If speed is leveled right they can be outpaced; they can be snared with a bola and knocked out or shot with tranq arrows through a 2x2x2 pen with open windows and a ramp to trap the castoroides to prevent carnivores from getting at it. Torpor goes down quick so a lot of narcotics and/or biotoxin is needed, if you can’t make their kibble use crops. I use starve tame because their food goes up relatively quick unless you allow it to go down for a while. Dedicated taming process, but worth it. My two beavers Frost and Char just had a baby, and unlike other dinos they gestate inside the mother instead of hatch from an egg. And they are mobile smithys

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