Hummingbird Migration Update: March 25, 2003


Today's Report Includes:

• Rufous Hummingbirds Arrive in Alaska!
• Tiny Birds Surviving the Cold: Challenge Question #8
• Amazing Steadiness in Ruby-throat Migration: Challenge Questions #9 and #10
• More Ruby-throat Sightings: Links to Lessons
• Why So Early: Discussion of Challenge Question #6
• Banding Hummingbirds: Discussion of Challenge Question #7

Rufous Hummingbird photo copyright by Jerry Blinn

And in other good news, Mike reports that the first hummingbird arrived in Alaska on March 21 at Ketchikan. This season's Rufous Hummingbird migration has been extraordinarily early, and this first Alaska arrival kept the pattern going. The tiny bird showed up two days earlier than the previous earliest arrival date (3/23/1995), and 11 days earlier than any report since Mike started keeping track.

The northward, coastal migration has been fast, but as Mike notes, " The move eastward was less dramatic. Two weeks of rain and a fairly low snow level in the Cascades has probably contributed to this, but since the eastward movement isn't really due until the first of April, so it's not like it's late or anything."

Rufous Hummingbird Migration Data Migration Map Courtesy of Mike Patterson Neawanna Wetland Ecological Observatory

If YOU see a Rufous Hummingbird in the West, make sure you report it to Mike Patterson. And if you see hummers, make sure you let him know if any flowers are blooming, too!

Rufous Hummingbird scientist Mike Patterson, holds an American Robin. How does holding a robin compare to holding a hummingbird? See Challenge Question #8

Tiny animals do, indeed, have more trouble surviving cold than large birds do. That's because as they get smaller, their body weight goes down much faster than their surface area. So smaller birds, like hummingbirds, lose heat faster than larger birds. To learn more about this, see:

• Hummidees, Jaybins, and Ravoons: A Lesson About Volume, Surface Area and Body Heat

Interestingly, although most of the many hummimgbird species live in tropical areas, many of them live high in mountains where temperatures often drop below freezing! Look at this table and think about what the numbers mean. Then answer the following questions.

Challenge Question #8:
"How many breeding male Rufous Hummingbirds would it take to balance one breeding male robin?"

(To respond to this question, please follow the instructions below.)

Aren't the numbers in this table fascinating? Why do hummingbirds lose weight in winter, while robins gain weight then? Why are female hummingbirds heavier than males, while female robins are lighter than males? If you want to analyze these numbers more carefully, see:

• Weighty Stuff

After you've studied the map and noticed where the farthest north sightings have been, answer the following:

Challenge Question #9:
"Why do hummingbirds travel faster close to bodies of water than farther away?"

Challenge Question #10:
"Looking at the map, predict when the first hummingbird will be reported in Canada."

(To respond to these questions, please follow the instructions below.)

• A Partnership that Works

Male Ruby-throated Hummingbirds are tinier than females. Why?

Delois Graves in Duncan, Oklahoma, writes on March 24, "Have had feeder up since March 10. This morning we had a hit and then it left. Has not come back yet." Lois's hummingbird may have been headed farther north when it discovered her yard and her feeder. What a nice rest stop for a weary traveler! Her feeder gave it some of the energy it needed to continue its journey north. Is your yard a welcoming place for traveling hummingbirds? Don't forget to

• Unpave the Way for Hummingbirds

And a big thank you to Lanny Chambers, who shares his hummingbird maps and data with us!

1. How many days earlier did each location report hummingbirds?
2. How many sightings this year were LATER than a previous early date?
3. What date did the first Rufous Hummingbird appear in Gig Harbor, Washington, in 2003?
4. What date did the first Rufous Hummingbird appear in Philomath, Oregon, in 2003?
5. Which place had the biggest difference between this year's early date and the previous one?
6. The average is _________________days ahead of past records.

We put the answers here:

• Looking at early hummingbird data

Nancy told us that even though banding usually is a straightforward process, there is always a chance that the tiny bird will fly off, or be stressed so she feels she must release it quickly. If this happens, there is always missing data. But she figures it's better to lose measurement data than to not have a band on the bird. After all, after release, many hummingbirds fly into the trap again. Having a band on ensures that Nancy will know exactly which hummingbird is which, and if one that escaped before measuring gets trapped again, she can always get the measurements then.

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 #8 (OR #9 OR #10)
3. In the body of EACH message, give your answer to ONE of the questions above.

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Please send all questions, comments, and suggestions to jn-help@learner.org