Skydancing Puzzle
Do Rufous Hummingbirds Really Fly in an Oval?

Do Rufous Hummingbirds really fly in an oval?

Books, including ones written by knowledgeable ornithologists, have stated for many years that the flight pattern of Rufous Hummingbirds forms an oval. Some feature drawings of a Rufous Hummingbird display like the picture to the right. And Journey North science writer Laura Erickson saw what looked like an oval flight display by what looked like a Rufous Hummingbird when she was birding in Ramsey Canyon in Arizona in April, 1982.

But Mike Patterson, who has been carefully watching Rufous Hummingbirds for 20 years in the Oregon and Washington areas, has never seen this oval display. Dr. William Calder is the ornithologist who wrote the Rufous Hummingbird entry in the basic reference used by researchers, the Birds of North America. Dr. Calder has researched the Rufous Hummingbird in the Rocky Mountains for over 20 years. Here's how he describes what he's seen: "After climbing away from female perched low in vegetation, near ground, a male reversed heading as he entered dive, levelling out after passing over female, then emitted a series of 4-5 rip-saw-like dit-dit-dit-deeer with Doppler-like decrease in pitch, followed by 3-4 less audible, dull "plops," presumably made by tail feathers." And David Allen Sibley, author of The Sibley Guide to Birds, shows the display in the same way that Mike Patterson has witnessed it:

Rufous Hummingbird display as shown in David Allen Sibley's The Sibley Guide to Birds

Some Hypotheses About the Oval
If the normal display pattern isn't an oval, but a rise and a J-shaped dive, how might the idea of an oval have gotten started?

Laura Erickson thinks it's possible Rufous Hummingbirds make pairs of rise-and-dive movements in different planes, so from some angles it LOOKS like a complete oval.

Mike Patterson has two hypotheses:
(A) There is an oval territorial display done on the wintering grounds that is different from the breeding display.
B) Some observations or written descriptions of the display haven't been done carefully.

Is it possible that written descriptions of a rise and then a J-dive could have been misinterpreted, and misdrawn as a complete oval? Let's see!

Try This! Drawing from Someone Else's Description
You need two partners and an animal--a classroom pet such as a guinea pig or gerbil, or a squirrel or pigeon outdoors. One partner will be the observer. This person will watch the movements of the animal for five minutes and write down a description of every move. Then the other partner, the transcriber, will use those notes to draw a pattern of the animal's movements. Does the drawing come close to what the observer actually saw?

Back to the Original Question...
Do Rufous Hummingbirds really fly in an oval? Scientists learn the answers to questions like this in two different ways: they make careful observations and experiments on their own, and they read about the careful observations and experiments that others have made. Sometimes errors enter--sometimes an ornithologist makes a mistake in the original observation, sometimes an ornithologist witnesses a unique event and jumps to the conclusion that it's common, and sometimes an ornithologist describes something in an unclear way. Little by little, by publishing their findings, and reading and discussing their work together at professional meetings and more informally, ornithologists learn from one another and build up the body of knowledge we have of birds.

How YOU Can Help the Research
If you live where Rufous Hummingbirds nest, you can help amass the information needed to solve this puzzle. Follow male hummingbirds and watch for them to make this display. Describe what you see carefully. Better yet, take videos of the displays. Send your information to us at Journey North. By documenting a large number of these displays in a large number of places, we can find out

  • if rufous hummingbirds do make the oval display occasionally,
  • if they make the oval display in some places but not in others,
  • or if they virtually never make an oval display.

That's the excitement of science: working together, people are still finding the answers to many questions, and every time we get one answer, we think of more questions!