The kaprosuchus will be deep in the swamps, this is not ideal as unwanted aggressive creatures will be lured unless taken care of.
The easiest way to knock out a kaprosuchus would be to use an argentavis or quetzal (argentavis would allow for the creature to be tamed earlier on as it is easier which would be ideal for smaller tribes) to transport to a small taming cage or box. Make sure if you are using an elevated point it is high enough to not get leaped at as the kaprosuchus has a very deadly leap attack, the cage must be tightly sealed as the kaprosuchus has a slim body which can fit through tight gaps and crevices which could lead to the tame losing torpor if not paying attention. The kaprosuchus will move around a lot as will other creatures so you will have to be accurate if you want to use your tranqs to their full extent and not waste any. Although the torpor depletion is quite slow you will want to either make sure the food is on hand or nearby on the knockout.
Here’s how I did it.
Step 1. Find low lvl Kapro
Step 2. Run at Kapro
Step 3. Punch Kapro til it faints
Step 4. Shove boa meat down it’s throat
This method worked twice for me, with a lvl 1 and a lvl 3. If you’re going for a high lvl, a crap load a health will see that this method still works
If your on the island go to the east side of the map. Go to the edge of the swamp and make a trap, even a two by two thatch one will work. Put door frames on the edges of the foundations, then finally a ramp for it to walk up on. You can also use this as a safety area to knock it out from. Vote ^ so others can see!!