Stewart Island_ Home of the World’s Largest Seahorse _ FD Ocean

Spring brings longer days and spectacular twilights to the southern most part of New Zealand. Stewart Island or Rakiura, the land of glowing skies. All around the coastline the island's iconic animals are coming together to breed and feed. Out in the deep ocean and the many sheltered inlets and on the beaches, every day is a struggle to find enough food for hungry mouths and to stay alive. As twilight fades this male southern brown kiwi has only one thing on his mind. Food. He's five years old and this is just his second breeding season. All day he's been sitting on the single egg his mate has laid and now he's ravenous. What he does next is unique among kiwis which live in New Zealand's forests. He heads to the beach. It's a mystery when and why these coastal kiwis added seafood to their diet. But the sand hoppers and small invertebrates buried in the sand are now vital to this male's survival. There's one drawback when beachcombing. Kiwis are the only bird with nostrils at the end of their beak. Perfect for sniffing out food beneath the forest floor. But they haven't yet evolved to cope with sand. By the time this young male calls it a night, the day shift on Stewart Island is waking up. This little blue penguin pair spent the night together in their nest burrow. Both keeping their precious eggs warm during the cool of night. It's common for mates to preen each other. It's likely they'll stay together for the rest of their lives, up to 25 years. It's the male's turn to go fishing today. Little blues are the world's smallest penguin, standing 30 centimetres tall and weighing just one kilogram. But the little bird has a big responsibility. If he doesn't make it home from the sea, the female won't be able to raise their chicks alone. So it's not just his life on the line. Every time he goes to hunt, he runs a gauntlet of hungry predators. Home for all these creatures is sculpted in a myriad of ways by the sea. Huge swells roll off the southern ocean to batter exposed rocky coasts. Wild westerly winds carry beach sand three kilometres inland at Mason Bay, creating a vast expanse of dunes. At Patterson Inlet, the sea has invaded the land. Twelve thousand years ago, rising seas drowned bush-clad valleys here. Today, it's a maze of sheltered inlets where pristine native forest still grows right down to sea level. And beneath the surface, the forest continues. 270 varieties of seaweed thrive in Patterson Inlet. The most spectacular is the giant bladder kelp that towers up from the seafloor. Gas-filled bladders keep the kelp upright, facing the energy-giving sun. Kelp photosynthesise just as plants do. But that's where the similarity ends. These holdfasts are not roots. They're merely an anchor against storm and tide. The kelp absorbs all its nutrients from the currents through its flat blades. All around Stewart Island, nutrient-rich currents from Antarctica converge with warmer waters from the north, creating a vast upwelling of food, which attracts a multitude of animals, both year-round residents and regular visitors. Near the kelp forest floor, this pair of pot-bellied seahorses is courting. They're normally solitary creatures, each with its own territory, but spring brings them together to mate and breed. When they're not dancing, they grip the kelp with their tails to avoid being swept away in the strong current. They swim only in short bursts, fluttering their dorsal fin up to 40 times a second as they steer with the small fins on the side of their head. Once their courtship is complete, in a bizarre twist, it's the male who carries the fertilised eggs in a special pouch for a month, and then gives birth to up to 1,000 live young. The offspring disperse immediately. With no protection from parents, only 1 in 1,000 will survive to adulthood. As many predatory fish patrol the forest, it helps to have eyes that move independently. They can eat and keep an eye out for danger at the same time, but camouflage in the kelp forest is their best defence. The male penguin could be a threat. If the fishing is poor, little blues will hunt for crabs and seahorses on the seabed. But luckily for the seahorse family, the male is passing through as fast as he can. He's detected the presence of one of his main predators, a New Zealand sea lion. This juvenile male can't yet challenge the bulls that have recently started breeding on Stewart Island, which leaves him time to inspect the kelp forest for anything edible. And penguins are definitely on his menu. Just like seahorses, the penguin relies on camouflage. He's white below and blue on top, which makes him hard to see from above and from below, which is critical because his top speed is just 6km an hour. Just when he seems to have eluded one predator, another spots the penguin. This 4 metre long great white shark often cruises around Patterson Inlet at a top speed of 40km an hour, and he's not fooled by the penguin's camouflage colours. Hundreds of tiny black dots on his snout can detect the bird's faint electrical signature. Luckily for the penguin, a 1 tonne shark won't bother expending too