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Hummingbird
Migration Update:
April
7, 2005
Today's Report Includes:
- Rufous Hummingbirds Continue Early Migration: Challenge Question #6
- Rubythroats Steadily Marching Up the Map
- Teacher Tip: Scientists "Sample" Data. You Can Too!
- Try This! Compare, Color, Predict
- Digging Into Data: Challenge Question #7
- Everybody Out! Males Establishing Territories
- Feeders Up?
- A Sappy Subject: Discussion of Challenge Question #4
- Timing is Everything: Discussion of Challenge Question #5
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 Distribution Map |
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| Rufous
Most
data courtesy of Mike Patterson, |
Ruby-throated
Most
data courtesy of Lanny Chambers, |
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| Rufous female at feeder. Photo Laura Erickson |
Rufous Hummingbirds Continue Early Migration: CQ #6
Mike Patterson sends us news on the Rufous migration from his study site at Oregon's Neawanna Wetland Ecological Observatory. This week Mike has the analysis we’ve all been waiting for. You may remember the Challenge Question where you figured out day 70 (the peak in normal years) would be March 12. Day 90 (when the main movement west of the Cascade Mountain Crest has normally happened) would be April 1. Mike believes that he has now received the majority of reports from WEST of the Oregon Cascade Mountain range. (See Mike's histogram of that data.) That means we can start looking at how 2005 compares with past years for the Rufous hummingbird migration. Here’s Mike’s analysis:
There is no doubt that the leading edge of the 2005 arrival front ran early this year. Most coastal observers from Oregon to Alaska reported arrivals much earlier than average (around 7-8 days); many claimed new records. On the other hand, the peak movement, which includes interior valley reports, was only slightly ahead of average (about 4 days). All in all, the migration looked a lot like the early migration of 2003, though more concentrated around the median and fading earlier. The 2003 migration was complicated by a west side cold snap in early March. This year temperatures were at or slightly above normal in March, though very wet in the last half.
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Surprise! What kind of bird is Mike holding? |
Mike ends his report like this: "Of course, none of this provides any explanation for why migration begins earlier some years and later others. Presumably the answer to that question is lying somewhere on the winter grounds.” That brings us to:
Challenge Question #6:
"What variables on the wintering grounds might influence an early Rufous Hummingbird's departure? List as many variables as you can think of.”
(To respond to this question, please follow the instructions
below.)
Rubythroats Steadily Marching Up the Map
Wow! Nearly 70 sightings fill in our map this week, showing more abundance among earlier arrivals, and spreading the distribution just a little farther than last time. Where do you see the cluster of data points on this week’s ruby-throated hummingbird map? In how many new states have ruby-throated hummingbirds been reported since last time? Look at their range map to see where they’re heading. How close are YOUR hummers?
Journaling Question:
What do you think keeps each species of hummingbird within their
distribution area as shown on the range map above?
Teacher Tip: Scientists "Sample" Data. You Can Too!
As hummingbird data flies in from observers each spring, teachers often feel awash in data. You may want to reduce the number of data points students plot on their migration maps. This activity introduces the mathematical idea of choosing random samples--and simplifies mapping! Use our idea of a candy bar to sweeten interest, and take advantage of lesson adaptations for both older and younger students.
Try This! Compare, Color, Predict
Do you see a beautiful pattern emerging when you compare the maps? Enjoy the colors!
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Ruby-throated
map 1 week ago
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Compare
with this week's map.
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Try This! Get out your crayons and match colors to those on the map legend: white, yellow, gold, orange, rust, red, pink. Next, lay a piece of tracing paper over the map. Use your crayons to color in the colored bands of white, yellow, and gold on the tracing paper. Extend the gold band to where you think migrant ruby-throats will appear up to April 11 (to correspond with dates/colors on the map legend). Then color an orange band where you predict they’ll arrive between April 12 and 25, and so on for the other dates/colors on the map legend. As the weeks pass, compare your colored map with the actual map in each update.
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Remember: The more sightings we have, the more accurate the picture of migration will be. That means: report your hummers the minute you see them. (Remember, the range map showing breeding and wintering areas for these species could only be created over time thanks to people like us who report their sightings!)
