You are here:

Content contained within the resource

Teachers' Domain - Digital Media for the Classroom and Professional Development Search Teachers' Domain Go User: My Folders Loading... Create a new folder Upload Media My Groups No groups created yet. Create a new Group Join a Group My Profile HELP | SIGN OUT Please sign in for full access This Teachers' Domain feature requires registration, which is simple, safe, and free. Register Now Citation "Marathon Migrators." Teachers' Domain. 26 Sep. 2003. Web. 3 Feb. 2012. .

To embed citation, copy and paste the embed code above into your document. Create a new Folder Title: Description (optional): CREATE NEW FOLDER CANCEL Create a new Group Title: Description (optional): Allow all access requests CREATE NEW GROUP CANCEL Join a Group Enter the group ID number: JOIN GROUP CANCEL Delete this Review Deleting this review will remove it from the Teachers' Domain system. DELETE REVIEW CANCEL Delete this Comment Deleting this comment will remove it from the Teachers' Domain system. DELETE COMMENT CANCEL Not yet registered? Register now to download, share, and save resources. It's simple, safe, and free! Learn More You are now "Test Driving" Teachers' Domain You may view up to 7 resources in this limited trial period. You have 6 views remaining. Register now for unlimited free access and to download, share, and save resources. Learn More Thank you for "Test Driving" Teachers' Domain You have viewed all seven resources permitted in this limited trial period. You may continue to browse the site, but to view, download, share, and save resources, you must register now. Registration is simple, safe, and free. First time here? As a user, you may browse Teachers' Domain and view as many resources as you wish without registering. However, for access to all of the features of Teachers' Domain, we'll need a little more information. Learn More About Registration: Registering with Teachers' Domain is FREE and allows you to: View as many resources as you like Save, sort, and share resources using My Folders and My Groups Download resources to your desktop See standards correlations for your state Register Now For more information: Learn about our online Professional Development Courses, or review our Privacy Policy. If you still have questions, please contact us. Welcome user: Not your account? SIGN IN TO CONNECT THIS ACCOUNT Sign-in Name: Organization: Change Organization Password: Sign In Forgot Your Password? What is this? Signing in now will connect your and Teachers' Domain accounts, so that in the future you will automatically be signed into Teachers' Domain when you come from . Marathon Migrators Resource for Grades 6-8 | Citation Media Type: Video Running Time: 6m 00s Size: 17.9 MB View or Download SAVE TO FOLDER Loading... Save Cancel Share | Source: NOVA: "The Mystery of Animal Pathfinders" Resource Produced by: Collection Developed by: Collection Credits Collection Funded by: See Also: National K -12 Subject: Behavioral Response Obtaining Resources Lesson Plans Using this Resource: How Animals Use Their Senses to Find Food There are many strategies animals use for staying close to their food sources, as this video segment from NOVA: "The Mystery of Animal Pathfinders" explains. One of the most remarkable of these strategies, however, is demonstrated by the red knot, a species of shorebird that flies 20,000 miles annually in its never-ending search for food, especially the eggs of spawning horseshoe crabs. Permitted use: Download and Share Alternate Media Available: Marathon Migrators (Audio Description) (Video) Accessibility Features: Audio Description, Caption Background Essay The timing of shorebird migration is no accident. The long-distance travels of these birds have evolved over countless generations, just as the physical characteristics of a species may change over time. Year after year, the process of natural selection has refined shorebird migrations. Birds that travel efficiently and that time their travels well are rewarded with breeding success, while birds that leave too early or too late pay the price with unsuccessful reproduction -- and sometimes their lives. In this way, dozens of species of shorebirds have come to rely on the bounty the ocean provides en route between their wintering and their breeding grounds. Eggs deposited on the beach by spawning horseshoe crabs are particularly important to shorebirds migrating along the Mid-Atlantic coast of North America. In the spring and early summer, from Maine to Mexico's Yucatan Peninsula, hundreds of thousands of horseshoe crabs move to shallow water to begin their breeding cycle. Males congregate first; females arrive shortly after, secreting a pheromone to attract mates. A male who has been successfully courted follows his mate closely as she moves ashore to lay 3,000 to 4,000 grayish-green eggs in a single shallow nest dug into the sand. The male fertilizes the eggs when the female begins to crawl away and drags him over the nest. Females may lay up to 90,000 eggs, in multiple nests and with multiple partners, each season. If shorebirds time their migration with the peak of horseshoe crab spawning, they will double their weight during a two- to three-week stay along the Mid-Atlantic coast. They gorge on eggs, many of which are on the surface of the sand, uncovered by the spawning efforts of horseshoe crabs laying their own eggs. Scientists estimate that during a stopover, the average shorebird consumes more than 100,000 horseshoe crab eggs. Until recently, there were enough horseshoe crab eggs to meet the demand. But that's changing quickly. The number of horseshoe crabs spawning on Mid-Atlantic beaches has declined in recent years, most likely due to the loss of spawning habitat along the Atlantic coast, and to the three-fold increase since 1990 of the use of horseshoe crabs as bait for other species. In Delaware Bay, which contains the world's largest concentration of horseshoe crabs, the number of spawning females per season has dropped from 1.2 million to 400,000 in just the last four years. Scientists agree that this alarming downturn is greatly impacting populations of shorebirds that have come to rely so heavily on horseshoe crab eggs. Print Background Essay Discussion Questions Why do you think that 70 percent of birds cannot be tracked as they migrate south? Horseshoe crabs have come to the same beaches to lay their eggs for hundreds of millions of years. How does this compare to the migratory pattern of red knots? Print Discussion Questions Standards About Standards | Report a Standards Mismatch About Standards | Report a Standards Mismatch About Standards | Report a Standards Mismatch   close Report a standards correlation problem To help improve this service, please report and describe any standards correlations that you find to be inaccurate. close About standards correlation Academic standards correlations on Teachers' Domain use the Achievement Standards Network (ASN) database of state and national standards, provided to NSDL projects courtesy of JES & Co. We assign reference terms to each statement within a standards document and to each media resource, and correlations are based upon matches of these terms for a given grade band. If a particular standards document of interest to you is not displayed yet, it most likely has not yet been processed by ASN or by Teachers' Domain. We will be adding social studies and arts correlations over the coming year, and also will be increasing the specificity of alignment. Grades:   Change grade range Grades: K 1 2 3 4 5 6 7 8 9 10 11 12 to: K 1 2 3 4 5 6 7 8 9 10 11 12 You must be signed in to see standards matches for your state. Loading Standards Comments and Reviews Add a Review Not yet reviewed. Please rate and review this resource: Rating Details (optional): Content: Presentation: Standards alignment: Overall rating: Your review: Post your reviewCancel Loading reviews... Teachers' Domain is proud to be a Pathways portal to the National Science Digital Library.   Major funding for Teachers' Domain was provided by the National Science Foundation. Teachers Domain® Home | Change Edition About Teachers' Domain | Contact Us | Privacy Policy | Terms of Use Teachers' Domain: © 2002-2012 WGBH Educational Foundation | shopPBS Educational Media