Navigation Links
Wolves lose their predatory edge in mid-life, new U of Minnesota study shows

Although most wolves in Yellowstone National Park live to be nearly six years old, their ability to kill prey peaks when they are two to three, according to a study led by Dan MacNulty and recently published online by Ecology Letters. The study will appear in the journal's December print issue.

The finding challenges a long-held belief that wolves are successful predators for their entire adult lives. It now appears that like human athletes, they are only at the top of their game for about 25 percent of that time. It also shows that physiology can limit predation.

"Wolves are not perfect predators," says MacNulty, a postdoctoral researcher in the College of Biological Sciences' Department of Ecology, Evolution and Behavior. "They lack physical characteristics to kill prey swiftly, so they rely on athletic ability and endurance, which diminishes with age. They're like 100-meter sprinters. They need to be in top condition to perform."

By comparison, mountain lions, with their short snouts, powerful muscles and retractable claws, are designed to kill, MacNulty says. Not surprisingly, they live and hunt alone.

In Yellowstone, wolves, who hunt in packs, depend on elk for survival. The finding is timely because the park's elk population is shrinking and wolves are being blamed. Wolves were hunted out of the area in the 1930s and re-introduced in 1995. But the study shows there isn't a strong correlation between the number of wolves in the park and the number of elk killed.

MacNulty says that number fluctuates based on the age structure of the wolf population at any given time. The higher the proportion of wolves over age three, the lower the rate at which they kill elk. For every 10 percent rise in the proportion of wolves older than three, the kill rate declined 10 to 15 percent. He notes that the drop in the elk population is also attributable to drought and to Grizzly Bears.

"Wolves are not the sole factor limiting Yellowstone's elk population," MacNulty says.

When older wolves can no longer hunt successfully, younger wolves share their kill with them, in what MacNulty describes as a lupine version of Social Security. While a high ratio of old-to-young wolves may benefit elk, it could strain the wolf population because there aren't enough workers to support retirees.

Montana legalized hunting wolves after they were removed from the endangered species list in 2007. Although hunting is prohibited in the park, packs wander beyond it boundaries and radio-marked wolves have been killed. MacNulty says hunting won't put the species at risk, but it actually skews the population towards younger wolves, which could mean more deaths, not fewer, for the elk.

MacNulty became a field biologist at Yellowstone after graduating from the University of Colorado in 1995, the year wolves were reintroduced, and focused his doctoral studies on their predatory behavior. He has continued tracking Yellowstone's wolves as a University of Minnesota postdoctoral researcher for Craig Packer, the world's foremost authority on lions.

MacNulty's next step is to create mathematical models to study the long-term effects of fluctuations in the age structure of Yellowstone's wolf population on the elk population. His collaborators include Douglas Smith (Yellowstone Center for Resources); John Vucetich, Michigan Technological University) David Mech (US Geological Survey); Daniel Stahler (Yellowstone Center for Resources) and Craig Packer (University of Minnesota).


Contact: Patty Mattern
University of Minnesota

Related medicine news :

1. Courage Center Jr. Rolling Timberwolves to Defend #1 Ranking at National Tournament March 18-22
2. Iberian wolves prefer wild roe deer to domestic animals
3. One-fourth of HIV patients believe their doctors stigmatize them
4. Father and Daughter From Tanzania Receive Their First Medical Examination in Newport Beach
5. Teens need to see their doctors more often
6. Can brain-injured, partially-blind stroke patients regain some of their lost vision?
7. Scientists explain how insulin secreting cells maintain their glucose sensitivity
8. When Should Children Wash Their Hands?
9. UCLA/RAND study shows that many children of HIV-positive parents are not in their custody
10. National Association for Home Care & Hospice (NAHC) Members Take Their Case to Capitol Hill
11. Nurses describe dedication, frustration associated with their jobs
Post Your Comments:
(Date:6/26/2016)... ... 2016 , ... Brent Kasmer, a legally blind and certified personal trainer is helping to develop ... The fitness app plans to fix the two major problems leading the fitness industry today:, ... all type program , They don’t eliminate all the reasons people quit their ...
(Date:6/25/2016)... ... 2016 , ... Experts from the American Institutes for Research ... June 26-28, 2016, at the Hynes Convention Center in Boston. , AIR experts ... planning, healthcare costs and patient and family engagement. , AIR researchers will be ...
(Date:6/25/2016)... , ... June 25, 2016 , ... The temporary closing of Bruton Memorial Library on ... Observer , brings up a new, often overlooked aspect of head lice: the parasite’s ability ... fumigation is not a common occurrence, but a necessary one in the event that lice ...
(Date:6/25/2016)... ... ... First Choice Emergency Room , the largest network of independent freestanding ... of its new Mesquite-Samuell Farm facility. , “We are pleased to announce Dr. ... James M. Muzzarelli, Executive Medical Director of First Choice Emergency Room. , Dr. ...
(Date:6/25/2016)... ... June 25, 2016 , ... Dr. Calvin Johnson ... Recently, he has implemented orthobiologic procedures as a method for treating his patients. ... the first doctors to perform the treatment. Orthobiologics are substances that orthopaedic surgeons ...
Breaking Medicine News(10 mins):
(Date:6/24/2016)... 24, 2016 Dehaier Medical Systems Ltd. (NASDAQ: ... develops, markets and sells medical devices and wearable sleep ... a strategic cooperation agreement with Hongyuan Supply Chain Management ... on June 20, 2016, to develop Dehaier,s new Internet ... agreement, Dehaier will leverage Hongyuan Supply Chain,s sales platform ...
(Date:6/24/2016)... , June 24, 2016 According ... by Type (Standard Pen Needles, Safety Pen Needles), Needle ... GLP-1, Growth Hormone), Mode of Purchase (Retail, Non-Retail) - ... This report studies the market for the forecast period ... reach USD 2.81 Billion by 2021 from USD 1.65 ...
(Date:6/24/2016)... KNOXVILLE, Tenn. , June 24, 2016 /PRNewswire/ ... market providing less invasive and more durable cerebrospinal ... million in funding.  The Series-A funding is led ... the Lighthouse Fund, and other private investors.  Arkis, ... less-invasive neurosurgical instrumentation and the market release of ...
Breaking Medicine Technology: