after killing 100-1000 of that specific creature and you would get more of that animal in the encounter than usually it would be
So if you are on tile for example 33:33 and there are 6 possible encounters with different monsters. Would that mean that you would run from each encounter that has monsters that you don't want to kill so you don't get increased chance?
Because if you kill different mobs and you get 100-1000+ kills and they all increase in % of encounter than you are at beginning. So you would need to run from other mobs and just kill 1 type of mob so this could work 
Well as we have a kill counter right now it could be more usefull if there would be a button that you could switch on/off after you got this achivable or learnable trait/perk... and then if you wana hunt brahmins then you just switch the button and in the encounters where you would normaly finde brahmins you will get more brahmins in that encounter than normaly you would... ofc the other enemys would not change in the enco...
While in the other hand there sould be a limitation about like you could not switch up multiple targets so you could not make swarms in the encounters and ofc if you looking for a specific animal then you probably wont have the the resorces to search for multiple animal type...
Its like you are dedicating your self to hunt for foxes in the forrest then you will not bother with deers and bears... you are looking for foxes and you probably looking for fox tracks and eventualy you will finde them. its like normaly in hunting sessions you looking for ducks then you wont shoot on swans