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Signs of Spring Update: April 18, 2003
Today's Report Includes:
- Happy Earth Day, Happy Birthday!
- Natural Laws: Populations and Ecosystems
- Try This! Seasonal Births?
- What's Most Important This Earth Day?
- Sharing the Planet--200,000 More People Every Day: Challenge Question #18
- Humankind: The World's Most Successful Species
- Inequities: Four Billion Have, Two Billion Have Not
- Tip to Teachers: Recommended Reading by Dr. Lincoln Brower
- Current Happenings: Strange Weather as Spring Progresses
- Flowery Math: Discussion of Challenge Question #17
Happy Earth Day, Happy Birthday!
It's BIRTHDAY TIME across the Northern Hemisphere. As spring unfolds, Nature welcomes billions of babies--some of them in your own backyard.
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It's no coincidence that so many baby animals are born in the spring. Reproductive cycles are timed to maximize the chance of survival.
- Baby owls and hawks hatch when receding snows are exposing mice just the right size for their little mouths. By the time the babies are learning to hunt on their own a few weeks after hatching, there are lots of inexperienced other baby animals around to practice on.
- Baby hummingbirds hatch later, when there is an abundance of flowers to provide nectar and tiny insects. Think about how much food a mom and dad need every day just to feed themselves. Now imagine another whole batch of mouths to feed. For many species, spring birthdays are best.
- Many baby caterpillars hatch out right when buds are opening, when tiny leaves are very soft and succulent.
- Baby cranes hatch when vegetation is short enough that they can see their parents easily to follow them. The babies grow as fast as or faster than the grass.
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Why isn't the world overrun with hummingbirds, monarchs, manatees or caribou--or any other wild creature? Given adequate resources, and no disease or predators, all populations increase exponentially.
But throughout the natural world, the growth of all populations are limited in specific niches in the ecosystem by lack of resources and factors such as predation, disease, climate fluctuations, etc.
Are humans born in specific seasons? Collect a data sample to help you find out. Ask everyone in the room what month they were born. Interview as many people as you can. Record all answers and graph the data by months. Look at the graph to see whether humans are born in specific seasons. Discuss whether the birth season is as important in the life cycle of humans as it is in the life cycle of animals. Explain your thinking.
Gaylord Nelson, founder of Earth Day, was asked his vision of the environmental challenges facing the nation and the world. Without pause, he replied:
"Achieving stability in population growth in the U.S. and elsewhere is the most important of the hundreds of challenges facing us."
Among all species, humans have the greatest capacity to shape and adapt to our physical environment, but ALL species have one thing in common: we all depend on the Earth for survival. So on Earth Day 2002, consider what human resource use and population growth mean to all living things.
How fast are humans being added to the planet? Listen carefully:
Every time you hear a beat, it means there's another person
on the planet. (This is not the birth rate, but the "net gain,"
which means births minus deaths.)
If you were to count the beats for 24 hours, 200,000 more people would
have been added to the planet.
Challenge Question #18
"If there are 200,000 more people each day, how many days does it take for a million people to be added to the human population?"
(To respond to this question, please follow the instructions below.)
For hundreds of thousands of years, the human population was almost stable. Birth and death rates were nearly even, but as this timeline shows, as human inventions improved and extended life, birth rates increased, death rates dropped, and the human population began to grow exponentially.
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Can you find these historic events on the timeline?
In pre-historic times, about 5 million people lived on earth. With the
introduction of agriculture in 10,000 BC, food supplies increased, but
death rates were still high, so population growth was slow and steady.
By the year 0 there were 250 million people. Massive numbers of people
were killed when the bubonic plague struck during the 14th and 15th
centuries, and the human population declined. Suddenly, the Industrial
Revolution improved the standard of living so dramatically that the
human population began to grow exponentially. The balance was broken.
In less than 200 years, the world population went from 1 billion to
6 billion people.
The world is becoming an ever smaller place. Global communications juxtapose the rich and poor, making all aware of our difficult ethical dilemma:
- Of the world's 6.3 billion people, an estimated one third live in poverty. That's 2 billion people, more people than were alive in the year 1900. (See graph.)
Consider how an ever-growing human population makes environmental, social and political problems fundamentally harder to solve. These are complex issues with no clear answers, yet they are the most important for children to learn about the world they will inherit.
Tip to Teachers: Recommended Reading by Dr. Lincoln Brower
"I think this is the most important environmental book I've read," says Monarch biologist Dr. Lincoln Brower about The Future Life, written by Edward O. Wilson. Wilson is a Harvard biologist and two-time Pulitzer Prize winner. "It's beautifully written-- a most compelling picture of the impact of overconsumption and overpopulation on our Earth. Basically, we have about 30 years to get our act together. The solution requires a major ethical change in our attitude toward other forms of life."
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Yellow-rumped Warbler
photo by Laura Erickson |
Spring is an "in between" season as winter turns to summer. And this week summery weather and wintry weather were both happening in many places. Duluth, Minnesota, had 80+ degrees Fahrenheit two days before an icestorm hit. One hungry, fluffed up Yellow-rumped Warbler flitted about Journey North science writer Laura Erickson's yard looking confused.
In Eagle River, Wisconsin, Gail Gilson-Pierce heard her first phoebes of the year doing their territorial call at Trees for Tomorrow. Do you know how to recognize the call of a phoebe? Listen to Lang Elliott's recording here:
Some people confuse the phoebe's song with the song of the Black-capped Chickadee, probably because the chickadee's "Hey, sweetie!" song is sometimes called the chickadee's "phoebe" song. Listen to the chickadee here:
What
signs of spring have been popping up in your area? Make sure you tell
us about them! Just click on the owl button.
Flowery Math: Discussion of Challenge Question #17
"How many saguaro flowers does a bat have to visit to sustain it for one day?
Ginny Dalton, Bat Biologist, tells us, "According to my calculations, 21 flowers. This is because a bat needs 20,200 calories per day and there are 960 calories in each flower. (20,200 calories/day divided by 960 calories per flower = 21 flowers)
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-spring@learner.org
2. In the Subject Line of your message write: Challenge
Question #18
3. In the body of your message, give your answer to ONE of the questions
above.
The Next Signs of Spring Update Will Be Posted on April
25, 2003.
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