As frequent visitors to the parks can testify, a lot of animals have developed a high tolerance to roads and vehicles - much to the delight of millions of visitors who view and photograph bison, elk, antelope and deer, as well as predators such as wolves, coyotes, black bears and grizzly bears.
That tolerance or habituation has limits, however. Park authorities and publications will tell you that visitors, themselves, must stay more than 100 yards away from bears and 25 yards away from other wildlife.
Just because a bear or bison strolls right by your car with nary a glance, doesn't mean they won't react if you hop out of the car.
"The big problem we have is with visitors who have these little pocket cameras," said Kerry Gunther, bear management specialist at Yellowstone.
Those little cameras don't have powerful lenses, so people compensate by trying to get closer to wildlife.
"We'd prefer that you stay in the car and shoot from there," said Gunther.
He also cautions against the idea of photographers circling around a bear, in order to get that "perfect shot." Inadvertently, a handful of shutter-bug visitors may move around until the bear feels theatened by not having a clearly defined path to get out of there, he said.
To help ensure that you do not put yourself or habituated bears at risk, said Gunther, please observe the following guidelines when viewing or photographing roadside bears:
Do not stop your vehicle in the middle of the road. Park on shoulders or in established turnouts and make sure your vehicle is completely off the paved roadway with the gear shift in park and the parking brake engaged.
For your safety, stay in your vehicle and view and photograph through a window. If you choose to exit the safety of your vehicle, stay nearby so you can get inside quickly if the bear approaches you. Bears, especially subadults can be curious and may approach people to search for and test new foods.
Do not stand in roadways. A driver distracted by the bear could easily hit you. Although the road provides a firm base, for obvious reasons photographers should not set their tripods up in the road - it is just not a safe thing to do.
Keep a safe distance from bears. In Yellowstone National Park it is illegal to approach within 100 yards of bears.
Do not surround, crowd, approach, follow, or block a bear's line of travel.
Do not run or make sudden movements. Such movements could provoke an attack.
If other people in the area are putting you in danger, leave the scene and/or notify a park ranger. You are responsible for your own safety.
Do not feed bears or leave food where they can get it. Feeding bears is against the law and fed bears usually end up as dead bears.