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Rockhopper Penguins change their minds when it comes to eating

Southern Rockhopper Penguin

Rockhopper Penguins change their minds when it comes to eating

by Nataly H. Aranzamendi

Rockhopper penguins comprise two different species: the Southern and Northern Rockhoppers1. Currently they are distributed and inhabit many offshores sub-Antarctic islands.

Rockhoppers are among the smaller species of penguins and they are better known to us thanks to their ability to displace using both feet performing little jumps (i.e. hopping). Unlike other penguins that slide on their bellies to get from one place to another, Rockhoppers are audacious climbers, because their habitat is very rocky, hence the “rock-hopper” name.

Unlike other penguins that love a fishy diet, Rockhopper diets are largely based on krill and other small invertebrates. This means that optimal levels of prey abundance are heavily influenced by fluctuations in oceanographic conditions, like temperature, the mixing of the water, and concentration of phytoplankton.

Southern Rockhopper Penguins have critical food moments during their breeding cycle

For adult Southern Rockhoppers, a critical “food” moment occurs during the reproductive cycle2 . Every year, male Southern Rockhoppers return to shore in small groups after months of oceanic life. Females show up a few days later, and the breeding season begins. Year after year, Rockhoppers return to their same old nests and start a new clutch.

After laying two eggs, moms and dads hang around their nests for a few days, before the male leaves for 2 to 4 weeks to feed in the ocean. When the male returns, it is the female’s turn to replenish her reserves. This will occur when the eggs are about to hatch. During this period, females are in charge of feeding, while males are in charge of chick guarding. Males will only eat again approximately 3 weeks after that.

Such a long cycle of eating and non-eating means that for males, the first foraging trip during incubation is the most critical for their survival. In a recent study2 , researchers have discovered that this critical foraging period is not as predictable as we thought before.

Sometimes Southern Rockhopper Penguins forage near-shore, other times they go far off-shore

Between 2011 and 2014, 62 male Rockhoppers from different colonies in the Falkland Islands were followed during the incubation period. These penguins were equipped with GPS loggers and time-depth recorders to record all the vital information about their journeys and the environmental conditions they encountered.

The researchers were surprised when they saw the data. Looking at the first years’ data (2011-2013), some of the penguins performed short daily trips in shallow waters and returned to spend the night at their nests, instead of engaging in the usual 3-week long trip. In 2014, however, most of the penguins went back to the previously known foraging patterns, in which they explored far away distances and stayed offshore for several weeks, while the female stayed incubating the eggs.

Photo Source: Liam Quinn from Canada [CC BY-SA 2.0 (https://creativecommons.org/licenses/by-sa/2.0)]

Southern Rockhopper Penguins will show some level of behavioral placticity

Such findings show that some species are capable to change their habits to some degree. In biology, this is known as behavioral plasticity, meaning that some species can show certain flexibility in behavior (e.g. choosing long vs. short foraging trips) when conditions fluctuate. As predicted, most of these behavioral changes were in relation to oceanographic conditions prevalent during those years. Years that showed a decrease in SST (sea surface temperature) were those in which penguins foraged mostly short distances, while years with normal to increased SST where those in which males foraged offshore. Fluctuations in temperature conditions and the amount of mixing in the water column most likely had impacts on the distribution of phytoplankton, which eventually serves as a good predictor of the presence of krill and small invertebrates, these penguins’ favorite food items.

What does this mean for the future of Rockhoppers? Such variations in temperature conditions could affect the energy expenditure in penguins. Years with decreased SST will mean better energy efficiency balance by penguins, because their prey will be available within a close range from the colony and penguins will not have to travel as far. In contrast, an increase in sea surface temperatures in the South Atlantic and Southern Oceans will inevitably force penguins to travel longer distances, threatening the survival of males. A warming planet therefore poses a threat for Rockhoppers, as increasing SST and alterations in water column mixing within the ocean have already been recorded and are predicted to continue.

It is our duty to safeguard our planet, for the health and future of Rockhopper Penguins and all other creatures that will be impacted by these changes.

Rockhoppers…are they different that what you thought? Did you learn something new by reading this post? Let us know what you think. Also, please help us continue to learn more about penguins by donating to Penguins International. We more than appreciate your support!

You can also read more about penguins in the following blogs:

References:

https://en.wikipedia.org/wiki/Rockhopper_penguin

Pütz, K., Harris, S., Ratcliffe, N., Rey, A. R., Poncet, S., & Lüthi, B. (2018). Plasticity in the foraging behavior of male Southern Rockhopper Penguins (Eudyptes chrysocome) during incubation in the Falkland/Malvinas Islands. Polar Biology, 41(9), 1801-1814.

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 (https://creativecommons.org/licenses/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: https://doi.org/10.1016/j.ympev.2018.10.025

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:

References:

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, https://commons.wikimedia.org/w/index.php?curid=24446501

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?

 

References:

https://en.wikipedia.org/wiki/Brood_reduction

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.

