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Nataly H. Aranzamendi

A story of prehistoric Crested Penguins

Fiordland Penguin

A story of prehistoric Crested Penguins

by Nataly H. Aranzamendi

Humans have caused the decrease of many island birds, but did humans cause the disappearance of some prehistoric penguins from New Zealand as well? Let’s find out.

Several members of the genus Eudyptes, known as crested penguins, live in the New Zealand archipelago. These species are: the Erect-crested Penguin, the Snares crested Penguin and the Tawaki (a.k.a. Fiordland Penguin). The isolated Pacific island is quite well-known for its stories of bird extinctions. Many taxa including birds and mammals have disappeared from New Zealand due to human pressure, excessive hunting and/or the presence of introduced predators.

The reason why island animals are so vulnerable to new pressures lies in the fact that they have evolved isolated, in a situation where many of them have lost their anti-predator defenses, becoming an easy target for introduced predators and hunters.

Photo Source: travelwayoflife [CC BY-SA 2.0 (]

Are crested penguins more sensitive to decline than other penguins?

Due to several studies showing that crested penguins have been declining since the 20th century, many scientists have assumed that crested penguins have been susceptible to human disturbance possibly since historical times, when the first humans arrived to the archipelago.

In a recent study1 using historic and modern DNA analyses from fossil records, scientists have tried to understand if the current distribution of crested penguins are due to extinction during prehistoric times caused by humans or due to range shift in the distribution of current species.

To test their hypotheses, the study used material from 84 prehistoric bone samples, initially identified as belonging to crested penguins. Those fossils were dug out in mainland New Zealand and right now are deposited in museum collections found in New Zealand and Australia.

How are prehistoric penguins being studied?

The analyses of crested penguins focused on the genetic diversity from genetic markers. The first analysis indicated that New Zealand had six prehistoric penguins inhabiting the island. Possibly, one of the new taxa identified corresponds to a previously undescribed lineage of crested penguin. Such findings indicate that New Zealand had a higher penguin diversity in the past.

The analyses found also that although the range of some penguins might have decreased in extent (e.g. Tawaki), their genetic diversity had remained relatively constant, meaning that it was probably not affected directly by humans. Similar findings were detected across the other species in relation to their genetic diversity. Such findings contrast with what has been found for other New Zealand animals, like fur seals or the Fouveaux shag, which were probably targeted by the first human settlers and that currently show reduced genetic diversity.

It is likely that the southern part of this island has remained relatively isolated and experienced less human pressure in comparison to the northern parts of the island, behaving as a refuge for penguins. In fact, no fossil record of New Zealand South Island endemic penguins exists in the archeological deposits from the North Island, ruling out that the Maori traded with penguins at that time.

The researchers argued that it is also likely that when European settlers arrived, many parts of the South Island were too isolated and remained inaccessible to them. This isolation could explain why the populations of Tawaki remained relatively stable.

Prehistoric penguins still remain a mystery.

The main cause of the disappearance of other prehistoric penguins remains a mystery. Most likely changes in environmental conditions or food sources might have played a big role in the likelihood of extinction of those species, just as it has been found for prehistoric penguins elsewhere.

This study highlights that some island species can be more resilient than others to human disturbances. It is really important for the future of any insular animal population to maintain adequate levels of genetic diversity.

More importantly, including genetic diversity assessments in future conservation proposals will secure the accurate management of species, as well as conservation decisions for penguins. The use of genetic tools in conservation biology has potentially a very bright future ahead.

As for crested penguins, we need to keep investigating which are the most immediate threats that are causing their decline. We want to see them “hopping” for many more centuries ahead.

What do you think after reading about New Zealand and crested penguins? Did you learn anything new? Read some other fun things about these animals we love:

Also, tell us what else you’d like to learn about penguins! We’re here for you.

Cole, T.L., Rawlence, N.J., Dussex, N., Ellenberg, U., Houston, D.M., Mattern, T., Miskelly, C.M., Morrison, K.W., Paul Scofield, R., Tennyson, A.J.D., Thompson, D.R., Wood, J.R., Waters, J.M., Ancient DNA of crested penguins: Testing for temporal genetic shifts in the world’s most diverse penguin clade, Molecular Phylogenetics and Evolution (2018), doi:

How will climate change affect King Penguins?

king penguins

How will climate change affect King Penguins?

by Nataly H. Aranzamendi

Recent changes in climate are impacting a variety of species worldwide, and penguins are certainly not immune. King Penguins in particular are extremely sensitive to these changes in their environment.

The King Penguin is considered an indicator species for climate change. With many of their major colonies declining in numbers in recent years, scientists have turned their attention to the causes and consequences of climate change on this species, and the potential actions that could save it from extinction.

Basic information about King Penguins

The King Penguin is an apex predator living in the sub-Antarctic region. King Penguins exclusively breed in year-round ice-free islands scattered throughout the Southern Ocean. To eat, they follow fish stocks around the Antarctic Polar Front, a boundary between colder, saltier water closer to Antarctica and the warmer less salty water of the South Atlantic Ocean.

King Penguins are central place foragers which means that they travel from their nesting sites to a distant foraging location, rather than just passing through an area exploring or traveling at random. Thus, King Penguins have foraging and breeding grounds distributed in a fragmented landscape.

A recent study1 that monitored the current and ancient conditions of penguin distribution and prey availability has found that the foraging range of King Penguins is displacing southwardly, possibly in response to warming waters. As a result, penguins will have to travel farther to find their prey. This implies that for many populations located in islands in which the foraging range is shifting, there will be decreasing numbers in the future. For example, the Crozet Island population, one of the largest colonies of King Penguins, is already showing declines since the past decade.

