What Deer and Elk Can Learn From #quarantinelife
As states slowly begin the reopening process and we transition out of a solid three months of self-quarantine, we can see that social distancing plays a definite role in slowing an infectious disease when the majority of the global population follows protocol. Like COVID-19, chronic wasting disease (CWD) has also blanketed the world with confirmed cases in deer, elk and moose in 26 states and three Canadian provinces as well as South Korea, Finland, Sweden and Norway.
CWD and COVID-19 are both infectious diseases and there are similar core principles that apply to them even if transmission routes may vary and one only affects wildlife. However, unlike coronavirus’s rapid spread, CWD has a longer incubation period, meaning it can take years for the disease to show in infected herds.
Dr. Michael Miller, senior wildlife veterinarian for Colorado Parks & Wildlife, likens waiting for new cases of CWD to emerge with watching paint dry.
“We have to think in terms of how patterns change [with regard to CWD] in a series of decades,” says Miller. “We have herds we’ve been monitoring since the mid-1990s and we’re just now getting to the point where the patterns are starting to present themselves in a way where we can see what’s really going on.”
Social distancing helped flatten the curve of coronavirus in a matter of months – not years – and is keeping susceptible individuals away from those who may be infectious. Banning crowds and closing non-essential businesses sends a direct message to society that it’s not OK for large groups to gather – even if, for us, crowds are somewhat natural. What if we could apply the same premise to deer and elk, essentially ask them to socially distance from one another to curb the spread of CWD?
Unfortunately, it’s not that easy.
“In terms of CWD or really any infectious disease, any time you’re gathering animals in a single point at the same time in large numbers or atypical social groupings, there is an increased potential for contact and increased transmission to susceptible animals,” says Miller.
Many animals engage in social distancing naturally unless they learn not to thanks to easy access to food sources provided by supplemental food programs, baiting and artificial feeding practices.
“In the case of CWD, the risk is compounded by the fact that the disease agent can persist in the environment for a while,” continues Miller. This creates “the potential for indirect transmission” when the time and place of overlap is “uncoupled…between an infected animal and susceptible animal.”
That means that in order for an animal to become infected, according to Miller, you only need the same place, not necessarily the same time. Baiting, feedgrounds and other artificial feeding practices essentially create that perfect storm for CWD to spread because they establish crowds of deer and elk that would not naturally happen in the wild, resulting in an open pipeline for CWD to spread to healthy animals.
Food plots, bait piles and mineral blocks, oh my!
Supplemental feeding programs, baiting and other artificial feeding practices increase both the density and frequency of contact, says Krysten Schuler, an assistant professor in the Cornell University College of Veterinary Medicine’s Department of Population Medicine and Diagnostic Sciences.
“I use the concept of a buffet or salad bar,” says Schuler. “You're putting a disease agent in contact with a host by drawing animals to one particular area with a feeding attractant. Even if the animals aren’t there at the same time, because they’re using the same space, they’re leaving behind prions.”
Because CWD can be transmitted through the feces, saliva and possibly urine of infected animals, any of those substances left behind seeps into the soil. Diseased animals that die or decay also contribute to CWD-prion-contaminated areas. Healthy animals that graze in these areas eventually become infected.
But there’s a difference between food plots and bait piles or mineral blocks: one is a concentrated pile of corn or salt meant to lure animals to a location; the other is crops like alfalfa, clover, oats or rye spread over several acres that cannot be easily replenished.
Bryan Richards, emerging disease coordinator at the U.S. Geological Service’s National Wildlife Health Center, points out that it’s a matter of scale.
“It's important to clarify that baiting and feeding along with high deer densities is another clear amplification risk factor,” says Richards. “Artificial congregations don't pose a risk for enhancing or elevating the risk of disease transmission. You have to have infectious agents there first.”
These food plots and bait piles can act as a repository for CWD, which Richards alludes to as “the gift that keeps on giving” in that the disease can be transmitted between infected animals and healthy animals; however, the spectrum between a hundred-acre food plot and a corn sprayer or bait pile is broad. Further, it’s hard to clearly define how amplified the risk can be for deer and elk that visit these places.
But what about feedgrounds?
Supplemental feeding programs aimed at helping elk and deer through difficult winters are a controversial topic because while they may help herds survive, overcrowding and congestion only adds to the possibility of healthy animals contracting CWD from infected ones. And, according to Schuler, many of the feedgrounds were “put in place as a stopgap measure to stop the elk from moving down into the lowlands where the cattle were grazing.” Unfortunately, while these feedgrounds may have been established with solid intentions – whether it be sustaining herds through severe winters or helping cattle ranchers – Schuler says that the programs have created populations that are “artificially inflated beyond what the habitat can support.”
Wyoming currently faces multiple lawsuits aimed at closing feedgrounds in the state since they are potential hotspots for the spread of CWD. In February, three groups filed a lawsuit to end the National Elk Refuge’s supplemental feeding program and, in April, four groups filed another lawsuit to close the feedgrounds at Dell Creek, Forest Park and Alkali Creek. While feedgrounds are unique to the West, with CWD’s current reach, eliminating forced congregating of elk and deer could help all North American herds.
Putting solutions in place
Unfortunately, there's no one-size-fits-all management approach because of the variety and systems that wildlife managers have to deal with that range from state to state and from herd to herd. If a herd is already infected, Miller says that’s where it’s important to limit attraction to artificial sources of food, water and minerals while also keeping “somewhat of a lid on infected herds in terms of population size” with particular emphasis on mature males as “that seems to help keep the disease under wraps.”
Schuler says it would be helpful to educate the general public – the hunters out there who may be used to bait piles – about the environmental transmission issues of the disease.
“And a lot of it really comes down to modeling,” says Schuler, acknowledging that CWD modeling is similar to current pandemic modeling as it’s a way of predicting future trends and spikes based upon current patterns.
Richards points out that one of the first things the Center for Disease Control and Prevention did during the current pandemic was establish a level of credibility that wildlife management and state agencies have struggled to do with regard to CWD and key stakeholders like hunters and landowners. Educating the general public is good, but having hunters and landowners on the supportive side of CWD management and prevention is critical to moving towards a solution.
“It’s a matter of laying out the science and showing what outcomes have been and what outcomes are likely to be in the absence of active management,” says Richards. “Basically, getting that buy in from hunters and landowners.”
Miller concurs and suggests that, like coronavirus, we need to focus on suppressing it – not really stamping it out.
“We need to knock it back,” says Miller. “Which is similar to a lot of the principles that have been enacted on our human population over the last couple of months to slow down the progression of coronavirus.”
And because of CWD’s slow moving transmission, part of that is honoring management strategy aimed at curbing its spread – even if that strategy doesn’t provide immediate results.
“This is my plea: trust the people who are managing these resources,” says Miller. “They’re really trying to do the right thing.”
Even if it takes five to ten years, Miller adds, “Some progress is going to be made.”