Dragons are largely opportunistic predators. They don’t much care what they eat as long as there’s enough of it. They have animals they won’t eat as they don’t provied enough nutrition. This changes as they age and grow.
Bonded dragons don’t often feel the need to hunt as riders keep herds of animals specifically for them to use
Rabbits and similarly sized animals are sufficient for a very young dragon, especially one who’s just learning to hunt. Aside from the elau (a large, flightless bird), it’s extremely rare for a dragon to eat birds.
White dragons: their acceptable hunting range is large. Wild dragons live on fish, walrus, caribou, and elau.
Silver: relatively speaking, they have a small area they call home. They prey on migrating flocks of elau and moose. Some have acquired a taste for fish and will hunt large marine animals off the east coast.
Blue: while the migratory yahal fall in their hunting area, they rarely eat them, preferring red tailed deer when their in season. In the off season, they eat non-migratory animals.
Gold: they particularly enjoy wild cows and yahal as well as red tails when their migration path brings them through their province.
Green: their primary diet is yahal and red tail and will eat wild cows if they can get them. Greens also have a fondness for the large fish that populate the Liusje River.
There are non-migratory animals in each territory that they’ll eat as well. Larger dragons will sometimes hunt bears.
They make a point of not hunting other predators unless there are no other options. Some argue that wyvern are an exception to this rule, but wyvern meat tastes bad to them so while dragons will happily kill wyvern (and vice versa), they won’t eat them. Wyvern, on the other hand, will happily eat a dragon if the opportunity is there.