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Wolves Benefit from Popularity
Recently, wolf biologists have been surprised by an upsurge in wolf numbers in the Great Lakes states. The Minnesota population has grown to an estimated 2,000 animals, a modern high, says Jim Hammill, a wildlife biologist with the Michigan Department of Natural Resources (MDNR). And not only have the wolves increased, but they have begun dispersing.
Last spring, prior to the birth of pups, biologists estimated that Michigan's Upper Peninsula was host to a minimum of 80 wolves and northern Wisconsin to another 83. These are the highest numbers in either place since the 1940s, Hammill says. Wolves have been located within 30 miles of Madison, Wisconsin, and nine wolves have been spotted in South Dakota, where wolves probably were wiped out more than half a century ago.
Hammill says the expansion has resulted from an increase in deer and, more importantly, from a growing tolerance for wolves on the part of local residents. About 20 years ago, when the U.S. Fish and Wildlife Service and the MDNR released four gray wolves into suitable habitat in Michigan's Upper Peninsula, all of the animals were shot or run over within seven months. Thanks to a better understanding of wolves today, more people support the presence of the predators.
To maintain that crucial tolerance, the MDNR and other agencies are developing a program to reimburse farmers for any livestock they lose to wolves, Hammill says. However, he fears that if the deer, a popular game species, declines again, "tolerance may not hold up very well."
Rolf Peterson, a wolf biologist at Michigan Tech University, says that the expansion is the "most successful wolf reintroduction in the world, and the best part is, the wolves did it themselves."
Looking for Miss Light
Anyone looking for the perfect spouse can't help but envy a common East Coast firefly. New research indicates that males of the species have a skill at matchmaking that even a dating service can't beat.
Jay van der Reijden, a zoologist at the University of New Hampshire in Durham, discovered that the keen sensory systems with which male fireflies peruse potential mates allow the males to determine which females will bear healthy offspring.
The mating season for fireflies is about five weeks long. For the first half of that time, males outnumber females, so females get to pick and choose, apparently basing their choices on male flash signals. During the second half of mating season, males are dying off, so females outnumber males. Now the males choose the mate. "I wanted to know why the male decides to leave or stay," says van der Reijden.
Van der Reijden examined specimens of mated and rejected females. "I noticed that the rejected females were likely to be parasitized by a small fly that bores a hole into the female firefly and lays an egg inside," she says. "This baby fly, or larva, eats the firefly's eggs, so the male can't sire any offspring" with those females.
The researcher is not sure how the males know which females are parasitized. "Insects are very sensitive to chemicals," she says. "The female has to seal up the hole where the parasite entered, so perhaps there is something chemical going on here that the male notices through antennal contact."
Regardless of the males' ability to choose prolific mates, the future may challenge the firefly. Some species are becoming rare as development claims firefly habitat.
Toxic Hazards: Are You In Danger?
At least one in every three U.S. counties harbors a facility capable of generating a toxic gas cloud at least 5 miles long, according to a new study by the National Environmental Law Center and the U.S. Public Interest Research Group. These facilities and
other industrial plants, the study concluded, expose more than
44 million Americans to potential death or injury from chemical releases, fires and explosions.
Five Most-Jeopardized States*
Five Most-Jeopardized Communities*
- Los Angeles
- Niagara County, New York
- Jefferson County, Texas
* Source: the National Environmental Law Center in Boston, based on data from the Toxic Release Inventory compiled by the Environmental Protection Agency
Birds of a Feather Sing Together
New research suggests that starlings, those European imports
that have swept across North America since their release here around the turn of the century, may rank high among the jam-session artists of the bird world.
Starlings live in colonies, and socializing seems to come naturally to them: Members of one colony frequently visit other colonies. And when the birds get together, they trade tunes, according to Marten Hausberger, a researcher at the University of Rennes in France.
Individual starlings each have their own distinctive songs, and their repertoires also include songs that are sung by all members of their colony. While monitoring the singing of six male and nine female captive starlings, Hausberger and her colleagues recorded the birds singing alone, with a mate and in same-gender groups. They found that males and females rarely share songs, even when kept in pairs. However, pairs of females increased their sharing of songs over time. Males kept together also shared songs, and, over time, their individual songs became more alike. The study backs up other research that indicates that birds in stable social situations show less variety in their songs than do birds in a changing social environment.
Yum, Gaseous Emissions!
A chemical that has a vague smell of oysters and can be mildly nauseating to humans apparently helps some seabirds locate food. Researchers from the University of California at Davis and the University of Washington have found that odor-sensitive seabirds, such as white-chinned petrels and prions, are attracted to the scent of dimethyl sulfide.
The chemical is produced when tiny ocean plants called phytoplankton are grazed upon by tiny ocean animals called zooplankton. Fish and seabirds, in turn, dine on the zooplankton--so the birds' attraction to the dimethyl sulfide aroma could well be a clue to how they forage above the water for food below the surface.