Wildlife Health

Big Horn Sheep at Glacier National Park, photo by Jenny Powers

Part of the National Park Service mission is conserving “wild life” within its units. To the NPS, “wild life” includes everything from mega-fauna such as bears and moose, to the smallest organisms such as bacteria and protozoa, native to parks. Some microorganisms in parks cause disease that must be managed; however, native diseases may be part of a naturally functioning ecosystem protected within a park. Rather than attempting to eradicate all “bad” organisms that cause disease in animals (the way that “bad” predators were eliminated at the turn of the 20th century), park managers and NPS veterinarians try to preserve the health of an entire ecosystem.

Diseases of all types, from bacterial and viral to parasitic and toxic, affect wild animal populations every day. Prevention of exotic disease introduction, e.g. from domestic pets or livestock or translocation of wildlife, is preferred to management of an established disease. When diseases occur, park managers have the challenging task of determining when to intervene in wildlife health issues and when to allow natural processes to regulate themselves. National Park Service management principles guide this decision-making.

Key Principles

In general, natural processes are relied upon to maintain native animal species, and to influence natural fluctuations in populations of these species. Some of the key principles that the NPS employs to determine if a disease is managed or if it is allowed to run its course in wild animals include:

• Is the disease native or exotic? If the host population has evolved in concert with the disease organism and the pathogen is native to the area, the disease and its host will generally be left unmanaged. If, however, the disease was introduced as a result of human influence then it may be eliminated.
• Is management of the disease prudent and feasible? If so then the disease may be managed if:
  • The disease is a threat to human health.
  • The disease poses a risk to threatened or endangered species.
  • The disease threatens areas outside of the park.
  • The native disease is acting under unnatural conditions which change the biology and epidemiology of the disease.

After considering these questions, the appropriate management action may be clear. In other cases, the National Environmental Policy Act (NEPA) is used as a decision-making tool to evaluate potential alternatives and garner public input.

Diseases

There are numerous diseases that affect wildlife. A few of the diseases that are currently of concern in the units of the National Park Service are: bighorn sheep pneumonia complex, bovine brucellosis, bovine tuberculosis, chronic wasting disease, foot-and-mouth disease, rabies, and West Nile virus. Click on any of these diseases to find out more. Some other disease agents that have the ability to cause large wildlife die offs in isolated areas, including National Parks are: tularemia, sylvatic plague, canine distemper virus, avian cholera, avian botulism, and epizootic hemorrhagic disease. These are only a few of the diseases which affect wild animals in NPS units.