Dragons are a Highly diverse group of creatures that belong to the reptilian group of back boned animals 

there are many varieties of the species Draconian

Including 

Marine wyvern 

flying wyvern 

brute wyvern\ or wingless dragons

and different elemental or nature based Dragons 

we will be looking  at flying and elemental Dragons 

Rathian:

The Rathian is an example of Sexual dimorphism in the draconian group and is the female form of the flying wyvern Rathalos and both are alpha predator thus making them some of the top predators in the environment that they inhabit and the rathian is also A very protective mother that display brooding behavior. they are also highly territorial both rathian and rathalos  are able to produce a Explosive Flame and inject a Highly powerful toxin desinged to knock prey items uncossince prey Items include  Velociprey or Jaggi

though the Rathian is a powerful Predator it has to compete with much more ferocious predators such as the Tigrex, Zinogre, Seregios, Plesioth, Espinas, Gore Magala, Najarala, Ivory Lagiacrus, and Deviljho. 

Rathalos: 

The male of the rath duo and their subspecies or variants. This monster is the top of the food chain in most of it's habits a more Aerial based hunter compared to the rathian he will use his claws to inject venom Into prey items opposed to the rathians tactic of using her tail and the Rathalos is most definitely not an easy predator to fight it still  faces the same threats as its female counterpart and like most other monsters will flee the area if an elder Dragon decides to wander the territory.