When environmental factors change suddenly, species can adjust to these changes using behavioral plasticity (i.e. changing behaviors) or by rapidly evolving. For example, penguins could change behavior and colonize new islands (i.e. disperse) and/or could start traveling farther distances.

What does that changing climate mean for King Penguins?

However, scientists have found that penguins traveling further are putting their energetic balance at risk, eventually having lower reproductive success. If that balance is altered in several hundreds of individuals at a colony, it will be disastrous.

In order to predict what will happen with King Penguins in the upcoming decades, scientists had to first reconstruct a palaeohabitat of the species’ demography, based on old climatic records and genome information. This allowed them to understand the primary causes of population changes.

They found out that massive changes in the ocean’s primary productivity caused large population changes in the past for penguins. Therefore, prey availability would be the most important limiting factor for the King Penguin’s distribution in the future.

If the worst scenario of climate change occurs, many big colonies will witness dramatic declines in numbers, because the distance to their foraging grounds will increase considerably. Most of the colonies negatively impacted are located in the northern range of the species’ distribution. The colonies at the South of the Antarctic Front will probably be the best refugia for King penguins, places such as South Georgia Island. Potentially, there will also be new colonies that could be recolonized.

The low genetic diversity of this species as well as the long time to mature and produce offspring will most likely not allow rapid adaptive evolution in this species. Changes in foraging conditions would be required for penguins to survive. Eventually, the outcome for many individuals could be local extinction or dispersal to new islands (if available).

How does the future look for King Penguins?

The predictions that scientists made for total numbers are dramatic. In the worst scenario, up to 70% of the present breeding pairs of King Penguins could disappear. Moreover, almost 50% of the current world population could lose their habitat, especially those located in the largest and northernmost colonies. Such predictions do not even take into account possible simultaneous changes that could impact penguin prey.

In summary, recent data is providing more and more evidence of our negative impact in the natural world due to climate change. Many species will lose their habitat due to range shifts everywhere, not only King Penguins. It is our responsibility as human beings to work together in this climate crisis and not let our planet drift toward the worst scenario in the upcoming decades. King Penguins will be really thankful.

A King Penguin feeding its chick

Did you know this about King Penguins? What do you think and/or what did you learn by reading this?

Learn more about penguins by reading some of our other blogs:


Cristofari, R., Liu, X., Bonadonna, F., Cherel, Y., Pistorius, P., Le Maho, Y., … & Trucchi, E. (2018). Climate-driven range shifts of the king penguin in a fragmented ecosystem. Nature Climate Change, 8(3), 245.

Magellanic Penguins Are Exemplar Parents

Magellanic Penguin with its chicks

Magellanic Penguins Are Exemplar Parents

by Nataly H. Aranzamendi

The number of chicks produced and that survive their first life stages determines the success of penguin parents. This has important consequences for populations. Let’s discover how Magellanic Penguins decide to distribute food among their babies.

Year to year variation in reproduction is a central theme in population biology with important consequences on the emographics of any animal species.

Each breeding season, parents have to provide quality food to their offspring in order to guarantee their survival. While some birds produce only one chick per season, others can produce more. In this case, it is expected that parents will distribute food evenly among their offspring.

One thing that has puzzled biologist for decades is that many birds seem to produce an amount of eggs that is larger than what they can successfully raise. Also, these birds lay their eggs in an asynchronous fashion. As a result, asynchronous chicks hatch several days apart, showing a visible difference in size, i.e. the first chick tends to be heavier than the last one. Thus, biologists have suggested that these asymmetries between siblings could facilitate a reduction in the number of offspring.

Do penguins use a brood reduction strategy?

The “brood reduction hypothesis” says that when food is limiting, parents would preferentially care for the offspring with more chances of survival, which is usually the heavier chicks. Brood reduction can also occur via sibling competition, as bigger chicks can succeed more in obtaining their parent’s attention and outcompete their smaller siblings 1.

In a new study 2 , a group of scientists tested the brood reduction hypothesis for three breeding seasons in Magellanic Penguins in Punta Tombo, Argentina.

Magellanic Penguins generally lay 2 eggs four days apart from each other. The first chick hatches with a 2-day advantage from the second, therefore, the chances for the smaller chick to survive are generally lower.

Scientists compared the feeding frequency of parents of two-egg broods vs. parents of single-egg broods, and checked if they were distributing food evenly or differently between their offspring.

The results show that once chicks have survived their first weeks of life, parents with two chicks fed them evenly despite their differences in size. Interestingly, the heavier sibling does not try to outcompete or interrupt its lighter sibling.

An indicator that chicks are hungry is the rate of begging. As soon as parents approached the nests, chicks started begging to request food. The results show that the rate of begging was also the best predictor of the amount of food nestlings were going to receive.

By Liam Quinn from Canada – Magellanic Penguin chicks, CC BY-SA 2.0,

How do Magellanic Penguins compare to other penguin species?

But what does this mean for Magellanic Penguins and how does it compare to other species? It is possible that in this species, neglecting any offspring could be very disadvantageous decision for a parent. Since feedings occur every 3 to 5 days, denying even one opportunity to be fed would mean a certain death for the smaller nestling.

This also most likely means that the period in which the researchers measured these behaviors coincided with a time when parents had already invested too much in their chicks survival.

In other birds with asynchronous chicks, parents can sometimes switch their strategy and preferentially feed the smaller chicks once they have passed their first day’s threshold. However, this switch was not observed in Magellanic Penguins.

Other penguins show different behaviors towards their offspring at the time of feeding. Chinstrap and Adélie penguins, for example, motivate their chicks with a chase prior to feeding, then they only feed the chick that passed the test and behaved more motivated.

