We’re not exactly to the point where the wolves are dwelling with the lambs, but new research indicates that the impact of wolves on elk may be overstated, and the so-called “landscape of fear” may not actually exist.
Under the theory of “landscape of fear,” which first emerged in the 1990s when wolves were reintroduced to Yellowstone National Park, elk would avoid risky places where they could be attacked by wolves, living under a perpetual haze of fear.
After a study from Utah State University ecologists Michel Kohl and Dan MacNulty, it turns out that the “landscape of fear” may be a myth, and that elk habitually visit risky areas at times when it’s unlikely wolves are active. In other words, the elks figured out that the wolves were only active at dusk and dawn and pretty lazy the rest of the night, leaving the elk plenty of time to access the risky areas.
“Contrary to popular belief, the wolf is not a round-the-clock threat to elk; it mostly hunts at dawn and dusk, and this allows elk to safely access risky places during nightly lulls in wolf activity,” says Kohl. “Despite their Hollywood portrayal as nighttime prowlers, wolves tend to hunker down at night because their vision is not optimized for nocturnal hunting.”
According to a Utah State University story on the study, “the researchers revisited data from 27 GPS radio-collared elk that had been collected in the early years after the reintroduction, 2001-2004, but never fully analyzed. These collars recorded the location of each elk every 4-6 hours. This was the first time GPS technology had been used to track Yellowstone elk, and no one imagined that elk might sync their habitat use to the wolf’s 24-hour schedule. Little was known about this schedule until researchers first equipped wolves with GPS collars in 2004.”
“In the days before GPS, when we tracked wolves by sight and with VHF radio-telemetry, we knew they hunted mainly in the morning and evening, but we didn’t know much about what they did at night,” says MacNulty, a veteran Yellowstone wolf researcher and associate professor in USU’s Department of Wildland Resources and the USU Ecology Center. “GPS data showed that wolves were about as inactive in the middle of the night as they were in the middle of the day.”
Kohl used the GPS data to quantify the 24-hour schedule of wolves, and he compared how elk use of risky places — sites where wolves killed elk — differed between periods of high and low wolf activity, says the USU story.
“Elk avoided the riskiest places when wolves were most active, but they had no problem using these same places when wolves were least active,” says Kohl. “An elk’s perception of a place as dangerous or safe, its landscape of fear, was highly dynamic with ‘peaks’ and ‘valleys’ that alternated across the 24-hr cycle in response to the ups and downs of wolf activity.”
“Our results can explain why many other studies found no clear-cut effect of wolf predation risk on elk stress levels, body condition, pregnancy or herbivory,” says MacNulty. “If our results reflect typical elk behavior, then actual killing rather than fear probably drives most, if not all, of the effect of wolves on elk and any cascading effect on the plants that elk eat such as aspen and willow.”
Photo courtesy National Park Service.