Mr Lehndorf (60) passed through Wanaka yesterday on his fundraising journey to Invercargill, via 1250km of the South Island's tramping tracks.
He has raised nearly $8000 for Friends of Flora so far and is confident of reaching his $10,000 goal when he arrives in Invercargill in about four weeks.
"The kiwi is our national icon.
"We are losing them [kiwis] at such a rapid rate.
"Unless something is done, the time will come when suddenly they will just not be there," Mr Lehndorf said.
He is a summer groundsman at the eco-friendly Resurgence Lodge at Motueka and has been a member of Friends of Flora since about 2000.
The organisation has worked with the Department of Conservation on pest eradication programmes and helped reintroduce the whio (blue duck) to the Kahurangi National Park.
Now, it is helping with the transfer of seven breeding pairs of great spotted kiwis to the park from Golden Bay.
The great spotted kiwis are native to the South Island.
They are the largest kiwi and there are about 22,000 left.
About 25 years ago, Mr Lehndorf worked in Fiordland as a forest ranger and then as a guide for Greenstone Valley Walks.
He is a keen tramper but has passed through some new terrain on his journey thus far and is looking forward to his first experience of the Motatapu Track to Arrowtown, which he starts today.
Mr Lehndorf began his journey at Collingwood on January 7, the day after his 60th birthday, and the Heaphy Track, Nelson Lakes National Park and the Waiau Valley have been on his itinerary.
Where possible, he has used Te Araroa Trail tracks but he had to use some of the canal roads between Lake Tekapo and Omarama.
His toenail injuries occurred on the Two Thumb Range between the Rangitata River and Lake Tekapo.
His travelling companion, Phil Soole of Brisbane, also suffered a knee injury there.
That forced the pair into damage control, so they walked beside the road between Omarama and Lindis Pass when they would have preferred to have followed the Ahuriri River and come down the Dingleburn.
However, they cut in at Forest Range Station and came into the Upper Clutha via Mt Grand and Lake Hawea, which Mr Lehndorf rated the most scenic part of his expedition so far.
Mr Soole has now returned to Brisbane and Mr Lehndorf's daughter's partner, David Slattery, will join him for the Motatapu Track.
Mr Lehndorf's wife, Marilyn, has been providing backup in the family campervan and other friends will join in on other sections of the journey.
His route beyond Arrowtown depends on weather and time and Mr Lehndorf is keeping his options open.
He hopes to walk the Routeburn, the Greenstone and Mavora Lakes Tracks, then travel via the Dusky Sound to Lake Hauroko to Te Waewae Bay.
Another option would be to follow Te Araroa Trail tracks through the Takitimus.
Mr Lehndorf has encountered all the elements: thick fog in the Waiau Pass and Clent Saddle and extreme heat on the Two Thumb Range.
"But it has reinforced my opinion that this is the best country in the world.
"And it is so accessible.
"Our hut system and our track system is second to none.
"We take it for granted and I don't think we should.
"It would be very easy to lose," he said yesterday.
Mr Lehndorf's campaign can be followed by visiting www.fof.org.nz/walk4kiwi.
