Complex sentence: One species, streaky-breasted flufftail, is known to be migratory, it is uncertain whether other species are as well; the white-winged flufftail may breed in Ethiopia and winter in South Africa but this is not known for certain.
Split into simpler sentences: One species, the streaky-breasted flufftail, is known to be migratory. It is uncertain whether other species are as well; the white-winged flufftail may breed in Ethiopia and winter in South Africa but this is not known for certain.