It's one of the bird world's most epic journeys. After dodging predators and fiercely guarding their nests in the North American Arctic tundra, the American golden-plover begins one of the longest migrations of any shorebird. The journey to their wintering grounds, primarily in the pampas grasslands of Brazil, Argentina, and Uruguay, is thousands of kilometers. Many don't survive, but scientist don't know exactly why, or where they get lost along the way.
An estimated 75 percent of bird and mammal species (including the golden-plover) and all insects are too small to track over long distances, because the tags scientists typically use are too large and heavy for these smaller species to carry. The majority of the weight comes from the battery, but the tag must also have room to hold a transmitter strong enough to communicate with a satellite that can receive and relay information back to scientists on the ground.
Because of these restrictions, vast amounts of information about the movements of, and threats to, these small species remains unknown.
Soon, that will change. The ICARUS initiative (International Cooperation for Animal Research Using Space) has developed a new tag that's light enough for medium-sized birds like the American golden-plover to carry. It's specifically designed to communicate with antennae that will be located on the International Space Station (ISS). The ISS flies in a low orbit roughly 400 km above the Earth as compared to satellites with mid to high-Earth orbits that range from 2,000 to more than 35,780km above the surface.
A low orbit is useful because signals from the tags tend to decay over distance, said Chris Guglielmo, a biologist at Western University and one of the Canadian leads on the ICARUS initiative.
The tag will have the ability to record precise geographic locations, temperature, bearings (what direction the bird is moving), and information about movement and behaviour, captured through an accelerometer. "All of this in a tag only five grams in weight," said Guglielmo, "though the goal is to make them much smaller." Eventually they may be small enough for a dragonfly to carry.
The ICARUS antennae and onboard computer will fly to the ISS on board an unmanned Soyuz Progress rocket, and be installed by Cosmonauts on the Russian segment. (The launch was originally planned for June 2017, but schedule setbacks resulting from the explosion and loss of the Progress MS-04 re-supply rocket late last year have resulted in a new launch date of October 12.)
Guglielmo's colleague Ryan Norris at the University of Guelph leads the first Canadian project that will use ICARUS tags to follow the migration of the American golden-plover. The study will begin in 2019.
Guglielmo hopes the results will tell them, for example, where the birds' key eating and drinking stopovers are, and how weather and environment affect their routes. He hopes they'll get some insight on how to protect them in areas where they are most at risk. "The shorebirds as a group are declining rapidly," he said, adding that in addition to threats along their migration route, they are at risk of decline from the effects of climate change in the Arctic, where they breed.
Though biologists know the general movement patterns of many bird migrants, Guglielmo said, "we want to go beyond just describing the path that birds take." For example, he wants to know exactly what tree or forest a bird winters in, and how is this habitat is associated with its survival.
Guglielmo said it's also an opportunity for scientists to answer basic questions about the ecology and evolution of migrants.
For example, he'd like to better understand how bird hormones impact migration. "If there is a hormone-disrupting chemical in a bird's environment, it's hard to predict what kind of effect it's going to have if you don't understand these hormonal controls. You need to understand how the system works, to understand why a pollutant has the effect that it has."
The ICARUS initiative hopes to be an eye-in-the-sky that informs humans about all the ways small animals are integrated into the global ecosystem. Other potential outcomes include increased understanding about the role of pollinators, and tracking animal-borne diseases like avian influenza. If all goes well, when the ICARUS tracking system blasts off this fall, it will be a giant step forward in our learning about the small migrants we know so little about.
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