CNN News:用无人机保护濒临灭绝的毛伊海豚

What species of dolphin is the smallest? Hector's dolphin, Risso's dolphin, Spinner dolphin or Dusky dolphin. The smallest dolphins are Hector's dolphins. They're usually around four to five feet long and 100 pounds.
And they are rare. You will only find Hector's dolphins off the coast of New Zealand. And there's a subspecies of them called Maui dolphins whose population has dwindled to just a few dozen left in the wild. The biggest threat to Maui dolphins is when they're caught by accident in the fishing industry. Disease, danger to their habitat and tourism are also suspected in reducing their numbers.

But there's a new eye in the sky and by that we mean a drone that aims to help Maui dolphins by locating, identifying and following them. The aircraft runs on electric and gas power. It's estimated to cost around $150,000 and it's aim is to use artificial intelligence technology to keep close tabs on the 63 adult Maui dolphins that are still alive.
On the opposite end of the dolphin spectrum in terms of numbers at least is the common dolphin. How common is it? Well exact numbers are hard to come by but these mammals are often found in pods by the thousand. They're common in all over the world. They're neither endangered nor threatened and when they stampede, so to speak, they're sight to see for sight seers.