African Penguins, which are close relatives of Magellanic Penguins, have offspring constantly interfering with each other at the moment of eating. Thus, older siblings eventually reduce the survival of younger siblings. One possible explanation for this difference in behaviors between the two species could be the fact that the starvation peak period for both species differs. It occurs earlier for Magellanic Penguins and later for African Penguins.
In any case, it is plausible that these observations were made in years of greater food availability, which could have helped the initial survival of the smaller chicks. Most interestingly, we have learned that Magellanic Penguins seem to be fair parents when it’s time to distribute food.

What do you think about these Magellanic parents? Let us know! And, have you read some of our other recent penguin blogs?



Wagner, E. L., & Boersma, P. D. (2019). Food allocation and feeding
behaviours of Magellanic penguin, Spheniscus magellanicus, adults and
chicks. Animal Behaviour, 148, 161-168.

Fish is a Superfood for Adélie Penguin Chicks

Adelie Penguin

Fish is a Superfood for Adélie Penguin Chicks

by Nataly H. Aranzamendi

Adélie Penguins are the most widespread species of penguins. They can be found along the entire coast of the Antarctic continent. Although Adélie Penguins live on sea ice, they need ice-free land to breed1.

During the breeding season, Adélie Penguins form colonies clustered together in larger “mega” colonies which might contain thousands or even millions of individuals. These variations in size and location makes them vulnerable to climatic fluctuations. With the reduction of sea ice taking place due to global warming, most Adélie Penguin populations have decreased over the past 25 years1.

Every year between October and November, at the end of the southern spring and beginning of summer, Adélie Penguins go back to their colonies and build nests made of piled up stones. Both parents take turns incubating the eggs. Once the chicks are born, they remain in the nest for approximately three more weeks before joining communal crèches1.

It is at this moment that parents need to provide chicks with the best possible food available, in order to secure their survival. In a recent study2 that analyzed 20 years of data from 1996 to 2016, scientists have tried to understand which factors can guarantee the successful growth of Adélie chicks and their chances to survive their first year, so they are able to return to the colonies.

Some penguins are increasing while other penguins are decreasing.

Scientists compared two areas in Antarctica: the Ross Island colonies and the Anvers colonies2. Penguin numbers are increasing in the first island while decreasing in the latter. Both sites also vary in the total numbers of penguins. The first island has the largest and most dense colonies.

Another difference between both study sites is that penguin parents in the Ross colonies fed their chicks mostly with Antarctic silverfish and crystal krill, while parents in the Anvers colony fed chicks almost exclusively with Antarctic krill.

Turns out that the difference in diets at the chick stage has immediate consequences in their survival2. Survival rates for the chicks fed with fish were higher than those fed exclusively with krill. The “fish chicks” also had higher return rates to the colonies after they left their nests. The body mass of the “fish chicks” that returned compared to those who did not was a difference of 219 g, which is approximately 6.5% of body mass at that stage. This shows that the amount and quantity of food that a chick receives can eventually affect the demography of penguin colonies.

Does penguin fish prey stay consistent throughout the breeding season?

However, the competition between penguin parents increases as the breeding season progresses. This was inferred by the negative trend that the researchers found in the proportion of fish in a chick’s diet over time. Fish became scarcer as time progressed and some chicks even started losing weight. Such an effect was more noticeable in larger colonies2.

When digging more in the data, the researchers found that in order for parents to keep up with the chicks’ demands, they had to take longer trips and dive at deeper waters looking for fish.

So, it looks like even though most parents prefer to feed their chicks with nutritious fish at all times, it is not always so easy to do it. The fact that such important food sources can have plentiful consequences might also help to explain why some colonies have been recruiting small numbers of new individuals every year.

Do penguins have enough silverfish left to eat?



Photo Source: The Antarctic Sun

The good news for Adélie Penguins is that the stocks of Antarctic silverfish are not commercially exploited and for now their numbers have remained stable3. However, an urgent next step is to quantify the proportion of these fish in the diet of all Adélie penguin chicks in other colonies.

At the moment, it still remains uncertain how the current changes in climate will affect these penguins, their prey and this delicate balance. Adélie Penguins are one of the best studied birds in the world in relation to changes in the environment developing in the Southern Ocean, but there is still a lot that needs to be discovered.

The continuous reduction in sea ice cover plus increasing sea levels puts Adélie Penguins as perfect candidates for habitat loss. It will be necessary to keep Adélie Penguins under the spotlight, to track further changes in their colonies and to keep monitoring their chick survival, a very important life-stage that impacts the demography of this species.

What a diet these Adélies have! Did you know about this? Let us know your thoughts.

Also check out some of the other blogs we have:

Ainley, D. G., Dugger, K. M., La Mesa, M., Ballard, G., Barton, K. J., Jennings, S., … & Wilson, P. (2018). Post-fledging survival of Adélie penguins at multiple colonies: chicks raised on fish do well. Marine Ecology Progress Series, 601, 239-251.
Gon, O. & Vacchi, M. 2010. Pleuragramma antarctica. The IUCN Red List of Threatened Species 2010: e.T154785A4633007. Downloaded on 30 January 2019.

Turns out that not all penguins are explorers

Gentoo Penguins in their colony

Turns out that not all penguins are explorers

by Nataly H. Aranzamendi

How far do juvenile penguins travel to find a place to breed? A recent study of movement patterns of five penguin species show us that not all species move far, and this could have consequences for their future.

Being an explorer is good for most penguins

Dispersal is the movement of an organism from the place where it was born to a breeding site, or simply to a different location. Dispersal generally happens when individuals are young and, depending on the species, this could take months to years.
When young individuals decide to venture out of their known colonies for the first time, they end up doing something important for the conservation of populations — they take their genes to a new place.

The movement of individuals among different populations — between colonies for example — is very important for most animal species, as it’s a way to maintain genetic diversity and genetic connectivity.

