How Magellanic penguins feed their youngsters


This video says about itself:

Magellanic Penguins on Isla Magdalena, Chile, December 2012

During our trip to South America, we visited the Magdalena Island in Chile. It is a reserve established in 1991, home to more than 150,000 of Magellanic penguins. These penguins make this spot on the shoreline of the Strait of Magellan their home. They return annually to this place between October and March to lay eggs and raise their youngsters.

Magellanic Penguins are often seen performing the “ecstatic display”. This can either be part of the mating ritual or can merely be indicative of territory ownership. Birds performing this display stretch their neck and point their beaks skywards whilst spreading their wings and making a braying noise. The display is often performed repetitively over periods of up to an hour or more.”

From the University of Washington in the USA:

Parents don’t pick favorites, at least if you’re a Magellanic penguin

February 14, 2019

Summary: Researchers wanted to know how Magellanic penguin parents in South America balance the dietary demands of multiple chicks. They found that when a Magellanic penguin parent returns to its nest with fish, the parent tries to feed each of its two chicks equal portions of food, regardless of the youngsters’ differences in age or size.

Parenthood can be a struggle, particularly for families with multiple children in need of care, nurturing, protection and attention. But a weary mom or dad may find solace in the reassurance that all parents with several offspring face a similar challenge — even the non-human variety.

Researchers at the University of Washington wanted to know how Magellanic penguin parents in South America balance the dietary demands of multiple chicks. As they report in a paper published Jan. 23 in the journal Animal Behaviour, when a Magellanic penguin parent returns to its nest with fish, the parent tries to feed each of its two chicks equal portions of food, regardless of the youngsters’ differences in age or size.

This finding surprised the team, since parents across the animal kingdom, including other penguin species, often allocate resources unequally to their chicks based on factors like offspring age, body condition, health and behavior, said senior author P. Dee Boersma. Boersma, a UW professor of biology and director of the Center for Ecosystem Sentinels, has for more than three decades studied penguins at Punta Tombo, a coastal region in Argentina that hosts one of this species’ largest breeding colonies.

“This is an exciting finding because, among animals, it is very unusual for parents to divide food equally among their offspring,” said Boersma. “This makes Magellanic penguin parents stand out not just among penguins, but also animals in general.”

Magellanic chicks are the same size when they hatch, but eggs within a nest hatch at different times. After mating, a Magellanic female lays two eggs about four days apart. One chick typically hatches at least two days before the other. Chicks grow to different sizes based on the timing of their first feedings. By the time both chicks are at least 20 days old, one chick is on average 22 percent heavier than its sibling, the team found. Yet despite these size differences, this study shows that when Magellanic chicks are older and more mobile, parents feed both chicks equally as well as rapidly.

“These findings raise some very interesting evolutionary questions about how and why this behavior — feeding chicks equally — arose,” said Boersma.

For this study, Boersma and her team observed parents feeding their chicks at Punta Tombo from 2003 to 2007. Past research showed that parents alternate roles when chicks are small: One stays at the nest to guard chicks while the other feeds offshore and brings back a belly full of fish to regurgitate into the chicks’ mouths. For this study, the researchers observed nests where the chicks were at least 20 days old to track whether chick behaviors, such as begging or competition during feeding, influenced the amount of food they received. The team weighed 218 chicks both before and after the feeding, and observed parent and offspring behavior during mealtime. Forty chicks came from one-chick nests — presumably cases where the second egg failed to hatch or the chick died of starvation — while the other 178 came from 89 two-chick nests.

As expected, chicks without a sibling received more food during a feeding and were heavier than chicks with a sibling. Before eating, singleton chicks weighed an average of about 5.7 pounds and received about 1.2 pounds of food on average per feeding. For two-chick nests, the heavier and lighter chicks weighed an average of 5.1 pounds and 4.2 pounds, respectively. Yet both chicks received about 0.8 pounds of food on average per feeding.

Parents with two chicks managed this equal division despite the rushed choreography of mealtimes. The researchers found that feedings lasted just 21 minutes on average, during which the parent used its flippers to keep one chick to its left and one to its right — turning its head to feed one and then the other. Light and heavy chicks begged a similar number of times and each switched sides five or six times during the feeding, yet siblings did not act aggressively toward one other. The researchers observed that the parent directed more non-feeding behaviors to the lighter chick, such as opening its mouth but not regurgitating any food. Yet ultimately the lighter chick received the same amount of food as its sibling.

