Although we were mainly concerned to see the wildlife, especially the birds, first time visitors were equally interested in the park's many geothermal features - geysers, fumaroles, mud pots and hot springs. Most people will have at least heard of the 'Old Faithful' geyser but roughly half of all the world's 1,000 or so geysers are in Yellowstone so there was much else for us to see. Also, the scenery is really spectacular with lakes, rivers, mountains and canyons as well as huge areas of forest, so endless opportunities for photography.
During our 12-night tour we managed to see 28 species of mammals and most of those were in Yellowstone. On several occasions we saw Grizzly Bears, including on one occasion a mother with four cubs. We also saw several Black Bears and Coyotes, lots of Bison and Elk, Mountain Goats, Bighorn Sheep,and many smaller 'critters', mainly chipmunks and ground squirrels.
Birds included the easily seen wetland species such as American White Pelican, Sandhill Cranes and lots of ducks; raptors such as Red-tailed Hawk, Bald Eagle and Golden Eagle; stunning Mountain Bluebirds and several woodpeckers. The 'star of the show' was probably a female Great Grey Owl on a nest that contained at least two chicks.
'Old Faithful' - so-called because its irruptions, although not the tallest or largest amongst Yellowstone's geysers, are the most regular and predictable - always draws a crowd.
Bison - once numbered more than 20 million in North America but now only about 30,000 remain in conservation herds; about 4,000 are in Yellowstone.