2017 Nevada Sporting Dog Alliance
At a time when public discourse on the topic of large predators, and especially the hunting of such animals, is increasingly fraught with misinformation and vitriol, we figured it was appropriate to reach out to one of our state’s resident experts on predators.
We recently sat down (via e-mail) with NDOW’s Predator Management Staff Specialist, Mr. Pat Jackson, PhD candidate, to briefly discuss predators in Nevada. Topics covered range from black bear disease transmission, delayed implantation, and selective harvest to sex (gender) ratios among mountain lions and genetic diversity.
The following is an exact written transcript of our e-mail interview with Mr. Jackson.
1. What are the management objectives for mountain lions? Bears?
The Nevada Department of Wildlife captures our objectives in our management plans and mission statement. Following is a portion of the Department’s mission statement:
“To protect, preserve, manage and restore wildlife and its habitat for the aesthetic, scientific, educational, recreational, and economic benefits to citizens of Nevada and the United States, and to promote the safety of persons using vessels on the waters of Nevada.”
Management plans speak to the need to recognize multiple uses, protection of public safety, and conservation of the species. In simple terms, the Department values the species and the ecological role that they play in the environment. The Department also recognizes that sustainable use is a viable conservation goal, while at times predation management is important in maintaining optimal levels of all wildlife species.
Public safety concerns may at times play an important role in dealing with specific animals, but human activities (such as food availability and trash disposal) substantially influence the likelihood of a predator-human conflict.
2. How does NDOW establish population estimates for predators that are typically more difficult to count than ungulates?
Population estimates are not always necessary to manage wildlife populations. Trends in populations can be inferred from research conducted on known-size populations with other indices like harvest data.
Populations managed on harvest data are routinely managed more conservatively than those on population data.
For mountain lions, we currently follow two indices:
- The total number of adult females harvested
- The total number of all females harvested
For black bears, the Department currently uses a mark-recapture method to estimate the statewide population.
We are currently engaged in the development of an integrated population model for mountain lions that will allow us to use the data we have on movements and harvest to inform the estimate.
We are also expanding our efforts to estimate bear populations using passive genetic sampling (that is, we don’t have to capture individual animals) in collaboration with Michigan State University and the University of Montana.
3. Overall, what is the status of predator populations (e.g., stable, declining, or expanding) in Nevada?
a. Mountain lions — stable
b. Bears — stable to increasing
c. Bobcats — stable to increasing (another species for which we are collaborating with researchers to develop better abundance estimates)
d. Coyotes — unknown
4. Do you subscribe to a top-down or bottom-up approach to predator/prey dynamics?
I don’t subscribe to either theory exclusively, but instead believe it’s normally a combination of the two. I believe habitat plays a crucial role in prey abundance.
With Nevada being the most arid state in the nation, precipitation is very important and often a limiting factor both in terms of free water availability and forage quantity and quality.
5. What, if any, are the major threats or hindrances to the bear population? Lions?
Mountain lions inhabit almost all of Nevada. At this time, I know of no major threats or hindrances to the statewide population.
Black bears are currently recolonizing Nevada. Smaller populations are always more susceptible to stochastic events. I believe black bear-vehicle collisions and black bear-human interactions may slow this recolonization.
It is important to remember Nevada’s black bear population is part of a larger metapopulation in California.
6. Are there any plans to facilitate expansion of black bears into their historic ranges?
Not at this time.
7. What is the status of the lion/bear interaction study?
This study was identified as Project 32 in the Predator Plan. It is currently in its last year of field work. Wildlife Conservation Society, the Department’s collaborator and project lead, will be preparing a final report and submitting papers for publication.
We can state that bears certainly do scavenge kills made by mountain lions, but they are not the only species that do. It is difficult to attribute much ecological effect without completing the complex analyses that will be applied.
8. Has NDOW ever used hounds for tracking and treeing problem predators for relocation?
While the Department has used hounds to assist in our work, including capturing predators for various reasons, our principal use of dogs is through aversive conditioning of bears after release.
9. Why isn’t consumption of bear meat required in Nevada?
Nevada state statute (NRS 503.050) does not require sportsmen to retrieve black bear and mountain lion meat from the field as is the case for big game animals.
NRS 503.050 would need to be amended to require meat from black bears and mountain lions to be kept.
No statute currently requires that meat be consumed — only that it be retrieved and not allowed to go to waste.
10. What dictates denning dates for bears?
Bears have evolved behavioral adaptations known as hibernation that avoid periods of food scarcity and cold temperatures.
