In the late 19th century Leonard Cockayne studied the ecology of New Zealand plants, examining their roles in natural systems. Cockayne disagreed with the popular idea that native species would inevitably be displaced by northern hemisphere competitors, which were seen as superior. He concluded displacement was largely the result of human activities such as forest clearance and swamp drainage.
Cockayne was mentor to ‘the two Lucies’, botanists Lucy Moore and Lucy Cranwell. They carried out important ecological field trips throughout New Zealand, including studies of alpine plants on Te Moehau, marine algae on the Poor Knights Islands and forest ecology on Maungapōhatu.
The Wildlife Service and the Department of Conservation
The Wildlife Branch of the Department of Internal Affairs was created in 1945 to conserve native species, manage game animals and control exotic pests. In 1946 Les Pracey of the Wildlife Branch and Kazimierz Wodzicki of the DSIR carried out the first studies into possum destruction of the New Zealand bush.
The Wildlife Branch studied game birds that had been released into the wild as well as browsing mammals including deer. It also protected native birds. Researchers pioneered techniques of pest eradication and the capture, breeding and transfer of endangered species to offshore islands.
The Wildlife Branch was renamed the Wildlife Service in 1974. It was merged into the new Department of Conservation (DOC) in 1987, and the pioneering work on endangered species recovery continued. There Don Merton received world recognition for his work with saddlebacks (tieke), Chatham Island black robins and kākāpō.
Razza the rat
In 2004 James Russell’s team of University of Auckland scientists released a single male Norway rat, complete with radio-tag, on rat-free Motuhoropapa Island. They were studying the difficulty of removing small rat populations from islands. Razza the rat escaped capture for 18 weeks, ignoring food traps, baffling trained rat dogs, and even swimming to another island. The fugitive rat made international news, was the subject of scientific papers and inspired a children’s book by Witi Ihimaera: The amazing adventures of Razza the rat.
Rodent invasion studies and island ecology
In the 21st century New Zealand scientists continued pioneering work on the ecology of offshore islands.
James Russell and Mick Clout led a group of University of Auckland scientists investigating the exploratory behaviour of Norwegian rats in the early stages of an island invasion. They deliberately introduced an all-male group of rats to a rat-free island and studied their behaviour from arrival. Another group studied the introduction of house mice to an island. Both experiments aimed to develop better methods of detecting and eradicating rodents.
Scientists have also investigated the use of genetic markers to determine whether rodents on an island following an eradication programme are new invaders or survivors from an earlier population. The expertise developed means that New Zealand scientists now work all around the world on island conservation projects.
Blue cod genetics
In 2012 Hayden Smith and Peter Ritchie began working on the population genetics of New Zealand blue cod. They wanted to establish whether New Zealand had one large intermixed population or several discrete populations in different inshore areas. Discovering more about the genetic relationships of blue cod populations would enable more careful management of cod populations around the coast.
Genomics in ecology
Genomic studies, involving the complete DNA sets of particular species, have great value in ecological studies. Genomics give precise information on species found in a particular habitat, on the structure of breeding populations, and on an area’s ecological history. Such information can play an important role in conservation management.
From 2010 Nicky Nelson, Alexei Drummond and other scientists from the Allan Wilson Centre carried out a genomic biodiversity study of Hauturu (Little Barrier Island). The aim was to categorise all species in the island’s ecosystem. One part of the study was a comparison of the plant species surviving on the island to the genomes present in organic material dug from the soil. This enabled scientists to determine which species lived on Hauturu before the introduction of browsing mammals. Such knowledge was important for making decisions about island revegetation.