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Robin Migration Update: March 13, 2001
Today's Report Includes:
This Week's Migration Maps and Data
Even though the weather was cold and snowy over the last week, robins are getting
restless. Despite snowy conditions, they arrived in many places. On March 5, a flock
appeared in Portland, ME, at the start of a blizzard!
West Virginia (find it on the maps) seems to have served as a major center for wintering
robins. Several people reported to Journey North about unusually high numbers there
all winter. Many of them are still in their winter flocks, showing little or no sign
of migrating yet, but a few are starting to sing while still in their flocks.
Harbinger of Spring?
Several observers, some in the southeast but some farther north, have asked why we
use robins as a "sign of spring" when they overwinter so far north. Why
do YOU think so?
Challenge Question #12:
"Why do we use robins as a "sign of spring" when they overwinter so
far north?"
(To respond
to this question, please follow the instructions below.)
Where Are the Robins? And Why?
From Brookfield, NS came this report: "You never know what a classic nor'easter
winter storm can blow in! We just had 2 days off school and had a pleasant but sad
surprise to see a lone male robin hopping around in the snowdrifts. We immediately
cut some apples in half to provide the robin with some well deserved energy food
for surviving the trip north to Nova Scotia!"
And from Burlington, VT: "It was mid afternoon and the blizzard had receded.
I heard the familiar song of the robin. I could not locate it in the trees. You must
know there was about 22 inches of snow on the ground."
In 2000, robin migration was in full swing by the end of February. But this year
it's different. Even though in some areas robins have been heard singing, they aren't
yet making their big push north. The maps below give you big clues as to the reasons
why.
You can see that February's temperatures were colder than normal in much of the area
where robins breed, and where few remain during the winter. Although it was warmer
than normal in much of the southeast where robins winter, you can see from the animated
snow map that the weather patterns are still not spring-like enough for robins to
push north. The robins would have to dig through snow and frozen ground to get their
worms! We'll keep watching and waiting as the snow line recedes north. Please tell
us when you see YOUR first robin, and when you hear your first robin song!
Announcing Journey North's 2001 Early
Bird Contest!
How long will it take robins to reach the end of the road? Once again this spring,
students at Sand Lake School in Anchorage, Alaska will officiate our annual Early
Bird Contest, and you're invited to predict when the first robins will be seen in
Anchorage. To enter the contest, simply answer this question:
Challenge Question #13:
"When do you think the first robin will be spotted in Anchorage, Alaska (61.22N
149.90W)?"
(To respond
to this question, please follow the instructions below.)
The Outlook From Anchorage
Because Sand Lake students were on break when this report was being written, teacher
Mike Sterling wrote to provide these clues about their winter to aid your predictions:
Dear Journey North,
The early robins may return to a very different place than they left last summer.
First off, they'll be returning to South-central Alaska after the warmest winter
I've seen in the 20 years I've lived here. Low temperatures in our neck of the woods
haven't dropped below zero since February of LAST year! And WINDY? We who live on
the Anchorage Hillside, nestled smack-dab against the Chugach Mountains, measure
the intensity of a winter by the number of sleepless nights it serves up. We're kept
awake by the warm, windy storms we call chinooks that funnel out of Prince William
Sound. Only rarely have we gone two weeks this winter without spending at least one
night listening to windows rattling.
The robins will for sure be returning to a very dry place. Early ice storms and scant
snowfall led to the cancellation of the World Sled Dog Championships in February,
for instance. The lack of snowcover even in he interior is making the Iditarod a
grueling experience for everybody. This lack of snowcover is worrisome--enough for
me to make a prediction: you'll be hearing about Alaska in May--and it won't be because
the robins returned.
Over the last decade a boom in the spruce bark beetle population decimated millions
of acres of mature spruce forest in South-central Alaska. The dry dead trees are
torches waiting for any excuse to burn. This year's thin snowcover is guaranteed
to melt quickly, and the icy ground will absorb no fire-retarding moisture. Opportunistic
grasses growing in the sunny spots beneath the needle-less spruce will be like tinder.
If we have a relatively dry April and May, the wildfire danger in south central Alaska
will be extreme. Should a fire break out this spring the robins will return to a
very charred south-central Alaska.
Sincerely,
Mr. Sterling
How Many Songs? Discussion of Challenge Question
#7
We asked: "Counting the first spring song--and all the
times your backyard robin sings until the end of the season--how many times do you
think your robin will repeat its song? (In your answer, explain how you arrived at
your estimate.)"
We heard from two groups of students who calculated their estimates in different
ways. Iselin Middle School 7th graders said if a robin sings at least once a day
during each day of spring, which is March 20 to June 21, it would sing 93 times.
Students in Ms. Lane's class guessed a robin sings about 20 times a day for a six-month
season, which is about 3,600 times a season.
Our robin expert, Laura Erickson, was impressed with the math skills of both classes.
She says this question may have sounded simple, but was much trickier than anyone
realized. She has some pointers to help.
First, it's easy to underestimate just how much a territorial robin sings. When Laura
was in college and sometimes stayed up all night doing homework, she remembers many
nights when a robin near a streetlight sang all night long. During the time the nest
is under construction and the female is incubating eggs, male robins sing a LOT.
