The “green bridges” would provide a safe crossing for creatures such as deer and badgers, according to the Badenoch and Strathspey Conservation Group.
Draft designs for turning the 4.7-mile Kincraig-Dalraddy stretch of the notorious A9 into dual carriageway has gone on display for public comment..
The upgrade is part of a £3 billion plan to dual the entire length of the road between Inverness and Perth by 2030.
Transport Scotland hope to start work on the Kincraig stretch in 2016.
Impact on wildlife
There are plans for four underpasses, but Roy Brown, of the Badenoch and Strathspey Conservation Group, said there should also be overpasses for animals.
He added: “I think the dualling is going to go ahead so it’s really a matter of what can be done to reduce the impact of it on wildlife.
“Obviously, putting a dual carriageway through a national park is going to have a significant impact on animals moving about and it is critical that mitigation takes place.
“We’ve been pushing over wildlife overpasses and underpasses. Research in Scandinavia shows that the overpasses really do work.
“The current plans offer a few underpasses, which would be used by vehicles, pedestrians and wildlife, a fairly strange combination.”
Deer movement ‘would be restricted’
Wildlife overpasses exist in famous locations around the world, including Banff National Park in Canada and in Montana in America.
Mr Brown fears the dualled road would restrict the movement of wildlife through the park, especially for badgers, roe deer and red deer.
He claimed the placing of overpasses would be a “bold statement of commitment to the environment” from Transport Scotland.
A spokesman for the Government agency said: “We recognise the need to meet stringent environmental requirements as we take forward one of the biggest construction projects in Scotland’s history.
“As part of the extensive ecology survey work in the scheme’s environmental statement which has supported our approach, we are upgrading four underpasses, which will allow for mammal movements.”