Evolution in Action – Campus Juncos at UCSD

Researchers from Indiana University at Bloomington has produced a series of videos titled “Ordinary Extraordinary Junco” covering a curious bird species belonging to genus Junco that has colonized the campus of the University of California at San Diego. We have decided to highlight the 6th episode of the series but other episodes are available for viewing from the vimeo channel of the project. The series are designed to reach public and student audiences of all backgrounds and ages. The key themes are evolution, animal behavior, ecology, and the scientific research process.

So often nature and science films focus on exotic organisms in far-off locations. This series demonstrates that exciting biology, including evolution, is happening every day in our own backyards. Juncos are among the most common and most abundant “backyard birds” found across North America, and they are easily observable by millions of people daily.

Although they are abundant and common across much of North America, the genus Junco also exhibits stunning diversity in feather color, body shape and size, and behaviors among the various species, subspecies, and races across their range. This diversity likely evolved very rapidly and quite recently. Juncos re-colonized North America by the end of the most recent ice age less than 14 thousand years ago. This rapid diversification is similar to Darwin’s finches in the Galapagos Islands or the Cichlid fishes in Africa well known for their adaptive radiation. For nearly 100 years, juncos have been a key research subject, in part because of their habit of foraging and nesting on the ground. Juncos also do very well in captivity. Therefore it is possible to catch and mark an entire population and track changes in time.

Examples like cichlid fishes or Darwin’s finches demostrate evolution that takes place longer timescales. Juncos are quite special in this respect since they help us understand formation of new species in more recent shorter ecological timescales. This new and resident colony of juncos in UCSD campus is a unique opportunity to observe evolution of new behavior. Birds provide an effective study system to observe evolution of new behavior. For instance urban birds in Mexico City use fibers of cigarette butts which contain poisonous compounds in making their nests. These poisonous chemicals keep many arthropod parasites such as ticks away from chicks. This behavior has never been observed in the wild.

This article is a part of the Evolution series aiming to categorize posts related to this central biological concept in Nature Documentaries.

(1) Pioneers in Science: Rowan and the Junco from Ordinary Extraordinary Junco on Vimeo.



  1. Nan says:

    They had a nest in my ivy plant on my balcony (2 miles SE of campus) last year, and the year before they raised two broods out there. Last year the babies were doing well and then one morning they were all dead. I have not seen the parents again, so I don’t know if they got into poison or…. This year there are Juncos that have excavated a nest in my hanging geranium plant out on my front porch and seem to be in the process of finishing the nest. I have not see our “usual” birds on the balcony this year.

    These little guys are cheeky and cute. Nice to see a film about them!

    • Uzay Sezen says:

      These birds are most certainly quite adventurous. I never heard of them nesting inside potted plants. That would have been interesting to document. This 6 part documentary series is focused on a resident population on UCSD campus but as your observations confirm they are expanding further into other urban areas. Keep on observing!

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