It’s taken less than a century for humanity to wipe out half of New Zealand’s land birds.
Researchers say it would take 50 million years to recover the number of bird species we have destroyed there.
Let’s put that number in perspective so we can all relate.
Humans in their modern form have been around for about 300,000 years, and our ancestors have only been on earth for about 6 million years.
Human Impact on New Zealand’s Land Birds
In a new study published in Current Biology, researchers used statistical modeling to estimate the rates that New Zealand’s land birds arrive at the island, form new species, and go extinct.
These three processes determine the species on the island at any moment but have been completely altered since humans colonized in New Zealand about 700 years ago.
Using computers to simulate a range of human-induced extinction scenarios, researchers predict it would take 50 million years to recover the number of species lost since humans first arrived in New Zealand.
If all species currently under threat are allowed to go extinct, it would require about 10 million years of evolutionary time to return to the species numbers of today.
Conservation Choices Now Impact Threatened Species
“The conservation decisions we make today will have repercussions for millions of years to come,” says Luis Valente of Museum für Naturkunde in Berlin.
“Some people believe that if you leave nature alone, it will quickly recuperate, but the reality is that, at least in New Zealand, nature would need several million years to recover from human actions — and perhaps will never really recover.”
Valente says the biodiversity observed today is the result of millions of years of evolutionary time.
Extinctions caused by human activities erase this history.
While the number of lost or threatened bird species often has been quantified, the broad-scale evolutionary consequences of human impact on island biodiversity rarely have been measured.
Valente plans to estimate evolutionary return times for several islands worldwide to see whether certain islands have more evolutionary time under threat.
They also want to assess which anthropogenic factors play the most significant role in determining those losses.
New Zealand’s Conservation Efforts
Valente says there is a bright side for New Zealand,
“The conservation initiatives currently being undertaken in New Zealand are highly innovative and appear to be efficient and may yet prevent millions of years of evolution from further being lost,” he adds.
Read the paper, Deep Macroevolutionary Impact of Humans on New Zealand’s Unique Avifauna in the August 5 issue of Current Biology.