Norwegian Rats’ New Zealand Odyssey


In her new book Invasive Predators in New Zealand: Disaster on Four Small Paws, zoologist Carolyn M. King tells the immigration story of the Norway rat, states The Spinoff.

Here’s an excerpt from that.

The Norway Rats

Norway rats are large, tough animals adapted to cold, wet conditions.

They are very good at swimming in cool water and digging burrows, but they are too heavy to be good at climbing.

On land, generations of rats have gnawed through solid wooden barn doors to get at stored grain.

Ships of the early 19th century were constructed of natural materials (timber for hull and masts, and flax for cordage and sails), all eminently gnawable.

Rodger’s detailed description of the British Navy of the Georgian era (1714–1830) comments that: Rats were always present, and always hungry, [and, along with scorpions, centipedes and other pests which were regarded as] native to the wooden world.

Rat Assassination

Rats could easily destroy most of the easily accessible sacks of dry provisions on board.

Rat-infested whaling ships, whose very timbers must have been redolent with delicious-smelling oil and strewn with scraps of blubber and meat, cruised around the coasts of New Zealand for decades between the 1780s and 1830s.

“it is almost impossible to get rid of them, the vermin seem to take possession, the sailors being mere tenants by sufferance, [On] the Julia, these creatures [the cockroaches] never had such free and easy times as they did in her crazy old hull; every chink and cranny swarmed with them; they did not live among you, but you among them,  [The rats were] tame as Trenck’s mouse, they stood in their holes peering at you like old grandfathers in a doorway.

Baron von der Trenck was an imprisoned Austrian military officer who had a tame mouse as a companion.”

Inevitable Beneficiaries

Fumigation was almost the only method of cleaning out the rats from the hold, and even that, as Melville noted, didn’t work very well.

The ships maintained and manned by the Royal Navy may have been kept somewhat cleaner, but even they could not escape their unwelcome passengers.

A large part of the reason why not is that they routinely carried their fresh meat on the hoof.

For the sake of avoiding months of dependence on salt pork, ships carried live cattle and sheep, pigs and goats, hens and geese in great numbers.

Somehow, they managed to combine the disciplined efficiency of a man-of-war with large elements of the farmyard and traveling circus.

Rats were, of course, the inevitable beneficiaries of these chaotic arrangements.

Ideal Conditions

After a long voyage far from any port, a ship’s hull would accumulate a heavy load of weed and barnacles that could easily become a drastic brake on its speed.

Then, the captain would look for a safe opportunity to beach the vessel to careen it.

On James Cook’s first visit to New Zealand, he took the chance to careen the Endeavour on the beach at a quiet anchorage in Queen Charlotte Sound.

The crew laid the hull over on the larboard (port) side, scrubbed the bottom clean, then righted it and laid it over on the starboard side for scrubbing, before finally righting and re-floating it.

The whole procedure took three days, from 16 to 18 January 1770, thereby providing the ideal conditions for rats to reach the land.

Consequences of Cook’s Actions

During Cook’s second visit to New Zealand, he brought the Resolution close in to shore in Dusky Sound in March 1773 and made use of a fallen tree trunk to provide a handy gangway for the crew and their animal companions to reach the land.

Cook could not at that time have guessed the massive scale of the consequences that could follow, but at least one member of his ship’s company was apprehensive.

Anders Sparrman was working in Cape Town when Cook arrived in 1772 and was invited to join the crew as an assistant naturalist to Johann and Georg Forster.

In May 1773, Cook moved the Resolution north to meet its companion the Adventure in Queen Charlotte Sound, where Pickersgill’s log records the “Sailmakers repairing Sails which we find much damaged by the Rats”.

Sparrman commented on the abundance of rats in the disturbed area.

He was “mortified at the thought of being responsible for introducing such animals”.


Throughout much of the 19th century, Norway rats continued to take over New Zealand in their millions, setting back human endeavors across both main islands.

In 1840, a Sydney firm attempted to establish a rural farming settlement at Riccarton, now part of suburban Christchurch.

Some European observers recounted their experiences in chilling detail.

They play havoc alike with eggs and young and even attack the parent birds.

While engaged in surveying work in the valley of the Waiho River in Westland in 1893, he reported that: The Norwegian rat, which swarmed in the country at one time, is now becoming extinct from some cause or other, and the native and black rats are taking its place – two animals perhaps not quite so destructive as the grey gentleman.

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Source: The Spinoff



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