Moss said the weapon used to kill the bird was likely a low-calibre firearm, but the bird appeared to have been shot with intent.
"For someone to shoot this bird is appalling. Not only is the kārearea a threatened species, it is a symbol of New Zealand and graces our $20 note."
DoC is investigating the incident.
If the perpetrator is found they could face a $100,000 fine and up to two years in prison.
Local residents Simon and Katie Ford discover the bird, which was still warm, in their back paddock.
"We were shocked someone would shoot such a beautiful animal," said Katie Ford.
"We are planting native trees and want to encourage the birds back."
Teenagers had been seen in the valley target shooting in the last week, she said.
"A few people have responded on our valley Facebook page about seeing the bird in the few days prior and are horrified that it has been killed."
New Zealand Falcons are the only falcon species endemic to this country and are a top predator. They can reach speeds of up to 100km/h and hunt a range of large prey such as mammals and lizards, but other birds make up most of their diet.
The population is estimated at 5000 to 8000, mainly in the southern part of New Zealand.
"Birds are their natural food source. Unfortunately this can include domestic poultry, doves and pigeons," Moss said.
"If people experience problems with falcons attaching domestic birds, contact your local DOC office for advice, but don't shoot them!"
The department is appealing for information about the shooting - contact the Kapiti Wellington office on 04 470 8412.
