According to disease expert Andy P. Dobson, wolves and other predators can aid in the removal of wildlife diseases within an ecosystem by killing and consuming infected animals. PHOTO COURTESY OF USFWS
As a globally renowned scientist, Andy P.
Dobson specializes in studying a topic that most people don’t like to think
about, but which is titillating nonetheless: diseases that make both people and
animals sick.
In the Lower 48 states, nothing rivals the
Greater Yellowstone Ecosystem in terms of large wild animals moving across it
and sharing terrain with non-native domestic animals that haven’t really been
here that long.
Recently, I was able to catch up with Dobson
and have a conversation.
Todd
Wilkinson: Our mutual friend, Bozeman-based writer David
Quammen, explored this subject in his book “Spillover: Animal Infections and the
Next Human Pandemic.” Why should inhabitants of the
modern world be paying attention to diseases that can spread from wild areas to
people/livestock and vice versa?
Andy
Dobson: I’ve watched what can happen.
TW:
You are fascinated by how diseases can become virulent and how pathogens can
jump species. We have several that fall into the worrisome category in Greater
Yellowstone. Tell us about your interest.
AD:
I worked on a bunch of emerging disease problems within the National Science
Foundation/National Institute of Health Infectious Diseases program that
started up in around 2000. It began with looking at pathogens in carnivores in
the Serengeti such as rabies and distemper as well as Nipah and Hendra viruses
in Malaysia and Australia.
Raina Plowright, now in the disease ecology
lab at Montana State University, was a student on this project. We chose a
canonical emerging disease which no one cares about so we can study it without
trying to eliminate it. The disease, mycoplasma, hit house finches. The disease
spread across the entire U.S. between 1993 and today, reducing the house finch
population by greater than 50 percent.
TW:
When it comes to some of the major maladies that are present in Greater
Yellowstone—brucellosis, bovine TB, CWD, and pneumonia in mountain sheep—are
there any that concern you more?
AD:
I think all are important. The problems they have created usually stem from
human mismanagement. Brucellosis is largely a consequence of feeding elk in
winter in Wyoming when it might be better to let their populations settle to
lower levels with healthier populations.
Similarly, CWD presents an expanding and
increasingly worrying threat to elk, mule deer and cattle. It’s a consequence
of loss of coyotes, wolves and other predators from the West over the last 50
years, combined with early attempts to ranch stock on really poor soils where
they are so nutritionally deprived that they gnaw on old carcasses and become
infected with prions from animals that have died from CWD.
TW:
You’ve spoken out about the value of predators.
TW:
What role can wild native predators play in slowing the progression of CWD? In
the Northern Rockies, there are some that deny they can function as a gauntlet.
Your thoughts?
AD:
Wolves and coyotes are our strongest defense against CWD, particularly wolves—they
are pursuit predators who always focus on the weakest animals in a group of
potential prey. As CWD manifests itself by reducing locomotory ability, wolves
will key in on this and selectively remove the individuals from the population.
These animals are then not available to infect uninfected individuals in the
herd, so there’s a bonus knock-on effect of selective predation.
TW:
Some claim wolves and coyotes will actually spread CWD.
AD:
Canids are not susceptible to prions, many millions of years of evolution as
scavengers have insured this. During the BSE [Mad Cow Disease] crisis in the
UK, it was estimated that a large number of domestic dogs in the UK was exposed
to the prions. Not a single dog was ever recorded as infected. So wolves and
canids do not transmit the prions/CWD in their feces and urine. It is nonsense
to suggest so. Carnivores are also much more territorial in the West and only
dispersing individuals range over areas comparable to those of elk, mule deer
and pronghorn.
TW:
Given your experience globally, look at the artificial feeding of upwards of
20,000 elk at the National Elk Refuge in Jackson Hole and Wyoming’s 22
state-run feed grounds. What’s your best scientific opinion?
AD:
As mentioned above, I think it’s really dumb. It’s much better to let natural
regulation reduce elk populations down to levels naturally supported by the
landscape. Aggregating elk on feed grounds at the time of peak Brucella
transmission and with CWD looming is arguably the stupidest form of animal
management I can imagine.
Todd Wilkinson
is the founder of Bozeman-based Mountain Journal (mountainjournal.org) and is a
correspondent for National Geographic. He’s also the author of “Grizzlies of
Pilgrim Creek” about famous Jackson Hole grizzly bear 399, which is available
at mangelsen.com/grizzly.