Set an alarm clock for an early wake up time. You'll have to wake up early to see bears in particular. To see these powerful predators, focus spotting time around Hayden and Lamar Valleys or along the eastern entrance road. Hayden and Lamar Valleys are home to lots of grizzlies. Scan the sage brush early in the morning for any signs of movement. Bears will also hang out in open meadows on hillsides early before too many people get out and the sun forces them back into hiding for the day. Also scan river beds. Bears typically nap mid-day and are not seen again until evening.
Get on the road toward a productive spot before sunrise to see black bears. Black bears are more common forest dwellers than their grizzly cousins. You can find them near Tower, Roosevelt and Mammoth Hot Springs. Yellowstone's Tower area is home to one particular black bear named Rosie who loves to show visitors her cubs along the road from Tower to Mammoth. Look for these bears in the long green grasses near Tower Creek or north of Roosevelt. Blacktail Plateau is another hot spot for black bears.
Pull off the road often and scan meadows and hillsides with binoculars and you might just see a wolf on the move. Wolves typical are active early in the day and in the evening, but can play for hours in one location while onlookers crowd a pullout. They will most likely be seen far off on an opposite hillside, but once in awhile they cross the road or can be seen feeding on a kill withing view of the road. The north end of Hayden Valley has been a hot spot in the past few years, but Lamar and the Slough Creek area are typically the most consistent areas for wolf watching, since the area is home to four packs. Try the pull-off at Slough Creek Campground and focus on the hillside across the valley.
Watch for movement or anything resembling an animal in the willows and it might just turn out to be a moose. These large mammals can often be found along the east entrance road and in the south end of the park. They hang out in beaver ponds or other wet areas with lots of willow plants and easy access to water. They love to eat aquatic plants and often find themselves in rivers and ponds early and late in the day. The Grand Tetons to the south are home to numerous moose, while Yellowstone has seen a decline due to years of drought.
Watch for action and listen for sounds at pull-outs. Be sure to turn off your car engine because you never know when you might hear a wolf howl or an elk bugle. The elk in the park are active early and late in the day. Evenings are best for these species as they emerge from the forest between 5 and 8 p.m. Elk are found all over the park in lower elevations early and late in the year, but in July and August, they retreat to higher ground where it is cooler. The elk rut in October is a sight to see and hear as bulls bugle to attract mates and send messages to other bulls.
Bighorn sheep and mountain goat are mountain climbers so don't forget to look up. You can see these two species in the upper reaches of the northeast corner. The steep cliffs surrounding Soda Butte Creek are home to both. Bighorn sheep can most easily be seen around Tower and again along the north entrance road by the Gardner River. Look for them to stand out from their rocky outcroppings early in the day. Late season visitors often see them by Roosevelt and in Lamar Valley.