• Look at the orange dots on today's Journey North map and then look at this temperature map.
• Some people say the leading edge of a hummingbird migration follows a certain temperature band. If that is true, what temperature range do you think ruby-throated hummingbirds follow?
• Why do you think they do it? (See answer, below map.)

Maximum Temperatures - March 29 and 30, 2008

Why Follow Certain 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.