By Kate Crowley
The past week has been so dreary and gray that not even the birds coming to our feeders could brighten the mood, especially when the temperatures got into the 40s and all of our snow turned to puddles and slush. I desperately needed some cheer and brightness, so I turned to animation. Yes, it was the Penguins of Madagascar that finally made me smile and feel cheerful again. My ten year old grandsons were as excited to go as I was. There is no age limit on the need for laughter.
The overriding theme of the movie is that everyone loves penguins. I’d have to agree. How can you not be captivated by these waddling, tuxedoed lovers of snow and ice? The truth is that not all penguins live in the Antarctic regions and none live in the Arctic, or as some cartoons would have us believe - the North Pole. All 17 species of penguins are found only in the Southern Hemisphere, ranging from the ice shelves of the Antarctic to the Galapagos Islands and many coastal areas of Africa, South America, New Zealand and Australia. In 2012 my dream of seeing penguins in the wild came true when Mike and I visited New Zealand and saw both the Little Blue and the Yellow-Eyed penguins. I shared that experience in a column in October of that year.
But in thinking about the penguins and our attraction to them I thought about the other flightless birds that have existed and why we still consider them birds. Isn’t flight the defining quality of a bird? And why did some evolve without that ability? Scientists have been studying this question almost since Darwin introduced the theory of evolution. Fossil evidence and DNA studies have shown that the flightless birds descended from flying ancestors, but that over time, some – due to habitat situations lost the use of their wings for flight.
Besides penguins, some of the other better known flightless birds include ostrich, emus, cassowaries, rheas, and kiwis. Many, many flightless birds such as the moa of New Zealand, the elephant bird of Madagascar, and the dodo of Mauritius fall under the category of ‘extinct’, specifically because of their flightless nature. Most of the birds that became flightless did so on islands, where predatory mammals and reptiles were nonexistent.
Flight is extremely energy intensive and requires energy dense food, plus a larger musculature and skeletal structure to support flight. If a bird could feed, display for the opposite sex, defend territories and reproduce without flying, then more energy could be put toward these other pursuits. Over time, through mutations and natural selection wings decreased in size and assumed other uses.
For the ostrich, their wings have shrunk in size, but they have become important for maintaining balance and to threaten enemies. Their wings like those of the penguin, still contain the exact same bones as found in the wings of species that can fly. Penguins were sea birds and as they became more proficient at diving, any ancestral wings used for flight would have reduced their mobility underwater. As they slowly evolved into flippers, the birds were able to swim faster and deeper. Penguin bones also became denser over time, making them less buoyant for diving. Diving deeper and longer increased their access to food resources, which would further reduce their need for flight. Studies being done today on other diving birds that can still fly indicate that bigger bodies improve diving efficiency, which could also explain why there are so many bigger-bodied penguins today.
One thing flightlessness has done is create birds that walk, in all sorts of weird ways – the penguin’s waddle is just one example. The other common thread running through all of their lives has been the ease of extermination once humans arrived on their island homes. Either directly or by importing predatory animals, we have taken a terrible toll on these unique members of the bird world.
As I look out the window at a scene that looks more like April than December I am thinking about stocking up on as many penguin films as possible. The Weather Service is predicting a winter snowstorm coming our way, but until I see it, you can find me watching cute penguins frolicking in the snow and ice.