Imagine a square occupied by a species, then imagine that the species is distributed in the four corners of this square. Now imagine that individuals from the four corners move freely within this area. Genetically speaking, the result would be a species with a constant interchange of genes. The opposite would be a square with its young individuals moving only in their respective corners and not breeding too far from home. Over time the later would result in a species with four differentiated populations if they never come in contact with each other.

What keeps a penguin from traveling somewhere?

As you might be thinking now, sometimes the free movement of individuals between locations can be blocked by barriers. Generally, we picture barriers as big walls or impassable mountain chains, but marine species can also face barriers located underwater or strong currents that mark the limit to free movement of individuals.

Using data from 32 colonies in five species of penguins, Dr. Gemma Clucas, Dr. Jane Younger and their collaborators have uncovered the movement of juvenile penguins. Following penguins in the wild can be a consuming task due to the location of remote colonies and the impossibility to tag a large number of birds. But thanks to the advancement of genetic tools, the patterns of dispersal can be inferred by looking at the genetic structure of the population. This is done by looking at the variations found in sections in the DNA between genes, known as SNP or single nucleotide polymorphisms.

Why do some penguins travel farther than others?

The researchers found that the differences between species could be determined by the habitat where a species was found. For example, Emperor penguins occupy the Antarctic continent, breeding mostly on sea ice. Even though they have colonies clustered by geographic regions, the researchers found that juveniles of Emperor Penguins can travel long distances between colonies facilitating “gene flow.”

A Gentoo Penguin tending to its egg

In contrast, Gentoo Penguins are distributed in colonies located closer to each other in comparison to other penguins. The difference though is that they possess an affinity for coastal foraging and, after breeding, juveniles tend to stay close to home. Such lifestyle might have caused the genetic differences found among groups of Gentoo Penguins.

Other penguins studied were King, Chinstrap and Adelie Penguins. All three species show differences in how they distribute their colonies and the geographic regions that occupy. However, as for the Emperor Penguin, their populations showed that dispersal of juveniles is occurring among most populations and apparently they do not face clear barriers in dispersal.

Why is it necessary to understand penguin dispersal?

The constant interchange of individuals between populations and the contribution of “new genes” could buffer threats for species. Genetic diversity is beneficial when species face new potential diseases, it helps populations in disequilibrium, e.g. too many old birds found or populations with low birth rates and survival.

As this study points out, understanding dispersal for marine species has become very important for scientists. Many marine environments are dramatically changing in a warming and overfished world and the limits of marine barriers are being altered. This can have effects on the persistence and distribution of penguins’ favorite prey items. The ability of individuals to colonize new locations will therefore be of utmost importance in a changing world.

Knowing which species are going to be more vulnerable to changes will help scientists to prepare for the future.

Does this amaze you about penguins? Did you learn something new by reading this? Please let us know.

Also please read some of our other blogs:

Reference: Clucas, G. V., Younger, J. L., Kao, D., Emmerson, L., Southwell, C., Wienecke, B., … & Lelliott, P. (2018). Comparative population genomics reveals key barriers to dispersal in Southern Ocean penguins. Molecular ecology 10.1111/mec.14896

Divorcing Penguins – Not All Penguins Stay Together for Life

king penguin

Divorcing Penguins – Not All Penguins Stay Together for Life

by Nataly H. Aranzamendi

Penguins are frequently portrayed as examples of fidelity and representatives of long-term relationships. Let’s discover how much of that is true.

Understanding monogamy in birds

Monogamous birds are those that choose one partner to breed and to raise their offspring with. As with humans, scientists have discovered that some birds can be “serial monogamists” and that they engage in new relationships after the death of their partner or by “divorce.”

Thanks to techniques that allow scientists to mark birds and follow them throughout their lives, they have discovered that not all birds mate for life and many of them divorce. Divorce in birds is confirmed when at least one bird of a “couple” re-pairs with another individual and when both former partners are still alive1.

Divorce rates in birds vary widely between and within species1 and penguins are not an exception. Mate fidelity in penguins is about 72% on average, with such rates ranging from 29% to 97% (measured for 12 species)2. Divorce accounts for 13% to 39% of this percentage of mate change.





A Yellow-eyed Penguin heading to its nest.

Scientists are trying to understand bird divorce

Scientists have been trying to understand the reasons for divorce in birds for decades, but this has been logistically challenging. Penguins, for example, are long-lived and travel considerable distances after breeding, making it hard to follow them throughout their lives.

One important detail is that annual survival of individuals needs to be known with high certainty. Otherwise, we would erroneously assign a separation, when in reality one member of the pair did not survive. “True survival” can only be assessed if penguins return to the same spot where they were first captured. So not finding them in the same place could be because they skipped breeding or simply decided to go elsewhere. Despite all the challenges to know “true survival” and divorce rates, scientists have managed to collect considerable data in divorcing birds.

So why do birds separate from their mate?




Photo source: Hannes Grobe/AWI, Creative Commons Attribution 3.0

The benefits of staying with the same partner can be multiple. More familiarity in a relationship can make birds better at protecting their nests. Pairs can improve coordination and breeding performance, meaning that they can get better at protecting their chicks after learning from bad experiences1.

However, in species when partners separate after breeding, reuniting year after year can often be a difficult process. When the costs of reuniting are high, it is likely that birds will opt for new partners.

Scientists have agreed that in order to divorce, benefits should exceed costs for at least one of the birds. The most common causes of divorce besides physical separation include bad reproductive performance and a partner with a low quality territory1.

It is expected then to find “improvements” when comparing former and new partners. The new partner will be considered more compatible if the pair produces more offspring than before or if the new partner has a better territory. It is also possible that not only one but both divorcing birds find better options after a separation1.

