These Punk Rock Penguins Have a Bizarre Breeding Strategy

These Punk Rock Penguins Have a Bizarre Breeding Strategy
Two erect-crested penguins. Credit: Lloyd Davis Photography

New Zealand’s erect-crested penguin lays two eggs, but rejects the first one–the opposite of how most birds prioritize their offspring.

Christopher Intagliata: For 60-Second Science, I’m Christopher Intagliata.

Hundreds of miles southeast of New Zealand, lie the windswept Bounty and Antipodes Islands. There you will find the breeding ground for the world’s most punk rock penguin.

[Penguin calls]

… has twin bleached-blond hairstyles.

Lloyd Davis: “It’s like if you took a penguin and put its flipper in an electricity outlet and it got a shock. It’s what you might picture it looking like.

Intagliata: Lloyd Davis of New Zealand’s University of Otago says the erect-crested penguin, as it’s known, also has a peculiar breeding strategy. The females conceive two eggs. The first one is usually the last.

Davis: “They just plop the egg on the rock. It’s quite bizarre to witness. And then 40 percent just turn their back on it. They don’t even try to incubate it. It’s almost like they don’t care.

Intagliata: Davis says that’s unusual–because most birds pour resources into the first egg, and the second, and however many more … but the last egg is almost an afterthought.

Davis: “The final egg acts like an insurance policy for them, so if they lose one of the other eggs, they can rear the chick from that one. This is actually the opposite. They favor the second egg in this instance, which is why it’s so confusing in the biological world. “

Intagliata: Davis and his colleagues traveled to the Antipodes Islands in 1998 to investigate that conundrum. They have narrowed down the possible explanations by analyzing their data.

First, they think the penguins might reject the first egg because it forms while the birds are migrating, so it’s smaller–inferior, perhaps–to the second, larger egg. The penguins may be acknowledging the reality that many species have to deal with: they don’t have enough resources to raise two chicks.

The study appears in the journal PLOS ONE. [Lloyd S. Davis et al, The breeding biology of erect-crested penguins, Eudyptes sclateri: Hormones, behavior, obligate brood reduction and conservation]

Davis notes that the penguins are now endangered.

Davis: “They seem to have gone down by about a third based on evidence we have and yet we know nothing about them, we know nothing about the causes, and we need to do what we can to protect these wonderful and forgotten penguins. “

Intagliata: After all, you could say the birds themselves are already putting all their eggs in one basket.

Penguin audio courtesy study author Thomas Mattern, The Tawaki Trust, Dunedin, New Zealand, and the Global Penguin Society, Puerto Madryn, Argentina.

[The above text is a transcript of this podcast.

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