Early possum research in the Orongorongo Valley

Authors: Chris Mclean and Chris Cochran, originally published in 'Built Heritage of the Orongorongo Valley' - a report prepared for the Orongorongo Club, 2014.


The first study of possums in the Orongorongo began in the 1930s when Brian Hildreth,

who built Boar Inn in the late 1920s, researched their habits. His pioneering work, done on

his own initiative, may have been the earliest possum research anywhere in New Zealand.


Boar Inn, old and new (left). Rimutaka Forest Park Archive
Boar Inn, old and new (left). Rimutaka Forest Park Archive

Official scientific research began in the Orongorongo valley after the war, largely because of

one man’s curiosity. Les Pracy, a bushman rather than a scientist, had been a keen hunter

all his life. As a young man, he poached possums on other hunters’ allotted Orongorongo

blocks. In 1937, he joined the Hutt Valley Tramping Club, mainly as a way of getting to the

Tararuas. Here he met the legendary government deer culler, Bert Barra. Soon afterwards,

Pracy left his engineering job in Wellington to become a government deer culler in the

South Island. War intervened and he joined the Air Force. On his discharge in 1945, he

spent months intensively trapping possums, legally this time, in the Pararaki Valley of the

Haurangi Range. While doing so, he became interested in learning more about possums to

maximise his profit.


In Wellington, Pracy called in on his former employer, the Department of Internal Affairs,

which had responsibility for noxious animal control throughout the country. Here he was

encouraged by ‘Skipper’ Yerex and Frank Newcombe, architects of the government’s deer

control campaign, to pursue his study of possums. But, as Pracy later recalled, a lack of real

scientific data soon led to the establishment of a field study in the Orongorongo Valley.


I went through all the files Internal Affairs had on opossums. This involved proposed liberations, and liberations and damage to roses and gardens – but when you really went into detail, there was no real basic information about the animal on file. Frank knew that there was very little basic information relating to opossums. He could see, looking ahead, that possums could be a problem. And it was Frank really, and the Skipper, and Ralph Keane too, that instigated the Field Investigation Unit, and that first study in the Orongorongos.

Les Pracy outside the original Orongorongo research station, 1946. RFP Archive
Les Pracy outside the original Orongorongo research station, 1946. RFP Archive

At first, Pracy worked alone trapping possums in a specific area on the eastern side of the

valley. He lived in McGregor’s Hut, near Greens Stream, trapping by day and writing up the

results at night. In time, he got a helper:


Each skin was taken out of a study area, a population study area. It was marked, you knew where it come from, the height, the track number, you knew all about that one animal and where he came from. This is in the population studies. Well when I look back at the amount of work that we did, with one trainee to help you, no wonder a joker used to fall asleep at the desk writing up the records by candle light.

Conditions improved when Pracy’s wife Val, a competent bushwoman, joined them.


Internal Affairs were very gracious, they let me take my wife over there during the summer period. That would be December, January, February, March of 46-47. I had to buy her food. Internal Affairs were pretty bloody mean really. But she did the cooking, she baked the bread, she did all the specimens and that left the trainee and myself free to do fieldwork.

Their work, later summarized by Joanna Lane-Taylor in her book on the valley, was varied

and extensive:


Temperature records were taken, including some high level ones, general effect of opossums on defoliation of marked trees, food preferences from field observation and from the feeding of captive opossums; stomach contents were preserved and sent to Miss Ruth Mason, Forest Department, for identification, then re-checked in a 30 × radius from each trap site to see if what was growing in the trap vicinity corresponded with the stomach contents. Opossums were weighed, reproductive condition noted, pouch young measured; skins were kept, graded in colour, and subsequently sold by the department, with prices and dealer gradings noted. Two hundred skulls and leg-bones were cleaned and labelled. Opossums were caught in box-traps, marked with an ear-clip and subsequently released, then re-trapped to estimate movement. An area of 500 acres behind the present Research Station was trapped to near extinction, showing a population density of 2.6 per acre.

Pracy’s work culminated in a scientific paper, Possum in New Zealand, co-authored with the

scientist, Ralph Keane. First published in 1949, it has been republished many times and is

a benchmark in possum research. Even before the paper’s publication, however, Internal

Affairs was using Pracy’s knowledge of possums to assess many other areas around New

Zealand.


Page from 'The Opossum in New Zealand: Habits and Trapping'
Page from 'The Opossum in New Zealand: Habits and Trapping'

Meanwhile, the Orongorongo research project became a more formal presence in the valley. In 1951, the City Council granted Internal Affairs a 21 year lease of land near Pracy’s plot. A research station was built the following year, using prefabricated buildings.


Noxious Animals Orongorongo River Research Station, 1957. John Johns photo, Archives New Zealand
Noxious Animals Orongorongo River Research Station, 1957. John Johns photo, Archives New Zealand

Between 1946 and 1965, first Internal Affairs and then the Forest Service had used the

Orongorongo to study possums. By January 1966 the station was disused, and its ownership was transferred from the Forest Service to the Ecology Division of the DSIR. The aim of the DSIR’s Orongorongo project, as set out by Dr John Gibb in 1966, was:


To investigate the major aspects of the structure and functioning of the forest ecosystem, with emphasis on the biology and the effects of introduced herbivorous animals.

This major long term study lasted from 1966 to 1990, with some parts of the research

carrying on to 1996. It was carried out by a team of DSIR biologists:


To give a better understanding of the links, interactions, and balances or imbalances between the forest plants and animals, and to provide useful information to those entrusted with managing native forests and their fauna. The research block has become one of the most intensively studied forest communities anywhere in the world, and the work has thrown light on many aspects of plant and animal ecology and on the management of forest assets and pests.

This quotation is taken from A Living New Zealand Forest, A Community of Plants and Animals by Robert Brockie, which summarises much of the research that was carried out by the DSIR. (6)


This work was undertaken from a group of buildings at the station, some inherited from

the Forest Service, and some built especially by the DSIR. To improve access, a road was

formed on the true left bank of the Orongorongo River right up to the site and this was

in use from 1968/69. The first major building, built by the DSIR, a large Nissen hut,

preceeded the road however, being erected in 1966; at that time the DSIR had their own

large ex-Army 4 × 4 truck. The construction of the main base building followed in 1974.


Landcare Research Station building. Allan Sheppard, 2012
Landcare Research Station building. Allan Sheppard, 2012

The Orongorongo project came to an end in 1990. With the dissolution of the DSIR in

1993, the station (and some of the Ecology staff who were working there) was transferred

to Landcare Research, which continued to carry out scientific work from the station.


In recent years, research has focused on possum control, bovine tuberculosis and pest ecology and impacts.


Latest Research

For more recent information about research in the valley, see:


https://www.landcareresearch.co.nz/uploads/public/Publications/Kararehe-Kino/Kararehe_Kino_15.pdf


https://zip.org.nz/findings/2017/11/are-rivers-an-effective-barrier-to-possum-migration


References:

  1. Scotney, Bonk, ‘Boar Inn’, Rimutaka Forest Park Archive

  2. Pracy, Les, conversation with John Rhodes, 29 July 2007, (tape two).

  3. Lane-Taylor, Joanna, The History of the Orongoronga Valley and Environs, E Hambleton, 1970, p.48.

  4. Kerr, Ross, A Chronology of the Tararua and Rimutaka Ranges, 2006, p.51.

  5. Obituary for John Gibb by Dr Michael Rudge in New Zealand Journal of Ecology, Vol. 28, No. 1, 2004

  6. Brockie, Robert, A Living New Zealand Forest, David Bateman Ltd, 1992.




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