The falcons have nested in a rotten log at the bottom of pine trees near the swing bridge which crosses the Hawea River.
The nest is only a couple of metres from a shortcut often taken by walkers and cyclists travelling to and from the swing bridge.
Veterinary nurse and falcon advocate Mary Chaffey was one of a group including Department of Conservation staff who erected a fence around the nest yesterday.
Ms Chaffey said they all wore hard hats.
"A couple of members [of the group] took hits to the head.
"So, that is our concern.
"If, unintentionally, cyclists and walkers and dog walkers and runners keep cutting through there, it will really agitate them to the point they will get bolder and bolder and bolder.
"The falcon will defend their young probably almost to the death.''
The Albert Town pair hatched one chick yesterday and have one more egg in their nest.
They were getting "a little bit more defensive about close encounters'' with people and dogs, she said.
"And, the more time they have to spend defending their territory, the less time they have to feed [their chick].
"It's also quite frightening for people.
"They are coming in with full force.''.
Ms Chaffey said photographers had been seen by nearby campers "provoking'' the birds in an effort to get a photograph.
She would like the public to stay on the roadway about 50m from the birds, and she hoped cyclists, wearing their helmets, would not attempt to "run the gauntlet''.
Only 4000 breeding pairs of falcons are left, making them more endangered than kiwis.
She expected it would be at least a month before the chick was ready to leave the nest.
