The death of an adult female kakapo (Strigops habroptila) on New Zealand's Anchor Island this past weekend brings the population of these rare flightless parrots down to just 127 birds.

The late kakapo, known as Sandra, was killed when her transmitter harness got entangled in a tree. All kakapos are outfitted with transmitters to help rangers in the Kakapo Recovery program keep track of the birds. Sandra's death marked the first time in 31 years of transmitter use that the devices have injured a bird.

"It's gutting for the team to lose one of the birds this way," Kakapo Recovery Program Manager Deidre Vercoe Scott said in a prepared statement. "Without transmitters, our mission to support and grow the kakapo population would be virtually impossible." She said the harnesses are designed and fitted so the birds can free themselves if they get caught, and the rangers are not sure why Sandra was unable to escape. Vercoe Scott told Radio New Zealand News that the recovery program will now review the use of the transmitter harnesses.

All kakapos live in semi-captivity on Anchor Island and Codfish Island, two predator-free havens off the coast of New Zealand. The birds—the world's heaviest parrots and the only flightless parrot species—had no native predators until local Maoris brought dogs and rats to New Zealand 1,000 years ago. The arrival of European settlers in the mid-19th century hastened the birds' decline, and by the 1970s the species was thought to be nearly extinct in the wild. The only captive birds were all males. The discovery of a small population on New Zealand's Stewart Island in 1977 inspired the creation of the recovery program that eventually relocated all known birds to predator-free islands. A very successful breeding program, which sometimes employs artificial insemination, brought the population to more than 100 birds for the first time in 2009.

Sandra's death follows the January 2 death of a male kakapo named Waynebo. Although no clear cause of death was found, rangers estimate that Waynebo could have been more than 100 years old, and suggest he died of old age.

Two females named Monoa and Purity were found dead in September 2011, one on Codfish and the other on Anchor Island. Autopsies gave no obvious cause of death.

Eleven kakapo chicks were born last year, marking another successful breeding season. Unfortunately, there won't be any hatchlings this year. Kakapos only breed when the fruit of the rimu tree is readily available, which only occurs every three years or so. This isn't one of those years.

For more on the kakapo, I recommend following the Kakapo Recovery page on Facebook, where you can also follow their star "spokesbird," Sirocco. Sirocco himself turns up quite notably (and perhaps naughtily) in the excellent Stephen Fry/Mark Carwardine BBC series Last Chance to See (a sequel to the original book and radio series by Carwardine and the late humorist Douglas Adams), a clip of which appears below:

Photo: Sirocco, the world-famous kakapo. Courtesy of the New Zealand Department of Conservation, via Flickr