Blog articles on fun facts and interesting information written by our penguin experts.

Penguin Digestive Systems – Penguin preppers and their secret militia

King Penguin

Penguin Digestive Systems – Penguin preppers and their secret militia

by Emma Williams

Spending most of your life at sea creates a big problem for a penguin digestive system; what to do when you are on land, separated from your food source. Penguins have evolved an apparently simple solution. Penguins are hoarders. Extremely accomplished preppers, they carry their own personal larders with them. A penguin’s digestive system can become a perfectly adapted storage cupboard of undigested food. The food reserves are used sparingly when they come on land to moult and to breed.

The penguin digestive system allows them to build up large reserves of adipose tissue, protein and lipids

On closer inspection, the solution is not quite so simple. To get through often long periods of fasting, penguins build up large reserves of adipose tissue, protein and lipids. However, this ability is not sufficient on its own; they enlist the help of a secret militia without whom they could not survive: Gastrointestinal microbiota. Penguins are not alone in housing this army of helpers. Most animals, including ourselves, have co-evolved GI tracts teeming with useful microorganisms that play a vital role in digestion. In the “feast and famine” world of penguins, they seem to really have their work cut out.

The penguin digestive system is teeming with useful microorganisms that play a vital role in digestion

These mini ecosystems have been studied widely in mammals but have been largely neglected in penguins. This imbalance has now started to be addressed and a comparative study of GI microbiota in penguins1 has yielded some very interesting results. The researchers looked at the inhabitants of the GI tracts of four different species of penguin: King Penguin (Aptenodytes patagonicus), Gentoo Penguin (Pygoscelis papua), Macaroni Penguin (Eudyptes chrysolophus) and Little Penguin (Eudyptula minor). They studied the gut contents of wild birds by examining their faecal samples.

A healthy Chinstrap Penguin in Antarctica

Thirteen different phyla were found in the penguins. The two most dominant were Firmicutes, literally strong skin, a phylum that are active in carbohydrate metabolism, and Bacteroides, a group of anaerobic bacteria particularly helpful in converting sugars. Both microbiota are also commonly found in mammals. Actinobacteria and Proteobacteria, vital for gut homeostasis, were also found to be strongly represented in the penguins. Each of the four species of penguin studied were discovered to possess different microbial makeups in their digestive systems. The prize for most diverse microbial composition goes to the Macaroni Penguin followed by King Penguin, and Little Penguin with Gentoo Penguin being a valiant runner-up.

It is likely that diet, environment, and phylogenetic differences account for the variation in gut microorganisms. Another study that looked at the GI microbiota of Chinstrap Penguins (Pygoscelis antarctica)2 found that age played a part. There were significant differences between the internal communities of adults and those of chicks. Interestingly, these differences were also apparent between parents and their own offspring suggesting that environmental factors are more important than genetic factors in the chick microbiota.

As well as their vital role in nutrition and energy release, the GI army is also ready to fight inside the penguin digestive system. These micro-soldiers create a formidable force, a close-protection squad, shielding their host from marauding invaders: Pathogens. Bacteroides in particular benefit their host animal by preventing infection by potential pathogens that may colonize and infect the gut.

The complex community of microbiota defend against illness and disease. Little is known about this process in penguins. Indeed, researchers1 discovered many “unclassified” bacteria within penguin digestive systems. As yet we do not know the significance of these atypical army of residents, but they are likely to have some role in digestion as well as health and disease.

Worryingly, human pathogens have also been documented in the GI tracts of wild penguins1, including Campylobacter, Heliobacter and Streptococcus. The impact of these pathogens on the health of wild penguins is not yet known, although a human pathogen has been implicated in the death of a Little Blue Penguin in captivity3

Due to their tendency to live in dense colonies and to huddle closely together, penguins are particularly susceptible to pathogen transfer. The potential for catastrophic spread of disease is likely to be high.

Of course, if penguins are hosting significant numbers of human pathogens without ill-effects perhaps they might hold the key to human immunity.

What is clear is that penguins need their carefully evolved and sophisticated micro-militia within their digestive systems. They play a major role in the release of energy reserves, nutrition, metabolism and immunity. Disruption of these micro-ecosystems is likely to be disastrous to their hosts health and well-being. Knowledge and understanding of these complex inner communities and the relationship with their penguin hosts is still in its infancy. It is an exciting branch of study that just might provide new insights that lead to benefits for both humans and penguins. Long-live the penguin digestive system militia!

What amazing digestive systems penguins have. Please let us know what you learned by reading this blog. We enjoy bringing you this information. And we appreciate any type of support you can provide us, so please consider donating to Penguins International.

Also read some of our other blogs:

Like our penguin blogs? Sign up for our newsletter to get them right in your inbox!

[mc4wp_form id=”8457″]

  1. Dewar, M.L., Arnould, J.P.Y., Dann, P., Trathan, P., Groscolas, R., & Smith, S. (2013). Interspecific variations in the gastrointestinal microbiota in penguins. Microbiology Open, 2 (1), 195-204.
  2. Barbosa, A., Balague, V., Valera, F., Martinez, A., Benzal, J., Motas, M., Mira, A., & Pedro-Alio, C. (2016). Age-related differences in the gastrointestinal microbiota of chinstrap penguins (Pygoscelis antarctica). PloSone,
  3. Boerner, L., Nevis, K.R., Hinckley, L.S., Weber, E.S., & Frasca, S. (2004). Erysipelothrix septicaemia in a little blue penguin (Eudyptula minor). Journal of Veterinary Diagnosis, 16, 145-149.

Why Don’t Penguins Fly?

Penguins swimming underwater

Why Don’t Penguins Fly?

by James Platt

Most of the world’s bird species have the capability of flight. In fact, of 11,000 known species of birds, there are only about 60 species including the Common Ostrich (Struthio camelus), Great Spotted Kiwi (Apteryx haastii) and 18 species of penguin that cannot fly at all, which is about 0.5% of all bird species. Why these different species evolved without flight could be due to several reasons; each one will have evolved to fit into a niche within its own environment.

Penguins were originally thought to have evolved separately from flightless birds, until quite recently when fossil records from New Zealand were discovered. These fossils revealed that they had likely descended from the order of Procellariiformes and its closest relatives including the Wandering Albatross (Diomedea exulans) and Antarctic Petrel (Thalassoica antarctica). This could be considered unexpected since the albatross is a bird that travels huge distances in the air. So why would a bird that has massive wings and uses them to glide across continents suddenly evolve into a flightless, chubby penguin?

