Hungry moose more tolerant of wolves' presence

Date:  March 13, 2019

Source:  University of Wyoming

Driven by the need for food, moose in western Wyoming are less likely to change their behavior to avoid wolves as winter progresses, according to new research by University of Wyoming scientists.

The findings, published today (March 13) in the journal Ecology, provide new insights into the interactions of the region's apex predators and their prey. The results also highlight the complexity of the relationships between wolves and big-game species, making it difficult to reach general conclusions about whether and how fear of wolves has impacted the ecosystem, the researchers say.

"We have known for some time that hungry animals will tolerate the presence of predators in order to forage and avoid starvation, and that phenomenon, called the 'starvation-predation hypothesis,' is supported by our research," says Brendan Oates, now with the Idaho Department of Fish and Game, who conducted the research as a UW graduate student. "In this case, close proximity of wolves does cause moose to move, but not enough to drive them from their preferred habitats -- especially late in the winter."

Oates is the lead author of the Ecology paper. Co-authors include his UW advisers: Jake Goheen, associate professor in UW's Department of Zoology and Physiology, and Matt Kauffman, a U.S. Geological Survey researcher based at UW. UW's Jerod Merkle, assistant professor in the Department of Zoology and Physiology, also was involved with the research, as were agency personnel from the National Park Service and U.S. Fish and Wildlife Service.

The scientists tracked movements of dozens of GPS-collared moose and wolves in Grand Teton National Park and the Bridger-Teton National Forest over a five-year period, detecting 120 unique encounters among 25 individual moose and six wolf packs. An encounter was defined as when moose and wolves were within about 1,600 yards of each other.

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Surge in Sierra bears reported; 9 caught in 2 days

By SCOTT SONNEROctober 2, 2014 10:31 PM

RENO, Nev. (AP) — You'd be hungry too if you couldn't find any food and were used to eating the equivalent of more than 80 cheeseburgers a day.

An already busy bear season has exploded in the Sierra Nevada with nine hungry bruins captured since Wednesday morning near Reno and Lake Tahoe as an ongoing drought continues to make food scarce in the mountains. A 10th was hit and killed by a car Thursday in south Reno.

Since July 1, Nevada Department of Wildlife officials have caught 42 black bears and released all but two back into the wild. They said two repeat offenders had to be killed — one so bold it was rummaging through picnic baskets in July on a busy Tahoe beach.

Cars have killed an additional 10 bears as the animals move into more populated areas from the parched foothills on the Sierra's eastern front, where streams are down to a trickle and the usual supply of berries and insects is lacking.

A surge in activity is expected with cooler temperatures this time of year, when a typical bear's food intake jumps from 3,000 to 25,000 calories a day, said Chris Healy, Department of Wildlife spokesman. That's the human equivalent of 83 McDonald's cheeseburgers.

The animals are going through hyperphagia, a physiological change in which they eat as much as they can to store fat for winter hibernation.

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Hunger Affects Decision-Making and Perception of Risk

June 25, 2013 — Hungry people are often difficult to deal with. A good meal can affect more than our mood, it can also influence our willingness to take risks. This phenomenon is also apparent across a very diverse range of species in the animal kingdom. Experiments conducted on the fruit fly, Drosophila, by scientists at the Max Planck Institute of Neurobiology in Martinsried have shown that hunger not only modifies behaviour, but also changes pathways in the brain.

Animal behaviour is radically affected by the availability and amount of food. Studies prove that the willingness of many animals to take risks increases or declines depending on whether the animal is hungry or full. For example, a predator only hunts more dangerous prey when it is close to starvation. This behaviour has also been documented in humans in recent years: one study showed that hungry subjects took significantly more financial risks than their sated colleagues.

Also the fruit fly, Drosophila, changes its behaviour depending on its nutritional state. The animals usually perceive even low quantities of carbon dioxide to be a sign of danger and opt to take flight. However, rotting fruit and plants -- the flies' main sources of food -- also release carbon dioxide. Neurobiologists in Martinsried have now discovered how the brain deals with this constant conflict in deciding between a hazardous substance and a potential food source taking advantage of the fly as a great genetic model organism for circuit neuroscience.

In various experiments, the scientists presented the flies with environments containing carbon dioxide or a mix of carbon dioxide and the smell of food. It emerged that hungry flies overcame their aversion to carbon dioxide significantly faster than fed flies -- if there was a smell of food in the environment at the same time. Facing the prospect of food, hungry animals are therefore significantly more willing to take risks than sated flies. But how does the brain manage to decide between these options?

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