These findings shed light on when, where and how animals decide whether to treat their offspring equally or give preferential attention to one. For Magellanic penguins, factors affecting this behavior may be food supply, digestion and the time between feedings. In other penguin species, food supply impacts feeding behaviors. Adélie penguins, for example, have a relatively stable and abundant food supply because long daylight hours in Antarctic summers allow them to feed around the clock. Boersma and her colleague Lloyd Davis at the University of Otago in New Zealand found that Adélie parents run from their chicks, and the chick that follows its parent the longest is typically fed the most. For Magellanic penguins, food is less plentiful, and chicks typically wait three to five days between feedings. Each year, about 40 percent of chicks die at Punta Tombo due to starvation, and research by Boersma’s group indicates that a chick is most at risk of starvation when it is between 5 and 9 days old. Magellanic parents are prompted feed chicks as soon as they arrive at the nest because food that digests too long in their stomachs is less nutritious for chicks.

These factors may pressure adults to feed chicks quickly and equally, Boersma said. In addition, chicks may avoid direct competition because that could delay the feeding, she added. The age of the chicks in this study — all at least 20 days old — may also help explain their findings.

“This behavior may have evolved because, once both chicks reach this age, it may be advantageous for the parents to try to raise both of their chicks to fledging — the stage at which chicks leave the nest — rather than preferentially giving one more resources than the other,” said Boersma.

If so, then equality on the part of Magellanic penguin parents is less of an egalitarian virtue and more an investment in survival of the next generation.

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Penguin evolution influenced by islands


This video is the film March Of The [Emperor] Penguins.

From Molecular Biology and Evolution journal (Oxford University Press):

New islands, happy feet: Study reveals island formation a key driver of penguin speciation

February 5, 2019

Ever since Darwin first set foot on the Galapagos, evolutionary biologists have long known that the geographic isolation of archipelogos has helped spur the formation of new species.

Now, an international research team led by Theresa Cole at the University of Otago, New Zealand, has found the same holds true for penguins. They have found the first compelling evidence that modern penguin diversity is driven by islands, despite spending the majority of their lives at sea.

“We propose that this diversification pulse was tied to the emergence of islands, which created new opportunities for isolation and speciation,” said Cole.

Over the last 5 million years, during the Miocene period, (particularly within the last 2 million years), island emergence in the Southern Hemisphere has driven several branches on the penguin evolutionary tree, and also drove the more recent influence of human-caused extinctions of two recently extinct penguin species from New Zealand’s Chatham Islands.

“Our findings suggest that these taxa were extirpated shortly after human settlement on the Chatham Islands,” said Cole. “These findings thus potentially represent important new examples of human-driven, Holocene extinction in the Pacific.”

“While our results reinforce the importance of islands in generating biodiversity, they also underscore the role of humans as agents of biodiversity loss, especially via the extinction of island-endemic taxa,” said Cole. As many of the bones were from middens, our results provide direct evidence that our newly discovered extinct taxa was hunted by humans.”

The publication appears in the advanced online edition of the journal Molecular Biology and Evolution.

About 20 modern penguin species exist, from the Antarctic emperor penguin, the forest dwelling Fiordland penguin and the tropical Galapagos penguin. A fossil record of more than 50 species can trace back penguin history to more than 60 million years ago — indicating that penguin diversity may have once been much higher than today.

Using historical skin samples and subfossils from natural history museums, along with blood samples, the researchers performed the largest survey to date, across all penguin taxa.

The team tested their island hypotheses using 41 near-complete mitochondrial genomes, representing all extant and recently extinct penguin taxa. They calibrated their mitogenomic evolution to make an evolutionary clock based on the fossil record.

“By using well-justified fossil calibrations, we resolve the timing and mechanisms of modern penguin diversification,” said Cole.

They found that the two largest-bodied and most polar-adapted penguins are sister to all other living penguins. The DNA evidence also showed that genetically similar penguin species may be at the earlies stages of diversification.

The study provides important new data and perspectives to the debate on the origins of penguin diversity. It will also help better understand the role of islands as drivers of speciation to other animals and marine life.

The new taxa have been named Eudyptes warhami and Megadyptes antipodes richdalei after John Warham and Lance Richdale, pioneers in penguin biology.

How young emperor penguins learn to swim


This 2016 video says about itself:

A Young Penguin’s First Plunge | Wild Antarctica

Emperor Penguin chicks are old enough now to fend for themselves. First they must lose those fluffy down feathers!

