June 26, 2017 at 1:00 pm
Following our Poll last month, we actually sat down to have a closer look at why penguins are actually black and white. And we compiled our results into an 8 minute video. Below there is both the video and an illustrated transcript with links to some of the sources we cite.
Penguins. Surely most people automatically associate that term with flightless, upright waddling and most importantly, black and white birds. We all know them from hundreds of movies, cartoons and documentaries.
And while it is safe to assume that the penguins’ preference for fish as food is common knowledge, it is also surprising that many have at least a vague idea about what the penguins’ black-and-white attire is good for. Blending in an Camouflage.
Many, many sources ranging from the popular to scientific spectrum state that the penguin’s black back makes the bird more difficult to spot while at sea. When seen from above they disappear in front of the dark blue of the ocean, while their white bellies help them to blend in when seen against the bright sky from below.
According to this idea, the black-and-white plumage helps penguins to be invisible to predators and prey alike.
But… is that so?
To answer this question, let’s go back to where this idea comes from.
This gentleman is Abbott Handerson Thayer, a prominent painter in the United States of the late 19th and early 20th century. He also had a knack for natural history; he was particularly fascinated by animal colouration.
He described a phenomenon known today as “countershading” which is pretty widespread throughout the animal kingdom. In a paper published 1896 in the ornithological journal Auk, he pointed out that many animals are
“painted by nature, darkest on those parts which tend to be most lighted by the sky’s light, and vice versa”.
But it wasn’t Thayer who first mentioned countershading in the context of penguins. In 1892, four years before Thayer’s paper came out, a book titled ‘Animal Colouration’ was published by Frank Evers Beddard, an English zoologist and – weirdly enough – earth worm expert. In it he discusses countershading in animals:
“the white under-side of […] of aquatic birds such as the penguins, are stated […] to be inconspicuous when seen from below and against the bright sky.”
Even though Beddard makes it sound as if it’s not his own idea, it seems his is the first written account of what may be the purpose of countershading in penguins.
And, at a first glance, it seems logical, right? That is, until you really start to think about it.
And funny enough Beddard himself called it straight away when he goes on to say…
“It appears however that this really not the case. If snowflakes […] are watched as they fall from the sky, which is naturally overcast and dull, they appear almost black.”
Let me illustrate what this weird snowflake analogy means for penguins.
Here are a few photos of penguins seen from below.
See where I’m going with this?
Unless you shine a bright light at penguins from the deep, their white bellies will do nothing to prevent them from appearing as a dark shadow.
So what about the black backs? The advantage, according to many books and articles is that the birds are harder to see from above. But, when you look at underwater footage of penguins, they often do not really blend in with the environment that well.
Here are some birds that are true masters of the art of camouflage…
..whereas penguins, even under murky conditions, are still quite visible. To be quite honest… penguins do a far from stellar job when it comes to blending into the marine environment. If they were serious about it, shouldn’t they all blue rather than black and white?
So, I think we should have serious doubts that penguins are black and white primarily for camouflage purposes. Sure, it helps under some circumstances, but that seems more like a by-product. Which brings us back to our initial question.
Why are penguins black and white?
In 2009, Hannah Rowland from the University of Liverpool compiled a comprehensive review of the function of countershading. And she points out a whole string of factors that may all play a role for the black and white colouration in penguins.
Dark colours absorb far more light energy than light colours. This means that the black backside of penguins is more efficient in absorbing heat from the sun than their white front. According to Rowland, penguins have been observed to use that to their advantage, by turning their backs to the sun when cold, and their white undersides to the light when hot.
That would also work when the penguins are resting at the surface in often cold water. In Galapagoa penguins, Dee Boersma (in Bernard Stonehouse’s ‘The Biology of Penguins’) observed that penguins floating at the surface had dry backs allowing them to absorb solar radiation. At the same time, she mentions that while “it is tempting to suggest that the penguins can offset loss of heat to the cold water absorbing solar radiation” her data did not allow testing of this hypothesis.
