Fumoon (1980)

Nuclear testing has resulted in the abrupt evolution of the Fumoon, a tiny but highly intelligent humanoid race on a small island, who are detected by Dr. Yamadano. The Fumoon are kidnapping animals from around the world to bring with them as they use their space ships to evacuate the earth, because they know Earth is shortly to be destroyed by an enveloping cloud of black gas created by a stellar explosion.