Sunday, 19 February 2017

US: Oceanic whitetip shark warrants 'threatened' listing




February 5, 2017 by Patrick Whittle

The oceanic whitetip shark's declining status in the wild warrants listing as threatened under the Endangered Species Act, an arm of the federal government has determined. 

The shark is found around the world, mostly in open water, and the conservation group Defenders of Wildlife called on the government to list the species. The listing would be the most widespread shark listing in the U.S. to date.

The National Marine Fisheries Service said in a document published in the Federal Register in December that the sharks are indeed likely to become endangered in all or at least a significant portion of their range "within the foreseeable future."

Threats to the sharks include fishing pressure all over the world, as their fins are prized in Asian markets for use in soup. The sharks have declined by 80 to 90 percent in the Pacific Ocean since the 1990s, and 50 percent to 85 percent in the Atlantic Ocean since the 1950s, said Chelsey Young, a natural resource management specialist for the fisheries service.

"The oceanic whitetip has very large pectoral fins, and so they have fetched a high price on the international market in Asia," Young said. "It incentivized the fin trade."

The fisheries service is collecting public comments about the shark's status until March and is expected to make a final decision in November. Listing the species as threatened would afford it protections aimed at recovery.

Wolfing it down: Brown bears reduce wolf kill rates says usu ecologist




Contrary to popular assumptions, researchers on two continents find wolves kill less often in the presence of brown bears

Date: February 8, 2017
Source: Utah State University

If you've ever been elbowed out of the way at the dinner table by older, stronger siblings, you'll identify with wolves competing with larger bears for food. A study by Utah State University ecologist Aimee Tallian and colleagues reveals wolves might be at more of a disadvantage than previously thought.

Tallian is lead author of a paper examining competition between wolves and brown bears on two continents published Feb. 8, 2017, in Proceedings of the Royal Society B [DOI: 10.1098/rspb.2016.2368].

"Wolves and brown bears coexist across most of their range," says Tallian, who completed a doctoral degree from USU in 2017. "Although competition between predators such as these is widespread in nature, we know little about how brown bears affect wolf predation."

With colleagues in Scandinavia and North America, Tallian examined how brown bears affected wolf kill rates at study sites in northern Europe and Yellowstone National Park.

"We found an unexpected pattern," she says. "Wolves killed less often in the presence of brown bears, which is contrary to the common assumption that wolves kill prey more often to compensate for loss of food to bears."

Tallian says the consistency in results between the systems on different continents suggests brown bear presence actually reduces wolf kill rate, but the researchers aren't sure why.

They surmise wolves, unlike lynx and mountain lion, may not be quickly abandoning their kills, as bears move in take advantage of the spoils.

"The wolves may be hanging around longer, waiting their turn to gain access to food," Tallian says.

She and her colleagues also wonder if wolves kill less frequently because it takes them longer to find prey.

"We think this may be the case, in the spring, when newborn ungulates make easy pickings for bears," Tallian says. "It may simply take more time for wolves to find calves, when there are fewer of them."


Monkey fights help explain tipping points in animal societies






Date: February 10, 2017
Source: Santa Fe Institute

Previous studies of flocks, swarms, and schools suggest that animal societies may verge on a "critical" point -- in other words, they are extremely sensitive and can be easily tipped into a new social regime. But exactly how far animal societies sit from the critical point and what controls that distance remain unknown.

Now an analysis of conflicts within a captive community of pigtail macaque monkeys has helped to answer these questions by showing how agitated monkeys can precipitate critical, large-scale brawls. In the study, fights were often small, involving just two or three monkeys, but sometimes grew to be very large, with as many as 30 of the 48 adults in the society. Bryan Daniels at the ASU-SFI Center for Biosocial Complex Systems, together with David Krakauer and Jessica Flack of the Santa Fe Institute, used ideas and models from statistical mechanics to ask whether the monkeys' conflict behavior was near a critical point. They report what they found in this week's Nature Communications.

Daniels, Krakauer, and Flack discovered that the distance from the critical point can be measured in terms of the "number of monkeys" that have to become agitated to push the system over the edge. Daniels says that in this system "agitating four or five individuals at a time can cause the system to destabilize and huge fights to break out." However, Daniels says, each monkey makes a distinct contribution to group sensitivity -- and these individual differences may allow distance from the critical point to be more easily controlled. Group members that break up fights can move the system away from the critical point by quelling the monkeys that contribute most to group sensitivity. Other group members, by targeting and agitating these individuals, can move the system towards the critical point and ready it for reconfiguration.

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