It only took humans a few hundred years to decimate New Zealand’s biodiversity, but conservation initiatives could save the remaining species.
New Zealand’s native wildlife and biodiversity serve as a prime example of the impacts humans have had on island ecosystems around the world. The island nation took millions of years to evolve its unique flora and fauna which over the past couple of hundred years have been all but decimated. New research published in Current Biology sought to understand the extent of human impacts and how long New Zealand’s wildlife would need to return to pre-human biodiversity.
Their answer—50 Million years.
Before humans inhabited New Zealand, it was an island of birds with no mammalian or reptilian predators. Instead, birds filled these niches. The flightless Giant Moa which stood 11 feet tall and weighed approximately 500 pounds, served an ecological role similar to deer or antelope. A now-extinct species of eagle, the largest species that ever lived, served as the apex predator. Today, we still see the unique array of birds that evolved in isolation including the iconic Kiwi; the Kea, the world’s only alpine parrot; and the Kakapo, the world’s largest species of parrot among others.
These species and many more lived in isolation, free from human impacts until 700 years ago when the Maori arrived resulting in species decline through the introduction of invasive rats and hunting. Then, 500 years later, European settlers arrived bringing with them more invasive predators and increasing the pressure on native wildlife.
In this time period, humans and the invasive species they brought managed to drive more than half of New Zealand’s endemic birds to extinction. Today, more than 30% of the remaining bird species are threatened with extinction and more species are following a similar trajectory.
To understand the broader impact humans and introduced species had on New Zealand’s biodiversity, researchers used an evolutionary model and molecular phylogenetics. They had two goals: 1) to estimate how long it would take for New Zealand to regain the variety of species that existed prior to humans and 2) to understand the impacts to biodiversity if we maintain the status quo and let currently threatened species go extinct.
First, they compiled a complete dataset of New Zealand’s native and resident land birds. This dataset was then used in computer analyses—a model they named DAISIE (dynamic assembly of islands through speciation, immigration, and extinction). By combining DAISIE with statistical models to assess speciation rates, they estimated how long it would take, on average, for bird diversity to reach pre-human levels in New Zealand.”Forbes
Using this model, they determined it would take 50 million years to establish the same biodiversity. The researchers also found that if conservation interventions do not make dramatic strides forward then it will take an additional 10 million years to recover the biodiversity that we see today.
Islands are at the frontline of the anthropogenic extinction crisis. A vast number of island birds have gone extinct since human colonization, and an important proportion is currently threatened with extinction.”Luis Valente, Rampal S. Etienne, and Juan C. Garcia-R. (2019). Deep Macroevolutionary Impact of Humans on New Zealand’s Unique Avifauna, Current Biology
Conservation Brings Hope
While the situation for New Zealand is dire, it is also clear that progress can be made by protecting the islands’ extant wildlife.
The conservation decisions we make today will have repercussions for millions of years to come. 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.”Dr. Luis Valente, Forbes
The Predator Free 2050 initiative is one such plan that brings hope for the future of native wildlife. While human habitation and climate change are also leading factors in the decline of New Zealand’s native species, Predator Free seeks to remove one of the leading threats to many endemic species and preserve the biodiversity that exists today.
Although this new data reflects the declining biodiversity in New Zealand, the same is true for archipelagos and islands globally. Data continues to emerge revealing the impact invasive species have on these ecosystems and the dramatic benefits that restoration can have for wildlife. Dr. Luis Valente continues to use this methodology to understand biodiversity on other islands around the world.
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