Making Sense of Robin Migration Maps
A Map-Reading Tutorial: Part 1
The American robin migration is a fascinating but complex study. Here we model a map-reading process to help you understand this migration. You will discover how to scan the data, see patterns, and make predictions. Let's study three American robin migration maps from spring 2007.
Look at this sample winter round-up map.
What do you observe about the locations of the dark triangles?

Did you notice that . . .

1. Robins winter in many places.

2. There are many more sightings in the eastern half of the continent than in the western half.

Why do you think that's true?

  • There really are more robins in the East. Why? Because the western states and provinces (except for those on the coast) get less rainfall. (See for yourself!) The greater amount of moisture in the East means good things for robins: more lakes and rivers for drinking water, more water for fruit-bearing trees, and softer soils where earthworms thrive.
  • Also: There are more Journey North participants in the eastern part of North America.

3. The largest number of robin sightings are along the coasts in the winter. Why do you think that's true?

  • Look at this map of extreme minimum temperatures and this map of extreme maximum temperatures. Do the coasts or the central part of the U.S. appear to have less extreme (more mild) temperatures?
  • What did you just learn about robins and moisture?
  • What did you just learn about the locations of Journey North participants?

Center the map on your computer screen.
Hold a piece of string or a rubber band taut across the screen. Move it to where half the triangles are above it and half are below it. At what latitude is the center of the wintering range of robins in this sample map?

Part 2: Six Weeks Later