While many birds go south for the winter this time of year, others are just arriving, including a small flock of juncos now foraging in my backyard. They arrived from their northern breeding grounds the same week a fascinating new film about juncos arrived in my mailbox.
The film covers the evolution, behavior, physiology and genetics of juncos and the methods biologists have used to study them. It was produced by a team of biologists and filmmakers at Indiana University and funded by the university and the National Science Foundation. When the team asked if I would watch and review it, I said yes, all the while thinking, “Why juncos?” They are, after all, one of the most common “backyard” birds in North America.
Quiet, non-aggressive, cheery little birds, nothing stands out about juncos, including their color — gray on top and white underneath. Only the flash of white feathers in their tails when they fly is likely to attract attention. As Joel McGlothlin, a Virginia Tech researcher, says in the film, “There’s nothing unusual about the junco — it’s just a little gray bird and it’s everywhere.”
However, if my forays into nature have taught me anything it’s that every species has amazing aspects to its biology and evolution that tells us more about ourselves and the world we live in. The project’s website echoes this in giving the reasons for doing the film:
“So often nature and science films focus on exotic organisms in far-off tropical rainforests, polar ice caps or deep ocean reefs . . . But we wanted people to realize that exciting biology, including evolution, is happening every day in their own backyards.”
Juncos have been a key research subject for several reasons: They are abundant; they forage and nest on the ground, so are easy to observe; and they are docile and thrive in captivity, which has enabled biologists to do research on them in controlled environments as well as in the wild.
As the film explains, the junco’s “stunning diversity in feather color, body shape and size, and behaviors among the various species, subspecies and races across their range” has made it “a rockstar study organism” for scientists who study migration, hormones, neuroscience, evolution, ecology and disease ecology. It’s “one of the world’s greatest examples of diversification and rapid evolution.” The title of the film says it all — “Ordinary Extraordinary Junco.”
The junco’s diverse forms led scientists to consider that North America’s juncos, which have dark eyes, are actually several species. However, new gene-sequencing technology has enabled scientists to sort through the junco genome and determine that all these differences are merely variations (subspecies or races) of the same species, dubbed the dark-eyed junco (Junco hyemalis). This junco evolved from Mexico’s yellow-eyed junco (Junco phaeonotus), which has extended its range into southern Arizona and New Mexico.
Time and isolation drives divergence in species, and the dark-eyed junco’s divergence happened recently in terms of natural history — about 10,000-20,000 years ago, when juncos started recolonizing North America after glaciers from the ice age started to recede. Given more time, they may diverge into more species.
Virginia’s slate-colored junco, one of six subspecies of dark-eyed juncos, ranges from the North Carolina Appalachians north through most of Canada and across to Alaska. The other subspecies inhabit western regions. The various populations can and do interbreed where their ranges overlap.
The film explores junco populations throughout the Americas, showing their range and adaptability and taking viewers through some spectacular scenery in the process. The birds are shown up close in their natural habitat and in captivity, and the researchers interviewed are knowledgeable and passionate about their subject.
Packed with science, the 88-minute film is also entertaining. To make it easy to use in high school and college classrooms, the filmmakers divided it into eight segments. It’s available for streaming online for free. According to the website, organizations that want to show the film on a big screen can also get high-quality discs in various formats for only the cost of shipping; companion resources are also available.
With all the research that’s been done on juncos, more research is warranted, say the researchers featured in the film. For example, they say, juncos can teach us more about speciation, adaptation, climate change, the brain, hybridization, evolution, gene expression, the effect of genes on behavior, hormones, sex and reproduction, monogamy, maternal care, violence, range expansion, communication, geographic variation, food, death, sensory systems, trait selection, disease ecology, olfaction and ourselves. Perhaps most important, as Ketterson concludes, “We can learn a lot about beauty in nature from the junco.”
I highly recommend “Ordinary Extraordinary Junco.” After viewing it, I looked at the juncos rustling around in my yard with new interest and respect.
- Pioneering junco research by eccentric Canadian scientist William Rowan in the 1920s, which led to his discovery of photoperiodism (the physiological response to changes in day length) in animals. He found this affected the size of male juncos’ gonads, which in turn triggered migration and other breeding behaviors.
- The ground-breaking research on the effect of testosterone on behavior, physiology and evolutionary fitness of juncos by an Indiana University team of biologists at Mountain Lake Biological Station in Virginia’s Blue Ridge Mountains. As Ellen Ketterson, the team’s leader and executive producer of the film, says, “People are more like birds than we would ever have guessed.” (Spoiler alert: The males with less testosterone had fewer but better-quality offspring that were more likely to survive because their fathers stuck around to help raise them.)
- Journeys through Central America to a stunning mountainous island and inland to magnificent mountain locations (“sky islands”), where researchers are studying why some junco species are unique to a defined geographic location and how they are affected by geographic isolation.
- A study of the rapid adaptations of a small group of dark-eyed juncos after they took up year-round residence at the urban University of California—San Diego campus on the coast instead of migrating inland to the mountains to breed. The adaptations include becoming bolder in novel situations and males’ heightening the pitch of their song to rise above traffic noise. The segment showing students socializing on campus in the spring while the narrator talks about breeding-season behavior not-so-subtly underscores how much we humans have in common with juncos.