An albatross flying through the air
Photo credit: Linda Martin

Why did penguins evolve to swim instead of fly?

To understand why they may have evolved in this way, first we must understand flight. Flight in birds is a tricky thing; it is a perfect balance between forces (lift, thrust, gravity and air resistance) that allow the bird to move through the air quickly and efficiently. Birds evolved hollow bones to allow them to be lighter and, therefore, lift off the ground much easier. They also have air sacs built into their body to keep a streamlined aerodynamic body shape that allows them to reduce air resistance. Birds need to stay light because the heavier they are, the more difficult it is to take off from the ground (Tobalske, 2007). In the case of some flightless birds like the ostrich, which weighs over 100kg, its wings would have to be huge to get it off the ground. Instead, they are incredibly fast runners. Similarly, with Emperor Penguins (Aptenodytes forsteri) that can weigh about 25kg, it would take large wings to fly and would not be very energy efficient. So they evolved to “fly” in the water instead. Now some penguin species have branched off and become much smaller and lighter than the Emperor Penguin, such as the Little Penguin (Eudyptula minor) at just 1.5kg, but by this time they were a fully distinct order of birds and had adapted to dominate the water.

An Emperor Penguin tobogganing on the snow
Photo credit: Mike Zupanc

It is believed that the Emperor Penguin is the oldest species of penguin and therefore was the first bird to try to dominate the ocean and land on the continent. But why in such a cold, harsh environment, and why would it become flightless? Well, it’s complicated and there could be many other reasons. There is a total lack of land predators which means they don’t have any immediate threats to fly away from. There is also an abundance of sea life to eat and a lack food resources on land, so they adapted to thrive off the oceans and then live on land, away from their biggest predator, the leopard seal (Hydrurga leptonyx). There are also many benefits to being flightless. Penguins have the opposite to most birds, they have incredibly dense bones that allow them to dive and swim better. Where most birds would have air sacs to stay aerodynamic, penguins can fill some of that extra space with a larger stomach and carry much more food for itself and its offspring — up to a 1/3 of its bodyweight. They can also dive much deeper than flying seabirds they may be in competition with and this allows them to make the most of what their environment has to offer (Alexander, 1999).

Part of the reason penguins swim is because flying is an energy-intensive activity

One more reason they may have lost the ability to fly is that flying is an extremely high energy activity and they need all the energy they can retain to stay warm (Elliott et al, 2013). Most birds use their energy for flying and the bird that is best at conserving its energy is the penguin’s closest relative, the Wandering Albatross. It uses wind to extend its glide times and allow it use as little energy as possible during its migration. It seems that this wasn’t energy efficient enough for some individuals and they evolved into penguins over the millennia as swimming is much more efficient because there aren’t as many forces to contend with (Culik and Wilson, 1991).

The evolution of the penguin and its loss of flight is far from a complete story and I suspect we will find out more in the coming decades as more fossils are uncovered. Leave your thoughts in the comments!

Isn’t it nice to learn why not all birds fly? Some of us might assume that just because something has wings they won’t always stay grounded.

We hope you enjoy learning this about penguins and we love bringing you this information. Please consider supporting Penguins International by donating to us today.

And read more about penguins in some of our other blogs:

Like our penguin blogs? Sign up for our newsletter to get them right in your inbox!

King Penguins

[mc4wp_form id=”8457″]


Culik, B., Wilson, R. and Bannasch, R., 1994. Underwater swimming at low energetic cost by pygoscelid penguins. Journal of Experimental Biology197(1), pp.65-78.

Alexander, R. (1999). One price to run, swim or fly?. Nature, 397(6721), pp.651-652.

Culik, B. and Wilson, R. (1991). Energetics of under-water swimming in Adelie penguins (Pygoscelis adeliae). Journal of Comparative Physiology B, 161(3), pp.285-291.

Elliott, K., Ricklefs, R., Gaston, A., Hatch, S., Speakman, J. and Davoren, G. (2013). High flight costs, but low dive costs, in auks support the biomechanical hypothesis for flightlessness in penguins. Proceedings of the National Academy of Sciences, 110(23), pp.9380-9384.

Tobalske, B. (2019). Biomechanics of bird flight. Journal of experimental biology, [online] 210(18), pp.3135-3146. Available at: [Accessed 8 Jul. 2019].

What’s up with “Down”?

King Penguin with its chick showing penguin down feathers

What’s up with “Down”?

By Megan Spofford

Have you ever seen a young penguin that looks like it has completely different feathers than the rest of the members in its colony? Did you think, “What’s wrong with that one!?” Would you describe it as a “floof-ball”? If so, it would serve you to know that the floofiness factor comes from a special type of feather called “down” which is small, lightweight, and FLUFFY. For penguins, the down has a gray or brown coloration. In this article we will explore what makes this type of feather so special, and to show you that no, nothing is wrong with that penguin!

What are the types of down feathers in penguins?

In the grand scheme of down, you will find there are three different types. Regular body down is a layer of lighter feathers found situated underneath and around the external contour ones that we see with our naked eye, and all birds possess it. Down feathers are classified as afterfeathers and plumules. Natal down is the first type of feather a baby bird will get, and it covers the entire body. Powder down is created from feathers that disintegrate into an ashy, powdery substance to coat the feathers of a bird in order to keep it waterproof from rain or any other type of wet substance it may encounter. This type of down is found on birds who typically do not spend time going into water, so a penguin does not have powder down. (Instead, penguins and other water birds have a uropygial gland, also known as a preen gland, at the base of their tail that secretes an oil which is spread over their feathers during preening. This oil serves to waterproof their feathers in the same way powder down does for other birds.)

What types of feathers does a baby penguin have when it hatches?

Altricial or Precocial?