In the penguin world, King and Emperor penguins have the highest rates of divorce, with more than 80% of King Penguins changing partners between breeding seasons. The main reasons for change were asynchrony in arrival and large access to new mates each breeding season3.

Approximately 40% of Adelie Penguins changed partners in two consecutive breeding seasons due to divorce and/or death. In contrast, Gentoo, Galapagos, Little, Magellanic and Yellow-eyed penguins have high rates of mate fidelity, with more than 80% of individuals on average breeding with the same partner in two consecutive years2.

Something that has puzzled scientists is that they have compared the reproductive success of penguins between former and new partners for some species and they have found no apparent increase in reproductive performance2. Nevertheless, we have learned so far that divorce is a complex issue for birds, possibly as complex to understand as it is in humans, and it could be triggered by multiple causes. Thus, consequences can be only measured in the long-term.

Only the continuation of long-term studies, i.e. following individuals for several years, will portray the whole picture of the reasons why divorce is a beneficial strategy in the avian world. This will help scientists to fully understand a phenomenon that seems to be widespread in birds.

Did you think penguins were married forever? Or would they get divorced? Let us know your thoughts!

Also read some other blogs about penguin life:


Choudhury, S. (1995). Divorce in birds: a review of the hypotheses. Animal Behaviour, 50(2), 413-429.
Williams, T. D. (1996). Mate fidelity in penguins, pp 268-285. Black, J. M. (Ed.). (1996). Partnerships in birds: The study of monogamy: The study of monogamy. Oxford University Press, UK.
Olsson, O. (1998). Divorce in king penguins: asynchrony, expensive fat storing and ideal free mate choice. Oikos, 574-581.

Chinstrap Penguins in a Warming World

Chinstrap Penguins

Chinstrap Penguins in a Warming World

by Nataly H. Aranzamendi

A warming planet is changing the environment that animals used to know, let’s explore what is changing for Chinstrap Penguins.

The food that Chinstrap Penguins prefer is harder for them to find.

Krill-Eating Penguins

Chinstrap Penguins live around the Antarctic Circle. They can breed in Antarctica, Bouvet Island, the French Southern Territories, and South Georgia and the South Sandwich Islands1. Their diet mainly consists of fish, krill, shrimp and squid for which they regularly swim up to 80 Km to obtain1.

A recent study found that when ocean conditions change, Chinstrap Penguins might have to travel farther and spend more effort to get their favorite prey2.

Chinstrap Penguins depend heavily on Antarctic krill, as other animals in Antarctica do. Krill are small crustaceans found in all the world’s oceans. In the Southern Ocean, the Antarctic krill is the most abundant species and is a key resource and a keystone species in these ecosystems3. The dependence of Chinstrap Penguins on krill is particularly relevant during the breeding season.

Small swarms of krill can aggregate around coastal and shelf areas, while large swarms are more likely to be found at sea. Sometimes, when wind currents change drastically, it creates very poor conditions for krill to feed (e.g. less availability of phytoplankton) and the krill must dissipate from small coastal aggregations, thereby becoming a sparse or even absent resource in these areas2.

Recent studies have found that climate change will bring an increase in frequency of El Niño events. But not only will those events increase in frequency, upcoming El Niños are likely going to be stronger than before, and are going to be associated with extreme weather events4, such as warm waters and variable wind currents. Variable wind currents have the potential to make krill distributions unpredictable.

Chinstrap Penguins are now traveling farther to find their food.

The distances that adult Chinstrap Penguins traveled from nest to foraging sites were measured during two breeding seasons in 2014 and 2016, in breeding colonies located at the Powell Island in the South Orkney Islands archipelago. Both breeding seasons were characterized by different environmental conditions. In 2016, an unexpected short-lived El Niño occurred provoking coastal down-welling and reducing coastal krill availability2.

Adult Chinstrap Penguins in 2016 had to travel farther and stayed at sea longer on each trip. The 2016 penguins also had to cover larger areas at sea on each trip. Normally, when penguins forage for krill, they prefer to do so in coastal waters, where small swarms are aggregated in dense packs. Penguins remain in these high density patches until those patches are depleted. Since strong wind currents make krill less aggregated, penguins have to travel farther for food.

Penguins normally travel far if they need to, but the energetic consequences of moving longer distances than usual are still not known. There is also another constraint. When chicks are out of the nest at the crèches, adult penguins are limited by the amount of time they can spend away and sometimes are forced to come back before they’ve finished foraging enough prey for themselves and their chicks.

Some adult penguins tracked in 2016 traveled between three to 10 times the maximum distances measured in 2014. Although the consequences of such differences were not measured in this population, the authors of the study suggest that such a shift in behavior could potentially cause nest desertions and increase chick mortality.

There is another factor that might represent increasing pressure for Chinstrap Penguins and other Antarctic wildlife: the commercial exploitation of Antarctic krill.

Antarctic krill has been always considered an abundant resource and has been heavily exploited in the past. Thanks to regulations implemented in the last decades there has been a rebound in krill abundance, to which some fisheries have responded increasing their quota. Krill fisheries prefer southern waters because, just as for the penguins, the fisheries can find swarms of krill grouped in a more predictably way3.

Impacts of fisheries and climate change are still unknown.

A Chinstrap Penguin taking a break after a long day of fishing.

The impact that the exploitation by fisheries and climate change combined will have on krill availability is still unknown but could be catastrophic for all wildlife in the Southern Oceans.

Luckily for some species, it was recently announced that krill fishing companies operating in Antarctica will stop operations in buffer zones close to breeding colonies of penguins from 2020 onwards3. This could alleviate the pressure coming from the fisheries industry, however we still have not found an accurate way to predict the impact of changing climatic conditions on the survival of this species. Whatever happens next for Chinstrap Penguins will have to be seen in the upcoming years.

