But this was not the only reason for their herding behavior. Science suggests they migrated to fend off starvation.

但它们的群居习性并非仅为安全。科学表明它们迁徙是为了避免挨饿。

Or maybe they sought safety in numbers, a defensive herding behavior.

或者他们可能在数量上寻求安全，这是一种防御性的放牧行为。