Penguins hatch from an egg with down covering their body, however they are not able to feed on their own or survive if they were to leave the nest/ brood pouch. This characteristic makes them “semi-altricial”. An altricial bird is one that is not able to regulate the temperature of their own body, usually due to being completely or partially featherless. They are also heavily reliant on parental care for feeding. The latter is a particular reason why penguins are not considered precocial. While similar to precocial birds in that they are both born with feathering, a precocial baby will be able to fend for themselves or follow their parents around and to learn how to hunt within the first few weeks of life. On the other hand, as an altricial baby gets older, the down feathering thickens, and they are able to self-thermoregulate, but natal down is not waterproof, so until the penguin’s body is mostly covered in contour feathers that can be waterproofed, the bird cannot go into the water or it could risk drowning and hypothermia. Since penguins hunt in the ocean, the babies must rely on their parents for food until eventually, the young bird is old enough to molt (when a penguin sheds feathers on its body and is restored with new ones) and the down is replaced with adult feathers.

What are the additional purposes of down feathers in penguins?

Down has a few different purposes; a couple of which we have already described when discussing powder and natal down. Looking at the third type of down, body down, an important purpose it serves is as an insulating agent for any bird of any age. This is especially important to penguins who live in the cold Antarctic regions! Additionally, body down helps with a penguin’s movement in water. This help comes in the form of bubbles of air that are trapped in the down feathers and ultimately give the penguin buoyancy or allow it to zip through the water quickly. Sometimes in these high speed instances, a “trail of smoke” can be seen behind the penguin, which is really just the expulsion of those air bubbles from their down.

Close up of penguin feathers

Down feathers for Human Application

Recognizing the special properties of feathers, humans have started research into creating a diving suit made of artificial feathers that would be more insulating and create less drag during underwater excursions. The fluffier down feather would be an important feature for both of those properties to exist. If this ever comes to fruition, we would be the silliest looking penguin there ever was!

Did you know you could get ‘down’ with penguins? Great info! Let us know what you think. And please help us continue to bring you this type of info by contributing to Penguins International.

Read some other information about penguins in more blogs:

Like our penguin blogs? Sign up for our newsletter to get them right in your inbox!

[mc4wp_form id=”8457″]


  4. Jan R. E. Taylor, Thermal Insulation of the Down and Feathers of Pygoscelid Penguin Chicks and the Unique Properties of Penguin Feathers, The Auk, Volume 103, Issue 1, January 1986, Pages 160–168,
  5. Starck, Johannes Matthias. Avian Growth and Development: Evolution within the Altricial-Precocial Spectrum. Oxford Univ. Press, 1998,
  6. Williams, CL, Hagelin, JC, & Kooyman, GL. (2015). Hidden keys to survival: The type, density, pattern and functional role of emperor penguin body feathers. Proceedings of the Royal Society B: Biological Sciences, 282(1817). Retrieved from 

Penguin Fight Club

Humboldt Penguins fighting

Penguin Fight Club

By Martin Franklin

As readers of a certain age will know, both the first and second rules of Penguin Fight Club are, “You do not talk about Penguin Fight Club.” 

That, however, would mean an especially short and (even more than normal) disappointing blog post. 

I’m therefore going to bend the rules this once, not least as penguin combatants themselves often discard the rules of Fight Club, in particular, as Brad Pitt’s character so clearly articulates, “Fourth rule: Only two guys to a fight. Fifth rule: One fight at a time, fellas.”

Numerous members of the colony at ZSL London Zoo involved in a brief squabble  (© Martin Franklin/ZSL)

Fictional penguins tend to bend the rules even further. For example, Batman’s old adversary “The Penguin” used technology to fight, frequently using modified high-tech umbrellas as weapons. Similarly, the clay-animated “Feathers McGraw” disguised himself as a chicken by pulling a rubber glove over his head, used robotic “Techno Trousers” to steal a diamond, and trapped Wallace and Gromit in a wardrobe at gunpoint. 

Real penguins do, however, thankfully tend to stick to a fairly well documented and more traditional set of agonistic behaviours (i.e. social behaviours related to fighting)1, 2, 3. These include:


1. Visual penguin displays from a short distance 

  • Staring. This may be a “sideways” stare (where the head is held to one side, with one eye fixed on the opponent), or “alternate staring” (where the head is moved from side to side, and opponent stared at with each eye alternately). The whites of the eyes may be exposed. 
  • Pointing. The bird points its closed bill directly towards the opponent (sometimes with neck-rotation). This is often used by birds on nests towards other birds that venture too close.
  • Gaping. The bird leans towards its opponent, with neck stretched and bill open.
Humboldt Penguin pointing, while standing (© Martin Franklin/ZSL)
Humboldt Penguin posturing (© Martin Franklin/ZSL)
Humboldt Penguin pointing, while incubating (and guarding) eggs (© Martin Franklin/ZSL)

2. Penguin Vocalisations (combined with visual displays)

  • Ecstatic displays (also called trumpeting). This can either be performed by an individual or in pairs (in which latter case it is termed a “mutual” ecstatic display). It involves stretching the neck upward and flippers outward, and making one or more loud donkey-like brays (potentially also rolling the head from side to side, depending on the species). Context, however, is everything, as although such displays often indicate ownership of (or claims to) territory (particularly nest sites), and are often seen in connection with fights, they can also be used to advertise availability for mating and communicate identity (e.g. to a partner elsewhere on the beach). 
  • Growling/hissing. This is produced during exhalation and may accompany, for example, “pointing” (particularly in the crested penguins) or “lunging” (particularly in Little Penguins).
Humboldt Penguin ecstatic display (single bird) (© Martin Franklin/ZSL)
Humboldt Penguins mutual ecstatic display (1) (© Martin Franklin/ZSL)
Humboldt Penguins mutual ecstatic display (2) (© Martin Franklin/ZSL)

3. Physical/Close Contact

  • Charging/lunging. The bird runs or lunges towards its opponent.
  • Pecking. The closed bill is used to make a hard, speedy jab (often following “pointing”).
  • Bill vibrating. Two birds rapidly and repeatedly clap their bill against the other’s bill (think of “fencing”).
  • Biting. A pinching grip (particularly on the opponent’s neck or back), making use of the sharp hook on the end of the bill (which is otherwise primarily useful for grasping fish), sometimes in conjunction with pulling and twisting.
  • Beaking (also called the tête-à-tête posture). Two birds interlock their bills, then pull and twist to try to dislodge the opponent.
  • Beating. During “biting”/”beaking”, the bird rapidly and repeatedly slaps its opponent with a flipper. (The author can attest that this is surprisingly painful when a bird elects to perform this on a human.)

