The Department of Conservation is awaiting post-mortem results to determine the cause of the deaths in the Matukituki valley near Wanaka.
The remaining six birds have been confirmed alive since the DOC operation on February 11.
DOC threats director Amber Bill said there was a concern the tracked kea may have been exposed to human food around the tramping huts in the valley, making them potentially more vulnerable to picking up 1080 cereal baits.
"While we are confident that predator control operations benefit kea populations at large, it's upsetting to lose six birds."
The 1080 drop followed the biggest forest mast in 40 years, which fuelled rodent plagues and created a spike in stoat numbers, posing a serious threat to ground-nesting kea and other native wildlife, she said.
Previous department research showed kea had increased survival and nesting success when 1080 was used to control rats and stoats.
While the risk of 1080 to kea in remote areas was low it increased with birds that had leaned to scavenge for human food.
"Our work to mitigate the risk to kea from 1080 is based on extensive research and the results of 222 monitored kea through 19 aerial 1080 operations at 12 South Island sites," she said.
The department was looking to launch a campaign discouraging people from feeding kea and interaction that could lead to scrounging behaviour.
Results of the post-mortem and toxicology testing on the dead birds are expected later this week.