From Woods Hole Oceanographic Institution in the USA:

Emperor penguins’ first journey to sea

New details of juvenile diving, foraging behaviors

January 17, 2019

Summary: New research reveals the previously unknown behaviors of juvenile Emperor penguins in their critical early months when they leave their birth colony and first learn how to swim, dive, and find food.

Emperor penguin chicks hatch into one of Earth’s most inhospitable places — the frozen world of Antarctica. Childhood in this environment is harsh and lasts only about five months, when their formerly doting parents leave the fledglings to fend for themselves.

New research by the Woods Hole Oceanographic Institution (WHOI) and colleagues reveals the previously unknown behaviors of juvenile Emperor penguins in their critical early months when they leave their birth colony and first learn how to swim, dive, and find food. The paper, published Jan. 17, 2019, in the journal Marine Ecology Progress Series, also highlights the unique connection between juvenile diving behaviors and a layer of the ocean, known as the thermocline, where warmer surface waters meet cooler deep waters below and where their prey likely gather in groups.

“This study provides insights into an important, but poorly understood, part of their life cycle, which is essential to being able to better predict the species’ response to future climate change,” says Sara Labrousse, a postdoctoral investigator at WHOI and lead author of the paper.

Researchers from Centre d’Etudes Biologiques de Chize? in France tagged 15 juvenile penguins before the animals left their colony in Terre Adélie during 2013 and 2014 fieldwork in December, when the weather usually starts to warm and the ice begins to break up, creating open waters near the nesting site.

The researchers attached tags to the lower backs of healthy chicks that had the best chances of survival. The tags recorded the penguins’ movements and transmitted diving and location data via satellite. More than 62,000 dives were recorded.

The tags revealed that the juvenile penguins initially moved far north to reach open water areas and warmer waters.

“This is when they are essentially learning how to swim,” says Labrousse. “That’s not something that their parents teach them. When they first go in the water, they are very awkward and unsure of themselves. They are not the fast and graceful swimmers their parents are.”

The tags showed that once the juvenile Emperor penguins became more experienced at diving, they headed south, entered the sea ice zone where they spent the winter months making deeper dives within sea ice.

“That was something that surprised us because we didn’t previously know how long they were staying within the sea ice,” Labrousse says. “It turns out that they spend most of the winter diving beneath the sea ice.”

The thermocline starts to deepen in autumn. The animals’ deeper dives likely were related to the depth of the thermocline and the seasonal change in the distribution of their prey, krill and … fish from the surface to the depths, Labrousse says. The deepest dive recorded by the tags was to 264 meters.

“The next step in this research would be to utilize tags that could record death at-sea,” says Labrousse. “That would give us data on their survival rates, which we don’t have for this study.”

Tags stopped recording dives after less than one day on two individuals, while one individual’s tag stopped after 31 days. The tags on the remaining 12 penguins, recorded trips lasting from 86 to 344 days.

“In those cases when the tags stop transmitting, we don’t know whether something happened to the animal or if it was due to a battery or other technical problem with the tag,” Labrousse adds.

Emperor penguins are the largest species of penguins. They are particularly vulnerable to climate change because their life cycles are so dependent on sea ice. Their breeding cycle begins in March (autumn in Antarctica) when the sea ice is thick enough to support their colony.

After laying a single egg each, the females leave the colony to catching fish and fatten up so they can feed their chicks. The males stay behind and cradle the egg on the tops of their feet, tucked under their brooding pouch for warmth and protection. Too little sea ice during this time can reduce the availability of breeding sites and prey; too much sea ice means longer hunting trips for adults, which in turn means lower feeding rates for chicks.

“Juveniles stay at sea for five or six years before they return to the colony to mate,” says Stephanie Jenouvrier, biologist at WHOI and coauthor of the study. “We need to better understand the dynamics of what happens during the time the juveniles are away from the colony. Understanding how they will respond to the changing landscape in terms of breeding and other life history stages is key to predict population responses and species persistence to future climate change.”

What Adélie penguins eat, study with spacecraft


This 12 December 2018 video from the USA says about itself:

2018 Fall Meeting Press Conference: Penguins! From space

The science team that led the expedition to document the supercolony of penguins on the remote Danger Islands in Antarctica will present new results from their research conducted on the expedition, including new, unpublished information on the age of the supercolony.

NASA satellite imagery of the penguins’ bright pink poop, or guano, helped the scientists first pinpoint the location of the supercolony of Adélie penguins.

In this press conference, the scientists will report new findings from the refined tools and techniques they’ve developed since the expedition to study penguins from space.

