The Sixth Extinction

I rate Elizabeth Kolbert's "The Sixth Extinction" as one of the top three non-fiction books ever written, simply for the clarity in which she presents scientific and irrefutable evidence of the damage humankind is doing to to Planet Earth.  We are in the midst of another mass extinction of species, the sixth in planet Earth's very long history.  But only this time, the cause is not cosmic in nature - like an orbital shift, a massive volcanic eruption leading to the cooling of the entire planet and an ice age, or the crashing of a meteorite that drove the dinosaurs to extinction - but by the actions of a species on Earth itself, Man.
 
New Zealand tells the story of man's interference best.  New Zealand is as far away from the old world as you can possibly get.  Its relative isolation meant that it maintained a unique ecosystem for millions of years.  Because it lacked predatory land mammals and reptiles, New Zealand was a bird paradise for all kinds of birds, including flightless birds.  New Zealand was the last major landmass on Earth to be settled with humans. 

Maoris settled in New Zealand, perhaps only as late as the 1300s.  They hunted for survival and drove both the giant Moa and the Hasst eagle to extinction.  Europeans came in significant numbers in the 1800s.  When humans first arrived in New Zealand, it was completely forested.  Today, only 30% of forests remain.  Trees were harvested for their wood and land was cleared for industrial scale agriculture.  But the true damage was the introduction of mammals from the Old World.  New Zealand, at the time when humans colonised it, was mammal free.  (It also has no snakes or crocodiles or scorpions.)  Humans thought it wise to import sheep, goats, cows, horses, deer, dogs and cats.  Humans also unknowingly introduced pests such as rabbits and rats.  At times, the naive thinking bordered on being comedic.  To control the rabbit population which had taken a liking to plants that were grown for food, the stoat was introduced. But stoats were voracious breeders and did just feed on rabbits but all kinds of birds as well. They were particularly good tree climbers, and took a liking to all kinds of eggs. 
 
The damage has been catastrophic.  Since the Europeans arrived, 43% of native bird species, many of them flightless birds, have been made extinct. There are also species of bats, frogs and other invertebrates that have also vanished in a short period of time.  Today, at least 50 species are on the IUCN endangered species list, including multiple species of penguins and dolphins.  The change in the habitat, caused by humans affects animals in ways that we sometimes cannot even predict.   The yellow eyed penguin for example like sandy beaches as much as humans do.  But they will not come onto the beach if they see potential predators around - a triat they learnt probably from being in the sea where there is real danger of being eaten.   And humans also love beaches.  One has to give.

What nature has created in millions of years, we have eliminated within a few hundred years.

New Zealand is trying to reverse the effect. Predator free zones have been created on islands on lakes or off shore islands (like Stewart Island in the South) where predatory animals are actually hunted down and eliminated, recreating the ecology before the arrival of humans.  Large areas are declared as nature reserves.  But this is just something it can do to stem the tide.  Climate change is on us.  Our seas are getting more acidic and glaciers on the mountains are obviously receding.  This will have complicated and perhaps unpredictable impact on life on earth.