much energy chasing a 1kg penguin, which equates to a mere snack. All around the Stewart Island coastline, dozens of other small islands are scattered. Sheer vertical cliffs mean these islands are inaccessible to many of the locals, but that makes them a perfect home for literally millions of these birds. Collectively, the islands are known as the Mutton Bird Islands, named after the birds, which are also called Sootishia waters. Like penguins and kiwi, these seabirds are not permanent residents. Every autumn, they set off on one of the most spectacular migrations on the planet. Roaming as far away as Alaska during the southern winter, they can travel up to 75,000km on this journey, and average more than 500km a day. But every spring, they return to these same islands to breed. They arrive about the same time as another ocean wanderer, which always returns to this neighbourhood. But the shear waters are so distracted, they don't take much notice of a great white shark. Huge swarms of krill are one reason seabirds flock here year after year. The tiny crustaceans drift just below the surface, and are easy pickings for a shear water, which can fly almost as well below the water as above it. These birds can chase fish to depths of up to 70m, second only to penguins in underwater swimming ability. Sootishia waters' feathers are so well waterproofed with oils, that after a dive, they pop back to the surface almost bone dry and ready to fly, or plunge straight back down. Chasing a flock of frenzied birds is not a priority for this shark, but Stewart Island's great whites are notoriously aggressive, and a shear water snack is better than nothing. At least 82 great white sharks share the waters around Stewart Island. But like Sootishia waters, these sharks leave the neighbourhood during winter to take a holiday in warmer waters. They travel as far away as Fiji and Tonga, and then return to the exact spot around Stewart Island where they were originally tagged. These great white creatures of habit also pick up hitchhikers on their travels. This pilot fish has accompanied the shark all the way from the tropics. It gets protection from predators and scraps of food, and repays by picking parasites off the shark. Sometimes the top of the food chain can get a little crowded, but great white sharks have a loose social hierarchy, where big fish generally give way to even bigger fish. Tail wagging and pointing petrol fins down are a warning to the other shark to back off. The scars on this four-metre male show what happens when warnings are ignored. Back in the sheltered waters of Patterson Inlet, the male blue penguin has joined a small group of fellow hunters. They can hold their breath for up to two minutes and dive to 60 metres, but the majority of dives are much shorter, around 20 seconds and less than two metres below the surface. When the fishing is good, there's no need to expend more energy. At the end of a hunt, the penguins will often come together in a group known as a raft, as they contemplate the safest way to get ashore. The thick native forest which covers parts of Stewart Island right down to the shoreline has a profound effect on the sea life in these sheltered inlets. The rivers that run off into the sea are filtered through the root systems, and so the inlet is silt-free. Even the bare seafloor beyond the kelp forest is a healthy ecosystem inhabited by truly bizarre creatures. Sea cucumbers burrow in the sand, using feathery tentacles to trap floating morsels of food to feed their hungry mouths. Nearby, one of the sea cucumber's relatives stalks what looks like a common sea snail, a favourite meal of the 11-armed starfish. The starfish positions itself to eject its stomach inside the shell to eat the contents, when suddenly the tenant appears. It's a hermit crab. To avoid becoming crab soup for the starfish, it makes its escape, with its home on its back. Crabs are resourceful with their protection, whether it's a borrowed home, a hard shell, or camouflage, because everyone loves to eat them down here, and none more so than the common octopus. The resident female has woken up to hunt, but for her too, the seafloor is a dangerous place to be exposed. Sharks, sea lions, and even her own kind all see her as a meal. Like so many of her neighbours, camouflage is her first line of defence, but she takes it to a whole new level, changing the colour of special pigment cells in her skin, while other cells mirror the colour of her surroundings. She can also change the texture of her skin, all this, in less than a second. When the coast is clear, she jets forward in her search for crab. Octopus are highly territorial, so when she spies an intruder under a rock, she's ready to fight, but the intruder attacks first. Octopus saliva contains deadly venom which kills their prey, but has no effect on their own kind. The intruder is bigger, and smothers the resident female, claiming this territory for now. Cannibalism in the octopus world is common, and nothing will go to waste. Above the surface, the day draws to a close. It's time for the shearwaters to head back to their islands. Their wings and bodies