The SPCA has doubled down on its call for a ban on 1080 poison used in pest control, but it hasn't offered up any alternative options.
It has come under fire for its position, which goes against Forest and Bird, the Department of Conservation, Federated Farmers and the Parliamentary Commissioner for the Environment, who all say 1080 is the only viable form of pest control currently available.
SPCA chief scientific officer Dr Arnja Dale initially told Summer Report on Wednesday the SPCA did not want a ban on 1080 and was instead "opposed to toxin use".
But when challenged, she confirmed that the organisation did want a ban on 1080 and all other poisons currently used for pest control.
"What the SPCA really wants is more innovation into the humane alternatives to poison use.
"We have a significant problem in New Zealand. We all want the same outcome, we are looking at it in different ways. It's important to understand that all animals are considered sentient - which means they feel pain - under the Animal Welfare Act.
"So it's our duty to ensure that when we do control animals populations ... that we do so in the most humane way possible.
"I think that when you look at it physiologically, and in terms of the ability for these species to feel pain, the animal, regardless of whether it's a cow or a sheep or it's a seagull, these are animals that are all able to feel pain."
The SPCA initially stated its position on a 1080 ban and preference for alternative pest control options in an article published on Monday.
But when Summer Report pointed out that the SPCA had not offered up any viable humane alternatives because none currently existed, Dr Dale said: "I do believe that New Zealand is an innovative country. There is research going on, I know a lot of those scientists, I know they will come up with innovative solutions that [are] more humane."
"Look, the SPCA are well known to be coming from a single value proposition that they're really focused on pain and suffering in sentient animals. In their article I found a lot that I agree with because for the same reasons as them I got into conservation because I want to prevent the cruelty that humans are causing on a lot of our native wildlife through the introduction of species such as rats and cats.
"But ... I think a ban is too far in this regard because I actually think in the scheme of things, banning 1080 immediately would increase overall suffering of all animals in New Zealand.
"I don't have a calculator to work it out exactly but with 25 million birds being killed a year by those species - one rat or one stoat will kill hundreds of animals a year - I think that's where most of the suffering is happening at the moment."
Pest control options were a balancing act, according to Prof Russell.
"When we undertake pest control we're really making a trade-off between three things. It's trying to understand the cost efficiency of the tool and the humaneness of the tool and how well it will scale and if we can get the three of them to work together to get to an optimal solution, it may not be perfect ... but if we don't actually do anything and leave these animals to their own devices then that's probably going to cause more suffering overall."
He believed the issue was fundamentally about money.
"I think we could make New Zealand predator free today if we could afford to put a possum trap or a rat trap or a stoat trap over every 25 or 50 metres of New Zealand but that is simply not affordable to do.
"So we need to use tools that can scale and at the moment 1080 is the only affordable tool we have to scale.
"If we have an increase in say 10 times the amount of funding for pest control, the option we have is do we want to do pest control over 10 times a larger area to save 10 times as many birds or do we want to do pest control that's 10 times more humane but only in the area that we were previously focusing on."
Alternative options a long way off
Prof Russell said there were a "number of tools we have developed in the laboratory or engineering sheds, tools that we know have potential to actually create more humane modes of removing these animals from the environment".
However, the real challenges were getting those tools through regulatory processes, trying to field test them and trying to get the social support from the public.
An option for pest control that had been widely discussed was gene editing.
"We're not doing any gene editing research in New Zealand at the moment but we're keeping a watching brief overseas where we're looking at field trials for species such as mosquitos for malaria control that are going to be starting in Africa realistically in the next few years," Prof Russell said.
"We're keeping in touch with overseas laboratories that are working on mammalian pest control through gene editing and seeing what the theoretical potential is so if it becomes viable and tested overseas then perhaps in 10 years or 20 years it could be a tool that we could consider for Predator Free 2050."