Wildlife and the Observer Effect

By observing something, you change it. It’s a phenomenon that occurs in all areas of science. We don’t know what’s inside a tree until we cut it down. We can’t observe tiny organisms without disturbing them and putting them under a microscope. We can’t see into the abyss without shining a light into it. In everyday life, it happens all the time. If I feel like someone is watching me work, I actually do work instead of switching between work and browsing the web, thus an observer would incorrectly assume that I am usually very focused.

Many wild animals are very sensitive to the presence of humans and change their behavior when they know we’re around. So how much do we really know about the lives of tortoises, rhinos, bumblebees, clams, and all the rest?


The cutest way to reduce the observer effect

A group of researchers wanted to learn more about the behavior of penguins when humans are not disturbing them. They took an adorable approach to the problem by creating a robotic penguin chick. The penguins fell for it, to some degree, so this allowed the researchers to collect data without aggravating the penguins[1]. This made me wonder if there are other cases of the observer effect on wildlife, whether it’s sometimes not possible to overcome, and how the effect might relate to my work. 

Observing by participating in chimpanzee tribes

Jane Goodall, without a doubt the world’s expert on chimpanzee behavior, has been criticized for her methods of studying chimpanzee tribes. In order to learn about the animals, she became a part of their lives, watching them, providing food for them, and interacting with them. Some say that some of the observations she made about chimpanzee behavior are invalid because of her interference with their tribe. Their feeding behavior and relationships may not accurately represent an undisturbed tribe of chimpanzees. Some of the things she learned are quite important and indisputable- for example, she found that chimpanzees use tools, refuting the assumption that only humans use tools. While her observations might not have been entirely representative of chimpanzees in the wild, she laid the ground work for future researchers to learn more. Her inspiring work and contributions to conservation mean that there will still be wild chimpanzees to study, and new scientists to do the studying.


First recorded observation of a black sea devil

On November 17th 2014, a black sea devil anglerfish was videotaped swimming in its natural deep sea habitat for the first time ever [2]. While this species is famous for its gruesome face, parasitic mating procedure, and built-in light bulb, we didn’t know how this fish swims until a couple of weeks ago! But is her gaping mouth her normal pose, or a reaction to the remotely operated vehicle encroaching on her? We might not yet know, but the scientists captured the fish and brought it to a lab to observe it more thoroughly. No doubt she will be influenced by the trip and her new home, but the scientists will learn so much more about the species by being able to observe her up close. 


Monkeys take advantage of human observers

Another example of researchers interfering with the very behavior they are attempting to study is the case of the South American somango monkeys. These little guys have figured out that when humans are around, they don’t have to worry about being eaten by a jaguar, so they can exploit food sources closer to the ground than they normally would. If this effect happens in other species, we may find that many studies of predator-prey relationships and foraging are skewed by the observer effect. A new study of grizzly bears suggests that they follow hunters to find easy meals, leading me to suspect that foraging behavior could be easily influenced in many other species. 



Mice and Men

While not quite wildlife-related, another recently discovered observer effect could have widespread ramifications.  A study found that male researchers stress out rodents, while female researchers do not. This calls into question the results of countless studies using rodents [3]. An interesting follow up study could look at the results from past studies on rodents and compare the stress and pain levels they found to the gender(s) of the primary researchers or technicians handling the rodents.


My research involves measuring vegetation in areas that are, or could be, habitat for New England cottontails, a threatened species. I often wonder if by trampling through the dense vegetation (as gracefully as possible), I am reducing the quality of the habitat I’m measuring. What helps me sleep at night is the assumption that the damage I cause is no greater than a windstorm or a hungry herd of deer. Regardless, I hope that the net benefit of my work will be positive. It is a good practice to be aware of the observer effect and document it as much as we can, but it’s not always possible or necessary to remove it. There are valuable things to be learned through observation, and the more we learn the more we can attempt to eliminate disruptive influences on our subjects. 


1. BBC News. "Rover dressed as a penguin aids conservation," by Victoria Gill. http://www.bbc.com/news/science-environment-29833843 

2. National Geographic. "Rare black sea devil caught on film for the first time," by Jane J. Lee.  http://news.nationalgeographic.com/news/2014/11/141125-sea-devil-deep-sea-fish-animals-science/ 

3. Nature. "Male researchers stress out rodents," by Alla Katsnelson. http://www.nature.com/news/male-researchers-stress-out-rodents-1.15106