Tagging animals is a practice used widely by scientists, farmers, and the food industry to identify animals in a group. While tagging makes it much easier to track individuals, attaching a piece of plastic or metal to an animal's ear or wing, for example, is bound to have an effect on behavior, and perhaps even on survival. In the field of penguin research, this has been a much-contested issue, as there are conflicting reports on the damaging effects of tagging penguins with flipper bands going back to the 1970s.
Led by Dr. Yvon Le Maho at the French National Center for Scientific Research, scientists showed that, over the course of ten years, king penguins with flipper bands (pictured here) had fewer chicks and a lower rate of survival than their unbanded counterparts. Though they could not test this directly, they think that these effects are likely the result of significant drag caused by flipper bands. This drag slows penguins down, making them more vulnerable to predators and less efficient at catching prey. Consistent with this idea, the team showed that banded penguins took longer to return home to breed and to feed their chicks, putting them in a reproductive quagmire.
The study further shows that banded penguins are more sensitive to climate conditions. In extremely good or bad years, banded and non-banded penguins fared similarly, but under 'normal' conditions there were significant differences. While this is not readily obvious, it has to do with the relative amount of resources available. Imagine you are fighting for the only slice of bread left. You are smarter and faster than the poor souls next to you, so you'll get the grub. Sadly, eating said slice will not really help you to survive the week, as it's not enough to meet your body's needs. Bye, bye for you. Conversely, if there are 100 slices of bread, you will eat your fill and leave some behind for all the rest to enjoy. However, if there are 20 slices around, only you and those that are almost as smart and as fast as you will get to eat. The rest will perish. This is essentially the predicament in which banded penguins find themselves. They cannot outcompete their non-banded friends, and are therefore at a disadvantage.
The results of this study have far-reaching repercussions. Penguins are often used to study the effects of climate change on marine ecosystems. However, most of these studies used flipper bands to track individual penguins, so the results may be biased. Other types of tags, such as the small implanted transponder tags used in this study, may be less harmful to animals and yield more reliable results. Because most scientists use tags to identify animals, these results are relevant to other fields of research. Therefore, it is important not only to develop less invasive technologies, but also to keep an open discussion on the methods we use to study animals around us.
For more information on this study, please visit Nature.com. You can also view this blog post at http://basicresearch1.blogspot.com/