Participants: Heather Lynch, Stony Brook University, Stony Brook, New York, U.S.A.; Michael Polito, Louisiana State University, Baton Rouge, Louisiana, U.S.A.; Casey Youngflesh, University of Connecticut, Storrs, Connecticut, U.S.A.

By Sarah Zielinski, 7:00am, January 2, 2019:

Poop provides a link in determining penguin diet from space

The best way to find out what an Adélie penguin is eating is to catch it and make it regurgitate its meal. This is about as pleasant for bird and researcher as you might think. It’s also invasive, time-consuming and expensive to do on a large scale, so scientists need other ways to determine diet. Now they have one; it relies on images taken by Landsat satellites.

The satellites don’t reveal individual penguins, let alone what they are consuming underwater. What those images do show, though, is poop. Lots of it. Because Adélie penguins cluster together at a predictable rate, researchers have figured out how to count penguin colonies just from their huge poop stains. Last year, for instance, a group led by Stony Brook University ecologist Heather Lynch reported finding a supercolony of 1.5 million Adélie penguins on the Danger Islands, off the coast of the Antarctic Peninsula, from their feces.

Figuring out dietary preferences from those images is a bit more complicated — but it also starts with poop.

Casey Youngflesh is a quantitative ecologist at the University of Connecticut in Storrs. Until a few months ago, he was a graduate student in Lynch’s lab. During that time, he made several trips to the Antarctic Peninsula, visiting Adélie penguin colonies by boat from either the tip of South America or the Falkland Islands. That required crossing some of the roughest waters on the high seas, and, he says, “it can get a little bit hairy sometimes, especially on the smaller vessels.”

Timing was essential. Visit too early and the colonies wouldn’t have started to nest. (The birds spend the dark winters following the sea ice before returning to land to raise chicks during the southern summer.) Visit too late and the colonies would be a mess, with large chicks running amok and poop mixing with mud. “Everything’s a lot cleaner and neater earlier in the season”, he notes.

Youngflesh and the other researchers on these trips gathered lots of data from the penguin colonies they visited. They at times counted birds or checked on packing densities. And sometimes they gathered poop in little smell-proof bags and brought it back to the ship.

To most people, the poop looks pink. (It also stinks, as you might expect.) The guano gets its color from the carotenoids in the carapace of krill the penguins eat. But what a penguin eats can alter that color. And so those subtle changes in color can indicate what a bird has consumed.

Back on the ship, Youngflesh would take each sample and make a “poo patty.” Each patty was “kind of the size of a hamburger patty,” he says (and, from the picture he supplied, looked a bit like one, too). He’d run the patty through a spectrometer, which measures the sample’s colors across the electromagnetic spectrum, even in wavelengths like infrared and ultraviolet that the human eye can’t see. Then the patty went into a dehydrator so it could be shipped back to the lab. There, Youngflesh would measure its nitrogen-15 levels, which correlated with where in the food web the penguin had been eating, higher (fish) or lower (krill).

Once Youngflesh had collected and analyzed poop from a dozen or so colonies along the Antarctic Peninsula, he used statistics to translate the fine spectrometer data to the coarser data in the Landsat imagery. Then each pixel of an image could be connected to the dominant item on the penguin menu: fish or krill. Adélie penguins in West Antarctica tend to eat more krill, and those in East Antarctica eat more fish, Youngflesh reported December 12 at the American Geophysical Union’s fall meeting in Washington, D.C.

Scientists have done diet studies of individual penguin populations, but it’s not easy to do that frequently. The new technique will let researchers get a snapshot of the Adélie penguin diet across the Antarctic continent, year after year, looking both in the past and into the future, Youngflesh notes. Going back through the Landsat archive didn’t reveal any big changes in penguin diet, but now researchers will be able to monitor it as the region changes and provide real data to Antarctic ecosystem managers.

Youngflesh says that researchers might be able to apply this method to other seabirds, “if they’re nesting on the ground and pooping all over the place.” Someone would have to collect more samples, though, to calibrate the satellite data. And if anyone should want more granular data about how a penguin’s diet differs from bird to bird or day to day, there aren’t many good substitutes for going to the bird itself and getting it to give up its lunch.

All black penguin filmed in Antarctica


This 19 November 2018 video says about itself:

Extremely Rare All Black [Emperor] Penguin Sighting | Dynasties: Behind The Scenes | BBC Earth

While filming Penguins, the Dynasties crew runs into one of the rarest sights in the animal world: an all black penguin, thanks to a mutation called melanism.