There is this great and dangerous forest in this world, way more bioproductive than anywhere on earth. The climate is humid subtropical, with cold but not freezing winters. There is plenty of fruits, nuts, herbs, roots and even some wood (palmetto) to be eaten in every season, even in the winter. There is also plenty of game, from hares to mammoth-size elephants. There is also small pockets of grassland all over the place which are dragons' hunting grounds.
I want that a race of humanoids (let's call them elves for simplicity's sake) to evolve in this forest and neither agriculture nor animal husbandry are options. Any livestock could be wiped out by some predator and farm will just be free food for wild animals. The only livestock they were able to domesticate to some extent is the Giant Deer, which can be used as a pack animal, a mount and a source of milk, but feeding on them is a terrible idea, they are dangerous, more tamed than truly domesticated and can quite easily flee to join a wild herd.
The thing is, I don't think the local fauna can keep up with a permanent settlement. All things I read about hunter-gatherers seen to indicate that they will overhunt the local prey population and than they have to move to somewhere else.
Also, I've research some sedentary hunter-gatherers and they usually only happen near coasts and other water-bodies that help providing enough food through fishing. However being in a forest mean that they rely almost exclusively on the local supply of food.
To complicate things even more:
I want them to be carnivores, not hypercarnivores, but at least mesocarnivores (30-70% of meat in their diet).
They must have big enough settlements to make great stone fortresses, otherwise a elven-city is just a big stockyard to some big predator. I cannot express this enough, but even the elephants are hunted in this place and they are not even the biggest prey to be found.
To make things a little easier:
They make insanely good bowmen, they are stronger than humans and use this strength to power bows that shoots harder than all but the strongest crossbows.
They can move through the forest relatively unharmed despite the crazy amount of predators and dangerous prey.
The Giant Deer extends their hunting grounds greatly.
The forest is only sparsely populated, but again individual settlements are quite large.
They are quite good engineers as well, so they could easily outdo a similar-size human settlement.
I am trying to make the world as low-magic as possible, but I can and will use it to implement a solution that is cool enough
So, any idea on how to make this work? Either on the elven societies or on the forest itself?
Edit: some details that I forget to add but are clearly relevant
Alternatives to farming is a non issue, the forest are more bioproductive than any crop would be, and on top of that animals would feed on the crops just as they would in the forest, so agriculture is just more work for less food overall. The real problem is how a big sedentary communities of mesocarnivores will feed themselves without exhaust the local fauna.
They can and they trade with the rest of the world, but they do not colonized the forest, they evolved in it. So I think self sufficiency is a must.
The other problem with trade is that to any one but them, this forest is hell on earth. No merchant in their right mind will go there, the elves are the ones to reach outsiders. And when they do is for luxury goods.
While hunting parties are a thing, they can not go that far away. They build fortress for safety, if you go into the forest and don't come back within a week they just assume you died.