Question How to make a leveling system and hunting system

how to add leveling and selective hunting

I was wondering how to code a way for creatures to breeding, 2 parts to this(breeding bar,this happens when two dinosaurs of the same species are close together for a while but not eating, running for their lives or sleeping.
The other step is going to their nest and after a few seconds, a smaller version of that dinosaurs spawns in the nest.
The young creatures are helpless and dont leave their nest,the older ones of the same species feeds the young (if the older creature aren't cannibalistic)
Predators are able to snatch young creatures from their nest if the Parents aren't around.
The babys start as level 1's and the adults are between level 10-40.
They level up by surviving and growing.
Not all dinosaurs level to the same with.
Small dinosaurs leveling up to 10-15,
Medium dinosaurs leveling up to 16-25
Large creature leveling up to 26-40

Example: triceratops breed, they walk to their nest and 5 small triceratops are spawned.
The parent/herd protect their young, bringing food to their young and keeping predators away to the best of their ability, once the young triceratops get to level 5,their are capable of following their parents/herd away from the nest.

Example 2: Tyrannosaurus breed,they walk to their nest and 5 small Tyrannosaurus are spawned.
The parents protect their young and brings them food as well as keeping predators including other Tyrannosaurus away from the nest, once the young get to level 5, their parents brings them a live creature(small dinosaur or small mammal)
If the young Tyrannosaurus are able to kill it, they will level to level 6 and they must leave their nest and hide or risk being eaten by their parents after a few minutes.

I also need help with coding selective hunting, this one is different from breeding but it goes hand to hand with both breeding and leveling but will give players a reason to be careful with creatures that they have with others.
Additionally information:some creatures can only target the level 1-5 version of large creatures and will completely ignore any version older than level 5(mainly pterosaurs, snakes, lizards and mammals when it comes to hunting larger species)

Example: an level 7 Tyrannosaurus raids the nest of level 1 triceratops but flees at the sight of a pair of level 10-11 triceratops.

Or

Example: an pack of ceratosaurus mixing between level 6 to 9 targets an nest of low level raptors but runs away from the sight of level 10 allosaurus,the allosaurus chases after them and even though it could easily win a fight with even an level 9 ceratosaurus, it target and grabs an level 6 ceratosaurus because of the fact that an level 6 ceratosaurus is a easy kill.

How would I go about coding this?

With c#