Wednesday, 24 February 2010

Caterpillars stop train: Joan Druett's "Exotic Intruders"

One of the titles we've recently released online is Joan Druett's Exotic Intruders: The introduction of plants and animals into New Zealand.

Joan's text is an interesting examination of those plants and animals that have found their way to New Zealand, often being intentionally introduced. Some of these (such as rabbitsmustelids, and the Sirex wasp) have gone on to become major problems, whereas others (trout and deer) have been commercially farmed.

There's a fascinating section on the acclimitisation societies, and the efforts they went to in order to make this corner of the world more like the country they had left behind. Julius Haast was quite typical of the colonial attitude when he stated that  'we should like to see the hare and the partridge in our fields, the stately deer, the roe, and the pheasant occupying our hills and our forests, whilst our Alpine rivers are well calculated for the propagation of the salmon and trout. The most rugged of our mountain summits,' he said, 'might become the venue of the chamois, and offer not only us, but to future generations, the excitement and manly pleasure of the chase.'

Upon being introduced to an unfamiliar environment, some of the new introductions perished, while others adapted only too well: 'In the neighbourhood of Turakina, in the Rangitikei district,' wrote Drummond, 'an army of caterpillars hundreds of thousands strong, was overtaken by a train as the insects were crossing the rails to reach a field of oats. Thousands were crushed under the wheels of the engine, and the train suddenly stopped. It was found that the wheels had become so greasy that they revolved without advancing, as they could not grasp the rails. The guard and engine driver placed sand on the rails, and a start was made. It was found, however, that during the stoppage the caterpillars had crawled in thousands over the engine and all over the carriages, inside and outside.'

Not only was the new environment problematic to some of the new arrivals, just getting them here was often fraught. On the long ship journey, many species of birds tended to moult in the tropics, and then died of the cold as the ship reached southern waters. With fish species, particular care had to be taken when transporting the ova, and Joan relates the experiences of William Ramsbottom, tirelessly tending to 50,000 fish ova on the voyage of the Beautiful Star, embarking from London on March 4, 1862, which all died in transit despite his strenuous efforts at protecting them from heat, spray, bilge water and other dangers.

A number of the exotic species that we take for granted these days caused enormous debate when they were first introduced. Sparrows were a particular source of contention with farmers upset at their consumption of grain and seedlings, and were apparently an accidental import in the first place, as the original intention had been to import hedge-sparrows, but house-sparrows were collected instead.

The stories behind some of the exotic flora and fauna are often fascinating. Joan covers George Grey's extensive efforts at introducing species to his retreat at Kawau Island, and discovers that one species, the parma wallaby "had last been recorded in Australia in 1932 and was considered extinct; New Zealand had the odd distinction of having an extinct animal in amongst its noxious pests. In 1968 the parma wallaby become protected, and no doubt the Government was rather pleased to send over to Australia as many of them as possible."

Often, one introduction necessitated another, as some pests could only be combated by introducing another animal to prey on them. For example, the Sirex wasp, which causes major damage to pine-tree plantations, was combated with the introduction of the European ichneumon wasp Rhyssa persuasoria, and the Ibalia.

My favourite illustration from Joan's book has to be the photograph of deer wearing their anti-stress hoods while being transported, where we get the chance to see exactly how ridiculous a deer wearing a balaclava can be.

Jason