Visitors can be migratory.Logical formLearned from14 sentences. Creatures can be migratory.Logical formLearned from14 sentences. Refuges can be for migratory birds.Logical formLearned from14 sentences. A butterfly can be migratory.Logical formLearned from14 sentences. Periods can be migratory.Logical formLearned from14 sentences. Ones can be migratory.Logical formLearned from14 sentences. Laborers can be migratory.Logical formLearned from14 sentences. Migratory birds can be endangered.Logical formLearned from14 sentences. Millions of migratory birds may flock during a winter.Logical formLearned from14 sentences. Migratory birds may spread a virus.Logical formLearned from14 sentences. Migratory birds may gather.Logical formLearned from13 sentences. A grasshopper can be migratory.Logical formLearned from13 sentences. Pests can be migratory.Logical formLearned from13 sentences. A period can be migratory.Logical formLearned from13 sentences. An area can be for migratory birds.Logical formLearned from13 sentences.