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Hummingbird
Migration Update: May 5, 2005
Today's Report Includes:
- Latest Hummingbird Maps and Data
- Rufous Reach the Edges of Their Range
- Rubythroats Stalled in Northward Progress
- You Say They’re Hungry!
- Feeding As Fast As They Can
- Journey North for Kids: Peek Inside the Hummer Nest!
- Try This! The Big Chase
- Ladies Second: Discussion of Challenge Question #8
- Year-End Evaluation: Please Share Your Thoughts!
Latest Hummingbird Maps and Data
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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, |
Rufous Reach the Edges of Their Range
Last week Rufous Hummingbirds stormed into Idaho. This week brought less
action. Mike Patterson offers thoughts from his “Hummingbirds
and Flowers” study site at Oregon’s Neawanna Wetland Ecological
Observatory: “With the appearances in Seldovia, AK, Alberta and
Montana, Rufous Hummingbirds have pretty much reached the edges of
their expected range. Both Montana records appear to be running early.” What
do you predict you’ll see on next week’s map?
For more information on tracking Rufous Hummingbirds see:
Rubythroats Stalled in Northward Progress
Meanwhile, the northward march of ruby-throated hummers seemed stalled. Where do you see the newest data points? Next, take a look at the temperature map below. Use the map legend to describe how last week’s temperatures compared to average temps in the breeding range of our hummingbirds. How do you think this influenced migration progress in the past week? In how many states and provinces do hummingbirds still need to arrive to fill out their breeding range? Stay tuned! Migration is full of surprises.
You Say They’re Hungry!
The recent sightings below are reminders that hummers arrive HUNGRY, and they know what they're looking for. You'll want to make sure your feeders are up, clean, and full! As you read this sampling of comments, also watch for clues that weather played in the movement of hummers the past week.
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Female Rufous. Laura Erickson |
Male Rubythroat |
May 1: “First Ruby-throated Hummer appeared at one of my feeders at 11:15 a.m. Sunday May 1, 2005.” Ottumwa, IA
May 2: "Late this year by about two weeks due to cold weather. WHOO!!! Here we go!! I LOVE these little beauties!!!" Aaronsburg, PA
April 27: “Finally! I usually see my first hummer around April 24th. I have seen them as late as 4-28. I am so excited! My feeders have been ready and continually refreshed since 4-18.” Long Level, PA
April 28: First of the season. A male appeared at the feeder among several red potted flowers. Then a female. Several other visits within minutes.” Frankfort, KY
April 28: Today while I was working on the front porch the first male Ruby-throated hummingbird "buzzed" me. I was sitting on the concrete and he flew right at eye level, just a few feet away, as if to say "HEY! I'm back !!" Two of my feeders have been out for a few weeks now. Glouster, OH
April 29: “This little guy was feeding at our feeder at about 7:45 pm. We have never had a hummingbird here earlier than May 5th. That was last year.” Innisfil, ON
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Photo Jackie Allison |
It sounds like these hummers were all taking time out for nectar. You might think "time out for nectar" means stopping to drink more nectar. But for Rufous hummingbirds, it means taking a break from feeding! That seems strange when this tiny, warm-blooded bird needs such a tremendous energy intake to maintain its high body temperature. Actually, a hummer makes only 14 to 18 feeding flights per hour, each taking less than a minute. For the rest of the hour, it perches quietly. Why? What’s happening?
Ecologists William Karasov, Duong Phan, Jared Diamond, and Lynn Carpenter were curious. They did a clever experiment and discovered the answer. The ecologists used radioactive isotopes as tracers to follow what happens to the nectar. They found that the hummers pass nectar through their digestive tracts very rapidly. The average time is less than an hour. In this short time, they are able to extract about 97 percent of the sugars from the nectar. So why do they sit around "doing nothing" when they could be sipping more nectar? The hummers don't have room for any more nectar until the crop is partly drained! (The crop is the part of their digestive system that stores food right after it is taken in.) As the hummers perch quietly, they are emptying their crops. The birds apparently wait until the crop is about half empty, which takes about four minutes, before foraging again. Next time you're lucky enough to see a hummingbird perch, you'll know it isn't "doing nothing!"