Of course, differences are observed in different species. 


For example, Adélie Penguins seem also to use a “bill-to-axilla” threat posture3 (which looks a bit like they’re trying to smell their armpits). Incidentally, it has been suggested that, just like in the worst human soap-operas, the most aggressive fights between Adélie Penguins occur when a female returns to her nest after an extended absence, only to find another female has pair-bonded with her former mate4.


Little Penguins (in which it seems around 10% of aggressive interactions escalate to fighting) similarly possess a significant repertoire of distinct agonistic behaviours (22 in cave-nesting birds and 13 in burrow-nesting birds). Some of these actions are common to most penguins, as already described above. Others (as far as the author is aware) are yet to be widely reported upon in relation to other species. These include the “zig-zag approach”, the “breast butt” (think of an angry soccer player with his arms held rigidly by his sides squaring up to another) and a variety of nuanced flipper-spreads.5


So what should the reader do, should he/she find him/herself on the wrong end of any such agonistic penguin behaviour? 

The author suggests (without any guarantees) that a generally sensible course of action might be to attempt the kind of “appeasement” or “displacement” behaviour deployed by penguins.  


Therefore, increasing the distance between you and your aggressor is probably the best tactic. However (and the following is not meant seriously):

  • If stationary, try the “submissive hunch”, the “face-away”, or “look-around” (rotate your retracted neck), or start “preening” yourself (good luck with that one). 
  • If walking through a colony, try “slender-walking” (with body stretched up, neck extended, flippers very slightly spread, and – if you can manage it – feathers sleeked down). 
  • Alternatively, get yourself a warm coat and egg and join the male Emperor Penguins during breeding season: aggression is suppressed at this time, allowing them to huddle together for warmth3.


But please repeat nothing of this: after all, you know the first two rules of Penguin Fight Club.


© Martin Franklin 2019


Martin Franklin is a bird keeper at ZSL London Zoo, and works extensively with Humboldt Penguins. Any views or opinions expressed in this article are the author’s own, and do not necessarily represent those of ZSL.

Wasn’t this a great read about penguin social behaviors and “Fight Club?” Let us know what you learned, and if you’re going to watch any movies this week.

And please help us continue to bring you more information about penguins by donating to Penguins International. We greatly appreciate your support.

Continue to read more about penguins in some of our others blogs:

Like our penguin blogs? Sign up for our newsletter to get them right in your inbox!

[mc4wp_form id=”8457″]



1 Merritt, K. and King, N. E. (1987). Behavioral Sex Differences and Activity Patterns of Captive Humboldt Penguins (Spheniscus humboldti). Zoo Biology, 6(2), 129-138.


2 Eggleton, P. and Siegfried, W. R. (1979). Displays of the Jackass Penguin. Ostrich, 50, 139-167.


3 Williams, T. D. (1995). The Penguins. Oxford University Press: New York.


4 De Roy, T., Jones, M. and Cornthwaite, J. (2013). Penguins: Their World, Their Ways. London: Bloomsbury Publishing.


5 Waas, J. R. (1990). ‘An Analysis of Communication during the Aggressive Interactions of Little Blue Penguins (Eudyptula minor)’. In David, L. S. and Darby, J. T. (eds). Penguin Biology. San Diego, California: Academic Press Inc. pp. 345-376.

Little (Blue) Penguins: Dive Shape Versus Coastline Health

Little Penguin

Little Penguins: Dive Shape Versus Coastline Health

by Sian Liversage

Little Penguins, otherwise known as Kororā in Moari and commonly called Blue Penguins or Fairy Penguins, are found all around the coast of New Zealand. As their name suggests, they are the world’s smallest penguin weighing in at a mere 1kg and 25cm tall. They have a varied diet composed of small fish, squid, and crustacean species.

A Little Penguin near its burrow.

Primarily nocturnal on land, they can sometimes be found close to human settlements, in and around buildings, keeping the neighbours awake with their vocal displays. A recent article was published about a sushi store in Wellington who found out first hand just how noisy Little Penguins can be! The pair had decided to cross two main roads to nest underneath the sushi store. Perhaps it was the smell of the fresh fish that had enticed them in? Unfortunately for them though, they had chosen an awkward spot, so the Department of Conservation had to step in to relocate them. They have since decided to keep away from the area, and the hope is they have chosen a nest box located along the wharf instead.

Little Penguins Commonly Nest in Coastal Areas with Heavy Automobile Traffic

This pair were lucky not to get hit by any cars when they decided to cross main roads to nest. Sadly, many penguin colonies around the world are in decline, and thanks to an abundance of media stories in recent years just like the one mentioned, we are now more aware that our coastal areas are severely affected by humans due to an increase in shipping, fishing pressures, and coastal land development. This awareness hopefully will encourage councils and governments to either protect whole areas or at least provide wildlife-friendly areas that allow penguins to go about their natural behaviours.

Because Little Penguins depend on these coastal areas for food, they offer an easy and convenient way to study the health of marine ecosystems around New Zealand. And thanks to their predictable behaviour, where every night they will return to the same location, it makes it even easier for scientists to research them.

Little Penguins Exhibit Varied Hunting and Diving Behaviour

A study conducted by the Department of Conservation marine scientists monitored hunting trips of 8 Little Penguins using tiny electronic data loggers2. These small devices are carefully attached to the penguins’ tail feathers for 2-4 days, where they record the length and depth of each dive. These scientists were able to find differences in Little Penguin diving techniques dependent on the environment in which the penguins lived. In areas with plenty of prey, “V-shaped” dives were made for short shallow hunts, “U-shaped” dives meant they had to work a bit harder searching the ocean bottom for food, and finally “W-shaped” dives meant it took them approximately a quarter of their time to hunt for their prey. This research showed that Little Penguins have a variety of diving techniques when hunting, which is dependent on the abundance of prey and their location. So, can it be assumed that studying the diving technique of Little Penguins can determine the health of the marine ecosystem in which the penguins live?

