When
Will Robins Reach the End of the Trail?
Making
Predictions Using the Plant Hardiness Zone Map
Short-distance migrants, such as American robins, are usually not winter-hardy
enough to stay in northern regions during the cold winter months. Robins
normally winter in the southern U.S., from Washington to California and
into northern Mexico. Unlike hummingbird or oriole migration, robin migration
is tightly connected to weather.When will the robins reach their northernmost
breeding territories this spring? While we wait to hear from our official
Northern Observation Posts (NOPs), you can make your own predictions with
the help of a special map that shows climate bands. In this lesson, you
will consider climate as a factor in robin migration and use the plant
hardiness zone map to predict the FIRST robins and the robin SONG for
Journey North's Northern Observation Posts.
Activity
1.
Click to enlarge the righthand map below and see how Plant Hardiness Zones
divide the United States and Canada into 11 areas. The divisions are based
on a 10 degree Fahrenheit difference in the average annual minimum
temperature. (You may want to discuss these terms to be sure everyone
is clear about their meaning.) For example, the lowest average temperature
in Zone 2 is -50 to -40 degrees Fahrenheit, while the minimum average
temperature in zone 10 is +30 to +40 degrees Fahrenheit. The colors on
the map give a picture of "climate bands" and show how cold
it gets. Growers and gardeners use this information to know which seeds
will grow well in their region. NOTE: When you click to enlarge the map,
the top of the new page includes a link to an enlarged map key. You will
find it helpful to print out the key.
2. Locate
your community on the Plant Hardiness Zone Map and find the minimum temberature
ranges for your zone on the key. Discuss when you see your first robins,
and when you hear the first true songs of males back on territory.
3. Print
out the map of the Northern Observation Posts. Locate them on the Zone
map. Then use the climate information on the Plant Hardiness Zone map
to make predictions about first robins and songs for each of the posts.
Download reproducible recording sheets to help keep track of predictions:
4. Keep an
eye on the weather maps and upcoming robin reports for news from the Northern
Observation Posts to see how your predictions turn out!
Try
This! Discussion
or Journaling Question
- Audubon
officials say their annual Great Backyard Bird Count (done in February
each year) has indicated something interesting: Bird species that usually
live year-round in Canada and the northern U.S. are spreading south.
What are some reasons why this might be happening?
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