Helping an Elusive Bird

The dense, wild undergrowth of a New Zealand forest might be the last place you would expect to find a penguin. But this environment is home to the mysterious yellow-eyed penguin (Megadyptes antipodes)—the rarest species of penguin in the world.

Where would you expect to find a penguin? The thick undergrowth of a New Zealand forest might be the last place on your mind. But this environment is home to the mysterious yellow-eyed penguin (Megadyptes antipodes). It’s the rarest species of penguin in the world.

Life is hard for the yellow-eyed penguin. Only 18 out of 100 chicks survive their first year. While that’s about average for a seabird, those that do survive must endure many threats over the course of their lifetime.

Even though yellow-eyed penguins nest in dense vegetation, they spend most of their time in the ocean, diving 40 to 120 meters (131 to 394 feet) below the water’s surface. There they catch fish and other prey. But life at sea can be dangerous for the birds. Commercial fishermen accidentally catch yellow-eyed penguins in their nets. Another consequence of fishing is that some species of fish are being hauled up faster than the populations can reproduce. This is causing some fish to decline in numbers. Overfishing forces penguins to compete with other predators for food.

Life is hard for the yellow-eyed penguin. Only 18 out of 100 chicks survive their first year. That’s about average for a seabird. But the survivors must overcome many threats during their lifetime.

Yellow-eyed penguins nest in thick vegetation, but they spend most of their time in the ocean. They dive 40 to 120 meters (131 to 394 feet) below the water’s surface. There, they catch fish and other prey. But life at sea can be dangerous for the birds. Commercial fishermen catch yellow-eyed penguins in their nets by mistake. Fishing affects the penguins in another way. Some species of fish are caught faster than their populations can breed. This causes the fish to drop in numbers. Overfishing forces penguins to compete with other predators for food.

The fish yellow-eyed penguins rely on are also responding to climate change. Ocean temperatures have risen by about 0.07°C (0.13°F) per decade over the past century. Warming waters can drive fish deeper or farther out to sea where it’s cooler—away from the penguins’ nesting grounds. As a result, biologists hypothesize that yellow-eyed penguins must expend more energy when they hunt. At the same time, they’re catching fewer or less-nutritious fish. This results in the penguins having a caloric deficit—the burning of more calories than are consumed.

Life on the shore isn’t any easier for yellow-eyed penguins. People have cleared land for farming, destroying much of the bird’s forest habitat. People have also introduced invasive, or non-native, animals like ferrets and stoats into the yellow-eyed penguins’ habitat. These predators often eat the penguins’ eggs. And stressed-out, malnourished penguins are highly susceptible to diseases, like avian diphtheria—a deadly type of bacterial infection in birds.

Climate change is also affecting the fish that yellow-eyed penguins eat. Ocean temperatures have risen by about 0.07°C (0.13°F) per decade over the past century. Warming waters can drive fish deeper or farther out to sea, where it’s cooler. That’s farther from the penguins’ nesting grounds. As a result, biologists think that yellow-eyed penguins must use more energy when they hunt. At the same time, they’re catching fewer or less-nutritious fish. This causes the penguins to have a caloric deficit. That means they’re burning more calories than they’re taking in.

Life on the shore isn’t any easier for yellow-eyed penguins. People have cleared land for farming. This has destroyed much of the birds’ forest habitat. People have also brought invasive, or non-native, animals into the penguins’ habitat. Some are ferrets and stoats. These predators often eat the penguins’ eggs. And stressed-out, underfed penguins easily catch diseases, like avian diphtheria. That’s a deadly bacterial infection in birds.

“They’re facing a suite of problems on land and at sea,” says Trudi Webster, a science adviser for the Yellow-eyed Penguin Trust, an organization in New Zealand devoted to protecting yellow-eyed penguins. “And there are interactions between all of these problems that just make it worse.”

Some combination of these factors led to one of the steepest drops in yellow-eyed penguin populations in recorded history. From 2014 to 2015, the number of breeding pairs on South Island, New Zealand, fell from approximately 439 to just 205 (see Falling Numbers). If scientists don’t come up with solutions fast, the bird may soon die out completely. Luckily, no one is giving up yet.

“They’re facing a suite of problems on land and at sea,” says Trudi Webster. She’s a science adviser for the Yellow-eyed Penguin Trust, an organization in New Zealand that protects the penguins. “And there are interactions between all of these problems that just make it worse.”

Some mix of these problems led to great penguin losses from 2014 to 2015. It was one of the biggest drops in yellow-eyed penguin populations ever known. The number of breeding pairs on South Island, New Zealand, fell from about 439 to just 205 (see Falling Numbers). Scientists need to come up with solutions fast, or the bird may soon die out completely. Luckily, no one is giving up yet.

Researchers like Webster are cautiously hopeful about yellow-eyed penguins’ future. Over the past two decades, scientists and volunteers have dedicated themselves to protecting the birds.

Many successful programs involve local citizens and conservation groups trapping and killing invasive animals that prey on penguin eggs and chicks. Other organizations have set up rehabilitation facilities that take in underweight penguins to feed them and provide medical treatments.

Researchers like Webster are concerned about yellow-eyed penguins’ future. But they’re also hopeful. Over the past two decades, scientists and volunteers have worked hard to protect the birds.

Many successful programs involve local citizens and conservation groups working together. They trap and kill invasive animals that eat penguin eggs and chicks. Other organizations have set up rehabilitation centers. They take in underweight penguins to feed them and provide medical treatment.

One of the most exciting projects starts at the nest. Yolanda van Heezik, a wildlife biologist at the University of Otago in New Zealand, and her students are working to identify yellow-eyed penguin “superbreeders.” These are penguins that naturally produce more, and healthier, chicks than average. Their chicks also have a higher rate of survival and often go on to become superbreeders themselves.

Van Heezik says that figuring out what makes these penguins superbreeders could be a key to encouraging higher breeding rates among other yellow-eyed penguins. Genetic studies will try to determine if there are specific genes, or units of hereditary material, that influence breeding and survival rates. In addition, researchers are studying the parenting habits of superbreeders to get ideas on how to increase the number of chicks that survive their first year. For instance, researchers will see if superbreeders feed their chicks in a way that’s more beneficial to the chicks’ health.

One of the most exciting projects starts at the nest. Yolanda van Heezik is a wildlife biologist at the University of Otago in New Zealand. She and her students are working to find yellow-eyed penguin “superbreeders.” These are penguins that naturally produce more, and healthier, chicks than average. Their chicks also have a higher survival rate. They often go on to become superbreeders themselves.

Van Heezik wants to figure out what makes these penguins superbreeders. She says this could be a key to boosting breeding rates among other yellow-eyed penguins. Some studies will look at genes, or units of hereditary material. These studies will try to find out if certain genes affect breeding and survival rates. Researchers are also studying the parenting habits of superbreeders. They hope to get ideas on how to increase the number of chicks that survive their first year. For example, researchers are looking at the way superbreeders feed their chicks. Maybe they do it in a way that’s better for the chicks’ health.

Yellow-eyed penguins will still face many obstacles. But these research, breeding, and conservation programs could give them a fighting chance. “They’re a fantastic penguin,” says Van Heezik. “I just hope we can come up with a solution to save them.”

Yellow-eyed penguins will still face many problems. But these research, breeding, and conservation programs could give them a fighting chance. “They’re a fantastic penguin,” says Van Heezik. “I just hope we can come up with a solution to save them.”