Signs of Spring Migration Update: April 12, 2002 Today's Report Includes: Migrating Marine Mammals: Humpback Whales Going the Distance. . .Or Not: Challenge Question #20 The Humpback Parade Singing Whales: What are They Trying to Tell Us? Anatomy of a Song: Challenge Questions #21 and #22 Beautiful Breaching Beasts 1000 Pounds of Food a Day Ready, Set, GO! Discussion of Challenge Question #18 A Weighty Matter: Discussion of Challenge Question #19 Migration Route of Atlantic Humpback Whales Map courtesy of MacalesterCollege Migrating Marine Mammals: Humpback Whales Where are humpback whales these days? This week's Signs of Spring report has the scoop on Atlantic and Pacific humpback whales. Between December and April each year, Atlantic humpbacks can be found from the Bahamas to the Grenadines in the island and reef systems of the West Indies. Calves are born and mating occurs in these warm waters, a safe haven for nurturing the newborn humpback calves. The most important area for wintering humpbacks is Silver Bank in the West Indies off the Dominican Republic. At the peak of the mid-winter season, this area hosts as many as 3000 humpbacks. Spring migration takes them to the rich feeding grounds of Stellwagen Bank off Cape Cod Bay, Massachusetts. Here, increasing plankton production leads to increased life all the way up the food chain. Later in summer, these humpbacks will swim farther north to The Bay of Fundy and Grand Banks in search of more food. North Pacific humpbacks spend winter around many warm water islands, including the Marianas and Hawaii as well as the coastal islands off of Mexico. From May to October these marine mammals migrate north to their feeding grounds along coastal Alaska and up into the waters of the Bering Sea. Going the Distance. . .Or Not Each year these humpback populations embark on round-trip journeys of 5,000 to 7,000 miles. One research study revealed that a humpback sighted off the Bahamas was seen again 32 days later -- 1,500 miles to the north and feeding at the Stellwagen Bank off Cape Cod Bay, MA. Challenge Question #20: "How many miles per day (on average) would a humpback need to cover to travel 1,500 miles in 32 days?" (To respond to this question, please follow the instructions below.) Many juvenile humpbacks have other plans. Rather than migrate to the islands in the Caribbean travel, some may travel no farther south than the Virginia coast. Researchers believe that if large amounts of prey are available, young whales may find the food more irresistible than the urge to migrate. (Doesn't this make sense when there's not much for them to do in the breeding grounds anyway?) The Humpback Parade Humpback gymnastics courtesy Tom Conlin Last year's mothers and juveniles are often the whales that appear back at the feeding grounds first. These are the animals least concerned with breeding. The females are recovering from their earlier calving and nursing period, and eager to get to the feeding grounds. The juveniles are not yet able to breed, and are interested in building up their blubber. Mothers with calves probably leave the breeding grounds next, but may take their time arriving. The last animals to leave the breeding grounds are usually the mature males and females who are not yet pregnant. Of course, whales don't always strictly follow this order; sometimes there will be a mix of early arrivals. Singing Whales: What are They Trying to Tell Us? Humpback whales in the breeding grounds often show some lively behaviors. Breaching, lobtailing (slapping the tail on the water), and pectoral fin slapping are common. The males in these waters are famous for their songs. Although a few songs have been heard in the northern feeding grounds late in the season, most of the singing happens in the southern breeding grounds. The whales sing mainly in shallow coastal waters, and their songs can be heard over distances greater than 185 km (114 miles). The songs have been compared to bird songs because of their complexity. It seems the songs are made up of 6 basic themes repeated over and over again. Each song can last up to 35 minutes and has a definite start and finish. Let's have a listen! Anatomy of a Song Imagine you could tell what kind of whale you were listening to just by the way it sings. Scientists love thinking about these kinds of things. We can discover a lot just by listening to animals. Now you're invited to try your ear on a couple of recordings. Listen to the following two whales' songs: Humpback Song Blue Whale Song Challenge Question #21: "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?" 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." (To respond to these questions, please follow the instructions below.) Beautiful Breaching Beasts Weighing 39 tons and growing to 12 meters (40 ft.) in length the humpback propel themselves with their powerful broad tail fins or flukes. This whale is equipped for awe-inspiring breaches. Giant acrobats of the sea, they control their movements with large (10 ft.) pectoral fins or flippers. These fins have a distinctive jagged leading edge that helps in their identification. The breaching whale leaps into the air while twisting then crashes down to the waters surface landing on its back. 1000 Pounds of Food a Day Humpback whales often feed in small groups, Small hairs and the sensitive bumps found on the head of humpback whales may help locate prey and time the opening of the mouth. The humpback, like all baleen whales, is a filter feeder. While the mouth is open, small fish or other prey still have an opportunity to escape, though most are probably far down in the throat pouch. After the mouth is mostly closed, the whale starts filtering sea water out utilizing their baleen hanging from the outer roof of the mouth. Large baleen whales can eat more than 1000 pounds of food, in a single day, filtering more than 100,000 gallons of water in the process. Ready, Set, GO! Discussion of Challenge Question #18 Photo Courtesy of Ann Cook We asked, "In what order would a red-wing blackbird do these steps in building a nest?" Congratulations and thanks to the third grade at Ferrisburgh Central School in Vermont, who put the steps in this order: 1. The male performs a "Symbolic Nest-site Selection Display," picking up and manipulating nesting materials in an area that the female is inspecting. Sometimes he performs the "Symbolic Nest-building Display," making nest-building movements by an existing nest from the previous year. 2. The female weaves stringlike fibers around vertical supports such as cattails. 3. The female weaves the bottom platform to this, using coarse, wet grasses and marsh vegetation. 4. The female builds the outer structure of the nest cup out of medium-sized, wet leaves and decayed wood. 5. The female uses mud to build the inner cup. 6.The female lines the inner cup with fine grasses. Congratulations and thanks Isabelle, Daniela, Laura, Isabel, Ashley, Oakes, Sam, Lillian, and Hannah. They know what they're talking about! A Weighty Matter: Discussion of Challenge Question #19 "How much weight would an average redwing nest need to hold? What are some reasons that a nest can hold so much more?" Avery and Kate, fifth graders from Ferrisburgh Central School in Vermont, did some calculating and came up with this reasonable answer. Good job, Avery and Kate! "We found that a fully grown male red-wing black bird weighs 2.5 ounces, and the female 1.5 ounces. Then we figured that a chick that is ready to leave the nest would be almost full grown. For purposes of solving the problem, we said that the birds might weigh as much as the mother, 1.5 ounces. Four chicks would weigh no more than 6 ounces. Then the nest needs to hold a maximum of 10 ounces. The nest is made to hold almost 2 pounds. It is made that sturdy for safety's sake. If the nest weathered, it would still hold the family. Please Report "Signs of Spring" From Your Part of the World! Report your "Signs of Spring" sightings to Journey North. Remember to share your sightings of first frogs, earthworms, red-winged blackbirds, barn swallows, emerging leaves, flowing sap, melting ice and other spring events. Your observations will be incorporated into "Signs of Spring" updates according to the schedule above. Thanks for sharing! 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. IMPORTANT: In the Subject Line of your message write: Challenge Question #20 (OR #21 OR #22). 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 19, 2002. Copyright 2002 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form