The mother cat went out to catch a bird.

Literal

Mother-cat [topic-は] bird [object-を] catch-[purpose-に] went-out

母猫 = mother cat (母 + 猫). The verb-stem 捕まえ + に + motion verb 出かける expresses purpose: 'went out in order to catch.' 出かける is more purposeful than just 行く.