But the same can be said about the camouflage idea – it has ever come under scientific scrutiny.
Dark feathers have been shown to be stronger and resist more abrasion and wear. Especially if birds are exposed to airborne particles, having black feathers may make the plumage more resistant to abrasion. While Rowland suggests that this may not apply to penguins, it seems she overlooked the fact that penguins spend long periods on land, often pretty dang exposed to the elements and associated abrasive forces.
Coloured feathers are also more energetically costly to produce than white feathers, which could be another reason behind the colour of penguins. With regards to the other explanations for the penguins’ black backs – thermoregulation and protection from abrasion – it makes sense that the penguins’ undersides are white. At sea only the part of the plumage that faces the sun is black. And on land, the penguins generally lay down on their tummies or huddle together backs exposed. So the parts that play no role in absorbing radiation or withstanding the elements don’t need to be black. So why waste energy to generate pigments for the belly feathers?
It has also been suggested that the black and white colouration of birds may actually be beneficial for recognition of conspecifics. This can be helpful when it comes to locating and capturing prey. For example, if a penguin notices a swirl of black and white bodies zooming around a cloud of something, that may be indicative of that something being quite edible.
So why are penguins black and white?
Well, quite honestly, we don’t have a definite answer – or an answer that has ever been scientifically tested. However, if anything, it seems that the common assumption that it’s all about camouflage doesn’t have enough legs to stand on. It takes a lot more, not to be seen.
June 1, 2017 at 10:07 pm
So last week we gave a presentation about the Tawaki Project to the Birds New Zealand South Otago branch. And we promised to record and put it online. Well, that did not work. And fortunately so… the bloody computer ate half of the presentation and refused to display many slides. A perfect excuse to try a new format for us. YouTube.
May 8, 2017 at 4:45 pm
There are many questions about penguins. How old can they get? How deep do they dive? Can they tap-dance? (No!)
One question that is also often brought up is: why are penguins black and white?
It seems as if despite the apparent trickyness of this question, a lot of people seem to have an idea. Of course, as a penguin scientist we also have our theories about the topic. And here we want to find out to which extent our theories line up with public ideas as to why penguins have black backs but flash bright white bellies.
Thanks heaps to Kiyomi Ogawa for the Japanese translation of our poll questions!
We will write a blog post about the results and current scientific theories about this simple yet complicated question in a week or two.
March 21, 2017 at 4:05 pm
What do catastrophic floods in Peru have to do with tawaki from Jackson Head?
Torrential rainfall in the Andes has wreaked havoc in Peru, killing 72 people and rendering thousands homeless. While many media outlets were quick to pin this catastrophe to the weather phenomenon El Niño, it’s actually not quite that. No yet, anyhow.
We witnessed the devastating effects El Niño had on tawaki from Jackson Head a mere two years ago. Many chicks died of starvation while their mothers desperately tried to find enough food on long, far-ranging foraging trips. In the end the breeding season turned out to be a pretty bad one with only a quarter of the chicks surviving until fledging. Then, last season, a stoat invasion befell the tawaki population pushing the breeding success down to close to zero.
If we are indeed on the verge of another El Nino, the penguins could be facing a third bad season in a row. So, when confronted with the terrible news from Peru, a visit to NOAA the world’s authority with regards to El Niño was in order. The first sentence of the current El Niño report is a bit of a relief “El Niño neutral conditions continued during February”. But…
…the Peruvian catastrophe shows all the hallmarks of an El Niño with much higher ocean temperatures than normal. What keeps it from qualifying as El Niño is that these warmer temperatures are offset by cooler waters further west along the equator. Some scientists have therefore dubbed the situation a ‘coastal El Niño’. And not only that. Further down the NOAA report it reads that after the March-May period “there are increasing odds for El Niño toward the second half of 2017 (50-55% chance)”.
If the severity of the ‘coastal El Niño’ at play in Peru now is an indication for what might happen towards the end of this year, the Jackson Head tawaki have to brace themselves for another tough season.
