Kakapo (Strigops habroptila), the critically endangered flightless parrots of New Zealand, have an unusual mating ritual. In the rare years when the birds breed, the males climb to the tops of hills, breathe in so deeply they swell up like balloons and then let out a series of deep, rhythmic booms that can be heard from up to five kilometers away. You can see and hear their low booming calls in this short video:

These booms don't happen every year. Kakapo only breed about three times per decade, during the seasons when the fruit of the rimu tree (Dacrydium cupressinum) is readily available. There hasn't been any kakapo breeding since 2011, when 11 chicks where born. Unfortunately, those have been rough years for the kakapo, with several natural and accidental deaths. At the end of 2013 only 124 of these rare birds remained.

But now we have a new kind of boom: a kakapo baby boom. This was a good year for rimu fruit and over the past few weeks six new kakapo chicks have been born, bringing the total species population back up to 130. (A seventh chick died just a few hours after hatching on March 11.) Here's some footage of the first of the surviving chicks, named Lisa One, who hatched on February 28:

Lisa One almost didn't make it. Her mother, who had already lost one embryo, accidentally crushed the egg in late February but rangers were able to piece it back together long enough to allow the chick to hatch. ("Lisa One" is a temporary name, by the way. All kakapo chicks are initially named after their mothers; they receive permanent names later in life.)

Five of the successful hatchings occurred on Codfish Island, one of the most successful kakapo recovery sites, where dozens of chicks have been born since 2002. Three of the chicks have been transferred to incubators and will be hand-fed by staff from the New Zealand Department of Conservation’s Kakapo Recovery program. Two more have been given to "foster mothers," female kakapo that have been sitting on dummy eggs in anticipation of the births, which took place in controlled conditions to improve the likelihood of survival.

The births on Codfish Island are great news, but perhaps the biggest news came from Little Barrier Island, where the sixth chick was born. Kakapo were only reintroduced to the island less than two years ago after it had been cleared of kiore aka Polynesian rats (Rattus exulans). This was the first year that the birds there did not receive supplemental food, and it seems they're doing just fine. In January three of the males started booming and the females were receptive to their courting. In February a female there, Heather, laid three eggs. One wasn't viable. One was moved to Codfish so there would be less competition among chicks. The final egg hatched naturally on Little Barrier Island; the chick, Heather One, was discovered by the staff on March 12.

That egg faced a temporary threat: a residual storm from a spent cyclone threatened the island. "Fortunately, Heather's nest was in a relatively sheltered spot away from any creek that had the potential to flood," Kakapo Recovery Program Manager Deidre Vercoe Scott said in a press release. "We also checked the site for loose branches and dug extra drainage around the site."

Kakapo still have a long way to go before the species can be considered recovered, but this is the first really good news for the birds in three years. With luck the next breeding season—anticipated for 2017—will be even more successful.

Photos courtesy New Zealand Department of Conservation

Previously in Extinction Countdown: