Hello and welcome. This is the Science of Birds. The Science of Birds podcast is a lighthearted exploration of bird biology for lifelong learners. Today is the best day of the week and that is Random Bird Thursday. Every random Bird Thursday episode is relatively short compared to the normal episodes. And random Bird Thursday episodes are unscripted, so they're a little more off the cuff. And what we're doing is spotlighting a bird species that probably won't get featured in one of the full-length episodes. There are over 11,000 bird species in the world, and this is our opportunity to celebrate one of the species that we might otherwise overlook. So which random bird are we talking about? Well, to figure it out, we got to push the random bird selector button and see what comes up. Ooh, exciting. We have a penguin. The yellow-eyed penguin, Megadiptes antipodes. That scientific name has a nice ring to it, doesn't it? Megadiptes antipodes. Now, many of us think about Antarctica when we think about penguins, but this species is actually endemic to New Zealand. It's the largest of the penguin species that breeds on the New Zealand mainland. Okay, let's dive in and talk all about this bird. So first we'll talk about the appearance of the yellow-eyed penguin. You probably have a mental image of what a typical penguin looks like. So yes, the body shape of the yellow-eyed penguin is similar to that. This species stands somewhere between 25 and 31 inches, or 62 to 79 centimeters tall. and that makes it somewhere between the fifth or sixth tallest penguin species of the 19. There are 19 penguin species total just as of last year because we added a new penguin species. So picture a penguin. Of course, it's got the dark back and the white belly. The key thing about this bird is it indeed does have yellow eyes and that sets it apart from the other 18 species. Some other penguins have kind of reddish orange eyes, but this one really does have, the it's the only one with the yellow eyes and it actually has these yellow spectacles so feathers that are surrounding the eye and that go around the back of the head that are yellow so it gives this kind of look of wearing glasses spectacles the forehead the crown and the sides of the face are this slate gray color with a little flecks of golden yellow in them and the back is again black but depending on the light it might look more of a slate color slate blue the feet are orange and the bill is kind of a reddish orange overall on the upper bill, and it has some cream color on the lower bill. Fun fact about this bird, you know, back in 1967, Van Morrison released the song Brown-Eyed Girl, which has been a big hit ever since. Well, originally, the lyrics were yellow-eyed penguin, and, you know, they worked on it, and it just never really kind of rolled off the tongue. Didn't really, the chorus didn't really work for that one, so they switched it to Brown-Eyed Girl, and I would say that's unfortunate. It's a real shame that we didn't have a beautiful song about this species Maybe someday Now in terms of its voice this bird is actually one of the more quiet penguins It mostly silent most of the time Only sometimes during displays a yellow penguin will make these trilled notes or high yells or grunts They do have contact calls, these little disyllabic high notes, so two syllables, and they have a bray-like call as well. So it has different vocalizations, but it just doesn't make these very often compared to some other penguins. So in English, we call this the yellow-eyed penguin, but this is a species from New Zealand. So the Maori have a name for it. They call it the hoiho. H-O-I-H-O. I'm not really sure if I'm pronouncing it right. Hoiho or hoiho. That's the Maori word for the yellow-eyed penguin. But the scientific name Megadiptes antipodes, Megadiptes is the genus, and this is the only penguin species in that genus, which means if you look at the The penguin family tree, the family Sphanicidae, remember we did an entire podcast episode on the family Sphanicidae, this bird is kind of sticking out on its own little branch. It doesn't have any really close relatives that are still living. Now, once upon a time, ornithologists thought that this species was relatively closely related to the little penguin, also called the little blue penguin, which you also find in New Zealand and some other places in the south, like in Tasmania. But it turns out with molecular genetic data, researchers figured out that yellow-eyed penguins have been on their own evolutionary path for about 15 million years. They split off between the genus Eudiptes, which is the genus for the little penguins and some other species. So those are the closest living relatives. But once upon a time, Megadiptes antipodes had a sister species called Megadiptes waitaha. Megadiptes waitaha. and that's another Maori word, Waitaha, W-A-I-T-A-H-A. Well, that bird is now extinct. Once upon a time, the Waitaha lived throughout New Zealand, but when Polynesian settlers arrived somewhere between the year 1300 and 1500, they ended up hunting the Waitaha penguin to extinction and that was the closest relative of the yellow-eyed penguin. Now, back then, the yellow-eyed penguin was actually restricted to southern islands. It was actually, as far as we know, found only on the sub-Antarctic Auckland and Campbell Islands. But then people killed off the Waitaha penguin and people killed off a bunch of sea lions, which happened to eat penguins. And so that created this ecological opening, this vacuum. And as we all know, nature abhors a vacuum. So the yellow-eyed penguin was able to colonize mainland New Zealand from the south after the Waitaha penguin went extinct. and it was probably a relatively small number of yellow-eyed penguins that were the colonists because what we have today is a genetic signature in the populations on the South Island, so on the mainland of New Zealand. That genetic signature is that they have low genetic variation and that's a common thing we see in something called the founder effect. You have a small number of colonists arrive on a new landmass, an island or something, and they only represent a small sample of the gene pool where they came from because researchers looking at the gene pools on those sub-Antarctic islands see that they have more genetic variation. So those are the source populations. So today, these birds are found on the eastern and southeastern coastline of the South Island and they're also found on Stewart Island, Codfish Island, and again, they're still on the sub-Antarctic Auckland and Campbell Islands. They breed in areas with really dense coastal vegetation, like forests, scrub, or thickets of tussock grass, usually on slopes or on clifftops. This species doesn't really migrate long distances. For a penguin they relatively sedentary They tend to hang out in the same place most of the year staying within something like 10 miles or so or maybe 16 20 kilometers of their home Now that said, some species do migrate up to maybe 500 kilometers away. So one of the big things about the yellow-eyed penguin is its conservation status. This bird is endangered. Even though it was able to expand its range from those southern islands onto the mainland of New Zealand, That all happened maybe, you know, 400 or 500 years ago. But then in the last 200 years, European settlement has really done a number on the habitat for the yellow-eyed penguin. Habitat destruction comes from development for farmland and just general disturbance from human activity, including tourism. And as is true for so many birds in New Zealand, there are the introduced mammalian predators, and they wreak havoc on yellow-eyed penguins. You got your ferrets, you got your stoats, cats, pigs, and so on Another thing that hit these penguins on top of all of that was they had some real major population crashes due to disease Avian malaria, there was a gyrovirus that caused respiratory illness, and there was diphtheritic stomatitis Which on the Otago Peninsula back in 2004 that killed about 60% of all of the chicks So this species has really been hammered by all of these threats. Now, why are these birds seemingly vulnerable to these diseases? Some researchers suggest that it could be related to poor nutrition because the marine environment where these birds forage has been altered by people. There's pollution. The fish species that they prefer have declined. There are fishing nets all over the place. Stuff like that. So what are the current conservation efforts to save this species? Well, there's intensive predator trapping, which again goes on in various places around New Zealand There's habitat revegetation And there have been some recent implementations of emergency bans on certain types of fishing with nets around the Otago Peninsula Which is the stronghold for this species on the mainland So as a penguin, you wouldn't be surprised to hear that its primary diet is fish The yellow-eyed penguin prefers fish that are found on the seafloor The primary species being blue cod, opal fish, silverside, and red cod There was this one recent study where researchers collected poop, feces, from these penguins And they were able to use DNA barcoding to figure out which fish species they were eating For barcoding, all you need are little bits of DNA, so even degraded DNA that's been digested. It's possible to identify species. And what they found in that study was that 100% of the samples had blue cod in them. So blue cod is a big deal for these birds. They'll also eat cephalopods like squid and also crustaceans like krill. Now, you might remember from when we did the episode on penguins