May 24, 2012

Today's Wildlife Disease News Stories


Giant Killer Mice Decimating Rare Seabirds

On a remote island in the South Atlantic, common house mice have become unrelenting killers, consuming millions of endangered baby birds a year, a new study confirms.

...The new study, though, reveals that the petrel chicks are in constant danger from house mice, which have grown to supersize proportions since being introduced to the island 150 years ago.

...House mice have no predators on Gough Island, and in summer their numbers reach "stupendous densities—300 mice per hectare," Wanless said. (A hectare is about 2.5 acres.)

That means there are about 1.9 million mice on an island that's just 25 square miles (65 square kilometers). What's more, the mice on Gough Island now grow 50 percent bigger than normal mice, reaching up to 10 inches (27 centimeters) long, not including the tail.

As other food sources diminish in winter, the mice turn to the huge numbers of bird chicks.

National Geographic - news.national.geographic
21 May 2012
R Kaufman
Location: Gough Island

Toxic substances found in Talvivaara birds

Tissue tests conducted at the organisation’s Oulu lab showed signs of organ damage in birds found dead at a Talvivaara processing pond in Sotkamo, eastern Finland. Toxicology screening found high levels of nickel, zinc and manganese.

Fresh results from laboratory tests by the Finnish Food Safety Authority Evira show that exposure to toxic metals was the cause of death among scores of birds found at the site of a Talvivaara metals recovery facility in Sotkamo earlier this month.

Tissue tests conducted at the organisation’s Oulu lab showed signs of organ damage in the birds, while toxicology screening found high levels of nickel, zinc and manganese. The bird species included laughing gulls, golden eye ducks and mallard ducks.

Evira researcher Marja Isomursu said that the effects of metal poisoning were found in the avians’ digestive tracts and lungs. She said that the birds were probably exposed to the toxic metals in the air and water surrounding the mine.

Apart from signs of poisoning, Evira found the birds in good health, with no evidence of disease or viral or bacterial infections.

Yle Uutiset -
22 May 2012
Photo courtesy of Yle Uutiset
Location: Talvivaara, Finland - Map It

Richer parasite diversity leads to healthier frogs, says new CU study

Increases in the diversity of parasites that attack amphibians cause a decrease in the infection success rate of virulent parasites, including one that causes malformed limbs and premature death, says a new University of Colorado Boulder study.

... The new study showed when the chorus frogs were exposed to all six trematode types simultaneously, the infection success rate was 42 percent lower than for frogs exposed to only a single species of parasite. “Our results show increases in parasite diversity consistently cause a decrease in infection success by the most virulent parasite,” said Johnson of the ecology and evolutionary biology department.

The primary study results support the idea that higher biodiversity can help protect against certain diseases, but few previous studies had considered the diversity of the parasites themselves. Because many parasites compete with each other, ecological systems richer in parasites can act as a buffer against virulent pathogens. Johnson said the combination of extensive field and lab work helped strengthen the study results.

University of Colorado Boulder -
21 May 2012

Cited Journal Article
Parasite diversity and coinfection determine pathogen infection success and host fitness. PNAS. 2012; published ahead of print May 21, 2012, doi:10.1073/pnas.1201790109

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