The use of the toxin sodium monofluoroacetate (otherwise known as 1080) for possum eradication has long raised concerns that a heavy toll is being taken on wildlife and the environment.
The Department of Conservation – supported by farm organisations among others – says it is the most suitable poison for aerial drops to kill possums which are destroying native bush. Destroying possums limits the spread of tuberculosis from the pests to livestock on farms.
But 1080’s critics say the poison kills not only pests, but also native birds and wildlife such as kiwi. Moreover, it is a cruel method of pest control and may contaminate the ground and waterways.
On Radio New Zealand’s Nine to Noon programme this morning, Roald Bomans told of studies to investigate the claim that aerial 1080 drops cause forests to fall silent.
He used bioacoustics, a developing area in ecology, to monitor native bird species in the Remutaka and Aorangi Ranges.
He did this by listening to recordings and developing a special detector for morepork calls.
Collectively his bioacoustic monitoring showed no negative impact on the populations of native bird species.
The interview can be heard HERE.
It follows a seminar led by Roald Bomans at Victoria University last month.
According to his notes on the university website (HERE) about the seminar :
I used recordings from autonomous recording units (ARUs) to monitor resident bird species over multiple aerial 1080 operations in order to investigate this claim.
The total amount of birdsong recorded did not decrease significantly in treatment areas relative to non-treatment areas. The calling prevalence of one species, the introduced chaffinch (
Diurnal monitoring was conducted for 10-12 weeks over two independent operations. The total amount of birdsong recorded did not decrease significantly in treatment areas relative to non-treatment areas. The calling prevalence of one species, the introduced chaffinch (Fringilla coelebs), showed a significant decline in the treatment area across one of the two operations monitored. Collectively, these results suggested no negative impact of modern 1080 operations on the populations of native bird species.
Extracting data from ARU recordings can be labour intensive.
In the second part of my study I developed a process for developing a parsimonious template-based detector in an efficient, objective manner and applied this method to the creation of a detector for morepork (Ninox novaeseelandiae) calls. The method was highly successful as a directed means to achieve parsimony. In independent validation tests, the final detector had a high precision (0.939) and moderate sensitivity (0.399).
This detector was used to monitor morepork in treatment and non-treatment areas across three independent aerial 1080 operations. Morepork showed no significant difference in trends of calling prevalence across the three operations monitored. Over a longer time period, a significant quadratic effect of time since 1080 treatment was found, with calling prevalences predicted to increase for 3.5 years following treatment.
Collectively, the results suggest a net-positive effect of modern 1080 mammal control on morepork populations.