Average Rubythroat First Arrival Dates
Your enthusiastic students are probably wondering, "When will our
hummingbirds return?" For many years, Journey North has collected
first arrival data from observers across North America. Your young scientists
can use these historic records — and their math skills — to
figure out the mean (average) arrival dates over a span of years. This
can help them make predictions about when they'll see these tiny pollinators
Ask students, When do you think we'll see the first hummingbirds this
year? As students suggest dates ask, What's your reasoning? What
factors do you think might influence when they show up? How could we make
a prediction that's based on real data? If it doesn't come up, let
students know that Journey North has records of when hummingbirds were
first sighted in different locations for the past 8 years.
digging into Journey North's archived records of first hummingbird sightings,
you may want to have students practice calculating mean (average) arrival
dates in one location by using data from Lanny Chambers, a Journey North
observer in St. Louis, MO.
Hand out the Calculating
the Mean student worksheet. If your students have the math skills
to complete the exercise, you can simply give them the list of "dates
of first sighting" from Lanny's data (see Calculating
the Mean: Sample). If they need more support, hand out the Calculating
the Mean: Sample and work through it together.
students to look at sample data from your state or town. Have they collected
hummingbird arrival data from year to year or do they know someone who
has? If not, pull up Journey
North's Archives of sightings. They can use the dropdown boxes in
the lefthand column to view first sightings of rufous and ruby-throated
hummingbirds each month from 1997 to the present. As students work in
small groups to review the data for their state, ask the following questions,
When Hummingbirds Will Return
can you tell from a first glance at the data? (For instance,
"Hummers were reported arriving in the north from March-May,"
"The last three years, they first showed up in our state
in April," "Their arrival dates change from year to
year," and so on.) What questions do you have? How might
we find answers?
can the data help us predict when they might arrive this year?
Let students pursue some of their ideas or suggest using
the Mean student worksheet.
factors might influence when hummingbirds arrive in our area?
If students suggest weather as a factor, challenge them
to compare weather maps from this year or previous years with
the hummers' patterns of arrival. This Graphic
Weather Archive features average temperatures, precipitation,
temperature departure from normal, and other data each month from
you think the hummers will be early or late this year? Explain
your thinking. (Consider having students predict first arrival
dates individually or as a class. This just might motivate your
eagle-eyed observers to pay close attention in the schoolyard
Connections — Journaling and Discussion Questions
factors do you think affected when the hummers arrived this year?
of these do you think influenced hummingbirds directly (e.g., storms)
and which influence them indirectly (e.g., temperatures might affect
availability of nectar and insect food sources).
List all the factors that might cause the data from observers to be
different from year to year. (Review the lesson, You're
the Scientist: Verifying Data Collected by Peers.)
- What general
conclusions can you draw about hummingbirds' arrival in their breeding
do you think scientists value the practice of long-term record keeping?
What types of things can they learn from doing this?