Five MacArthur’s Warblers in a Spruce Tree

No Avian Ecologist’s Christmas Tree is Complete without a set of MacArthur’s Warblers 

On the car ride to a recent Christmas party, I found myself flipping through pictures on my phone. I came across an interesting picture that I had saved from my ornithology class from the week we covered community structures. It showed a set of colorful birds in a tree — a picture inspired by a foundational study in the 50’s by eminent ecologist Robert MacArthur that addressed the question of how five closely-related bird species with nearly identical ecological requirements could live in the same place — occupy what appeared to be the same niche — without any one of them outcompeting the other. After observing, documenting, and modeling the foraging behaviors, nesting sites, activity times, and feeding zones of the five bird species, he concluded that each species varies  in some degree in how they utilize resources — which not only explains how several nearly-identical species can live together in one place over time, but how a suite of these species is able to perform ecosystem functions that one species, by itself, would not be able to do alone.

Anyway, the birds that MacArthur studied — five species of insect-eating wood warblers — have come to be known as “MacArthur’s Warblers”. The following illustration, by Deborah Kaspari — the same one shown in my ornithology lecture and later saved to my phone —  shows all five species in a conifer tree (source) superimposed on top of one of MacArthur’s original (and quite beautiful) diagrams.

The moment I saw this picture is when I knew I had found the perfect gift for one of my best friends — an avian ecologist: a set of “MacArthur’s Warblers” — beautiful symbols of the intersections between the theoretical and actual, mathematical and ecological, and the creative and scientific. 


The cloth birds were cut out from canvas, stitched on a machine,  stuffed with cotton batting, painted with acrylic paints, and attached to string. Of course, they were waiting to be discovered inside of the Christmas Tree (in their corresponding locations) on Christmas day! 🙂

Of course, making these birds led me to reflect on a few things, and I would like to share a few thoughts here: 

  • Studying birds and their behavior in the field is more than just fun for humans or good for birds.  If done thoroughly and systematically, bird study can give us clues about how all of nature works — shining light on the complex mechanisms, processes of, and relationships in nature.
  • MacArthur’s work reminded me of just how much there is to observe (and record) when watching birds in the field: feeding zones (Do they feed in the treetops? Do they feed close to the ground?), foraging habits (Do they glean? Do they sally?), food choices (Budworms? Flying insects?), most active times, and more.
  • The more thoroughly and systematically you record your observations (e.g., in a field notebook), the better able you (or somebody reading your notes) will be able to find rules and patterns.
  • The study reminded me that so many great discoveries are rooted in simple observation of the natural world. You can observe to enrich yourself, or you can observe  on behalf of someone else (e.g., act as a citizen scientist).
  • There is so much you will never be able to notice or appreciate if you don’t do the background reading first. The more you know about the natural world (through studying, researching, or just plain thinking), the more you realize how full of wonder and mystery it is — and really, some of the most marvelous or mysterious things that occur in nature are also happen to be some of the most abstract (e.g., evolution by natural selection). The great thing is that nature is a kind of rabbit hole — one thing in nature always leads to another; there are always new horizons (“When you try to study something in isolation, you find it hooked to everything else…”). There is still so much to discover.
  • What originally moved me to read more about MacArthur and his Warblers was the artwork by Deborah Kaspari. This was a subtle reminder of the power art has to connect people to science and nature — and more generally, the role that creativity plays in science and the process of discovery, innovation, and problem-solving. “Science and creativity” is a theme I plan to explore more over the course of the next year.

Here’s to a wonder-filled and creative new year.

Further Reading

MacArthur, R. H. (1958). Population ecology of some warblers of northeastern coniferous forests. Ecology39(4), 599-619.

Fretwell, S. D. (1975). The impact of Robert MacArthur on ecologyAnnual Review of Ecology and Systematics6(1), 1-13.

Michael Kaspari. (2008) Knowing Your Warblers: Thoughts on the 50th Anniversary of Macarthur (1958). Bulletin of the Ecological Society of America 89:4, 448-458

DeHaan, R. L. (2011). Teaching creative science thinking. Science, 334(6062), 1499-1500. Chicago


One thought on “Five MacArthur’s Warblers in a Spruce Tree

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s