The west monsoon season runs from mid-December to June, and brings humidity and higher rainfall.

[5] Common trees in the Tanimbar and Kai forests include Dillenia papuana, Pometia pinnata, Manilkara kanosiensis, Inocarpus fagifer, Heritiera littoralis, Diospyros spp., Garcinia celebica, and Myristica lancifolia.

The Indonesian tomb bat (Taphozous achates) is native to the ecoregion and neighboring Timor.

Bannister's rat (Melomys bannisteri) is endemic to the Kai Islands, and closely related to M. lutillus of New Guinea.

The other rodents of the Kai islands are Hydromys chrysogaster and Uromys caudimaculatus, which are also found in New Guinea and Australia.

[11] Endemic birds include the Tanimbar megapode (Megapodius tenimberensis, Megapodiidae), Tanimbar cockatoo (Cacatua goffiniana, Cacatuidae), blue-streaked lory (Eos reticulata, Psittaculidae), green-cheeked bronze cuckoo (Chrysococcyx minutillus rufomerus, Cuculidae), Kai coucal (Centropus spilopterus, Cuculidae), Banda myzomela (Myzomela boiei, Meliphagidae), golden-bellied flyrobin, (Microeca hemixantha, Petroicidae), Wallacean whistler (Pachycephala arctitorquis, Pachycephalidae), cinnamon-tailed fantail (Rhipidura fuscorufa, Rhipiduridae), long-tailed fantail (Rhipidura opistherythra, Rhipiduridae), black-bibbed monarch (Symposiachrus mundus, Monarchidae), Kai monarch (Symposiachrus leucurus, Monarchidae), Kai cuckoo-shrike (Edolisoma dispar, Campephagidae), slaty-backed thrush (Geokichla schistacea, Turdidae), fawn-breasted thrush (Zoothera machiki, Turdidae), Tanimbar starling (Aplonis crassa, Sturnidae), Damar flycatcher (Ficedula henrici, Muscicapidae), Great Kai white-eye (Zosterops grayi, Zosteropidae), Little Kai white-eye (Zosterops uropygialis, Zosteropidae), and Tanimbar bush-warbler (Horornis carolinae, Cettiidae).