Biologists are trying to understand why Newfoundland's caribou population has dwindled dramatically since the 1990s. (CBC)

Wildlife biologists in Newfoundland are using helicopters to spray caribou with red paint as part of an effort count of their population on the island.

In March, they're conducting a census of the Middle Ridge herd in eastern and central Newfoundland.

“It's a bit of a tricky endeavor but we use low flying helicopter typically. So we'll make sort of a low pass over them and a spray system that sort of deploys the [red] markers,” said wildlife biologist Casidhe Dyke.

“It's a bit of unique experience, to say the least, but the biggest thing is making sure we got skilled pilots in the situation.”

Dyke says the red paint will come off when the caribou lose their winter coats.

In 2008, Newfoundland wildlife officials said the island’s caribou population dropped by almost two thirds during the previous decade.

They said that about 90,000 caribou roamed the island’s bogs and forests in the mid-1990s, but by 2008, the population had dropped to 37,000.

Two years ago, the Newfoundland and Labrador government announced a $15.3-million program to find ways better manage the herds, and to develop better scientific knowledge about the herd. The 2010 census is part of that program.