Try This!
If hummingbirds make feeding flights 14 to 18 times every hour during daylight, and each feeding flight lasts less than a minute, about how much time in each daylight hour do hummers feed?
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Photo Dorothy Edgington |
Journey North for Kids: Peek Inside the Hummer Nest!
If you could compare a hummingbird’s nest with a coin, which coin
would it be? Our photo study shows you that, and many more amazing sights.
You’ll love peeking into the nest and seeing the babies grow. There’s
plenty of time for your questions and answers, too:
Try This! The Big Chase
“First hummer for this year at kitchen window feeder about 3 PM. April 30 With 3 feeders on windows that aren't in sight of each other, there are still disputes over them,” writes an observer in Park Forest, IL. It’s more proof that hummingbirds are territorial 24/7 and 365 days a year. In fact, any male or female hummingbird that enters another’s territory gets chased. It doesn’t even have to be a REAL hummer, according to naturalist Sarah Dalton. She told us about hanging a brightly colored stained glass hummingbird by the feeder one day. “Hummer #1 showed up, tried to drive it off, and set it swinging,” said Sarah. “Hummer #2 showed up as if to say ‘What are YOU doing here?’ and they both got into it. Later one of the birds returned and tried again to drive the stained glass hummer away. When it found it wouldn’t go, the hummer finally ended up sitting on the stained glass bird’s back, trying to peck its eyes out!”
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Ladies Second: Discussion of Challenge Question #8
Last time Mike Patterson told us that reports of females arriving
ahead of males are unusual, but seem to occur more in years when
the migration
is delayed. We wondered how you’d answer the two questions below:
(1) Why does it make sense for females to arrive after males?
“It makes sense for males to arrive before females because the
female comes after the male establishes his territory and picks the
site for the nest,” said Iselin Middle School 7th graders Krishna,
Ammie, Maninder, Yasmin, Jharna, Joe, Jasmit, and Oliver.
Yes! Our expert Laura Erickson reminds us why: “The most successful
males are those who get the best territories, and males have the best
chance
of getting
a territory when they arrive first. So under most circumstances males
arrive first. Females do best when they can be certain that there will
be food available. So they generally arrive later than males, when
the weather is more likely to be mild and more flowers and insect food
are
likely to be available.”
(2) Why might females arrive ahead of males in years when the migration
is delayed?
“The females might arrive ahead of males because they are preparing to
go and the biological clock is telling the female that she has to go.
Therefore, the female arrives ahead of the males,” said Iselin
Middle School 7th graders Ruchika, Hillary, Nikita and Shannon.
Krishna, Ammie, Maninder, Yasmin, Jharna, Joe, Jasmit, and Oliver thought “If
the migration is delayed, it means the weather is bad. Therefore, the
male will not have had time to establish his territory. The males may
be late, but the females aren't. The female will arrive before the
male because she left on time without the male having a head start.
Nice job,
all of you.
Laura Erickson gives us more to think about: “It's hard
to be certain about this. Females may be more set on a calendar schedule,
with their bodies preparing for nest building and egg laying at a precise
day length, and so they may not be able to either speed up OR slow
down the way males can. But really, only the birds know for certain,
and they're
not talking!”
THANK YOU, students, for a season of wonderful contributions in thinking
about questions with no easy answers!
Year-End Evaluation: Please Share Your Thoughts
Please take a few minutes to share your suggestions and comments in our Year-End Evaluation. The information readers provide is critical for planning new initiatives and for improving Journey North. We'd appreciate your help. THANK YOU!
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Journey
North |
The FINAL Hummingbird Migration Update (Data Only) Will Be Posted on May 12. Thanks for joining us in helping to make a safer, better journey north for the world’s tiniest, feistiest fliers!
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