in general that most of them are pelagic foragers, meaning they're going to be feeding and swimming around in the upper layers of the oceanic water column but the yellow white penguin this is one of its distinctions is an almost exclusive benthic feeder benthic forager and when we say benthic we're talking about the bottom we're talking about the bottom of the sea but they tend to be in relatively shallow coastal water so they're not going way out and diving down like a thousand feet or anything their habitat is near shore Their foraging trips tend to be day trips Where they go out for maybe 12 miles away from the coast or so 25 kilometers, something like that And in the evening they might make shorter trips Like 5 miles away or maybe 8 kilometers or so So in the forests and scrublands or tussock grasses When these birds breed, they are typically monogamous They pair up with some courtship behavior Which is where they introduce some of those sounds the musical trilled notes and high displays The nest is usually tucked down in some roots of a coastal forest or in scrub or down in some dense grass. I'm not sure how much they dig a burrow. There might be some excavation going on there a little bit. I'm not actually sure. But here's another interesting distinction. The yellow-eyed penguin doesn't breed in what we would call a colony, like so many other penguins. These are solitary breeders. They pick a secluded nest site away from people and away from penguins. They're antisocial. Kind of like me. Just kidding, I'm not antisocial. I'm an introvert, but yeah, if I was digging a nest or tucking it in some roots, I would definitely want it away from everybody else. There are usually two eggs laid in the nest, and that's going to happen in September or October, which is the austral spring. and both parents are going to share the incubation duties and that incubation period lasts between 39 and 51 days. One of the parents is going to stay at the nest to guard the chicks for the first six weeks while the other goes out to feed at sea. But the other parent is going to come back every day to provide food. After 97 to 119 days, so three or four months, in February or March, the little guys are independent, They're ready to rip, and they actually are really independent at that point. They're off on their own. As far as we know, this is a relatively long-lived species. We know they can live up to 20 years, and it seems like males maybe outlive females. And a male is going to reach sexual maturity at about four to five years of age, whereas females, it's about two to three years. So what is my personal experience with a yellow-eyed penguin? Well, I've seen a few penguin species in my day, but I have not seen this one. But it's not because I didn't try. I was in New Zealand back in 2019, and I made a special effort to see the yellow-eyed penguin. I went to a known hotspot for the species on the Atago Peninsula, and I spent some time there among the tussock grasses, looking out over the sea, checking out the sea lions, all the good stuff. No penguins. Now, had I stayed there longer, maybe if I was there in the evening when they were coming back, I'd have better luck. But I was kind of in a hurry, as I recall. I think I either had to like fly out that day or early the next day. So yeah, no yellow-eyed penguins, but maybe someday, hopefully. You know, penguins could be a fun goal for someone, right? To go out and have a goal of seeing all the penguin species, because now there are 19. And it's not unreasonable, as long as you're able and willing to go to Antarctica. And why you would do that, I have no idea, other than to see penguins, I guess. Actually, I really want to go someday. I'm jealous because I have colleagues that go there like regularly and spend weeks of every year down there working. So they're just like, yeah, penguins, penguin-schmenguins, I see them all the time, no big deal. But as you may know, yeah, if you're not working down there, it costs a lot of money to get to Antarctica. So how about you? Have you been to New Zealand? Have you seen yellow-eyed penguins? Maybe you live in New Zealand. Maybe you have tea with yellow-eyed penguins every evening as they come back from their foraging trips. Maybe you babysit a young yellow-eyed penguin in the nest when you want to give the other parent a break or that you want the penguins to go have a date night. That's very nice of you, by the way. And now we must end this silliness and say that that is Random Bird Thursday episode number 10. In case you didn't know, this is the 10th one we've done. and that's the yellow-eyed penguin. The hoi ha or hoi ho. Hoi ha. If you speak Maori, you can let me know what the correct pronunciation is. But it's the yellow-eyed penguin, Megadipides Antipodes. I'll talk to you next time. Thanks, guys.