Fortunately, Little Penguins are Adaptable

To support this assumption, another recent study was conducted which also looked at diving behaviours and diets in Little Penguins off Motuara Island3. They concluded that the species appear to be highly adaptable to local environments, given the variability in diving behaviours as well as in prey. These results therefore suggest that some locations would naturally be more difficult to adapt to than others, reflected in longer and deeper dives (aka “W-shaped” dives). Therefore, these penguins may prove to be useful environmental monitors for changes in the specific sites in which the individuals live. And with the combination of long-term site monitoring and population trend monitoring, it could lead to enough evidence to show that the coastline requires more protection if the ecosystem changes for the worse.

Some studies have already proven that a variation or lack in availability of food can result in problems for the penguins4. Results showed delays to the start of breeding, a reduced likelihood that a second clutch will be produced, and a higher chance of chick mortality. In addition to this, researchers have found that adult and chick body conditions are poor, resulting in the chicks’ immunity being reduced and causing the fledging period to become longer. Therefore the parents must work harder for longer. Without the varied diet that they require, these issues could cause a population to decline in the future, so perhaps by continuing the research into penguin diving techniques around the New Zealand coastlines, we can determine whether the area requires environmental protection or not.

Did you learn something new about Little Penguins by reading this? Please let us know. We also more than appreciate any support you can provide to help us continue bringing you information about penguins by donating to Penguins International.

Want to learn more about penguins? Read some of our other blogs:

Like our penguin blogs? Sign up for our newsletter to get them right in your inbox!

[mc4wp_form id=”8457″]


  1. RNZ News. 2019. Web:
  2. Department of Conservation Marine Ecosystems Team, Science and Policy. 2015.
  3. Chilvers L. 2019. Variability of little blue penguin diving behaviour across New Zealnad. New Zealand Journal of Ecology, Vol. 43, No. 2, 2019
  4. Dann P, Norman FI, Cullen JM, Neira FJ, Chiaradia A 2000. Mortality and breeding failure of little penguins, Eudyptula minor, in Victoria, 1995–1996 following a widespread mortality of Pilchard Sardinops sagax. Marine & Freshwater Research 51: 355–362.

Measuring Penguin Welfare and Stress

Humboldt Penguin

Measuring Penguin Welfare and Stress

by Jemma Dias

Animal welfare has been defined by Broom (1986) as “an animal’s physical and mental state with regards to its ability to cope with its environment”.  Animal welfare is a relatively new science, focussing on the quality of our care for captive animals. It is also considered to be an extremely important topic, not only based on our moral responsibility to provide appropriate care for the animals we chose to keep, but also to enhance production, be it for profit or conservation. There is a wealth of factors which affect an animal’s welfare, such as social interaction, diet and overall health. As a result, welfare can fluctuate daily, even hourly, and, therefore, should be monitored regularly. Results from this should lead to alternations in husbandry practices with the aim to improve animal welfare. Welfare assessment can also be applied to wild colonies to assess the influence of environmental change, such as tourism or climate change.

Types of welfare monitoring in penguins (and other animals)

Welfare monitoring for any species can be undertaken in two ways. The first uses behavioural measurements. This requires behavioural observations, as well as an understanding of the individual’s “usual” behaviours. For instance, an increase in abnormal behaviours, such as stereotypes, can indicate significant stress. 

Indicators of stress in captive penguins

Other behavioural indicators of stress may include:

  • a reduction in activity and subsequent increase in time spent resting
  • an increase in aggressive behaviours and decrease in affiliative behaviours towards conspecifics and keeping staff
  • poor appetite, but also anticipation of feeding events
  • alterations in grooming behaviours, such as excessive grooming
  • increased vigilance or avoidance of stressful stimulus
  • poor reproductive success, limited interest in mating opportunities and infanticide in some species
  • unequal enclosure utilisation limited to a few or even one area of the enclosure, often the area in which food is provided

In penguins, species specific behaviours such as diving, incubating and pair-bonding may also be relevant to welfare assessment. It should also be noted that not all instances of these behaviours should be considered indicative of stress. For instance, occurrences of behaviours, such as grooming, at a particular time of day may be due to weather conditions. Assessment should consider the proportion of time spent performing the behaviour over a full 24-hour period to best understand the cause of a behaviour.

Humboldt Penguin
Whilst excessive grooming can be a sign of poor welfare, this Humboldt Penguin at ZSL London Zoo was seen to take breaks between preening.
Little Penguin
This Little Penguin at Perth Zoo exhibiting vigilance behaviours on behalf of the rest of the group, who were either preening or swimming at the time.

Sherwen et al. (2015) monitored the effect of zoo visitors on the welfare of 25 Little Penguins using behavioural measures. The penguins’ behaviour was studied in two randomly imposed conditions: enclosure closed to visitors and enclosure open to visitors. The investigation found an increase in intra-group aggression and vigilance in the presence of zoo visitors. The penguins spent a greater period of time positioned behind structural features in the enclosure and chose to stand at a greater distance from viewing areas with visitors present. These results suggest that visitors acted as a stressor for the penguins, likely fear-provoking, indicating welfare is affected by visitors.

Stress in penguins and other birds can be measured in hormones

The results from behavioural welfare assessments can be validated by physiological measures of welfare. The most significant physiological measure of welfare is the presence of stress hormones. Glucocorticoids, such as cortisol and corticosterone, are released into the blood during a stress response. Monitoring the levels of stress hormones can show the occurrence of stress, as well as supporting theories on the cause of stress and instances of stress related behaviour. 

Glucocorticoids can be extracted from blood, faeces and saliva samples. Although blood samples are considered to be the most reliable source of glucocorticoids, obtaining them can be invasive and can act as a source of stress, skewing results. Ozella et al. (2017) used the non-invasive method of assessing faecal glucocorticoids to examine physiological stress caused to African Penguins in the presence of visitors, although they did not find an influence of this on faecal glucocorticoids. 

Other types of measurements of stress in penguins

Other physiological measures of stress include body-condition scoring and evaluation of recurring health issues and poor recovery times, as well as monitoring of the internal environment. Culik et al. (1990) investigated the effect of disturbance on the heart rate and behaviour of nine incubating Adélie Penguins with the use of safety-pin electrode ECG and implantable radio-transmitters. Minimal resting heart rate was found to be 86 bpm (beats per minute) which rose to 127 bpm following disturbance by humans, and 145 bpm in the presence of a helicopter. Though the study sample was a wild group, the rise in heart rate, indicating stress, can be applied to captive groups. On the other hand, the study also found evidence of habituation to human presence in a hand-reared chick. This suggests that captive penguins can also experience habituation to human-related stress.

