useless trivia: What Word Means: Howls?

Questions

The hummingbird is the only bird that can ----------?

The bat is the only mammal that can ----------?

Of all known forms of animals life ever to inhabit the Earth, only about ---------- still exist today.?

Hippopotamuses have killed more people in Africa than all the lions, elephants, and water buffalo combined, usually by ----------?

Cats have amazing hearing ability. A cat's ear has ---------- muscles that control the outer ear (by comparison, human ears only have six muscles). These muscles rotate 180 degrees, so the cat can hear in all directions without moving its head.?