New Zealand has lengthy been referred to as a spot for the birds—fairly actually. Before folks arrived 700 years in the past, the archipelago hosted an idiosyncratic ecosystem, practically freed from mammals. More than 200 hen species stuffed a meals net all their very own. Rather than cows or antelopes, there was a household of flightless birds referred to as moa. And rather than apex predators like tigers, New Zealand had Haast’s eagle.

Ever since a bunch of farm employees drained a swamp within the late 1860s and uncovered its buried bones, this eagle has captivated researchers. Julius Haast, the explorer and geologist who revealed the primary notes on the species, described it as “a raptorial bird of enormous dimensions.” Today, biologists estimate that the eagles weighed as much as 33 kilos—roughly 50 % greater than any raptor identified as we speak. But with a wingspan of solely two to 3 meters—simply past the vary of a bald eagle—this was an oddly proportioned hen.

The form of Haast’s eagle was certainly one of many puzzles that scientists confronted as they studied this long-extinct species, preserved in only a few skeletons, plus scattered bits and items. For practically a century, there was a debate over whether or not such a big hen may fly; even after that feud was settled, questions remained about whether or not the hen was able to killing moa, which in some instances would have been greater than 15 instances bigger than the eagle itself. Now, new scientific methods, mixed with a clearer understanding of New Zealand’s geological historical past, has positioned the Haast’s eagle amid a a lot bigger ecological dialogue: how species involves “invade” new territories.

Scientists now consider that this superlative hen was one in a wave of feathered invaders that conquered New Zealand over a comparatively quick interval. And this was not the one wave of invasions. Haast’s eagle—regardless of being gone for hundreds of years—has revealed that we reside in a way more related world than we as soon as thought, says biologist Michael Knapp of the University of Otago, who has studied the eagle. If such seemingly remoted islands have repeatedly attracted so many incoming species, he says, then “natural invasions” should be a significant power in ecosystems the world over.

Digging for solutions

New Zealand has at all times held an necessary place in scientists’ understanding of extinction. When Western scientists first encountered moa, the concept species may go extinct was only a few a long time outdated. Their skeletons quickly grew to become a scorching commodity. “You could pretty much name your price,” says paleobiologist Paul Scofield, senior curator on the Canterbury Museum in Christchurch. “It was really what enabled our museum.” Haast himself launched the museum and assembled its preliminary assortment by exchanging moa fossils for numerous different archeological and zoological curiosities.

New Zealand retained uncommon species—together with, famously, the flightless kiwi. Combined with these extant oddballs, the moa fossils helped to ascertain the concept New Zealand was a misplaced world, a spot the place historic creatures, sheltered by distance from the remainder of the world, managed to outlive mass extinction occasions. Later geologists confirmed that these rocky islands had as soon as been part of a supercontinent they known as Gondwana, however break up away about 80 million years in the past. In 1990, a tv collection described New Zealand’s islands as “Moa’s Ark,” popularizing the catchy title of the long-held mannequin of how its bird-filled ecosystem got here to be.

By the tip of the Nineties, although, scientists realized that there was a interval throughout the Oligocene, about 25 million years in the past, when geologic and climatic adjustments may need put all of New Zealand underwater. Such a flood would have worn out most—if not all—of the islands’ species. The concept, which grew to become referred to as the “Oligocene drowning,” met resistance from some scientists, launching a heated debate over simply how a lot land was coated.

Fortunately, new applied sciences have been rising to reply that query. Scientists started to extract and sequence DNA from fossils; this meant researchers may evaluate historic DNA to fashionable genomes and create household timber of the evolutionary relationships between residing and extinct species. Such “phylogenies” may roughly pinpoint when two species break up aside from their frequent ancestor—knowledge helpful in settling the combat over New Zealand’s geological historical past.

In 2005, a group of scientists revealed a paper that in contrast DNA sequences extracted from two Haast’s eagle fossils to the genomes of 16 fashionable eagles. The scientists ascertained that the nice misplaced hen’s closest residing family members included Australian species, as anticipated. The genomic knowledge instructed that the household tree had break up inside the previous few million years. Subsequent evaluation has put the divergence time round 2.2 million years in the past.

Score one for the Oligocene drowning speculation: The eagle appeared to have arrived after the time of the proposed submergence. But later analyses of a number of different New Zealand species confirmed divergence instances on the order of tens of thousands and thousands of years. Some species had endured by way of the Oligocene, then.

By 2014, geological proof had satisfied most scientists: Yes, a lot of New Zealand had drowned, however small slivers of land—maybe 20 %—had remained above water. While a couple of of the islands’ species date far again to Gondwana, many others, together with Haast’s eagle, have been newer arrivals.