No evidence of 1080 bird deaths

The chaffinch might be a little more susceptible to 1080 than other birds. Photo / Wairarapa Times Age

Critics of the aerial application of 1080 have long claimed that the poison kills the very native birds it is supposed to protect, to the point where entire forests 'fall silent,' but Te Herenga Waka - Victoria University of Wellington scientists have found no evidence of that.

Associate Professor Stephen Hartley and Master's students Roald Bomans and Asher Cook, from the University's School of Biological Sciences, used bioacoustic monitoring to track the short-term general and species-specific trends of birdsong in treated and untreated areas. The study was conducted for a five- to eight-week period before and after three different 1080 drops in the Aorangi and Southern Remutaka Ranges of the lower North Island in 2014 and 2017. Untreated sites in the Tararua and Northern Remutaka Ranges were studied for comparison.

The results, published last week in the 'New Zealand Journal of Ecology,' showed little evidence of short-term negative effects on native bird communities.

After the 2014 Aorangi operation, the mean prevalence of birdsong increased slightly in treated sites, while it remained at near-identical levels in untreated sites over the same period. In the 2017 Aorangi operation, birdsong decreased in both treated and untreated areas, but there was no evidence that that was connected to 1080 in the former.

In the 2017 Southern Remutaka operation, birdsong increased in treated sites two to six weeks after 1080 was dropped, and decreased in untreated areas.

In all cases, both increases and decreases were minor.

Of nine native bird species studied for specific impact, five showed no impact, three showed increases in birdsong after at least one operation, and one (the tomtit) showed an increase, a decrease, and no change.

One introduced species, the chaffinch, showed a very slight decline after one of the three operations, which the researchers said could plausibly be linked to 1080, as the species was known to eat grains, and the toxin was delivered via cereal baits.

"We know from previous work that most native New Zealand forest birds benefit in the years immediately following effective mammal control," Associate Professor Hartley said.

"This study confirmed that modern 1080 operations do not cause forests to go silent, and that few, if any, native birds are suffering short-term adverse effects. Regrettably, without appropriate control of introduced mammals, population declines and extinctions of Aotearoa's native and unique biodiversity will continue."

The study was part-funded by Tbfree NZ.