are designed for long-distance flying, not quick take-offs and landings, and they need a long run-up to get airborne. Soon, tens of thousands of birds circle the muttonbird islands. With dense forest below, breaking through the canopy to land seems like mission impossible, here on the southernmost tip of New Zealand. As spring edges towards summer, twilight in the deep south can last until 10 at night, but sooner or later, these sooty shearwaters returning from their days fishing at sea must come down to earth. With their bodies built for long-distance flying, maneuvering into land is an awkward process. Basically it's a crash landing, and they have to do this every day. Soon, shearwaters are plunging through the canopy all over the island. It takes them a moment to get their bearings. Before they head for home, no worse for wear. Sooty shearwaters nest in a maze of underground tunnels which they dig themselves, well insulated from temperature extremes. This pair rekindles their bond. They may have spent the year as far apart as Alaska and Japan before reuniting to breed again. They'll probably keep meeting here, in the same burrow, to raise chicks together for another 15 years. Little blue penguins often come ashore for the night in a group, as there's safety in numbers. Like all penguins, little blues are ungainly on land and easily spooked. The penguins know a lone seal is no threat on land, but they're still cautious as they tiptoe around him. His belly full from a good day's fishing, the male penguin is greeted by his mate with great enthusiasm. Tomorrow, he'll stay on the eggs while she goes to sea. It's been 30 days so far, and the eggs could hatch any day now. Soon there'll be extra mouths to feed, and a lot more fish to catch. Nearby, the Kiwis' burrow is a stone's throw from the penguins. The Kiwis' nest is also constantly tended, but in a unique twist. This bird is not one of the parents. She's the couple's chick from last year. She won't breed for at least three more years, so she helps out at home with about 20% of the egg incubating. Amongst New Zealand's Kiwi species, it's only the Stuart Island birds that live in these family groups, with older offspring helping out. It's a behaviour they may have evolved during an ice age, when the deep south was much colder and the birds needed to huddle together for warmth. With a helper on the nest, the female Kiwi takes the opportunity to forage in bush nearby. The nights at this time of year are so short, she often forages until well after dawn, while the male mines the nest. But she usually stays clear of the busy beach at this time of day. These oyster catchers live together peacefully during the winter months, but now that it's the breeding season, they're highly territorial. An eastern curlew has flown halfway around the world to escape winter in Siberia. It'll stay until March, fattening up on crabs to fuel it for the long flight home. Below the surface, the intruder octopus is also hunting crabs in his new territory. A paddle crab can attempt to swim away, but its escape tactics are no match for the hunting skill of an octopus. It's almost as if he's playing with the crab. He injects venom to immobilise, and enzymes that liquefy the crab's flesh, so he can suck it out and feast. The octopus's efforts attract the attention of the blue cod gang that rules this neighbourhood. Cod don't have a swim bladder, which is a gas-filled organ that helps control buoyancy in many species of fish. Instead, they stand over the seabed, rarely straying more than a kilometre from where they were born. The largest cod in this gang are males, which can live to be 30 years old. Blue cod eat anything that moves, and some things that don't. A clump of muscles broken loose from the rocks is a challenge, but blue cod jaws are powerful. Perseverance pays off for the aggressive males, and the spotted wrasse, which scavenges for scraps, but could become cod food at any time. In a remote bay on the Stewart Island coastline, the little blue penguin mates are about to become parents again. For 37 days, they've taken turns to run the gauntlet of predators to return to their nest. One chick hatched, and another on the way. Only one in five little blue chicks survive long enough to become an adult and breed. Most die soon after leaving the safety of the nest, but these chicks' chances are better than average. Their unique island home is free from stoats and ferrets. For the parents, with two new beaks to feed, life now becomes busier than ever. Today it's the mother's turn to run the gauntlet. For the inhabitants of the seafloor, every day is a struggle of life and death. The octopus is hunting crabs again, but this time as he leaves the safety of the forest, he's ambushed by the blue cod gang. A large male cod attempts to death roll the octopus. In defence, the octopus unleashes a cloud of ink and escapes, but he's minus the tip of his arm, and with that, he's lost a few million brain cells, as two-thirds of the octopus's neurons are located in their arms. He'll regrow his arm over the next few months, another one of his species' amazing survival techniques. On the