What a diet these penguins have! Did you know about this? Let us know what you think.

Also check out some of the other blogs we have:

Lowther, A. D., Trathan, P., Tarroux, A., Lydersen, C., Kovacs, K. M., & Handling editor: Howard Browman. (2018). The relationship between coastal weather and foraging behaviour of chinstrap penguins, Pygoscelis antarctica. ICES Journal of Marine Science, 75(6), 1940-1948.
Cai, W., Wang, G., Dewitte, B., Wu, L., Santoso, A., Takahashi, K., … McPhaden, M. J. (2018). Increased variability of eastern Pacific El Niño under greenhouse warming. Nature, 564(7735), 201–206.

The Journey of the Little Penguin

Little Penguin

The Journey of the Little Penguin

by Nataly H. Aranzamendi

The Little Penguin is the smallest species of penguin, weighing only one kilogram (2.2 pounds) and ~33 cm (13 inches) tall. Every year during the reproductive season, parents engage on daily journeys to find food for their newborns, and their adventures are witnessed by ecotourists at nature parks that protect the delicate habitat of these native birds.

We sat at dusk waiting for the last rays of sun to fade away. The audience was impatient, with whispers going around like a wave. The scene finally became completely dark and we could barely distinguish the horizon. It was an unknown wait, without knowing what to expect or where to look. Suddenly, tiny silhouettes appeared on the horizon. It was the beginning of an amazing night. It was the start of the penguin parade.

I visited Phillip Island in Australia in 2013 for the first time and I was tremendously excited to see this so-called “parade.” I had never heard something like that happening in the natural world. The people I asked gave little information. “You will have to see it yourself,” they said. Little Penguins will arrive after sunset by the hundreds, sometimes thousands. The time of the arrival could be predicted based on the activity of the day before and the time of sunset.

The total number of Little Penguins is estimated to be around 250,000 breeding pairs.

As a bird biologist, I was baffled. Was that really true? Was I expecting a synchronized parade of wild animals in front of our eyes? My doubts grew bigger when I saw the theater-like scenario where people sat. Turns out the rumors were true. Hundreds of Little Penguins marched that night in front of my eyes, all in a “coordinated” feeding parade, running through the crevices under us and rushing to deliver food to their babies.

Phillip Island is located in the south-southeast of Melbourne, Australia and it holds one of the most important colonies of Little Penguins with around 30,000 individuals1. The total number of Little Penguins is calculated to be 250,000 pairs and luckily this species is not threatened by extinction. In general, their numbers have remained stable on recent decades2.

Little Penguins’ favorite food is anchovy and they can rely on it year-round3, especially when they have to feed their offspring. However, the percentage of anchovy that Little penguins eat varies throughout the year3 and recently it has been discovered that they also rely on alternative foods, as they can complement their diet with gelatinous plankton4 and even jellyfish5.

Location of Phillip Island
Location of Phillip Island

Fortunately, Little Penguin populations are stable. But they are still impacted by humans.

Even though their numbers are relatively stable, Little penguins have not escaped the impact of humans. Because these animals live very close to human settlements, they are threatened by growing urbanization and the risk of losing their breeding habitat. In fact, it is likely that actual colonies hold the last few habitable places for penguins6.

As could happen with other fish eaters (including us!), Little penguins have been found with high concentrations of heavy metals in their bodies (e.g. mercury, arsenic, etc.), especially those living in colonies close to human settlements7. Sadly, Little Penguins are also victims of introduced species (e.g. foxes), plastic pollution, fishing and increasing warm water events2.

Fortunately for many populations of Little Penguins, there are many actions in place to protect them and to assure their brighter future. Several protected areas and sanctuaries in Australia and New Zealand have monitoring programs and scientific research that will continue giving us more information about them.

Management of tourists has been effective at buffering the negative impacts of human activities. Also, the management of invasive species has been fundamental to keep colonies predator-free as, for example, a single fox could cause massive damage in a breeding colony. Moreover, educational programs targeting schools and general public have been central to promote the conservation of such iconic species.

The penguin parade I saw was unforgettable. It was fantastic to watch those apparently little, but nonetheless strong, persistent parents rush back to fulfill their parental duties. I wondered if they were carrying enough food, if those babies were going to make it or if those parents were going to try again next year. Too many single stories to have an answer. Nonetheless, that night I felt optimistic, thinking that as long as they had people caring for them and a protected safe haven in Phillip Island, penguins will keep coming back in the future and more people will get to see them in this unique penguin parade.

2 BirdLife International 2017. Eudyptula minor (amended version of 2016 assessment). The IUCN Red List of Threatened Species 2017: e.T22697805A112478911. Downloaded on 09 November 2018.
3 Kowalczyk, N. D., Chiaradia, A., Preston, T. J., & Reina, R. D. (2015). Fine-scale dietary changes between the breeding and non-breeding diet of a resident seabird. Royal Society open science, 2(4), 140291.
4 Cavallo, C. R., Chiaradia, A., Deagle, B. E., McInnes, J., Sanchez Gomez, S., Hays, G. C., & Reina, R. D. (2018). Molecular analysis of predator scats reveals role of salps in temperate inshore food webs. Frontiers in Marine Science, 5, 381.
6 Rastandeh, A., Pedersen Zari, M., & Brown, D. K. (2018). Land cover change and management implications for the conservation of a seabird in an urban coastal zone under climate change. Ecological Management & Restoration, 19(2), 147-155.
7 Finger, A., Lavers, J. L., Dann, P., Kowalczyk, N. D., Scarpaci, C., Nugegoda, D., & Orbell, J. D. (2017). Metals and metalloids in Little Penguin (Eudyptula minor) prey, blood and faeces. Environmental pollution, 223, 567-574.

