It is not a precise way to measure public sentiment. But as five seasoned bushwalkers made their way on foot through the New South Wales deputy premier John Barilaro’s electorate of Monaro, taking several days to reach Charlotte Pass before hiking up Mt Kosciuszko itself, they received more words of encouragement and support than opposition to their message.

The walkers were walking in protest against legislation shepherded through the NSW parliament by Barilaro in June that declared feral horses, or brumbies, a protected heritage species in Kosciuszko national park.

Carrying large yellow signs that said “park not paddock”, the walkers set off from Sydney’s botanical gardens on 3 November and walked 560km over the next 36 days, arriving at the summit of Mt Kosciuszko on Saturday.

Alan Leird, a 66-year-old retired scientist, and his partner Marg Sharp, walked the entire distance along with Donna Powell, Paul Millgate and Tom Vaughn.

Leird and Sharp did not do any special training, apart from a few practice runs up their local mountain.

“If you can walk 20km a day you can probably walk 20k the next day, and you just keep doing that for 36 days,” Leird said.

Members of the group Save Kosci reaching their destination Mt Kosciuszko. Photograph: Photos: Supplied by Save Kosci.

They were joined along the way by more than 600 other walkers, who spent between a day and two weeks trudging alongside them in protest against the decision to allow feral horses free rein over the national park.

As they reached the summit they were joined by 178 people, walking from Jindabyne, Thredbo or with the main group from Charlotte Pass.

They were motivated, Leird said, by a deep love of Kosciuszko national park and concern about increasing damage caused by feral horses.

“I have been skiing and hiking in the Snowy Mountains for a good 45 to 50 years,” he said. “It is just horrible to see the damage that the feral horses are doing to the park … they widen the water courses, damage the sphagnum mosses.”

Leird said it had become more common to see feral horses high in the mountains, even during winter.

“These days if we go skiing up near Dead Horse Gap … we ski through horse poop that’s on the trails,” he said. “We see feral horses in the area.”

The walkers, who trekked under the banner of a hastily-formed organisation called Save Kosci, are calling for NSW to scrap the Kosciuszko Wild Horse Heritage Act 2018 and reduce feral horse numbers.

A 2016 draft wild horse management plan recommended reducing numbers by 90%, but previous management plans allowed for horses to remain in some less-sensitive areas of the park with regular trapping to reduce numbers.

As the walk was under way, a group of 145 scientists met in Canberra to call on the NSW government to repeal the horse protection legislation and implement the 2008 horse management plan.

Both scientists and bushwalkers intend to make the management of feral horses in the national park an issue for the state election next March.

The bushwalkers staged a protest outside Barilaro’s electorate office on 22 November, outnumbering a group of local protesters in favour of protecting the brumbies 10 to one, and collected more than 1,000 signatures along the walk.

While they copped some abuse from people driving past, Laird said, more people slowed down to offer them words of encouragement.

The Save Kosci convener, Linda Groom, said the group was able to win over most people they spoke to.

“Once they understand the facts, they are quite willing to face the difficult issue of culling horses if we are to control the population,” she said.