Signs of Spring Update: 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 #23 Humankind: The World's Most Successful Species Inequities: Four Billion Have, Two Billion Have Not Tip to Teachers: Recommended Reading by Dr. Lincoln Brower Males First, Females Later: Discussion of Challenge Question #17 Going the Distance...Or Not: Discussion of Challenge Question #20 Anatomy of a Song: Discussion of Challenge Question #21 Discussion of Challenge Question #22 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 backyard. 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. Natural Laws: Populations and Ecosystems 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. Try This! Seasonal Births? 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. What's Most Important This Earth Day? 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. Sharing The Planet: 200,000 More People Every Day How fast are humans being added to the planet? Listen carefully: Metronome (144 Per Minute) 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 #23 "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.) Humankind: The World's Most Successful Species 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. Courtesy of World Population Balance 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. Inequities: Four Billion Have, Two Billion Have Not 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 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." Males First, Females Later Discussion of Challenge Question #17 Last time we talked about blackbirds and said: "List as many reasons as you can think of that female blackbirds return a couple of weeks later than the males." First graders Jenna and Daniel from Ferrisburgh (Vermont) Central School thought of a good point: "The males might have to fight off other blackbirds on their territory. They try and get the best territory they can." When males first return, marshes are still frozen, with little food available. Females stay in wintering areas where food is more abundant, since they will be using up their food reserves to produce eggs. Also, because females don't defend a territory in the same way as males, there is no reason for them to appear until the territories have been established. Cold birds have to shiver to maintain their body temperature, which takes energy. To conserve this energy to be in better condition to produce eggs, female blackbirds stay in the warmer southern areas as long as possible. Going the Distance. . .Or Not Discussion of Challenge Question #20 "How many miles per day (on average) would a humpback need to cover to travel 1,500 miles in 32 days?" Fourth graders Kameron and Patrick from Ferrisburgh Central School have the answer: "We used calculator and divided 32 into 1500 and got 46.875. The whale need to travel 47 miles a day on average." Right on! Anatomy of a Song Discussion of Challenge Questions #21 and #22 Challenge Question #21 asked you to listen to songs of a humpback and a blue whale. Then we asked, "How are the two whale songs different? Close your eyes and listen to them while you describe them in the best detail you can. Do they sound like any other mammals you know? What other sounds do they remind you of?" Here's a delightful answer from Ferrisburgh first graders Jenna, Daniel, Nick, Alicia and Lane. Maybe you'll agree! "The two whale songs are different. The blue whale has one low sound and has a lot of vibration with it. It has the same rhythm to it and repeats the same sounds over and over. The humpback has a lot more sounds, high and low. It also has more melody to it and it doesn't repeat as much. The humpback sounds like a bear growling and a dolphin singing at the same time. It also sounds like a creaking door at Halloween. The Blue Whale sounds like a newborn calf, except a lot louder." Discussion of Challenge Question #22 "Whales make some amazing sounds. What do they use them for? Do some research and list some of the ways sounds are used by whales." Ferrisburgh third graders Isabel, Isabelle, Daniela, Lillian, Laura, Ashley, Oakes, Sam, Jennifer, and Hannah did some good research. We're pleased to share their answer: "We researched the humpback whale on the PBS site, Song of the Sea. It said that humpbacks are probably using their songs as threats. The males sing complicated songs. They are trying to keep away other males. It said when another male comes near while they are singing, they start fighting. Some people think that the songs are love songs to females. On Journey North, they said that people don't understand why the grey whales make their noises. We think that they are singing the songs to communicate. They might be singing songs just for the fun of it. They might be entertaining themselves. The songs tell their feelings." How to Respond to Today's Challenge Question: 1. Address an E-mail message to: jn-challenge-spring@learner.org 2. IMPORTANT: In the Subject Line of your message write: Challenge Question #23 3. In the body of the message, give your answer to the question above. The Next Signs of Spring Update Will be Posted on April 26, 2002 Copyright 2001 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form