February 27, 2017 at 3:13 pm
The tawaki moult is in full swing. All of the penguins we fitted with satellite tags have returned to the mainland to grow a brand new coat of feathers. The question we had was whether they would do this in the comfort of their own home (aka ‘nest’). After we found Jackson Head almost devoid of any penguins in February last year, we started to doubt that the birds return to their colonies to moult as it is commonly believed.
So last weekend, we headed over to Milford Sound to catch up with our friends at Southern Discoveries, hitched a ride to Harrison Cove and, together with Andrea Faris, dived into the bush to have a look for penguins. It did not take long to find ample signs of moult – feather trails leading to piles of the fluffy stuff. All clear indications that Harrison Cove is indeed a popular hang out for a change of feathers.
Overall we encountered 20 penguins, some holed up with (presumably) their mates in their nesting caves looking rather bedraggled, others in the final stages of shedding the old feathers, but many apparently through the moult entirely and more or less ready to go on yet another long migration.
For us this means that we can plan to come back this time next year to deploy trackers on these birds to examine where they travel to get in shape for another tough breeding season.
January 31, 2017 at 10:47 am
The summer holidays are over. Whether we can call the post-breeding and pre-moult migration of tawaki a holiday is another question. Judging from the distances that the birds cover in the two to three months after their chicks have hatched, there is a fair amount of effort involved in their journey.
Back in mid-November we deployed satellite tags on 20 tawaki from Gorge River. Since then more than 3,000 locations were transmitted through the Argos system satellites. While some of the tags stopped submitting halfway through the birds’ journeys – most likely because the penguins managed to preen them off their backs – we still have a number of birds that are actively transmitting.
And one of them, a female tawaki, is close to home. Another 250km and she is back where she started 82 days ago. She travelled 3,830 km and distanced herself 1,370 km from her nest site in Gorge River. So the last few kilometres are peanuts. The amazing thing, however, is that this journey was just the prelude to the winter migration which the bird will go on after the moult in February. That, however, we will not be able to track as the tracker will fall off once the bird starts shedding its feathers. Good thing the Tawaki Project has another two years to go.
December 29, 2016 at 6:55 pm
Well, here’s a little secret for anyone who’s planning to watch the upcoming next movie in the Alien franchise. The scene pictured below is not on an alien planet – it’s Milford Sound. And there are two tawaki breeding colonies in the frame, Sinbad Gully and Harrison Cove. The latter one, of course, is our main Fiordland study site.
So a great opportunity to let the person sitting next to you know of your insider knowledge and tell them about the Tawaki Project. (Perhaps you may want to wait until the movie is over before spreading the word about our work.)
December 24, 2016 at 11:18 am
Doing research is one thing, sharing the knowledge you’ve gained another. Far too often, scientific results are published in scientific journals that nobody reads or has access to. As much as we try to spread the word about the fantastic creatures that tawaki – and other NZ penguin species are – a lot of our time is used up with data analysis, writing reports and trying to secure funding for upcoming field seasons. But this time we were incredibly lucky to share our experiences with two professional story tellers. Richard Robinson‘s incredible photographs capture the beauty of our flippered friends and Bill Morris‘ fantastic account about penguins in New Zealand will no doubt help to raise much needed awareness for a seabird that in our country is taken for granted and, as a result, often underappreciated.
Go and support their work! Buy the latest issue of New Zealand Geographic!
December 22, 2016 at 3:53 pm
The Tawaki Project’s Fiordland season wrapped up in the current issue of the Advocate South (also known as Fiordland Advocate).
December 3, 2016 at 4:08 pm
So much for ‘once chicks fledge they will not touch try land again for almost a year’. This tawaki chick from Rollers Beach, Stewart Island, obviously had different plans. After its first splash in the big blue, it found itself a nice little rock not far from the cave it hatched in. It then spent the better half of a day perched there preening extensively and enjoying the life in fresh air (as opposed to the ammonia contaminated, dank gas not really qualified to be called ‘air’ inside said cave).
Ultimately, however, high tide forced the young one to get wet again… and start the adventure of its first year at sea.