In the central states and southeastern Canada, robins may nest as many as four times
a season; on average in the east, a robin population is involved in nesting behaviors
for about 120 days each year. Males sing the most when they first arrive through
while the female is incubating the first brood, and then have big spurts while she's
incubating later broods. Even during singing lulls he usually sings a lot before
dawn and just after sunset just about every single day for these 120 days. Laura's
best guess is that he spends about 60 days singing a lot, and 60 days singing less
often.
But how many songs does he produce each day? Laura says this is where it gets REALLY
tricky! Her best guess is that robins sing about 13,000 songs every day during the
time when robins are singing a lot, and about 6,500 a day during the slower times.
This means a robin may sing a total of about 780,000 songs during their heavy song
periods and 390,000 songs during the slower days, for a total of 1,170,000 songs!
She decided to round that down to a million songs. But that's still a LOT of singing!
Now it's your turn to conduct a robin song study. Everything you
need to know is in the lesson below. You'll also find the data Laura used to make
her guess, and why scientists have more trouble counting robin songs than songs of
other species. See:
Still feels like Winter: Discussion of Challenge
Question #8
Challenge Question #8 asked you to answer: "Which would
be worse for robins in March: a blizzard dumping over a foot of snow, with temperatures
dropping below zero, or an ice storm dropping a half-inch of sleet, with temperatures
in the upper twenties? Explain your answer."
It sounds like a lot of discussion took place over this answer! Brian, Clively, Noel,
and Vincent from grade 7 at Iselin Middle School said their group was split. Grade
five students from Tom Longboat P.S. in Scarborough, Ontario were more certain: "We
think the ice-storm would be worse because the robins would have more difficulty
finding a food source when it is covered with ice. Also sleet would be more difficult
for a robin because the snow wouldn't stick to its feathers, but the ice might, making
it difficult for them to fly."
Good thinking, students! The ice storm would be MUCH worse for robins! When temperatures
drop low in late winter and early spring, robins forget all about earthworms and
eat berries and old crabapples. That sleet would coat the tree branches, and the
coat of ice would make it hard for them to get the berries. Also, sleet sticks to
bird feathers much more firmly than snow does. If a robin's feathers get plastered
down with a layer of icy rain, it could easily succumb to hypothermia.
Robins can easily shake off any snow falling on their feathers. Since robins won't
be feeding on the ground anyway, a foot of snow there wouldn't affect them much,
and not nearly that much snow would collect on berry and apple tree branches. Snow
that collected on the branches would drop off when robins alighted on the branches,
so they'd be able to find food. Food is THE most critical need a bird has in cold
weather.
Food or Shelter? Answer to Challenge Question
#9
We asked: "In cold weather, which is more important to a robin: food or shelter?"
Students at TR.Leger School; Ms. Sheer's Fourth Grade at Glenwood School, Chapel
Hill, NC; Tom Longboat P.S. in Scarborough, Ontario; and Iselin Middle School Grade
7 all agreed that food is more important than shelter. Why? Food fuels the robin's
metabolism, giving it the fat and energy to feed, move, and survive.
Seasonal Behaviors: Discussion of Challenge
Question # 10
Last time we talked about robin behaviors reported by Journey North observers. We
asked, "Which behaviors listed below would you NOT see
during the breeding season? Explain."
These sightings of robins in groups are winter observations:
- 10 to 20 robins in every tree
- sitting evenly spaced about 3 feet apart
- flying in large flocks overhead
Why? Robins would NEVER be seen in daytime groups during the breeding season, when
they're defending nesting territories. However, in "The American Robin"
(Copyright 1999), Roland Wauer points out something unusual about robins: Male robins
are known to form overnight roosts year-round, even in spring when they are defending
their nesting territory during all the daylight hours. No other songbird does this
unusual behavior.
Next, the feeding observations. Observations like these wouldn't be typical in the
breeding season:
- looking for rosehips on rose bushes
- eating the dried leftovers from orchards and grape arbors
- searching for any berries that remained on sumac and mountain ash
- flocks of robins eating berries off the pyracantha or firethorn bushes
Why? It all boils down to this: During spring and summer, robins forage mostly
on the ground in places where the soil is rich and moist, where earthworms and insects
thrive. In fall and winter they feed mostly on berries and other fruit on a wide
variety of shrubs, trees, and vines.
Try This!
Over the next several months, create a list of robin behaviors you observe. See if
you can separate the observations into (1) spring and summer behaviors and (2) fall
and winter behaviors. How did you reach your conclusions? Include your comments.
Which behaviors seem most difficult to categorize for season? Take note of that,
too, and gather more information to help you figure it out.
Isotherm: Discussion of Challenge Question
#11
"Why do you think it would make sense for robins to migrate
with the 36-degree isotherm?"
It takes warmth to melt the snow and start thawing the ground deep enough so that
worms can come near the top; a robin can't pull worms out of the soil if they are
deeper down than its bill can reach. Remember that 36-38 degrees F. is the AVERAGE.
This is about what the daily temperature average must be for the soil to thaw down
far enough to reach the worms.
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-robin@learner.org
2. In the Subject Line of your message write: Challenge Question #12 (or #13).
3. In the body of each message, answer ONE of the questions above.
Please Report the First Robin you SEE, the first robin you HEAR singing, and other
interesting robin observations. Your reports will be incorporated into these Robin
Migration Updates.
The Next Robin Migration Update Will be Posted on March 20, 2001.
Copyright 2001 Journey North. All Rights Reserved. Please send
all questions, comments, and suggestions to our feedback form
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