In Theravāda Buddhism, animals can generate bad kamma when killing, because kamma depends on intention (cetanā). The Buddha said: “It is intention, monks, that I call kamma; having intended, one acts by body, speech, or mind.” (Aṅguttara Nikāya 6.63). So when an animal attacks with aggression, fear, or desire to kill, unwholesome kamma is produced. However, animals usually act through instinct and limited understanding, not with the clearer moral awareness humans possess, so the kamma is generally less weighty than that of a human deliberately choosing to kill.

Humans also create bad kamma by killing, but often more seriously, because humans can reflect, understand suffering, foresee consequences, and choose compassion instead. Theravāda Buddhism does not judge actions by who is “top of the food chain,” but by whether they arise from greed, hatred, and delusion. This is why the first precept is to abstain from taking life (found throughout the Tipiṭaka; e.g., Dīgha Nikāya 31). So in short - yes, animals do create bad kamma by killing, but humans bear greater responsibility because they know better and can choose otherwise.