Tsuchinoko's can be found in the following areas; Graniny Gorki, Sokrovenno and Bolshaya Pass South. I have had the best luck with Graniny Gorki. To help expedite a Tsuchinoko being caught, you can run around and shoot (lethal weapon) all other animals in the area; if there are no other animals they won't get caught in your traps. If a different animal gets caught in your trap you'll need to reset it. To reset a trap; crawl over it like a claymore and it'll be back in your inventory to set.