The activities are as follows:
- Teacher Guide
- Student activity, Graph Type A, Level 3
- Student activity, Graph Type B, Level 3
- Student activity, Graph Type C, Level 3
- Grading Rubric
When the animals that humans keep in captivity escape into the wild, we call them feral. You may have seen feral animals, such as pigeons, cats, or dogs, right in your own backyard. But did you know that there are dozens of other feral species all over the world, including goats, parrots, donkeys, wallabies, and chameleons?
Sometimes feral species interbreed with closely related wild relatives to produce hybrid offspring. Feral dogs, for example, occasionally mate with wolves to produce hybrid pups, which resemble both their wolf and dog parents. Over many generations, a population made up of these wolf-dog hybrids can evolve to become more wolf-like or more dog-like. Which direction they take will depend on whether dog or wolf traits help the individual survive and reproduce in the wild. In other words, hybrids will evolve traits that are favored by natural selection.
You might be surprised to learn that like dogs, chickens also have close relatives living in the wild. These birds, called Red Junglefowl, inhabit the jungles of Asia and also many Pacific islands. Eben is a biologist who studies how the island populations of these birds are evolving over time. He has discovered that Red Junglefowl on Kauai Island, which is part of Hawaii, have recently started interbreeding with feral chickens. Now there is a hybrid population. Eben wanted to figure out if the hybrids on Kauai are evolving to be more like chickens, or more like Red Junglefowl. One of the biggest differences between chickens and Red Junglefowl is their breeding behaviors: Red Junglefowl females only lay a handful of eggs every spring, whereas chickens can lay eggs throughout the entire year… up to 300 or more eggs! What about Kauai’s feral hybrids? Do they lay eggs seasonally (like Red Junglefowl), or year-round (like many chickens)? Eben thought that Kauai’s feral hybrids would breed year round. He figured that natural selection would favor the hens that lay the most eggs (and therefore produce the most offspring). These hens’ offspring would inherit traits from their mother, and therefore breed year-round too. Thus, after multiple generations, hens that lay year-round might begin to outnumber hens that reproduce only in the spring.
To test his hypothesis, Eben’s research group collected hundreds of photographs and videos of Kauai’s hybrid chickens. Tourists delight in photographing Kauai’s wild chickens and uploading their media to the internet. Fortunately for Eben, their cameras and cell phones often record the dates that images are taken. Eben looked at media posted on websites like Flickr and YouTube to find documentation of feral chickens throughout the year. This allowed him to see whether chicks are present during each of the four seasons. He knew that any hen observed with chicks had recently mated and hatched eggs, because the chicks only stay with their mothers for a few weeks.
Featured scientist: Eben Gering from Michigan State University
To learn more about feral chickens and Eben’s research, check out the popular science articles below:
- New York Times Article, “In Hawaii, Chickens Gone Wild”
- Nature Article, “When Chickens Go Wild”
- MSU Today, “Invasive Feral Chickens Provide Evolutionary Insights“
- MSU Today, “How Did the Chicken Cross the Sea?“
Mini documentary you can watch in class. The video gives a brief history of chickens on the island of Kauai, and shows mother hens with their chicks:
Students can watch the same videos that Eben used to collect his experimental data. They can find these videos by searching YouTube for “feral chickens Kauai” and many examples will come up, like this video:
About Eben: One of the most exciting things I learned as a college student was that natural populations sometimes evolve very quickly. Biologists used to think evolution was too slow to be studied “in action”, so their research focused on evolutionary changes that occurred over thousands (or even millions) of years. I study feral animal populations to learn how rapid evolutionary changes help them survive and reproduce, without direct help from us.