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Signs of Spring: March 27, 2000
Today's Update Includes:
- Just Like Magic
- Capture Leaf-Out in "Fifteen Days of Spring!"
- Reminder! Ice-Out Contest Continues: Challenge Question #10
- On Thin Ice: Response to Challenge Question #5
- Where's the Ice? Discussion of Challenge Question #7
- Lake Minnetonka: Results of Challenge Question #8
- Some Birrrrrrds Like It Cooler: Discussion
of Challenge Question #9
Just Like Magic
Take a look at the bare branches outside
your window. Consider what's about to occur. Read naturalist and author Annie Dillard's description of leaf-out
below, then see if you can capture the magic in your own words. (If you like what you write, you're invited to
send it to us at: jnorth@learner.org) "There's a real power here. It's amazing that trees can turn gravel and bitter salts into these soft-lipped lobes, as if I were to bite down on a granite slab and start to swell, bud, and flower. Trees seem to do their feats so effortlessly. A big elm in a single season might make as many as six million leaves, wholly intricate, without budging an inch; I couldn't make one."
From the book Pilgrim at Tinker Creek, by Annie Dillard
Today's report wraps up winter and looks to spring with an artful activity for a snapshot in time.
Capture Leaf-Out in "Fifteen Days of Spring!"
With this week's vernal equinox, spring arrived in the Northern Hemisphere. Want a beautiful keepsake of spring 2000? Journey North artist Mary Hosier has a terrific activity for you! She leads you through the process of creating a time line book to capture the leaf-out of schoolyard trees as it happens before your eyes. Working with paints and fresh leaves or pressed leaves gathered as your chosen tree leafs out, you'll make a fold-out time line book. Then personalize pages with notes from your JN field notebooks: temperature, weather conditions, sensory observations, other phenology tidbits, and facts you find in field guides. You'll end up with an artful time-line of your first spring of the new century! See Mary's illustrated instructions at:
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Reminder! Ice-Out Contest Continues!
Even if you're thinking spring and leaf-out, ice still covers parts of the Northern Hemisphere. Remember to send us your predictions for:
Challenge Question #10:
"When do you predict ice-out will occur on the Tanana River in Spring 2000?"
A general rule of thumb is that breakup occurs on the Tanana River about a week after the north-flowing Nenana River flows free. For specific weather information to help you make your guesses for this year, visit:
(To respond to this question, please follow the instructions below.)
On Thin Ice: Response to Challenge Question #5
In our March 6 report announcing the return of red-wing blackbirds, we asked: "Why do you think red-wings return just as marshes are thawing each spring?"
Red-wings eat a lot of insects and other invertebrates and in the spring. Many invertebrates live in the water, so obviously birds can't get these invertebrates unless the ice is melted.
But let's take it a little deeper. During the long winter, some aquatic insects and fish die. If they float
to the top, pieces of their bodies get embedded in the ice. These pieces may start emerging through cracks as the
ice breaks up. Some plant matter also gets stuck in the ice. Red-wings, crows, and grackles often walk on the surface
of the ice as it is breaking up and feast on this "detritus" before it sinks to the bottom of the water
when the ice disappears.
Where's the Ice? Discussion of Challenge Question #7
In the News Flash announcing ice-out at Walden Pond, we asked: "When ice-out occurs, what happens to the ice when it melts?"
Ms. Petereit's class sent this reply, which shows that everyone was thinking hard to answer this question!
"We were very divided on this question. Some people think that the ice melts from the edges in toward the middle and some people think the exact opposite. One person thinks that the ice sinks and then melts while others think that the ice breaks apart and melts and still others think that the ice stays and melts in place. Most people agreed that the ice first becomes very slushy on top before it melts." (cpetereit@whitemountains.k12.nh.us)
From Jim Gilbert, here's more: It doesn't sink, because ice is lighter than water. (That's why ice cubes float in your glass of water or soda.) Ice begins its retreat from the shore, creating a belt of open water around the lake or pond. Then a wide band of ice beyond the open water becomes soft and mushy while the rest of the ice cover darkens. Finally a strong wind moves the main ice sheet, which weakens and begins to break along great stretches. Ice crystals on the edges of these floating sheets melt rapidly in the water, which is above freezing temperature. Then one day, the wind sweeps the remaining ice sheets ashore. These sheets are composed of long six-sided ice crystals whose strength comes from being side-by-side with other crystals until they're moved and crushed by the breaking up of the sheets.
Lake Minnetonka: Results of Challenge Question #8
"When do you predict ice-out will occur on Lake Minnetonka in Spring 2000?"
Surprise! Lake Minnetonka's March 18 ice-out beat the email messages you sent with your predictions! Even so, we want to thank the classes of Mrs. Ference (EFerence@ByramSchools.k12.nj.us) and Ms. Petereit (cpetereit@whitemountains.k12.nh.us) for their April predictions.
Mrs. Ference's class, who predicted April 10, wrote: "We were amazed to learn that Walden Pond in MA ice-out happened the same day as our Lake Lackawana did here in Byram Township, NJ on March 9th."
Some Birrrrrrds Like It Cooler: Discussion of Challenge Question #9
We asked, "How can Tree Swallows survive colder weather than other species?" (We hinted that the answer has partly to do with their sleeping habitat, and partly to do with their guts.)
Hooray for Ms. Petereit's class (cpetereit@whitemountains.k12.nh.us) and Katie Vernali(KitKat2V@aol.com), who both replied that Tree Swallows can survive colder temperatures because they sleep in more protected areas to prevent them from getting cold. Ms. Petereit's students added, "We also thought that maybe they had longer intestines or something like that to digest their food better in order to get more energy from their food."
Kristina Anderson thought it had more to do with their eating habits. She added, "Also, they may not mind the cold and stand it more." (blaznbabe4@hotmail.com)
Bird authority Laura Erickson gives us the rest of the story: "Most swallows sleep on branches, but Tree Swallows sleep inside cavities. This shelters them from wind and provides a little insulation to trap their body warmth, so they can stay a little warmer than other swallows on cold nights. Like other swallows, Tree Swallows eat mainly soft-bodied flying insects, which are very easy to digest. But cold-blooded creatures don't fly about when temperatures dip below freezing. Tree Swallows have longer intestines than other swallows so they can digest plant material as well as animals. (Remember: plant tissues have cell walls, which animal tissues don't have.) Tree Swallows can live for many days on berries and some kinds of seeds."
Please Report the Unique "Signs Of Spring" from Your Part of the World!
Your sightings of first frogs, earthworms, emerging leaves, flowing sap,
melting ice--and other spring events will to be incorporated into these
"Signs of Spring" updates.
How to Respond to Today's Challenge Question:
Please answer ONLY ONE question in EACH e-mail message.
1. Address an E-mail message to: jn-challenge-spring@learner.org
2. IMPORTANT: In the Subject Line of your message write: Challenge Question #10.
3. In the body of EACH message, give your answer the question above.
The Next "Signs of Spring" Update Will be Posted on April 10, 2000.
Copyright 2000 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to jn-help@learner.org
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