Wildlife: Dolphin Days are Here Again and more

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Grizzly Bear, © Jess Lee

© Jess Lee

Please Bear With Them

The grizzly bear's removal from the list of federally endangered species was a hand-clapping success story just two years ago. But with high numbers of bears being killed by hunters around Yellowstone National Park, the grizzly's path to recovery may not be so clear. Here are the bare bones:

-Bears are naturally expanding their territory but there is concern more will get killed if they are forced even farther afield in search of whitebark pine seeds, a dietary staple. Warmer than normal temperatures (read: global warming) are prolonging beetle infestations that have already laid waste to tens of thousands of acres of whitebark.

-Humans killed 48 bears last year, out of 82 total deaths. At least 20 were at the hands of hunters who felt threatened or who mistook a grizzly for another animal. (Grizzly hunting is still illegal.)

-The population numbered nearly 600 when the federal government removed protections. Today the population is growing an average of 4 percent to 5 percent a year, according to the U.S. Geological Survey.

The good news is that the population is being closely monitored. A high death rate next year would trigger a review of the bear's status.

 

The Eyespots Have It

"Come hither" or "back off?" For a butterfly, it's all in a flip of the wing and a flash of eyespots.

Working with bush brown butterflies and evolutionary modeling tools, Yale University researcher Jeffrey Oliver confirmed what biologists, including Darwin, have long suspected: Butterflies use the eyespots on the upper sides of their wings to attract mates and those on the undersides to divert predators.

Oliver and his colleagues found the eyespot patterns on the upper side of the butterflies' wings evolve much more quickly than the patterns on the underside and at different rates in males and females. Sexual selection signals like eyespots tend to come and go repeatedly over time, so the higher rate of change supports the theory that the eyespots on the top side are used to attract mates. The underside eyespots evolved at the same rate in both sexes, a scenario consistent with natural selection for characteristics designed to thwart ever-present enemies.

Bush browns and other butterflies often perch, wings folded, undersides exposed, a position from which they can quickly flash hidden eyespots on their forewings to confuse predators and buy time for escape. Exactly how the eyespots on the upper side of the wing are interpreted by potential mates is not fully understood. What we do know now is that different patterns on different sides of the wings keep butterfly communication spot-on.

 

Meat Your Mate

Mating tip number one for wild male chimpanzees: Share your meat.

A recent study of chimpanzees living in the tropical rain forests of Taï National Park in Ivory Coast revealed that females mate more frequently with males who regularly invite them to partake in some prey du jour. Indeed, males who shared their meat (typically red Colobus monkey) with a female doubled their mating success with that particular female.

"Our results strongly suggest that wild chimpanzees exchange meat for sex, and do so on a long-term basis," says lead researcher Cristina Gomes of Germany's Max Planck Institute for Evolutionary Anthropology.

The meat-for-sex hypothesis helps explain why males readily share meat with females. Chimpanzees are highly promiscuous. When it comes to mating, females have some choice in partners, while males usually have control of their kills. By swapping meat for sex, males get to spread their genes and hone their hunting skills. Females get the protein and calories they need to supplement their diet of fruits and leaves without investing a lot of energy and risking injury.

It's a wild meat-market mating scene that allows both sexes to score long-term.

 

Dolphin Days are Here Again

They look like small belugas, are most closely related to orcas and until recently were going the way of the dodo.

They are Irrawaddy dolphins, and experts believed that only a few hundred were left before researchers with the Wildlife Conservation Society recently discovered nearly 6,000 of the creatures in Bangladesh's Sundarbans mangrove forests and the nearby Bay of Bengal. "This discovery gives us great hope that there is a future for Irrawaddy dolphins," says Brian Smith, the study's lead researcher.

But all is not wine and roses. The six- to eight-foot dolphins, which live in brackish waters along South Asia coasts, are increasingly threatened by accidental entanglement in fishing nets. During the study, researchers encountered two dolphins that had drowned because of nets—a common occurrence, according to local fishermen.

Additional threats include the diversion and damming of rivers, which increases the salinity of coastal waters, and climate change, which is expected to raise sea levels and change salinity levels as Himalayan glaciers melt. The society and the Bangladesh government are now hoping to create a protected area to keep the dolphins afloat.

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