The unique behaviour of New Zealand sea lions

Imagine you’re hiking through the forest, at least a kilometre away from any coast.

You hear a rustle – perhaps a curious weka, or a possum?

But actually, it sounds more like something big is dragging itself through pine needles along the ground…

It’s a New Zealand sea lion (pakake/whakahao)! Normally found near the ocean, they’ve taken to the forest as a unique story of conservation success – and new opportunities.

As an ecologist, I love to learn about different species and the habitats they need to thrive. I was particularly surprised to learn that in the summertime, during the breeding season, female New Zealand sea lions may move with their pups up to 2 km into the forest.

It’s also a completely unique behaviour for sea lions – and frankly an impressive feat for a mum wrangling pups! We have never seen anything like this in the US (where I’m from) – or in the rest of the world.

Indeed, the New Zealand sea lion is the world’s only sea lion that you can find in forests. It’s so surprising that this news goes viral on the internet occasionally!

Female New Zealand sea lions require unique habitats for their survival.

While staying in forests is interesting to us, it’s necessary. Mums move inland with their pups to protect them from wind, storms, and being bothered by young males. It’s also beneficial for the pups’ health, since moving to other areas can reduce parasitic infections.

Equally important are other habitat elements. Mums need access to beaches when pups are first born, and throughout the time they are caring for pups in the forest since they return to sea to forage. Tall grasses are also beneficial as they transition from the beach to the forest over time – again offering protection from weather.

As female New Zealand sea lions return to the mainland, this means that conserving these species also gets a little more complicated.

When looking for sea lions, it’s one thing for DOC rangers to spot them in habitats like sandy beaches and coastal grasses. It’s another challenge entirely to tromp through forests to find sea lion pups hiding under the trees (and avoid a mama sea lion in the process!)

Adding to this challenge, many New Zealanders live, work, and play along the coast. As sea lions move from the beach to the forest, it can be funny to see them visit the local swimming pool or snooze on a couch at the park.

But human interactions with sea lions don’t always go well, and it can sometimes be dangerous to them or us – including our pets.

Sea lions have been gone from New Zealand’s mainland for 200 years and have only started returning recently. So how can we predict where sea lions will be on the mainland in the future, and what current habitats are suitable for them?

I decided to undertake these challenges with the help of DOC, WildCoast, and my colleagues in Germany and the US.

We made a map!

While we can’t know for sure where female sea lions will go on the mainland, we can use models to make helpful predictions.

I used a method called ‘species distribution modelling’ to make several models that capture female sea lion’s breeding habitat requirements and inland movement.

I used sea lion tracking data from the Enderby Island colony (Auckland Islands) to pinpoint what this existing colony prefers. Then I compared that against the mainland and Stewart Island’s coastlines up to 2.5 km inland to predict where females could have the most successful breeding colonies.

With this model, I found over 395 possible breeding sites, from Stewart Island (which is officially called a new colony), to as far north as the northern tip of North Island (where sea lions were once located historically).

Let’s think about that number for a second…

There is currently only one official breeding colony on the mainland right now, and a few other spots where pups have been born but the populations are too small to be considered a colony. 395 possible sites mean there is potential for an incredibly bright future for sea lions! All signs point to many more sea lion pups in the future, if we do our best to welcome them on the mainland.

What does this mean for DOC and New Zealand’s people?

I mentioned before that a major challenge for sea lions is negative human interactions. We need to watch out for and consider any potential dangers from roads, and prepare people in advance that a new sea lion mum may happen to find a safe spot in their backyard, on their farm, or even in their home. It’s important to make sure that sea lions are not only welcomed by everyone, but also that everyone feels safe around them as they recolonise new areas.

I made an additional assessment of potential human impacts, and it turns out that over 50% of the sites include fencing or grasslands for grazing, and another 75% have roads within them. Also, many of these sites are on private land or unprotected areas.

Human interactions are inevitable.

As more sea lions appear around our coasts, we will need to adjust to having them in our towns and daily lives.

So, what can we do?

Actually, you can help! DOC has been closely observing sea lions and keeping records of any sightings or incidents that are reported by the public.

From my study, we now have a map that DOC can use to prepare for future risks, and assess areas in advance to see if the model predictions of habitat suitability are true. This map is also available for everyone, too! By being informed and on the look-out, and you could be lucky enough to spot one somewhere new! Especially if you see a female or a pup around, please let us know!

Click here for more information on how to report a sighting.

As other species move into new areas due to climate change or human pressures, or return to areas they once inhabited due to protection efforts, we can use the story of the NZ sea lion as an example.

You can read more about this here in a scientific paper that my colleagues and I wrote.

These sea lions not only matter to New Zealand, but to the world. While I haven’t seen one yet and can only imagine what it would be like to see them in the forest one day, they certainly mean the world to me.

— Veronica Frans, MSc. –

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Veronica Frans (@vffrans) is a PhD student at the Center for Systems Integration and Sustainabilityat Michigan State University (USA). She is doing a dual PhD in Fisheries & Wildlife and Ecology, Evolution & Behaviour. She is interested in ecological modelling, human interactions, and conservation applications. Her published research was completed with Amélie Augé, Jim Fyfe, Yuqian Zhang, Nathan McNally, Hendrik Edelhoff, Niko Balkenhol, and Jan O. Engler.