Gentoo Penguins–Fastest Flippers in the Falklands

Gentoo Penguin with its chicks

Gentoo Penguins–Fastest Flippers in the Falklands

by Mike King

Bird and nature enthusiasts often enjoy citing facts that highlight species whose abilities go above and beyond those of other animals. Some avian examples are the largest bird in the world (Common Ostrich), the smallest bird in the world (Bee Hummingbird), the world’s fastest flyer (Peregrine Falcon), and what scientists consider the world’s smartest bird (New Caledonian Crow). Gentoo Penguins (Pygoscelis papua) lay claim to a more abstract, but equally impressive title: the fastest swimming bird in the world. Observers have estimated that Gentoos can swim up to 36 kilometers per hour, however there is no true scientific evidence for this number. There is more than just speed to these birds, continue reading to learn more about how Gentoo Penguins use their superior swimming among other adaptations to survive in the wild.

Where do Gentoo Penguins live?

Gentoo Penguins live deep into the Southern Hemisphere, occupying Antarctica, Argentina, the Falkland Islands, and other small islands in and around the Antarctic Circle. Like many penguins, they are mostly black from head-to-tail except for a stark-white front. They have a somewhat unique appearance in relation to other penguin species because of the white “headband” that stretches over the top of their head from eye-to-eye. Their bill also has an interesting appearance due to the black coloration that extends above and underneath the crimson area where the beak parts. They are the third-largest species of penguin behind Emperor Penguins and King Penguins respectively.

Close up of a Gentoo Penguin

Information on the Gentoo Penguin life cycle

Gentoo Penguin tending its egg.

Due to the large range of Gentoo Penguins, their habitat and feeding preferences vary widely. They prefer areas with little to no ice including rocky cliffs, coastal plains, and valleys. They live in colonies that range in population from less than 50 to thousands of breeding pairs. Breeding pairs typically lay 1-2 eggs at a time in nests built from stones, moss, grass, and feathers. Gentoo chicks typically stay in their parents’ nest for about a month. Like most penguins, Gentoos spend all day out foraging. They forage mainly in the shallows, and their food preferences vary greatly by geographic distribution. Antarctic penguins chase the many abundant schools of krill on which so many marine animals rely within the Antarctic Circle. South American Gentoos spend more time chasing after small fish, squid, and crustaceans. They prefer shallow waters that are near shore, but will occasionally venture up to 16 miles (25 km) offshore and dive to 655 feet (200 m) deep in search of enough food to sustain a brood of chicks. A Gentoo Penguin can dive for food up to 450 times per day!

Gentoo Penguins can swim really fast!

As previously mentioned, Gentoo Penguins are the fastest diving bird in the world. This allows them to adapt to many ecological challenges including limited food and threats of predation from leopard seals, sea lions, and orcas. This is why they successfully occupy such a great geographical range. Due to previous habitat degradation caused by human interference in the ecosystem, the IUCN Red List had Gentoo Penguins previously listed as Near-Threatened as recently as 2016. Fortunately, they have now been moved to the Least Concern category thanks to steady population increases.

Although this is good news for the penguins, they still face a number of threats from humans such as fishing bycatch, pollution, climate change, tourism, and marine traffic. Oil spills occasionally poison local populations, and unfortunately the Falkland Islands are currently being evaluated by oil companies as a potential area to drill in the future. Algal blooms like the one that has been damaging marine ecosystems in the Gulf of Mexico and Mid-Atlantic Ocean are intensified by a warming climate. These algal blooms are one of the biggest threats to Gentoo Penguin populations because they poison the shellfish penguins rely on for food. This caused a major mortality event in 2002, and it has taken years for the species to recover. A recent study has also identified tourism as a factor that harms reproductive success in breeding Gentoo Penguins.

As with many bird species, the main conservation action that is currently in place is a long-term population monitoring program based at several breeding colonies. Although scientists can use this information to better understand population trends and fluctuations, it falls short of a solution for the many issues Gentoo Penguins are dealing with currently. Conservation legislation is considered to be the most important step toward stabilization for the species. This includes the establishment of protected breeding habitat, the minimization of oil pollution and breeding colony disturbance, and close inspection of the ecological impacts of fishing operations. Although the list of conservation actions that are currently being implemented seems short in comparison to the list of threats, organizations like Penguins International are working hard to ensure that Gentoo Penguins have ample space to thrive in the ever-changing ecosystems of today.

Did you know all this about Gentoos? Let us know your thoughts. Also read more information about penguins in our other blogs:

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:

References:

https://en.wikipedia.org/wiki/Ad%C3%A9lie_penguin
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. http://dx.doi.org/10.2305/IUCN.UK.2010-4.RLTS.T154785A4633007.en. 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:

References:

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:

References:

https://en.wikipedia.org/wiki/Chinstrap_penguin
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.
https://en.wikipedia.org/wiki/Krill#Human_uses
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. https://doi.org/10.1038/s41586-018-0776-9

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.

Sources:

https://www.penguins.org.au
1 penguinfoundation.org.au
2 BirdLife International 2017. Eudyptula minor (amended version of 2016 assessment). The IUCN Red List of Threatened Species 2017: e.T22697805A112478911. http://dx.doi.org/10.2305/IUCN.UK.2017-1.RLTS.T22697805A112478911.en. 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.
5 http://www.sci-news.com/biology/penguins-eating-jellyfish-gelata-05262.html
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.

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