The number of bird strikes on Tasmanian power lines is still "too high", says the Tas Networks boss, with 18 bird of prey electrocuted this past year, but the Greens are questioning the accuracy of the company's recording processes.
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Species such as the Wedge-tailed Eagle, Grey Goshawk and White-bellied Sea Eagle are injured or electrocuted when they fly into the lines or perch on power poles near live electrical infrastructure.
There were 18 documented instances last year, but Tas Networks says on its website that they don't know the true extent of the problem.
We had 18 strikes. I think the vast majority, if not all, were fatalities. That was down from 24 the previous year, and down from 33 in the year prior to that.
- Tas Networks CEO Lance Balcombe
In a Government Business Enterprise Committee hearing this week, Greens MHA Rosalie Woodruff questioned the number of bird strikes recently documented by Tas Networks.
Tas Networks chief executive Lance Balcombe told the committee that it continued to make significant investment in protecting these threatened bird species.
"We had 18 strikes. I think the vast majority, if not all, were fatalities. That was down from 24 the previous year, and down from 33 in the year prior to that," Mr Balcombe said.
"It is trending the right way. It is still too high, but we are continuing to work on our Threatened Bird Strategy."
In 2016 it is understood there were 11 documented bird strikes on lines and in 2017 there were 13.
Dr Woodruff said Tas Networks should be more proactive about taking responsibility for all suspected bird of prey electrocutions.
"Will you commit to working with Craig Webb (of Raptor Rescue) and other vets to reverse the balance of proof, so there is the assumption that the bird has been killed by the power lines - instead of requiring volunteers and other people to deal with lots of post mortems and a whole lot of other things to identify the reason [for death]?"
Mr Balcombe said most bird of prey carcasses went to the museum for autopsy to further understand the science.
"We have a process to follow, but if a deceased eagle is found within proximity of the power lines I'd say 99 to 100 per cent of the time we will assume responsibility for that."
Mr Balcombe said mitigation strategies included the installation of bird flight diverters on 65 kilometres of line in Tasmania this year, which included the automatic installation at or near the site of where a dead bird is discovered to prevent future strikes.
He said that $25,000 was given to Raptor Rescue to build bushfire prevention and sprinkler systems to protect its aviary's from fire threats.
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He added that when new parts of the network are built the design standards would take into account strike prevention, and the identification of eagle nests in the North West transmission area was underway.
"There are opportunities to think about how we build the distribution network in particular, where there are new elements and there are bird risk areas," he said.
"We can arrange the set up of the distribution lines so they are more in a delta formation, which reduces the risk of the birds hitting two phases which triggers electrocution. We can offer perches for the birds to rest on, rather than sitting on top of power poles."
The Tasmanian Wedge-Tailed Eagle is the largest bird of prey in Australia and it is believed there are less than 1000 adult birds left in the wild, but true numbers are unknown.
Its main threats include loss of nesting habitat, nest disturbance which results in birds leaving or deserting nests, collisions with buildings and vehicles, electrocution and human cruelty.
The Grey Goshawk, found in Tasmania and elsewhere, is believed to have less than 110 breeding pairs in this state, and the White-Bellied Sea Eagle has less than 1000 birds and is also threatened in Victoria.
