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Wildlife: Spineless Wonder and More
© Roger Steene/Museum Victoria
With its eight arms you might say an octopus is “handy,” but handy with a tool?
Yes, says a duo of Australian scientists from Melbourne’s Museum Victoria. Diving off Indonesia between 1998 and 2008, the pair recorded what they believe is the first evidence of tool use by an invertebrate.
The researchers observed veined octopuses digging halved coconut shells from the sea floor, cleaning them out and stacking them like bowls under their bodies. These clever animals then “stilt-walked” away carrying this portable armor to be deployed as needed in the trek across open patches of seabed.
Octopuses often hide in found objects or use them to block entrance to their lairs. But by cleaning up the coconut shells, carrying them long distances—up to 60 feet—and reassembling them as shelter, the veined octopus takes it to sophisticated new levels.
What makes this different from a hermit crab moving into an empty seashell? When the octopus is moving with the coconut halves, “it’s not getting any protection from them,” says Julian Finn, one of the researchers. It’s the carrying for later deployment that is unusual and constitutes tool use, he says.
Finn believes the multidextrous mollusks probably once used clam shells the same way. But when people began halving coconuts and tossing the remains into the sea, veined octopuses figured out how to recycle them to make a better shelter.
Makes you wonder what they could do should a Swiss Army knife find its way to the ocean floor.
Respect for their Elders
It doesn’t come in the form of monthly checks, but older wolves do have a sort of social security check to rely on: their younger brethren.
“Wolves are not perfect predators,” says Daniel MacNulty, a postdoctoral researcher in the department of ecology, evolution and behavior at the University of Minnesota. “They lack physical characteristics to kill prey swiftly, so they rely on athletic ability and endurance, which diminishes with age.”
MacNulty has studied Yellowstone wolves since their reintroduction into the park in 1995 and has recently published a new study that found two- and three-year old wolves are in their hunting prime. After that, their skills deteriorate markedly.
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“For example, when 22 percent of the wolves in Yellowstone were three or older, the kill rate was 0.4 elk per pack per day,” he says. “If the older wolves were 52 percent of the population, the kill rate dropped to 0.22 elk per pack per day.” In general, the kill rate declines 10 percent to 15 percent when there is a 10 percent rise in the number of wolves more than three years. This means that younger wolves in the pack probably bear more of the workload when it comes to kills.
The findings are notable now that it is legal to hunt wolves in Montana and Idaho. Many people believe that wolves are behind a recent drop in elk numbers (which are still historically high), but MacNulty points to drought, which harms the elk’s food supply, and predation of elk calves by grizzlies as contributing factors. He believes that hunting wolves won’t necessarily help elk.
“It’s been shown in other hunted populations of wolves that hunting skews the population toward younger age classes,” he explains.
Nuts and bolts: More wolf deaths could actually mean more elk kills.
Learn more about these amazing creatures.
The heavyweight migration champion of the world is the Arctic tern, according to a recent study using tiny tracking devices to follow the bird’s annual travels.
The three-and-a half-ounce birds fly an epic 44,000 miles from pole to pole each year—Greenland to Antarctica and back again. Added up over a tern’s lifetime—which can stretch more than 30 years—that’s equal to about 1.25 million miles, or three round trips to the moon. Talk about some serious frequent-flier miles!
It’s the wildlife equivalent of “Go west, young man,” except that the species on the move this time will be trying to stay ahead of global warming. And they will have to move an average of a quarter-mile every year or risk extinction, according to a team of scientists from the California Academy of Sciences, University of California-Berkeley and the Carnegie Institute of Science.
The team’s study found that, depending on where plants and animals live, they could have to move their home range anywhere from 50 feet to six miles every year between now and 2100 to find suitable habitat as the climate changes.
With less than 10 percent of the parks, nature preserves and other protected habitats around the world expected to have the same climate conditions within their boundaries in the next century, there may be few safe places for wildlife to go unless government officials and conservationists act now to protect them.
Tumble for the Bumble
Talk about a buzz kill. First honey bees got hit with a mysterious disease causing a precipitous decline and now bumble bee populations are having problems.
Both are important crop pollinators. Honey bees, originally imported by European colonists four centuries ago, became more important in agriculture. But when “colony collapse disorder” was recognized a few years ago, demand for native bumble bees rose. This led to commercial rearing and unregulated transporting of the bees—which may be behind the recent spread of disease among wild bumble bee populations.
For example, two species of common bumble bees were shipped to Europe in the early 1990s for commercial rearing with European bumble bees and then returned to the United States. The U.S. bumble bees could have been exposed to European pathogens and then spread disease to less common, wild bee populations.
Defenders recently joined the Xerces Society and the Natural Resources Defense Council to petition the U.S. Department of Agriculture to prohibit the movement of bumble bees outside of their native ranges and to require permits that prove the bees are disease-free before they cross state lines.
“In the United States, pollinators, including bumble bees, provide essential services estimated at $3 billion annually,” says Bob Irvin, senior vice president of conservation programs at Defenders of Wildlife. “With some precautionary efforts in place, we can protect our native bee populations so they can continue to pollinate native plants and important food crops.”
Ice Out, Polar Bears In
As global warming claims their sea-ice habitat, polar bears are increasingly spending time on dry land and closer to people, according to a recently published study.
The study looks at 27 year’s worth of data collected by U.S. Minerals Management Services staff tracking bowhead whale migration routes in northern Alaska. Polar bear sightings were also recorded—and a marked shift in habitat use by these marine mammals was noted.
The data show only 12 percent of bear sightings associated with no ice between 1979 and 1987, compared to 90 percent between 1997 and 2005. What it suggests, says Karen Rode, a U.S. Fish and Wildlife Service polar bear biologist and one of the authors of the study, is that “bears that use the nearshore area are more likely to occur on land in recent years because their preferred habitat, sea ice, is unavailable.”
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Polar bears typically spend most of their time on or near the ice hunting for seals, their favorite food. With the ice disappearing, hungry polar bears are starting to make their way to human habitations near coastal areas to scavenge for dinner. This can be a dangerous situation for both people and bears and, says Rode, has major implications for polar bear management in Alaska.
“Federal and state wildlife officials must continue working with coastal residents to reduce the potential for human-bear conflicts with measures like polar bear patrols and bear-resistant metal lockers for food,” says Defenders’ Alaska director Karla Dutton. “We don’t have to guess who’s coming to dinner—we know, and we have to be prepared.”
Defenders at Work
Find out what Defenders is doing to help save polar bears.
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On the Blog
April 19, 2017 | 12.29 PM
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