal damage. In the study, internal organs of 46 percent of birds examined had cadmium concentrations above the toxicity threshold. "This is truly unusual," says Larison. Lacking adequate kidney function to regulate calcium in their blood, the birds lose calcium from bone, say the researchers. Furthermore, they add, the Colorado ptarmigan habitat is naturally calcium poor, placing the birds in a vicious circle A Vicious Circle (1996) is a novel by Amanda Craig which dissects and satirizes contemporary British society. In particular, it describes the world of publishing -- its aspiring young authors, busy agents and opportunist literary critics. : A low-calcium diet increases cadmium uptake, and cadmium ingestion ingestion /in·ges·tion/ (-chun) the taking of food, drugs, etc., into the body by mouth. in·ges·tion n. 1. The act of taking food and drink into the body by the mouth. 2. retards calcium absorption. Poisoned ptarmigans are unlikely to themselves be a major source of concentrated cadmium to predators because they don't usually eat the birds' internal organs, the team notes. However, willows in the ore belt may also be deadly to other local herbivores, such as beaver and moose. |
|
||||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion