Fever for Hummingbirds?
a Temperature Theory of Migration
An age-old theory says that some migrating birds arrive in an area when
the average temperature is a specific value. (Robins, for instance, are
said to arrive with 36 degree average temperatures.) Do hummingbirds migrate
northward along with a specific average temperature? Try answering this
1 period + occasional time over several weeks
To test whether hummingbirds arrive along with a specific average temperature,
first find out about when these migrants generally return to your region
each spring. Begin the study about a month before their average arrival
on this map to see a larger one.
The lines and colored bands show places that had the same average temperatures
last week. These will migrate across the continent as temperatures warm
in the spring. (Look at or print a new map each week!)
* Can you find the approximate location
of your hometown? What was its average temperature last week?
* How did that compare with your temperature
records? If they varied, explain why you think they did.
* Name another city or state that had the
same average temperatures at yours did.
* Name another city or state that had higher
(Definition: The lines that connect places with the
same average temperatures are called isotherms.)
your average weekly temperature.
Think about how you could find that — or simply use Our
Average Weekly Temperatures data sheet.
week, ask yourselves, "Have we seen any hummingbirds yet?"
Continue to calculate your average weekly temperature and keep
your eyes peeled! Finally, ask yourselves this question:
What was our average weekly temperature when
hummingbirds showed up in our area?
Journey North's reported hummingbird
sightings, keep track of the dates of the first 10 or so sightings
in one state or province. Then calculate an "average first arrival
date" for hummingbirds in that area. Then look at an average
weekly temperature map; what was the average temperature on the
date the hummers arrived?
the patterns you see on the temperature and migration maps. Do you think
there is a relationship between temperature and hummingbird migration?
of hummingbirds' basic needs could be affected by temperature, and how?
other factors might influence the date of the hummingbirds' arrival?
you see a connection between the arrival of hummingbirds and the appearance
of flowers or insects? What do you think causes them to appear?
Follow Certain Average Temperatures?
Scientists believe that by migrating north as average temperatures
reach about 35 degrees F, ruby-throated hummingbirds push the limit.
At those temperatures, they are just able find insects and flowering
plants that couldn't survive below freezing.
Choose a faraway
Journey North school and see if you can predict the arrival of the first
robins and earthworms in their location. You can find the daily high
and low temperatures
of most cities via these links or in the newspaper. You can also exchange
temperature data online with another class. Make your own classroom connection
or join the Journey North Classroom