From the website ReconnectwithNature.org:
American white pelicans are often seen in the company of double-crested cormorants. They often forage for fish together, although they don't usually eat the same fish and they don't hunt at the same depths of the water, the Cornell Lab reports. Cormorants will even build their nests and raise their young within pelican colonies.
While the two birds usually peacefully coexist, pelicans do sometimes steal food from cormorants, particularly as the cormorants return to the surface with their catch. That's not their only target, though. Pelicans are well-known fish thieves and will even steal food from other pelicans.