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Lanny Chambers, Journey North's Ruby-throated Hummingbird Expert and creator of Hummingbirds.net |
Digging Into Data: Challenge Question #7
Scientists can learn a lot from faithful records kept by citizen observers over many years. Now it's your turn to be the scientist and see what you can learn. Today we share 10 years of data sent by Lanny Chambers, our Ruby-throated hummingbird expert. Lanny has yet to see his first hummer of 2005, but you might be curious: When did Lanny's all-time earliest hummer arrive? His latest? What was the range of dates for hummer arrivals? What was the median date? Find those definitions, helpful directions, and Lanny's data here:
Then come back and answer
Challenge Question #7:
"When do you think Lanny's first hummingbird will arrive in 2005? What
is the range and what is the median of Lanny Chambers's first
arrival dates for Ruby-throated hummingbirds in St. Louis, Missouri?"
(To respond to this question, please follow the instructions
below.)
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Approximately
how wide is this hummingbird nest?
Photo Dorothy Edgington |
Male hummingbirds usually arrive on the breeding grounds way ahead of the females. They start to establish their territories. This is very serious business! The males look for areas with lots of nectar-rich flowers and with perches from which they can survey their domain. The size of a hummer's territory varies with the number of flowering plants and the amount of nectar those plants will provide. An average territory is about 1/4 of an acre. (That’s about 1/4 the size of a football field.) Any hummingbird that enters the territory, whether male or female, gets chased. And if the flowers in his territory finish blooming, the male knows what to do: he simply changes his territory to another spot with more flowers.
In order to have Ruby-throated hummingbirds in the future, hummers living today have to reproduce. This involves a LOT of critical steps, starting with territorial defense. Do males share the responsibilities for nesting and raising babies? What’s the most important job that a male hummingbird does? How many times in one summer does a hummingbird lay eggs and raise babies? How many days does a mother hummingbird sit on the eggs before they hatch? How long before the babies leave the nest? How do the babies compare to their mother in weight when they leave the nest? You’ll find out here:
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Teacher
Tip
Before you begin, introduce the phrase Nesting Phenology. Invite students
to scan the subheadings in the reading selection: Territorial Defense, Nest Building,
Egg Laying, Incubating Eggs, Brooding and Feeding Nestlings, and Taking Care
of Fledglings. Ask students: Based on the headings, what do you think "Nesting
Phenology" means? What will the focus of this reading selection be? What
kinds of facts do you think will be revealed in this article? (Scanning
the Text for Clues)
Besides this tip, teachers will find many more strategies to help students read,
revisit, and reflect on this selection in the link to our Reading and Writing
Connections, found at the top of Ruby-throated
Hummingbird Nesting Phenology.
Feeders Up?
Kathy in Roseboro, NC put her feeder up on Saturday, April 2. She saw her first ruby throated on Monday, April 4, 2005. Because it's good to have your hummingbird feeder up one week before the hummers arrive, when should you put up YOUR feeder? Put your feeder up and get your site on the map. Then please report your first hummingbirds the day you see them! Things you need to know:
Unpave the Way for Wildlife Project
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A Sappy Subject: Discussion of Challenge Question
#4
" How do ruby-throated hummingbirds survive when they arrive before any
flowers are blooming?"
Three cheers for Jeremiah, who answered, “The rubythroated hummingbirds
get food from woodpeckers. Let me explain.
Woodpeckers make tiny holes in the trees to draw out sap. The woodpeckers
stay around
or migrate
earlier than the hummingbirds. When the woodpeckers
leave there is still sap slowly coming out of the holes. The hummingbirds
the come through
and use the sap as food and a source of nutrients
until the flowers start to bloom and grow.” To read more about
the sapsucker, the "good
partner" that makes it possible for hummingbirds
to take advantage of tree sap as an important
food source in the spring, see:
Timing is Everything: Discussion of Challenge Question #5
Last time we asked, “Why are Rufous hummingbirds able to start their journey north so much sooner than Ruby-throated hummingbirds? Look at the distribution map above, consider their food, and try to give two reasons or more.”
Notice the geography of the western states, where the first Rufous hummers migrate first along the coast.Temps warm up sooner along the coast than inland, and these milder temps mean earlier plant food. Also, may early insects are ones that spent the winter in the water and emerge in time to feed hungry birds. Rufous hummers have a readier food supply than rubythroats, who must return from the tropics in a long flight over the Gulf of Mexico with no place to stop or feed. The rubythroats go by daylength to return mostly in April, after the danger of coldest winter weather is past, and when their food sources are more likely to be ready. (Also see answer to CQ #4.)
How to Respond to Today's Challenge Questions:
IMPORTANT: Answer only ONE question in each e-mail message.
1. Address
an e-mail message to: jn-challenge-humm@learner.org
2. In the Subject Line of your message write: Challenge
Question #6 (OR #7).
3. In the body of EACH message, give your answer to ONE of the questions
above.
The Next Hummingbird Migration Update Will Be Posted on April 14 (data
only).
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