By Hamish MacLean for the Otago Daily Times
The little-understood leopard seal has been visiting New Zealand shores more and more in recent years - enough that it was made an official resident in May, and increasing sightings of it have already begun for spring.
Around the country there is a rising trend for reports of the pinniped with massive jaws.
A leopard seal never changes its spots - but the spate of spring sightings indicate it has changed its behaviour.
Until this year, the species was considered a vagrant in New Zealand waters, meaning there were theoretically only 15 individuals in New Zealand in any given year.
But the rising numbers of sightings meant that in May it was granted resident status by the Department of Conservation.
The reasons it is being spotted more during spring are unclear, LeopardSeals.org research assistant Giverny Forbes says, but this season has proved no different.
In the first four days of September, she saw a leopard seal each day.
"We do get this spike - we're not sure exactly why it happens.
If you see a leopard seal:
- Stay 20m away and do not disturb the seal
- Call 0800 LEOPARD to report sighting
- Take photos to send to email@example.com
"There is evidence that they might change their haul-out period [a time spent on land]. It's also possible more of them are moulting and that's why they're coming ashore more. It's possible that more people are getting out of the house and seeing them, but then sightings drop back in summer again ...
"There must be something special about this time of the year that brings them ashore at the right time more often when more people are seeing them as well."
Reports of sightings, provided by LeopardSeals.org research, helped trigger the change in the seals residency status.
In its Conservation status of New Zealand marine mammals, 2019, the department noted leopard seals are now considered naturally uncommon.
There are believed to be fewer than 250 individuals in New Zealand, after "an increasing frequency of sightings on the mainland, and new evidence that the species is continuously present in New Zealand".
Miss Forbes has identified 19 individual animals since she began researching the species in 2015. And LeopardSeals.org research has identified more than 100 individuals in the past four years.
In 2017, the New Zealand education, conservation and research organisation received 568 reports of the animals, resulting in 288 unique sightings, with spring (144 sightings) well ahead of winter (61), summer (54) and autumn (28).
Last year, the number of reports increased and the nation-wide group received 774 reports, resulting in 339 confirmed distinct sightings. And again spring (144 sightings) was well ahead of winter (85), autumn (56), and summer (53).
In Otago alone, there were 122 reports, and 71 sightings, in 2017; and 109 reports, and 63 unique sightings, last year.
And still, the amount left to learn about the seals better known for inhabiting the Antarctic pack ice is formidable.
"We're just scratching the surface, trying to understand their occurrence," Miss Forbes said.
"But then you've got diet, you've got their place in ecology, you've got their movements around New Zealand. Are they breeding here? Are they breeding in the Subantarctics? How are they interacting with other species? How are they interacting with other seals?
"Even for Antarctica, I'd say our full knowledge of leopard seal biology is relatively low - in New Zealand it's even lower still."
New Zealand researchers have started a diet analysis, which is not yet complete.
But there is evidence of the species eating krill, a few different species of fish, shags, gulls, little penguins and "the odd duck" as well.
The research Miss Forbes is focusing on is human interaction with the wildlife - perhaps due to their large canines, and sharp trident-shaped teeth, the animals have a reputation for being fearsome, but she has not seen evidence to support that.
Those teeth, which looked like they could tear, were actually used to sieve krill out of water, she said.
"If we're seeing a lot of these seals in New Zealand and humans are coming into contact with them all the time, we need to know how to manage that. Because leopard seals have this reputation of being aggressive and vicious ... ferocious ... lots of people are quite worried about safety. And some people have also threatened leopard seals based on that opinion of them," she said.
"Not once have I seen one try to attack someone, or chase someone, or act in a way that I describe as aggressive or vicious. I've seen them be defensive - and giving warning signs to people who get too close - but I've never seen that turn into an attack."
Leopard seals are protected under the Marine Mammals Protection Act 1978.
- This story first appeared in the Otago Daily Times