Not long after the insects were believed extinct, climbers found dead tree lobsters on Ball’s Pyramid, a sheer rock cliff of an island separated from Lord Howe by 12 miles of water. In 2001, nearly four decades later, scientists scaled the rock, a third-of-a-mile-high, and discovered a small group of living tree lobsters dining on tea tree at night. It turned out they were not extinct.
But some scientists worried these tree lobsters might actually be a distinct species because they looked mysteriously different from the preserved Lord Howe tree lobsters. Their legs were skinnier with smaller spines and the little stubs sticking out from the abdomen called cerci were slightly off. They were darker. It wasn’t clear if they’d always been on Ball’s Pyramid or if birds, mistaking them for nesting material, carried them there. The two islands were never connected by land, and the insects couldn’t swim.
The researchers collected living specimens to create a new population of tree lobsters that could be reintroduced to the wild if the ones on Ball’s Pyramid ever disappeared. Now thousands of living descendants and eggs from the Ball’s Pyramid couple are held in zoos and museums around the world.
But more recently, Dr. Mikheyev and his colleagues managed to reveal that the genetic differences between Lorde Howe and Ball’s Pyramid insects were within the range of the same species. This meant that they had to make sense of stick bugs’ massive genome — about a quarter bigger than the human genome. They did this by comparing genetic samples from living Ball’s Pyramid tree lobsters with material extracted from Lord Howe specimens preserved in museums. Age, inbreeding, environment or diet might explain their new look.
The finding could make it possible to restore the insects to their former home on Lord Howe island.
But rats remain a problem on the island, where they have killed off five bird species and around a dozen invertebrates, and still threaten 70 other species.
Following years of research and debate, the Lord Howe Island Board decided in September to go ahead with a rat eradication program. Beginning in mid-2018, helicopters will drop cereal laced with rat poison onto the island.
If all goes to plan, threatened or endangered species like ground lizards, snails and the Little Mountain Palm could then recover on this World Heritage site.
The tree lobsters may be able to return, too. Confirming their identity was important because the consequences of introducing a new species mistaken for an old one to Lord Howe Island were unpredictable.
Return candidates must also be chosen. Would they come directly from Ball’s Pyramid, or their captive bred descendants? Ideally, the most genetically diverse tree lobsters have the best shot at recolonization. This means more genetic analysis.
As the Lord Howe tree lobster saga continues, one thing is certain: The tree lobster was never a lobster in a tree, but it is just as much a tree lobster as it ever was.