Painstaking scientific detective work examining damage to New Zealand forests and wildlife is pointing the way to better pest extermination techniques.
Department of Conservation animal ecologist Clare Veltman says her job is like a "whodunnit" mystery novel.
She has to identify culprits and decide how to deal with them as effectively
and cheaply as possible.
"If we've got a fixed budget, we must figure out where to make most difference," she says.
Past practice had been to target all potential pests, but this was expensive, cumbersome and not necessarily effective.
Careful research was gradually providing more understanding of the long-term dynamics of forests, and would lead to answers to questions such as whether pests need to be controlled all the time.
One question being examined was whether if it was a waste of money doing stoat control in a beech "mast" year, when seeds were produced and rodent and predator populations soared.
Forest damage could be caused by natural events such as native insect infestations as well as by browsing animals.
Recovery was then influenced by stress factors such as altitude and soil fertility.
Even where damage was done by possums or deer, recovery could not be guaranteed by simply removing the animals, if for example the seed sources had gone or light could not get to the forest floor.
DOC spent more than half its operating budget on pest control, and needed research to ensure any changes came about through this work, and not other factors.
This involved very careful surveillance, employing techniques ranging from old-fashioned technology such as tracking tunnels to DNA profiling to estimate population numbers.
- NZPA
Herald Feature: Conservation and Environment
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