Robin Migration Update: April
Today's Report Includes:
Migration News: Robins in the Home Stretch
Things are slowing down! This week’s maps are dramatic signs that
the robins are mostly home and busy establishing territories.
In many place,
Robins have begun nesting:
the past couple of days, American Robins have been observed by our naturalists
here at the outdoor school with nesting materials in their bills.”
(April 13, Sonora, CA)
a robin sitting on a nest with 2 eggs. There are many other signs of
nestbuilding all through the yard.” (April 22, Clarksburg, PA)
robin has built a nest in the wreath on our front door and as of tonight
has laid two eggs. We really want her to be able to hatch the eggs and
for the birds to be okay. We hope the opening and closing of our door
now and then will not disturb them too much…” (April 16,
Highlands Ranch, CO)
on in those nests? You'll find out in this week's report!
Eggstra! The Story of Robin Eggs
The main purpose of a robin's life is to make more robins. Migration,
territory, courtship, nest building, egg laying, incubation, and care
of the young--all are parts of the breeding cycle. These activities happen
so robins can pass their genes on to new generations. Robins instinctively
know the best ways to accomplish that. YOU may not know the answers to
all these questions, but robins do:
- Why is
it important for mother robin to keep her brood patch hidden when she's
not sitting on eggs?
- Why do
you think most birds lay their eggs in the morning rather than in the
afternoon or evening?
- Why do
you think four is the best size for robin clutches?
- Can you
think of a reason why robins' eggs might be blue?
- What reasons
can you can think of to explain why robins time egg incubation different
from hawks and owls?
Curious? Find the answers here as you read the story behind those little
Robin Cam and Journaling Questions
At Upland Hills School in Oxford, Michigan, a pair of robins nested on
a ladder in a geodesic dome greenhouse being constructed by students.
The students at the school made a wonderful compromise so they could continue
to build the dome without disturbing the robins. Meanwhile, one student
studying the babies produced a video showing the baby robins at every
stage from egg to fledging. Upland
Hills School Nest Cam video clips bring the nesting process to life!
Watch video footage of the mother robin incubating her eggs:
the video clips of (a) the first baby to hatch; (b) one of its first meals,
and (c) how many brothers and sisters hatch out.
the videos, how will you answer these questions in your science journal?
- What do
you think made the mother robin choose this nesting spot, on a ladder
inside a partly-finished geodesic dome, for her nest site?
- Why does
the mother wiggle back and forth as she starts incubating? Why don't
the eggs break under her?
- What is
the mother feeding these tiny nestlings?
- Why does
the female open her beak when the male flies in?
- Why doesn't
the male feed the babies?
and Clean! Photo Julie Brophy
Scoop on Poop: Link to Lesson
Take a close look at this robin's nest after the babies have fledged.
Would you expect it to be this clean? Baby robins remain in their nest
for about 13 days. Just about every time the nestlings gulp down some
food, they poop. Let's see--that's 13 days x 4 babies x 356 insects and
worms on average each day--that's a LOT of poop! How on earth do robins
keep their nest clean? Find out here:
Survivors: Challenge Question #9
Whew! Now you know that building nests, incubating eggs and feeding babies
is a lot of work. Last time you read Be
Mine! Robins and Their Mates. We said that one scientific study showed
that about 75% of all fledgling robins die before November their first year.
Of those that survive that long, about half die before the next November.
About half of all 2-year-old robins die each year, and about half of all
robins of every other age die each year, too. If this is true, what’s
the answer to...
Challenge Question #9:
"If 200 robins were fledged in a town one year, how many of the
fledglings would be alive in November? How many would be alive the following
November? How many would be alive the November after that? How many
years would it be before all these fledglings had probably died?"
(To respond to this question, please follow the instructions
in Anchorage: Early Bird Contest Results
Back in our March 2 report, we asked Challenge Question #4 to launch our
Early Bird Contest: “When do you think the first robin will be spotted
in Anchorage, Alaska (61.22 N, 149.90 W)?”
The long-awaited official word came on April 22 with this news from Sand
Lake Elementary teacher teacher Mike Sterling: “Robins
were seen in Anchorage on April 12. The first was pretty isolated, though
now the tops of every big spruce around have territorial males proclaiming
their sovereignty over all they see. The geese and ducks are here, too.
We even saw a flock of snow geese in the schoolyard last week. Woo! Lots
of snow still on the ground, though low temperatures are not dropping
much below freezing.
“The first song I heard was on April 12 as I rode my bicycle in
to school. The kids in class have noticed robins in their yards every
day since them. Now there are robins all over the place.”
Hooray! No one had a bulls-eye on the date, but Iselin (NJ) Middle School
7th graders Najea, Brett, Melissa F, and Richard were
the closest to winning the contest with their April 7 prediction. Congratulations!
Thanks to Javed, Gabriel, Justin M, Shivam, Eliott, Om, Mark,
Rima, Sinnamon, Jennifer, Mihir, Josh, Nick S, John and Lukasz for
entering the contest with their predictions too!
From the Northern Observation Posts: Only a Few Still
At Sterling, AK, Elementary School, Sara Heppner said,
“This morning (April 21) a robin greeted me from the top of a tree
in my yard. He was singing loudly and happily, maybe because for once
it wasn't snowing or raining on him!”
How many NOPs have yet to see their first robin? Who is still waiting
to hear the first song? What’s the weather like? View the latest
comments of our NOPs and the charts that show when NOP robins first appeared
and when they first sang:
curious about wintry weather in parts of Alaska and Canada, take a look
at this fascinating Web site:
Temps and Robins: Compare This Week’s Isotherm
Were YOUR robins home with the 37-degree isotherm? Maybe you are still
keeping track of the isotherms in your area. Compare the latest map with
the one from last time:
- Have robin
movements shown a pattern similar to the change in the 37-degree isotherm?
(Compare with the migration maps at the top of the Web report.)
- Do the
changes in where the 37-degree isotherm is correspond to where robins
have been singing?
to calculate the isotherm in YOUR region, see:
Stuff: Discussion of Challenge Question #8
Last time you learned
about robin nesting behavior and we gave you some robin weights. We asked:
“Which are heavier: winter robins or breeding robins? Which loses
more weight in spring: male or female robins? Why do you think this is?”
A look at the figures showed you that winter robins were heavier than breeding
robins, and females lose more weight in spring than males do. This is all
because robins are large enough that the eggs are a fairly small percentage
of a female’s weight. Females wait to head north, so they don’t
need as much body fat as males do. Males migrate early, when weather is
colder; when they arrive, their larger size is helpful for them in claiming
and defending a territory. Thus, males have an advantage if they don’t
lose as much body weight. (Isn't
Mother Nature wise?)
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The FINAL Robin Migration Update Will Be Posted on May 11, 2004.
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