Welfare assessment on penguins requires wider publication. However, trial of behavioural and physiological measures will allow keepers of captive populations to discover the most appropriate methods for their group and individual penguins.

Animals can experience a lot of stress and react is various ways. It’s incredible. Please help us continue to bring you this type of information by donating to Penguins International.

Read more about the birds in our other blogs:

Like our penguin blogs? Sign up for our newsletter to get them right in your inbox!

[mc4wp_form id=”8457″]


Culik B., Adelung D., & Woakes A.J. (1990). The Effect of Disturbance on the Heart Rate and Behaviour of Adélie Penguins (Pygoscelis adeliae) During the Breeding Season. In: Kerry K.R., Hempel G. (eds) Antarctic Ecosystems. Springer: Berlin, Heidelberg

Ozella, L., Anfossi, L., Di Nardo, F., & Pessani, D. (2017). Effect of weather conditions and presence of visitors on adrenocortical activity in captive African penguins (Spheniscus demersus). General and Comparative Endocrinology, 242, 49-58.

Sherwen, S. L., Magrath, M. J. L., Butler, K. L., & Hemsworth, P. H. (2015). Little penguins, Eudyptula minor, show increased avoidance, aggression and vigilance in response to zoo visitors. Applied Animal Behaviour Science, 168, 71-76.

Penguin Architecture – What does a penguin nest look like?

Magellanic Penguin burrow nest

Penguin Architecture – What does a penguin nest look like?

By Megan Spofford

One of the most fascinating characteristics of birds is the fact that they are egg-layers, and because of this, they must create highly specialized shelters to house them — nests. Amongst the penguin species, the variation in nesting materials is almost as diverse as the penguins themselves. Materials available vary based on habitat, but all eighteen species have developed specialized nests to protect their eggs in creative ways.

Types of Penguin Nests

Scrape nests

A scrape nest is essentially an indentation in the ground that has been scraped out by the nails of the penguin that created it. The species that create this type of nest are Snares, Erect-crested, Rockhoppers, Gentoos and Yellow-eyed Penguins. Within a scrape nest, the penguin will add things such as rocks, sticks, vegetation, bone, feathers, etc. — pretty much anything it can grab with its mouth — to create a throne worthy of jealousy. Interestingly, Yellow-eyed Penguins go out of their way to build nests that are not within sight of another penguin (probably to avoid a confrontation over territory). However, nearly all of the other penguin species live in breeding colonies that have nesting sites in close proximity to each other. Erect-crested Penguins, Macaronis and Northern and Southern Rockhoppers additionally utilize tussocks, which are thick and long isolated bushels of grass that protect their eggs.

Mounds or flat ground

While those whole build scrape nests do use various items to fill their shelter with items that include rocks and pebbles, there are species that use only rocks and pebbles without scraping a depression first. These species of penguins build nests on top of rocks and pebbles by gathering and setting them out in an array or stacking them. Adelie, Chinstrap and Royal Penguins almost exclusively build their nests on the rocky shores they inhabit, while Macaroni and Gentoo Penguins utilize this method in some regions. In some cases, especially with Gentoos and Adelies, individuals will steal materials from each others’ nests to add to their own, and spark territory wars in the process. Macaroni Penguins (who only come to shore for breeding purposes) create mounds as well as use tussocks. 

Gentoo Penguins adding vegetation to their scrape nest.
African Penguin nest boxes placed by African Penguin & Seabird Sanctuary, donated by GreenRscreed.
Photo Source: GreenRscreed


Burrows are the most utilized nest by penguins as six of the eighteen penguins use them, but they vary in structure based on what is available. Penguins will use the scraping technique to form a new burrow, but the difference between the two is that the burrow has a covered top, so the entire structure resembles Bag End from The Hobbit, without the door.

Penguins can also utilize natural burrows such as caves, cracks, and holes, or even under tree branches in the case of Fiordland Penguins, who nest in vegetation of the rainforest of New Zealand. Little Penguin burrows are created solely by the males. Magellanic Penguins dig burrows up to 1 meter deep in soil or guano beds. Galapagos Penguins, who nest the farthest north of all the species, do so in between dried lava formations decorated with twigs and leaves; that is if they nest at all. This species is environmentally cued to breed only if cool water temperatures are below 25 degrees Celsius.

The final three species: African and Humboldt Penguins are also burrowers, but they use guano (bird poop!) as their major building tool. They fill cracks and holes in the ground with guano which can build up after many years, and provide great space for burrowing. Unfortunately, it is also nutrient dense and has been harvested by humans as a fertilizer. In doing so, the availability of valuable burrowing area for penguins is severely reduced, and they are forced to lay eggs in more vulnerable locations. Guano harvesting is a contributing factor to the endangered status of the African Penguin, and has led to substantially decreasing numbers in Humboldt Penguins as well. Because of this, scientists have started placing artificial nests made from various durable materials on the islands they inhabit to increase the rate of hatching.

The “no-nesters”

While most penguins have reason to build a nest, there are two species of penguin that are “no-nesters”. The Emperor and King Penguins nestle their eggs on their feet and keep the egg warm by a brood pouch, a patch of bare skin,on the belly of the penguin to protect their eggs from the harsh elements of the Antarctic and sub-Antarctic environments in which they live.

Each type of nest, or lack thereof, is a fascinating natural piece of architecture. If you were a penguin and had all the resources available for each type of nest, which would you choose?

A King Penguin doesn’t use a nest. It incubates its egg on top of its feet.

Isn’t it amazing how different species of the same bird do things so differently? Let us know what you think about all this. We love being able to provide you with this information and can’t do it without your support. Please consider donating to Penguins International so we continue to do so.

And read more about penguins in some of our other blogs:

Like our penguin blogs? Sign up for our newsletter to get them right in your inbox!

[mc4wp_form id=”8457″]


  5. Carlson, A. L. and J. S. Townsdin (2012). Galapagos Penguin (Spheniscus mendiculus), version 1.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.

Galapagos Penguin Conservation

Galapagos Penguins

Galapagos Penguin Conservation

By Sian Liversage

One of the most endangered species of penguin in the world is the Galapagos Penguin. They are endemic to the Galapagos Islands, and are the only penguins that nest entirely in the tropics. They can survive here due to the cool, nutrient-rich waters. Although they are related to the African, Humboldt, and Magellanic species who are all burrow-dwelling penguins, they have adapted their ways to living in caves and crevices in the coastal lava.

