So far as humans know, the world record for longest nonstop flight by a land bird is held by E7, a female bar-tailed godwit. In 2007, as a satellite tracked her, she flew 7,200 miles from Alaska to New Zealand in eight days. The Web site of the U. S. Geologic Survey’s Alaska Science Center displays the bird’s route. (Scroll down to see a photo of E7 and click on the USGS Newsroom report for details on her epic journey.) With recent improvements in technology, satellite tracking is answering many questions about animal movements across the globe. Godwits were monitored to learn how a deadly bird flu might be transmitted someday, but wildlife managers are collecting similar data from birds, sea mammals, and fish with an eye on helping far-flung species in decline.
One of the best Web sites to get a quick look at the variety of animals now being tracked by satellites is TOPP, which stands for Tagging of Pacific Predators. The interactive map on their homepage is designed for users of all ages to follow the travels of individual marine animals that this organization has tagged, but you should read the instructions first. Or you can click on one of the animal images at the top to zero-in on that species. Begun in 2000, TOPP is one of 17 projects of the Census of Marine Life. TOPP researchers in eight countries have attached a variety satellite tags to more than 2,000 predators belonging to twenty-two species, including elephant seals, white sharks, leatherback turtles, squid, tuna, and birds. Go to “About TOPP” for a short video overview of the project.
ICARUS, short for International Cooperation for Animal Research Using Space, is another site with information on tracking animals by satellite. Founded in 2002, it is an international consortium of scientists investigating the migration and dispersal of small animals, such as bats, insects, and songbirds. Click on “Technical Challenge” on the menu bar to learn about the satellite system that is needed to track small animals. According to the site, the lightest satellite tag is currently nine grams. Some tags are even solar powered.
For large animals, the weight of a modern tracking transmitter is not an important consideration. And whales are the largest of them all. One site where you can follow the travels of whales and seals in the Atlantic is STOP, WhaleNet’s Satellite Tagging Observation Program. There you can find actively transmitting harp and harbor seals, as well as more than 135 archived tracking records of whales, porpoises, and turtles. New animals will be tagged, but the equipment remains costly, the beacons typically cost several thousand dollars. At Jean-Michel Cousteau’s Ocean Adventures Web site, a page entitled Tag, You’re It! Tracking a Grey Whale Journeydescribes the process of tagging the enormous animals with a transmitter that not only sends information on location and time, but also dive depth and other parameters. A news release from the Alaska Fisheries Science Center “Satellite Tagging Humpbacks in the South Pacific: Windows on the Whales’ World,” reports on how the technology is, for the first time, revealing the routes humpback whales travel as the navigate the vast South Pacific. The tags in this survey were monitored by the ARGOS system of worldwide satellite tracking—the space network, which nearly all of the animal migration studies appear to rely on. Conceived in France in 1978, the system gathers all sorts of global environmental data, but is used to monitor just about anything, including human adventurers and yacht races.
The Southwest Fisheries Science Center, a division of the National Oceanic and Atmospheric Administration, has used satellite tags to study the movements of two types of killer whales in Antarctic waters. One type specializes in pinniped predation, while the other kind consumes mostly fish. On this page, click on the map, and a larger version will appear where you can see the movements plotted as the clock advances. Another page, this one by the Cascadia Research Collective based in Olympia Washington, looks at whale tagging around Hawaiian Islands.
An important side benefit of tagging marine animals is that they provide a mobile platform for collecting all sorts of information. An article on a University of California at Santa Cruz Web site, “High-tech Tags on Marine Animals Yield Valuable Data for Biologists and Oceanographers,” reports on how the animals can be used as ocean sensors, collecting data on water temperature and salinity. Such oceanographic information coupled with the animals movements and feeding patterns, reveals much about marine environment they navigate.
Fish of all sorts are now being tagged. Most of the fish species targeted are important to fisheries, like the declining bluefin tuna. Others are followed simply to learn more about their role in the marine ecosystem. View the TED talk (below) by marine biologist Tierney Thys on her investigation of giant ocean sunfish movements in the Western Pacific. Her research on the bizarre, big-headed Mola mola is a perfect example of how the satellite tracking can finally tell us how an open ocean creature really lives.
Satellite tracking of endangered species, like the leatherback turtle, are yielding important information to help guide future conservation efforts. Watch this video on the efforts of Stanford University researchers to tag leatherbacks breeding on the beaches of Costa Rica.
Closer to shore, manatee movements are being watched. Go to Manatee Migrations at the Save the Manatee Club to see how satellite tags are being used to help conserve these endangered herbivores. From year to year, the Florida manatees may extend their travels depending on water conditions.
As already mentioned above, birds are frequent subjects for satellite tagging. The new transmitters can often provide more information than has been gathered after decades of banding and conventional radio telemetry studies. At the University of California’s Santa Cruz Predatory Bird Research Group there is an interesting report on bald eagle migrations. “As the bald eagle continues its recovery in the face of human expansion in California, this exciting new tool can effectively produce a wealth of information to help plan for the continuance of healthy local and wintering populations.”
Large land mammals are not immune from the researchers’ tags. At Elephants Without Borders, there is a page on their tagging efforts of some sixty elephants so far. Satellite monitoring is providing critical conservation information on the animals as they roam in and out of national parks and cross the borders of four countries in southern Africa. The results: “EWB’s research is revealing that elephants are using old pathways, and historical corridors to exploit “new lands.” One example EWB has discovered pertains to Angola. The end of civil conflict in Angola has provided the requisite security for elephants to return to this war-torn country. Elephants are trekking from northern Botswana through the Caprivi Strip into southeast Angola, where elephant numbers have increased from 36 in 2001 to over 8,000 in 2007. The elephants have not returned to Botswana and are now resident in Angola, despite the many unexploded landmines. This “re-colonization” is a natural dispersal which results in a more dynamic ebb and flow of elephant numbers within a “natural migratory system.”
Although satellite monitoring of small animals is not yet possible, I had to include monarch butterfly migrations simply because it amazing. You can watch PBS’s NOVA show, which follows the winged insects as they flutter from Canada to Mexico in one of the most incredible animal migrations on Earth. Robert Anderson is a freelance science writer who lives in Los Angeles. There are still many unanswered questions about how the special fourth generation of these butterflies manage to navigate to a small area in the mountains of Mexico, having never been there before.
And just for completeness, I include several sites on human migration that I came across. (Humans are generally not monitored with tags unless they are criminals.) At the TED site, author Robert Neuwirth talks about the ongoing trend of human migration to urban areas in The “Shadow Cities” of the Future. And geneticist Spencer Wells talks about Building a Family Tree for All Humanity, a project that reveals how humans have spread around the globe. At PBS’sNewshour, you can find a Map of Human Migration that graphically traces the major dispersion routes of our ancestors.