Hummingbird Migration Update: March 18, 1999
Today's Report Includes:
On Your Mark, Get Set, GO!!
Hummingbirds are on the move! Suddenly Ruby-throats are appearing as far north as Georgia, and lots of Rufous Hummers are turning up as far north as the Canadian border.
Little Birds with Big Hearts
Hummingbirds are tiny! Both Ruby-throats and Rufous Hummers weigh between about 1/10 of an ounce and 1/7 of an ounce. Hummingbirds have the largest RELATIVE heart size of all birds: their hearts weigh about 2.4% of their total body weight. This heart beats about 1200 times every minute!!
Challenge Questions # 4, 5, 6, and 7:
This week's we're going to try more Hummingbird Math
Discussion of Challenge Question # 2
We asked, "Why do you suppose all the sightings of wintering and early migrating hummers cluster along the Gulf Coast, the Mexican Border, or near the Pacific Ocean?"
When hummers fly over the Gulf of Mexico, they're exhausted. It takes time for them to feed and recover before they head north again. Rufous Hummingbirds, which mostly come up through the mainland of Mexico rather than over the Gulf and can feed as they go, stay close to the Pacific Ocean for another reason that also holds eastern hummers near the Gulf. The Gulf and the Pacific Ocean are huge bodies of water that keep nearby land at a steadier, and usually milder, temperature than areas further inland.
Discussion of Challenge Question # 3
We also asked, "Let's say a Ruby-throated Hummingbird fattens up in the Yucatan Peninsula of Mexico, and then lights out over the Gulf of Mexico from Campeche. It flies in a straight line to Galveston, Texas. It can't rest or feed while over the Gulf, and can't soar or glide, so it must beat its wings the whole way. How many times must it flap its wings during that over-water journey?"
LOTS of students pulled out their maps and calculators!
The first trick of the question was figuring out the distance between Campeche and Galveston. We calculated this distance as 725 miles, but depending on your map, you may have come up with a slightly different distance. Using our distance, we figured that it took the hummer 24.1666 hours to complete the flight. We multiplied this times 75 beats per second times 60 seconds per minute times 60 minutes per hour to get 6,524,999 beats altogether.
Mrs. Kreger's and Ms. McNamara's 4th Grade Classes St. Wenceslaus School in New Prague, MN, and third grader Nick in Sterling, Alaska, all came pretty darned close. Remember--this kind of calculation has a pretty wide margin of error. But 6.5 million wingbeats is a LOT of flapping!
The next Hummingbird Migration Update will be posted on April 1, 1999.
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