ocean floor nearby, distant cousins of the octopus watch the drama unfold. Scallops cautiously open up and take a look around, with a hundred eyes. Unlike the octopus's keen eyesight, the scallop's primitive eyes can just make out shapes and patterns of darkened light. So when the shadow of a predator passes, the scallop reacts. A scallop's arch-nemesis is the super-stealthy eleven-armed starfish. The slow approach improves its chances. No sudden shadows. It's a textbook hunt, but the scallop has one more trick up its mantle. It can swim just a few metres at a time, which is a short-term solution. The starfish may be slow, but it can crawl 28 metres in one day on its tube feet, which are also sensitive odour detectors. If the tubes on the tip of an arm pick up a scallop's scent, that's the direction the starfish will head in. In the kelp forest, the female seahorse is hunting too. The mating season is finished and the male has departed. However, one of their offspring is feeding in the kelp nearby. His hundreds of siblings were dispersed by the currents, and it's just coincidence that he remained here. He's now a few weeks old and won't be tolerated in his mother's territory for long, as she has no maternal instincts. The youngster was born knowing what to do. Eat anything small enough to suck up, and if it's too big, best leave that for the adults. The female seahorse uses excellent colour vision to line up her prey. Despite the name, a pot-bellied seahorse has no stomach with which to digest food. She extracts so little nutrition from each tiny shrimp that she must continuously hoover them up. In one three-hundredth of a second, another shrimp starts its journey down her gut. Alive, on the barren sand, the scallop faces a much slower death. The starfish has caught up, and this time it's not letting go. The scallop has no more defences, just a hundred eyes with which to watch the nightmare unfold. The spotties gather like vultures as the starfish begins to eat the scallop alive. In the sea, there's always someone higher up the food chain than you. These little blue penguins now have hungry chicks to feed. So in an instant, the tables turn, and the spotties flee into the kelp. But these deaf little underwater hunters know how to pick them off, one by one. Early morning over Stewart Island, and it's time for the morning commute to the fishing grounds. For the sooty shearwaters, the march through the forest is one long traffic jam. With their eggs laid deep in their burrows, the mated pairs will take it in turns to fish daily at sea. It's impossible for these birds to take off from the forest floor, with the canopy of trees above. So it's an hour's waddle to the nearest clifftop launch pad. It's a good day on the water, with swarms of krill and small school fish just offshore, which the birds can see from above. Sooty shearwaters descend in their thousands, along with seagulls. Soon, an all-out feeding frenzy is underway. Now, white-capped mollymauks join the fray, slightly smaller cousins of the giant albatross. These majestic birds have a wingspan of two and a half metres, and need an even longer runway than the shearwaters. Then it's time to size up the opportunities below. Unlike the diving shearwaters, mollymauks are usually surface feeders, catching fish, krill and squid just below the waves. But there's always one exception to the rule. All this commotion attracts the attention of other Stewart Island residents. A great white shark arrives, right on cue. He's not here for moon jellies or any small fish. He's hoping other predators will be attracted to this feeding frenzy. It could be three weeks since his last meal, probably a nice fat fur seal. Now it's time for him to eat again. So far, nothing but seabirds. Then a second shark arrives to investigate. Still, the seabirds don't perceive any threat. But the sharks are growing tired of waiting for a decent meal. This bird is dicing with death. She saw the first shark just in time, but she wasn't expecting this. When this bird breeds, she'll be passing on genes for incredible luck. Back on land, there's activity in one of the burrows. Just up from the beach, the kiwi family is about to grow a little bigger. It's taken three months of dedicated incubation by the entire family. The egg is so enormous because the chick emerges fully developed, attached to an internal yolk sac, which fills the hatchling's little pot belly. This provides immediate food and can sustain it up to 17 days. All kiwi chicks are on their own as soon as they hatch, but this unique Stewart Island chick may spend up to seven years living in the family unit and help to incubate future generations. By contrast, the penguin chicks are completely dependent on their parents for food. They've been fed constantly for four weeks and now weigh almost as much as their parents. From now on, the chicks will be left alone during the day while both parents fish to meet their appetites. In three more weeks, they'll instinctively head to sea themselves. Then they too will have to run the gauntlet of sea lions and sharks and take their chances in this unique southern big blue backyard.