White Pelicans are among the most interesting birds that frequent the prairies in the summer. They are big. In fact, very big. They are one of the heaviest flying birds in the world with an adult weighing up to 19 pounds. It is a magnificent sight to see a group soar overhead.
From a photography point of view they are terrific subjects. Being big, they give us a lot to shoot at, but they tend to be happiest on islands, meaning that they are usually a long ways off.
If you are interested in seeing them or taking pictures, check out the larger sloughs and lakes on the prairies. Around Calgary, Frank Lake, McGregor Lake, Weed Lake and the lower Red Deer River are good places to look. Take binoculars as they will tend to be in the middle of the lake or hanging out on islands.
As an aside, the horn that some have on their beak denote that they are a breeding adult. It is only present during the breeding season.