Let’s go back a little in time…
Have you ever seen those pictures of the land masses on earth hundreds of millions of years ago where the earth was basically one big happy continent? Then over time, more hundreds of millions of years, that big land mass began to split asunder so that the present day continents could move and slide to where they were supposed to be on the globe.
The two big-dog land masses (supercontinents) back then have been given the names Laurasia, the northern most one, and Gondwana, the southern most one. Aren’t you glad that they drifted apart so that we weren’t stuck with those names?
In fact, the continent of Gondwana was named by an Austrian scientist, Eduard Suess, not to be confused with a certain Dr. Seuss (different spelling).
Gondwana included most of the landmasses in what is today the Southern Hemisphere including South America, Africa, the Arabian Peninsula, the Indian subcontinent, the Australian continent … and New Zealand.
About 85 million years ago a large fragment of eastern Gondwana began to break away from the Antarctica and Australian land masses. The sea flooded the rift between the land masses eventually becoming what is now the Tasman Sea and what was to later become New Zealand was created. Just think of the Cretaceous Period newspapers at the time: “New Zealand Breaks Away!”
Then over time, lots of time, what is now New Zealand continued to migrate away from the other land masses until some 55 million years ago, New Zealand assumed its current position approximately 2000 kilometers from eastern Australia which thankfully to many New Zealanders, it has maintained ever since.
This long 85 million year separation and isolation from the other land masses allowed New Zealand to evolve its own unique flora and fauna from the common ancestors it shared with Gondwana. Also, once separated, geologic events including volcanic activity and a number of ice ages placed further unique selective pressure on the plants and animals developing there. New Zealand is also unique in that it separated from Gondwana prior to the evolution of marsupials and mammals, and hence its ecosystems evolved with the absence of such animals. Ecological niches filled by mammals in most lands instead became filled by birds, insects and reptiles in New Zealand, hence the unique species in New Zealand see nowhere else in the world.
But this very uniqueness and specialness is what also makes New Zealand flora and fauna so vulnerable to outside. It simply hadn’t evolutionarily grown up with many of things in the outside world. Early on, the introduction of a few mammals both by the Maori and by Europeans had devastating effects on indigenous animal life. The animals on the islands particularly the birds simply had not evolved to withstand the predation of seemingly common animals such as rats and dogs.
New Zealand has strict rules on the bringing of animal, plant or any bio-material into the country. Anything brought into the country is carefully inspected and anything suspect is not allowed or destroyed.