Penguin parade? Did you know they did that? Have you seen one? Let us know.

Be sure to read our other penguin blogs, too.

Stressed Penguins

Southern Rockhopper Penguin having a rough morning

Stressed Penguins

by Nataly H. Aranzamendi

The word “stress” has become part of our daily lives and daily vocabulary, but did you know that penguins can also get stressed? Let’s read about it:

Stress hormones in penguins

The role of hormones

Human disturbance can affect penguins and their behavior1. Penguins might simply ignore visitors and continue acting normally when humans approach but they can also react negatively by running away from our presence, staying away from their nests, or in rare cases they might react aggressively toward us or towards each other.

Aggressive or stressed reactions are triggered by internal physiological mechanisms that are mediated by hormones. Stress responses, for example, are mostly mediated by corticosterone.

Corticosterone is a hormone involved in energy regulation, immune reactions and stress responses2. Corticosterone has been largely studied in birds and the literature is vast. Some examples show that birds with increased levels of corticosterone have slower feather growth2. Other studies show that levels of corticosterone are associated with certain personality types. Corticosterone can affect birds in their early lives as it is responsible for increased begging for food in chicks and for high levels of aggressiveness2.





Ball-and-stick model of the cortisol molecule, a steroid hormone that controls the body’s response to stress.

The role of corticosterone in penguins




Tourists with a king penguin
Photo Source: Tourists and King Penguins at Salisbury Plain, Creative Commons Attribution-Share Alike 2.0 Generic

Corticosterone in penguins

As said before, the production of corticosterone can affect plumage quality. This is important for species that produce ornamented plumages to attract mates. The King Penguin for example produces ornamented colors when it’s time for breeding: the yellow‐orange and UV spots on its bill and yellow‐orange auricular feather patches3. Scientists found that physiological stress experiments during feather molt might affect the quality of color, in particular the production of yellow3, highlighting the possibility that ornamentation in birds is a costly physiological process.

The most well-known stress response in penguins occurs when humans visit their colonies. In a colony of Magellanic Penguins, scientists discovered that capturing penguins caused high levels of corticosterone4. However, penguins living in tourist-visited areas did not show such a strong response in comparison with penguins in isolated areas. This shows that penguins in tourist-visited areas have probably habituated to the presence of humans4. However, caution is needed when interpreting these results, as the long-term consequences of this physiological habituation are still unknown.

Corticosterone can also be involved in parental care, as it acts in combination with other hormones. In a study made in nesting Macaroni Penguins, scientists found nesting females with high levels of corticosterone5. Interestingly, those females produced heavier chicks than females with low levels of corticosterone. Thus, the authors concluded that corticosterone in this species, more than other hormones, were key for parental care5.

Stress responses change throughout a penguin’s life

Something important to remember is that responses to stress are not necessarily stable throughout an individual’s life. A study in Adelie Penguins showed that repeated handling did not affect corticosterone levels, although they found significant differences among individuals6. When the researchers extended the study for a longer period, they detected high increases in corticosterone levels, only when birds had fasted for over 50 days6. This finding highlights that stress responses are not equal at all times.

Interestingly, corticosterone is also related to personalities. As in humans, birds can have distinctive repeatable personalities. Nesting Adelie Penguins with low levels of corticosterone and with proactive personalities were more likely to be successful at times when environmental conditions were predictable. In contrast, when conditions became unpredictable, penguins showing high levels of corticosterone and reactive personalities were the more successful rearing chicks7.



Adelie Penguins in their colony

In summary, we have seen that the daily lives of penguins are governed and highly influenced by these invisible particles called hormones. One single hormone can affect the most important aspects of the life cycle of a penguin: it influences molt quality, successful reproduction, chick rearing and eventually survival.

Although corticosterone triggers an important mechanism that is useful to confront life threatening situations, like escaping or responding to a predator when being attacked, it can also have negative consequences. Corticosterone might affect early life and long-term survival, if individuals are exposed for prolonged periods of time to high levels of corticosterone. Thus, this hormone can also impact individual’s health2.

An important take home message for humans that have the opportunity to visit penguin colonies is to avoid stressing penguins by getting too close. Respect the recommended distances when visiting colonies of nesting penguins. We do not want to make penguins’ lives more stressful than normal.

Did you know penguins got stressed? Pretty much like humans. Love hearing your thoughts.

Also, read more about penguins in our other blogs:


FRENCH, R. K., MULLER, C. G., CHILVERS, B. L., & BATTLEY, P. F. (2018). Behavioural consequences of human disturbance on subantarctic Yellow-eyed Penguins Megadyptes antipodes. Bird Conservation International, 1-14.

Schull, Q., Robin, J. P., Dobson, F. S., Saadaoui, H., Viblanc, V. A., & Bize, P. (2018). Experimental stress during molt suggests the evolution of condition‐dependent and condition‐independent ornaments in the king penguin. Ecology and evolution, 8(2), 1084-1095.

Walker, B. G., Dee Boersma, P., & Wingfield, J. C. (2006). Habituation of adult Magellanic penguins to human visitation as expressed through behavior and corticosterone secretion. Conservation Biology, 20(1), 146-154.

Crossin, G. T., Trathan, P. N., Phillips, R. A., Gorman, K. B., Dawson, A., Sakamoto, K. Q., & Williams, T. D. (2012). Corticosterone predicts foraging behavior and parental care in macaroni penguins. The American Naturalist, 180(1), E31-E41.

Vleck, C. M., Vertalino, N., Vleck, D., & Bucher, T. L. (2000). Stress, corticosterone, and heterophil to lymphocyte ratios in free-living Adelie penguins. The condor, 102(2), 392-400.

