After "tragic" losses at the only mainland northern royal albatross colony during breeding last year, things are looking positive with 29 chicks hatched this summer. But don't count your albatross yet.

Photo: RNZ/ Lynn Freeman

Last breeding season extreme weather conditions meant more nests than usual failed at Pukekura-Taiaroa Head on the Otago Peninsula and only 13 chicks fledged from 29 fertile eggs, of which just over half hatched.

Otago Peninsula Trust Ecotourism Manager Hoani Langsbury said: "At this stage all the chicks have hatched and our breeding survival is 29 chicks in the colony.

"Compared to the final fledging last year we're feeling quite confident, but we've still got March to go through and March can be quite a good warm month in Dunedin.

"Even in really good breeding years chicks have been lost to viruses in the final few weeks before they leave. I would be hoping that we are in the high 20s. I would be pretty comfortable with that, considering where we are currently at."

Concerns for the birds are centred around climate change. If periods of extreme summer heat continue, it could impact the ability of the colony of about 250 birds to reproduce at Taiaroa Head.

The Northern Royal Albatross population on the Chatham Island is between 23,000 and 27,000, Mr Langsbury said. The website New Zealand Birds Online put the total breeding population on the Chathams at about 6500 to 7000 pairs or about 17,000 mature birds.

So worries aren't about the species overall, but it's only mainland foothold for the birds in the world. The Department of Conservation (DOC) lists them as at risk-naturally uncommon, with their threats being climate and habitat changes, heat stress, fly-strike.

"Similar to last year we have had what we believed to be influences of climate change impacting on the hatching success. But at this stage I'm waiting to have a final report and discussion with DOC about what the numbers look like," Mr Langsbury said.

"It's certainly not as bad as last year but not good either.

"There's the fact we started off with 51 eggs or nests up from the usual 30 … the reason for that is all the failed birds from last year - because they failed so early in the season - returned to breed again this year."

In 2018, he told the Otago Daily Times the loss of albatross embryos was "tragic", but not a first.

The start of February this year saw another hot week like the period last year that affected the birds.

Photo: Supplied / DOC

"If this went on for several years there would be definite concerns around viability of the population here with the changes in environmental conditions due to climate change," Mr Langsbury said.

Summer heat can be a challenge for the nesting adults and young chicks as overheating and fly strike can cause mortality, according to the Royal Albatross Centre.

Otago Peninsula Trust General Manager Robyn McDonald said in a January statement that the trust was "concerned about increasingly hot summers and the effect it has on albatross chicks.

"Otago Peninsula Trust helps with care for the albatross on very hot days by providing water for the nest irrigation system. All our water is trucked in, which costs us around $40,000 each year. We raise funds for water and support to ensure we are able to assist the Department of Conservation to keep albatross and chicks cool on blistering hot days."

Efforts were underway to get a desalinisation plant at Taiaroa Head to provide a constant supply.

"We certainly think we're going to need that in the next few years if temperatures keep increasing," Mr Langsbury said.

But more monitoring was needed to confirm if it was climate change influencing failure at the egg stage for the bird, he said.

"The key at the moment for us is ensure that good information is captured over the next few years to inform husbandry on the headland. It may be that they actually survive, but the way they currently are being managed with regard to habitat and all that needs to change.

"We have always been worried about predators - stoats and ferrets and all those sorts of things. We might need to change what we are worried about."

That would all be on the table when the trust discussed the breeding season with DOC in a few months' time, he said

The Ministry for the Environment's website states that: "Compared to 1995, temperatures are likely to be 0.6 degrees Celsius to 0.9C warmer by 2040 and 0.6C to 2.8C warmer by 2090.

"By 2090, Otago is projected to have from four to 25 extra days per year where maximum temperatures exceed 25C, with around 13 to 45 fewer frosts per year."

'They chose this place'

DOC's website states that the nesting site on Taiaroa Head is a hot spot - "a sheltered area where summer ground temperatures can reach 50 degrees celsius.

"These conditions aren't ideal for a genus that's far better adapted to subantarctic conditions, but they chose this place."

Asked if continuing nest failure might prompt the birds to breed elsewhere, Mr Langsbury said:

"That's a really good question. We don't really know why they came here in the first place, except for the fact they like the roaring forties and we're right on 45 degrees south. The reason they started breeding here was actually the militarification of the headland the 1880s providing flat land for them to land and nest on, so that part of it won't change.

"It will just be how many years of a bird failing to successfully fledge a chick before they decide to go somewhere else. They may never learn that … this is something that will take a couple of decades before we can see what that pattern looks like."