Doc raised the alarm this week that four northern royal albatross (toroa) eggs were discovered missing from Taiaroa Head on Otago Peninsula during daily monitoring of the colony’s nests late last week.
Doc coastal Otago operations manager Annie Wallace said because the investigation under way continued to come up empty, it increasingly pointed to an orchestrated effort to steal the protected eggs.
If anyone had been "blundering around" the Doc reserve on Wednesday night last week, it was unlikely they could have avoided being seen on the CCTV footage that had since been collated and reviewed, Ms Wallace said.
While the investigation was continuing, the reason the eggs went missing could remain a mystery unless people came forward with information.
"It feels like it’s been really well planned.
"I think there’s a high chance that it will remain unsolved."
The suspected theft had shocked people locally, nationally and internationally.
Armchair experts had put forward their own theories as to what happened.
Commenters suggested the eggs could have been blown off their nests, an idea Ms Wallace called "implausible".
"If they had, there would have been evidence, and [it was unlikely] four would have blown away on one night."
There were similar issues with those who believed predators were the culprits.
Some people had come to Doc suggesting stoats rolled the eggs away and took them to their dens.
Yet, that phenomenon involved eggs of a species that were much smaller than albatross eggs.
Moreover, rangers had searched all over the headland, uncovering nothing.
Predator trapping, undertaken across the headland, had also caught nothing.
Staff had not seen predators on CCTV cameras of late, and a predator would not have been able to get four eggs away in one night with no evidence, she said.
The CCTV cameras on site provided good coverage of all the normal access points to the reserve.
Port Otago’s security footage had been reviewed to assess whether the reserve was accessed by water.
Specialists were also required to access further footage available from Blue Penguins Pukekura.
However, Ms Wallace said she feared it was unlikely that footage would turn up anything either.
No stone would remain unturned, but the investigation had ruled out seemingly plausible explanations for the eggs’ disappearance.
There had been "a lot of discussion" about a potential market for the eggs, Ms Wallace said.
Investigators had been in contact with staff who dealt with the New Zealand Customs Service and the Convention on International Trade in Endangered Species.
"They’re looking into that — they haven’t come up with anything yet, but that’s not to say there’s not things going on internationally that we don’t know about."
Two jewelled geckos (moko kakariki) were taken from Otago Peninsula in 2010.
One was smuggled into Germany and later sent back to New Zealand after being spotted on Facebook in 2013 by Dunedin herpetologist Carey Knox.
Albatross eggs at the colony have also been targeted once before, in 1938.
At that time, one of Dunedin’s early conservationists Lance Richdale spent weeks over the breeding season protecting nests at the colony.