Cockrem, J. F., Barrett, D. P., Candy, E. J., & Potter, M. A. (2009). Corticosterone responses in birds: individual variation and repeatability in Adelie penguins (Pygoscelis adeliae) and other species, and the use of power analysis to determine sample sizes. General and comparative endocrinology, 163(1-2), 158-168.

Penguins Wrapped in Plastic

Penguins Wrapped in Plastic

by Nataly H. Aranzamendi

Every day we encounter more and more animals affected by our plastic consumption and penguins are not the exception. Can we do something to stop it?

How much plastic do these penguins face?

An overview of the problem

Plastic found in our oceans comes mostly from land based sources (80%), with only 20% from marine sources. Half of the latter are mostly abandoned fishing gear: fishing nets, lines and parts from abandoned vessels (10% of total plastic)¹.

Plastic from land sources reaches the ocean mainly through rivers and, in fact, the 20 most polluting rivers are in Asia. However, not all rubbish is exclusively produced in Asia. This is because high income countries sell non-recycled plastic to low income countries, which usually have poor managing systems¹. Thus, it is likely that the plastic entering the ocean from rivers comes from everywhere in the world.

Since plastic can float, driven by oceanic currents and the wind, islands of floating plastic are concentrated in some latitudes with more frequency than in others. So, although less people live in coastal areas in the southern hemisphere, there is a lot of plastic concentrated in the southern oceans¹, putting penguins at a high risk of contact with plastic.

Examples of the plastic trash and debris we have collected during our conservation and habitat rehabilitation projects.

How does plastic in the ocean affect penguins?

Why exactly is plastic bad for penguins?

Penguins can interact with plastic in three ways: by entanglement, by directly eating it or by indirect ingestion of other organisms that have consumed microplastics2. Microplastics are produced from the breakdown of bigger pieces of plastic, which end up ingested by small organisms and transferred along food chains2.

Tangled in a web of plastic: Approximately 36% of seabird species have been found entangled in plastic litter. Most of the time, fishing gear incorrectly disposed of can be blamed, accounting for 83% of bird entanglements (although it is hard to differentiate the losses due to bycatch)3.

Unhealthy food: Fortunately, penguins seem to be eating less plastic than other seabirds of their same size, but they are still doing it4. Penguins could mistake floating plastic as their favorite food items. Plastic bags might look like jellyfish and floating plastics like fish.

Moreover, plastic floating over months in the ocean releases a volatile compound (DMS) that smells like food, confusing the olfactory senses of birds5, although presently there is limited knowledge of how much this is true for every species6. In any case, several species of penguins that have been found beach-washed, contained significant amounts of plastic in their intestinal tract7. Whether this ingestion caused the stranding events is still unknown.

The invisible food: Microplastics can contain chemicals and contaminants that interfere with biological processes in animals2. The exact mechanisms that affect animals are still debated, but the presence of microplastics is ubiquitous worldwide in aquatic environments.

What can we do to stop this threat of plastic to penguins?

What can we do to help?

Heartbreaking photos of our loved seabirds eating plastic leave us wondering if there is anything that we can do. The answer is yes! We can chose to not let plastic win and take individual actions to help our birds.

Beware of what kind of fish you buy and find out how it was caught. Some fish are caught with more sustainable practices than others. Avoid eating fish that were caught with dubious high-impact practices to send a message (i.e. we do not buy bycatch!). Follow the actions of your local government regarding fishing practices and express your opinion. This will help fish and penguins!

Do not rely on recycling. Remember that many countries are doing their best to recycle as much as they can, but these efforts are still far away from efficiency, and most countries are doing it poorly.

Avoid single use plastic. Analyze every item that goes in your shopping bag and items of your daily routine. Do we really need a daily disposable coffee container? Do we need tomatoes wrapped in plastic?

Look for alternative options e.g. buy loose tea instead of individually packed tea bags, replace your old shampoo bottle for a shampoo bar, let ear buds be a thing of the past, etc. See some of the great ideas in this blog: Go Green: Eco-Friendly Products We Should All Be Using

It might feel like one person will not make a difference, but millions of people changing their habits for sure will be noticed. Remember that we can make a difference in the future of our seabirds and our beloved penguins.

Thoughts about the unfortunate results of plastic/litter? Any steps that you will take? Love hearing your thoughts.

Also, read more about penguins in our other blogs:

1. Ritchie H. & Roser M. (2018) – “Plastic Pollution”. Published online at Retrieved from: ‘’ [Online Resource]
2. Avio, C. G., Gorbi, S., & Regoli, F. (2017). Plastics and microplastics in the oceans: From emerging pollutants to emerged threat. Marine environmental research, 128, 2-11.
3. Ryan, P. G. (2018). Entanglement of birds in plastics and other synthetic materials. Marine pollution bulletin, 135, 159-164.
4. Wilcox, C., Van Sebille, E., & Hardesty, B. D. (2015). Threat of plastic pollution to seabirds is global, pervasive, and increasing. Proceedings of the National Academy of Sciences, 112(38), 11899-11904.
5. Savoca, M. S., Wohlfeil, M. E., Ebeler, S. E., & Nevitt, G. A. (2016). Marine plastic debris emits a keystone infochemical for olfactory foraging seabirds. Science advances, 2(11), e1600395.
6. Dell’Ariccia, G., Phillips, R. A., Van Franeker, J. A., Gaidet, N., Catry, P., Granadeiro, J. P., … & Bonadonna, F. (2017). Comment on “Marine plastic debris emits a keystone infochemical for olfactory foraging seabirds” by Savoca et al. Science advances, 3(6), e1700526.
7. Pinto, M. B., Siciliano, S., & Di Beneditto, A. P. M. (2007). Stomach contents of the Magellanic penguin Spheniscus magellanicus from the northern distribution limit on the Atlantic coast of Brazil. Marine Ornithology, 35, 77-78.