By Michael Rosenfield, WBZ-TV

MANCHESTER, NH (CBS) – The moose population is facing a dramatic decline in New Hampshire and Fish and Game officials are heading north to find out why.

Crews will descend from a helicopter to tag some of the state’s 4000 moose in the coming weeks.

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“We would hope that we will learn enough from this to know if moose are going to be so severely impacted that their numbers may decline irrevocably,” said Kristine Rines, Moose Project Leader for New Hampshire Fish and Game.

The moose will be tranquilized, blood will be drawn and ticks will be counted. Those ticks could be a key factor in the moose drop-off.

But there may be other factors at play, and wildlife experts want to know why moose are dying off at a higher rate even though hunting permits are down.

“So we’re suspicious there are changes in the environment out there,” said Kent Gustafson, Wildlife Program Supervisor with Fish and Game. “Either parasites or diseases or some other issues that are causing additional mortality to the moose that we have.”

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Crews will be looking for moose in several northern New Hampshire communities flying just above the tree tops in search of moose to tag.

The moose population is down about 40% from more than 7000 since the 1990’s.

Part of the decline is blamed on hunting.

But it is not clear why the moose population has been decreasing significantly more recently.

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State officials call the recent decline ‘significant’ and ‘dramatic.’