New Zealand consists of two major islands - North Island 115,000 square kilometres and South Island 151,000 square kilometres.
Roughly 1,600 kilometres in length, with Stewart Island located 260 kilometers south of the South Island. There are other smaller islands or island groups around the coast that are (or were) ecological havens prior to human intervention. One of the areas of importance is the Chatham Islands, An archipeligo of 10 islands, about 800km east of NZ.
New Zealand is 2,240 kilometers from Australia, and has been a land apart for around 85 million years, when it split from Gondwana.
Due to New Zealand's isolation from continental land-masses, and that it was relatively unoccupied up to 1,000 years ago,
New Zealand developed a high level of endemic biodiversity.
Before human occupation there were no mammals apart from bats and marine species, and certainly no preditory mammals.
There are around 40 current species of flightless birds around the world today, and New Zealand is home to more flightless birds than any other country.
Flightless birds are called 'ratites' and they are clearly different from other birds, easily identified by flat breastbones that lack a keel to anchor the
strong pectoral muscles required for flight.
Darwin predicted that all ratites were related and one part of the scientific community still argue this, however
DNA evidence shows that most of the known Ratites split off from the general Avian gene pool about 90 to 70 million years ago,
but the New Zealand Moa (and a few others) have divergance dates of around 45 million years.
This evidence dispels the "All Ratites are related" theory as New Zealand was an island nation 85 odd million years ago,
and the evolution
to flightless-ness(is that a word?) occured after New Zealand was no longer part of the great continent of Gondwana.
For most New Zealand birds, flight was not necessary, maybe even risky, with the only preditors coming from large and small flying birds.
Before humans arrived, a quarter of all New Zealand birds were flightless. Many more were poor fliers, and as they did not need to be light enough to fly they grew,
becoming larger than their flying relatives. The only self defence required was to be able to stay clear of flying predators, so camouflage, ground nesting,
and the ability to 'freeze' when disturbed were the survival tools developed over millions of years. These defence tools made them easy prey for humans and the introduced Rats and Dogs.
The relationship between Moa and The Haast Eagle
Moa developed over 30 million years into 10 unique species. Each type of Moa was different in the adaptions they used to deal with the habitats they lived in.
Weighing from 20 to 250kg, from up to 3m tall, they were present in all of New Zealand habitats from the alpine ranges to the marshy coastland.
As our Moa developed, so did its main predator, the Haast Eagle.
This eagle was the largest on earth with a wing span of 3 meters and claws the size of modern day tigers.
The Hasst Eagle went extinct about the same time it's main food source, the Moa, did (around 1,500 AD), however there are enough fossil records
for us to see what she looked like.
There are three main pressures and drivers of biodiversity change
anywhere in the world on any definable ecosystem
- Human activities & hunting
- Predation by introduced predators,
- Habitat modification
All landmasses, including New Zealand, have records of species extinctions for the millions of years prior to human occupation.
This is normal, geological habitat changes, preditor development, food scarcity, and all this before we examine the ice ages and other climate changes that occured.
New Zealand however can show the specific damage caused by humans, given the land was empty of human prior to the Maori arriving 1,000 years ago, and strong fossil records to study.
In the 800 years before Europeans arrived in New Zealand, about 40 indigenous land and marine species have become extinct along with
over 50 bird species. This appears to be wholly due to the occupation of New Zealand by the Maori since about 1250 AD.
There has also been considerable damage to the ecology since Europeans arrived, however again we have the ability to measure and track the damge caused.
The next section records bird extinctions between 1,000 AD and 1,800 AD