Many wild animals have settled down in the reserve.
Tips
usage
Implies long-term settlement, not a temporary stay. Works for people, and figuratively for animals, species, or even ideas and industries putting down roots.
grammar
Two parallel verb-object phrases: 安家 (settle a household) + 落户 (register residence, 户 being the 户口 household registration). The second half evokes formally registering as a resident.