When non-human animals are in a picture. Most non-insect animals are lethal to yukkuri.
Most small animals (notably birds, mice and ants) in the yukkuri world have adapted to prey on yukkuri. It's unclear if yukkuri counts as a carnivorous or a herbivorous meal as most animals who prey on them are omnivores. Even when not preying on them, just like humans animals seem to be fond of hurting yukkuris
Yukkuri themselves prey on earthworms and insects though they haven't been known to eat any larger animal or raw meat.
The following tags implicate this tag: dog and cat (learn more).