These penguins form strong pair bonds and remain with the same partner for their entire lives. Females will lay between one to two eggs a year, the eggs are incubated for approximately 35-40 days, and the fluffy dark brown chicks will fledge around nine weeks old.

How many Galapagos Penguins are left in the wild?

The estimated population size is only 1,351 individuals. This is because some are accidentally caught by fishers or invasive predators will kill them, but one of the biggest issues is climate variability. The population has fluctuated over the last 33 years, especially during the 1982-83 and 1997-98 periods where El Niño events occurred, causing the population to decline by approximately 60%.  During these events, water temperatures increase, making their food less abundant, which in turn affects the breeding success of pairs. Increasing occurrence and severity of El Niño weather events — due to climate change — is an enormous threat to the future of the Galapagos Penguin population.

Despite these threats, the population has been slowly recovering, thanks to the Galapagos Conservancy. Their aim is to reverse the decline of the population, and to strengthen it to a point where they can withstand threats like the El Niño events.

Conservation efforts are slowly helping the Galapagos Penguin populations

To do this, they have provided breeding opportunities by building 120 shaded nest sites constructed of stacked lava rocks. This is because there are limited nest options, old sites may no longer exist, marine iguanas may have overtaken them, or they may regularly flood. Because their ability to breed also relates to the unpredictability of food, Galapagos Conservancy want to ensure that when breeding conditions are good and food is abundant, all penguins have the option of a high-quality nest site to keep their eggs safe and cool from the sun.

Researchers will then monitor the population two or three times per year to determine the status of the population, and whether the human-built nest sites do, in fact, contribute towards the reproductive success of pairs when conditions are good and food is abundant. 

Galapagos Penguin in its burrow with eggs
Adult penguin using an artificially constructed nest. (Photo © Dee Boersma)

The most recent monitoring trip in 2017-2018, observed several juvenile penguins in good condition, indicating a successful breeding season. These successful pairs were seen using both natural nest sites as well as constructed ones. Since the project began, almost a quarter of all penguin breeding activity has been observed using constructed nest sites – making it an incredibly beneficial method to use to in order to help increase the number of individuals.

Going one step further, the researchers are now pushing towards making a marine protected zone in Elizabeth Bay, a key area around the Mariela Islands that represents the highest density of breeding Galapagos Penguins. This will not only benefit them, but also other species such as seabirds, marine mammals, and fish.

Visitors can help Galapagos Penguin conservation efforts as well

Galapagos Penguins artificial nest boxes
Artificially constructed penguin nest. (Photo © C. Capello)

Furthermore, they have established the Center for Ecosystem Sentinels, focusing on Galapagos and Magellanic Penguins. This encourages visitors to upload any photos of penguins they have taken on the island, in order to help provide useful data such as date and location of the penguins. As the database expands, it helps to determine when the penguins are moulting and help to keep track of when juveniles appear in the population.

Due to the endangered status of the Galapagos Penguin, any conservation initiative regarding preserving this species is vital to their survival, and without continuing the conservation measures that are already in place, the species could be at risk of being lost.

Don’t you want to go see these penguins even more now to help their conservation? Please help us continue learn more about this type of information, and protect penguins by donating to Penguins International.

And, read more about penguins in some of our other blogs:

Like our penguin blogs? Sign up for our newsletter to get them right in your inbox!

[mc4wp_form id=”8457″]


  1. BirdLife International. 2011. Species factsheet: Galapagos Penguin Spheniscus mendiculus. Downloaded from BirdLife International.
  2. Carlson, A. L. and J. S. Townsdin (2012). Galapagos Penguin (Spheniscus mendiculus), version 1.0. In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA.
  3. Galapagos Conservation. Webpage:
  4. Galapagos Conservancy Webpage:

Gentoo Penguins and the Impacts of Tourism

Gentoo Penguins

Gentoo Penguins and the Impacts of Tourism

by Nataly H. Aranzamendi

Tourists want to visit Antarctica because it’s one of the most pristine places in the world

Until relatively recently been an unreachable location for humans. Lately, with ecotourism increasing in this isolated corner of the world, a threat for our beloved penguins might be surging.

In the past, many people have tried to reach Antarctica, the frozen continent, because it was one of the last unconquered places on Earth and was the conquest dream of early explorers. However, this situation is changing now with the growth of ecotourism. In just the past year more than 58,000 tourists visited Antarctica during the austral summer1. Such massive human activity represents a potential threat for penguin colonies, which are the most visited attractions. 

Unfortunately for the penguins, most of the visits occur during their time out of the ocean, while they are nesting, which is a critical period for penguin populations. 

Protecting Penguins – How do we minimize impacts of tourists on penguins ?

To protect the inhabitants of the frozen continent, the International Association of Antarctica Tour Operators (IAATO) has set up strict guidelines for tourists and tour operators to follow to minimize impacts on this delicate ecosystem. For example, only 100 tourists can approach penguin colonies at a time, and they have to maintain a minimum distance of 5 meters from nesting penguins. 

Although such guidelines seem to be working in Antarctica, there is mixed evidence about how penguins respond to humans at other locations. For example, some penguins get stressed in the presence of humans (see Stressed Penguins).

Some species of penguins have even shown evidence of habituation to humans when visits are constant. This means that the repeated exposure to humans decreases the physiological responses of animals to such stimulus, ending in lower levels of stress hormones and no responses from the penguins. 

In a recent study1, researchers have measured a combination of corticosterone and metabolites, as a proxy of physiological stress in 19 Gentoo Penguin colonies. The aim of this study was to quantify if those metabolites varied in relation to the number of tourists visiting the colonies and if the current guidelines implemented in Antarctica were enough to protect nesting Gentoo Penguins. The researchers were also expecting to observe habituated individuals in colonies that receive a greater influx of people. 

Scientists can actually measure penguin stress

In order to study the amount of stress hormones in penguin colonies, the researchers used a non-invasive technique measuring metabolites in guano (i.e. in penguin poo). This approach could minimize the stress provoked by direct handling and the presence of researchers. 