Bears conditioned to use human foods and garbage have demonstrated that hibernation is not essential if they can consume sufficient calories.
Across the U.S., bears tend to enter and emerge from dens at similar times if they are not influenced by non-natural food sources.
11. Are there barriers to genetic diversity among mountain lions?
There is no evidence indicating that mountain lions are suffering from barriers to genetic diversity.
Some research suggests gene flow tends to move from areas with the least exploitation toward regions of greater exploitation, which is not unexpected.
Although widely distributed, mountain lions are not equally distributed across the landscape.
12. Does delayed implantation control bear populations?
Delayed implantation allows bears to avoid pregnancy when caloric intake is insufficient to support cubs through winter.
While this may appear to function as population control, if implantation had occurred and cubs were born, they may have died from malnutrition and reduced the female’s survival odds.
I would not characterize delayed implantation as controlling bear populations.
13. What are appropriate sex ratios among lions and bears?
Appropriate sex ratios are difficult to determine. Unexploited populations tend to have different sex and age ratios than exploited populations, but variability is biologically acceptable and does not necessarily influence recruitment or population growth.
NDOW monitors:
- Adult female harvest in mountain lions
- Overall female harvest in mountain lions
If the 3-year mean percentage of adult (≥3-year-old) females in a management zone exceeds 35%, the Department establishes a separate harvest objective to limit harvest.
For black bears:
Light Harvest
- <30% females in harvest
- 55% adult females
- Mean male age >4 years
Moderate Harvest
- 30–40% females
- 45–55% adult females
- Mean male age 2–4 years
Heavy Harvest
- 40% females
- <45% adult females
- Mean male age <2 years
Bears are managed to maintain a light harvest that does not influence population growth.
14. Does selective harvest of mature males benefit populations?
There is no evidence that selective harvest of males benefits lion or bear populations. It does provide the least detriment.
15. What are the rates of infanticide?
NDOW does not have information on infanticide rates.
16. Are wildlife crossings being considered?
NDOW is working with the Nevada Department of Transportation to identify big game wildlife crossings to limit public safety risks.
Crossing structures in high-traffic areas benefit all wildlife, including bears and lions. In some areas, fencing may be more appropriate and cost-effective.
17. Is disease transmission a concern among wild bears?
Bears are susceptible to diseases such as rabies, bubonic plague, and trichinellosis.
There is no current disease of concern that is limiting population growth.
Hunters are advised to cook bear meat thoroughly to avoid trichinellosis.
18. Is there transmission of plague from prey species to predators and humans?
Bubonic plague is normally spread through fleas from infected animals.
Predators that eat ground rodents may become exposed. If exposed and sick, seek medical attention and inform medical staff of possible plague exposure.
19. Are bears more numerous today than historically?
Modern population estimates, while imperfect, are more rigorous than historic estimates. Comparing the two directly is subject to conjecture.
Recent estimates suggest substantial recovery in many areas, and most jurisdictions believe bear populations are growing.
20. How do bears expand despite habitat degradation?
Fire has not drastically impacted Nevada bear habitats.
In other regions, bears do well in new habitats, feeding on spring vegetation and fall mast. Timber management changes may have favored bear growth.
21. What harvest data does NDOW collect?
Harvest forms collect age, sex, and size data. This allows monitoring of trends and determining the level of harvest pressure on populations.
22. Do Karelian Bear Dogs reduce repeat conflicts?
Use of Karelian Bear Dogs in aversive conditioning has shown significant impact on how long it takes bears to return to an area.
NDOW is investigating further using satellite collars.
More information:
http://www.ndow.org/uploadedFiles/ndoworg/Content/Nevada_Wildlife/Bear_Logic/Beckmann-Lackey-deterrent-tech-2002.pdf
23. Are there biological reasons not to hunt predators?
Predators serve important ecological functions. Regulated and monitored harvest generally does not provide compelling biological reasons to avoid hunting predators.
In some cases, limited lethal removal is necessary for sensitive prey species.
Social and moral arguments vary. There is no single correct answer — only compromises.
24. What role do sporting dogs play in predator management?
The use of dogs can increase hunter success and may allow greater selectivity in harvest.
Lion hunters using hounds have demonstrated selectivity. In Arizona, bear hunting data showed no selection difference among methods. In Nevada, data show hound hunters have been more selective in the bear hunt.
Dogs that put game at bay provide opportunity for selectivity, but the hunter must choose to exercise it.