The study showed that the amount of glucocorticoids found in Gentoo guano had a large degree of variation within-colonies, which was larger than the differences between colonies, independently of the number of tourists that visited the areas. 

Gentoo Penguins

According to the researchers, the lack of differences in stress levels highlight that Gentoo Penguins do not seem to be affected by tourism, as the number of landings in colonies varied significantly from no visits to more than 21,000 landings in one season! The researchers argued that such variation in stress hormones might be a result from other external sources at the colony (e.g. predators, other penguins, food availability, etc.). 

The study also indicated that unlike other species of penguins, Gentoo Penguins do not display signs of habituation, as lower and more consistent corticosterone concentrations would have been expected in more visited areas. 

It seems like Gentoo Penguins are not affected by tourism and guidelines might be effective for them. However, caution is needed when interpreting those results. Other authors have argued that measuring glucocorticoids from “poo” might have limitations as it mixes results from many individuals. To confirm these findings, repeated individual measures are still needed. 

In other species of penguins, individuals might react differently to stressing factors according to personality. Perhaps individual personality studies could explain why intra-colony levels of corticosterone showed such levels of variation.

Although this study focused only on one penguin species, it gives a positive look on how our activities can be managed to a minimal impact. Perhaps Gentoo Penguin are unaffected by the presence of intruders, which could potentially provide us a great opportunity to continue observing the most intimate details of their lives. 

We want to see these penguins and we never know what we might or might not be doing when we visit their habitat. This research is incredible! We enjoy bringing this to you and hope you enjoy it as well! We more than appreciate any help you provide us with your kind donations to Penguins International.

We have other blogs about these birds, as well, if you’ve missed a few:

Like our penguin blogs? Sign up for our newsletter to get them right in your inbox!

[mc4wp_form id=”8457″]

  1. Lynch, M. A., Youngflesh, C., Agha, N. H., Ottinger, M. A., & Lynch, H. J. (2019). Tourism and stress hormone measures in Gentoo Penguins on the Antarctic Peninsula. Polar Biology, 1-8.

Fiordland Penguins: How far would you go for your food?

Fiordland Penguin Tawaki

Fiordland Penguins: How far would you go for your food?

by Sian Liversage

We usually think of penguins surrounded by icebergs and snow, but in the depths of the rainforests of New Zealand is one of the world’s rarest penguin species – the Fiordland Penguin, a member of the crested group of penguins. New Zealand Maori call it Tawaki.

First, some facts and information about Fiordland Penguins

These birds have chosen to ignore the penguin stereotype in favour of the southwestern coast lines of the South Island, as well as Stewart, Codfish and Solander islands. They seem to have chosen a secluded life, and are known to be very secretive, mainly because they nest in dense bush, caves, rock crevasses, tree logs and roots. This, combined with the areas in which they live, being notoriously hard to reach, therefore hinder efforts to determine their exact population size, the threats they face, and their behaviours.

How many Fiordland Penguins are there?

The current population estimate is between 5,000-7,000 individual Fiordland Penguins, making them Nationally Vulnerable, and it is presumed that this figure is on the decline. The warming of the oceans, tourism and fisheries are highly likely to have an effect on the penguins, but effects on their lives still need to be studied scientifically.

So far, there has been very little research on Fiordland Penguins

Only a handful of studies have been conducted on these birds in the last 40 years, with the most comprehensive one being carried out in the 1970s. Despite the difficulties of doing so, 5 years ago a team of scientists launched the first long-term study to be conducted in order to try to understand these allusive penguins.

Their most recent 2018 study discovered and impressed researchers with the lengths at which individuals will go to in order to find food. The aim of the study was to learn more about their migration habits after breeding. Once penguin chicks have fledged, the adults need to pack on the weight in preparation for their annual moult. This annual moult is called a “catastrophic moult”, where they lose and regrow their feathers all at once over a period of 3 weeks. This takes up a lot of energy and stops them from being able to hunt for prey. 

So, during this critical weight gaining period, they need to ensure they have enough body fat to make it through the feather moulting stage. The researchers originally assumed that because the birds live and breed on the New Zealand mainland, they wouldn’t travel far to hunt.

Fiordland Penguins travel extremely far for their food!

Nevertheless, this assumption was thrown out of the water when researchers fitted GPS satellite trackers to 20 birds, with the aim of tracking their movements in real time. They discovered that they swam to the Auckland Islands, carried onto Macquarie Island, and then ended up halfway to Antarctica within a couple of weeks. A record was set by the champion of the group who swam almost 7000 kilometres in two months! This was a surprising outcome, given the limited time they have between the end of the breeding season in December and the onset of the annual feather moult in February. Researchers concluded that they think this behaviour could be down to instinct rather than actual necessity. Oceanic productivity reaches its peak during this period, so it appears unlikely that food limitation was the driving force of this behaviour.

Fiordland Penguin Tawaki

Further on from this study, the researchers are now keen to discover more about where they go, this time during the non-breeding season, where they spend months foraging out at sea. Small tracking devices will be attached to their legs and will stay on the bird for a whole year. This is the first time this sort of research is being done, so it will paint a significant picture of where they travel throughout the year. With years of data recorded, the researchers are gradually unravelling the secret life of the Fiordland Penguin. These birds spend 80% of their lives at sea, so it is hoped that this newfound knowledge will contribute towards the protection of these mysterious penguins.

This is some great information about Fiordland Penguins! Did you learn something new? As usual, we love providing you with the info, and couldn’t do it without your help. Please consider donating to Penguins International so we can provide more educational penguin knowledge.

And read more of our blogs, in case you’ve missed any:

Like our penguin blogs? Sign up for our newsletter to get them right in your inbox!

[mc4wp_form id=”8457″]

Penguins International
PO Box 100483
Denver, CO 80250 USA
phone: 628-400-7301

Your Donation

Makes a Difference

Reach Out To Us

Penguin Hug

Send a Pen Pal to Your Favorite Person

It’s like getting a hug from a Penguin

Brighten Someone’s Day for FREE

Email your favorite people a positive message. It’s a penguin post called a Pen Pal. Send as many as you want for FREE.

Send Your First Pen Pal Right Now!

Brighten Someone’s Day for FREE

Email your favorite people a positive message. It’s a penguin post called a Pen Pal. Send as many as you want for FREE.

Send Your First Pen Pal Right Now!