Biologists Go High-Tech to Unravel Waterfowl Mysteries
By Mike Checkett, DU Regional Biologist
We all know that ducks sometimes fly great distances and often at great heights, but have you ever seen a duck in space? Now you can. In actuality, the ducks are not in space but are being tracked by satellites orbiting in space as improvements in technology have allowed research biologists to go high-tech and attempt to unravel waterfowl mysteries. For years, scientists have attached tiny radio transmitters to wild animals and manually tracked the radio signals from the ground with handheld receivers. Conventional VHF (very high frequency) radio telemetry (using pulsed radio signals) has been an important research tool in waterfowl studies for more than two decades and has contributed to a greater understanding of waterfowl behavior and ecology. However, recent advancements in construction of satellite platform transmitter terminals (PTTs) small enough to mount on waterfowl have opened the door to new research opportunities.
Satellite telemetry utilizes a PTT that is attached to an animal and that sends an ultrahigh frequency (401.650 MHz) signal to satellites. PTTs are programmed by scientists to transmit at a specific interval. When a satellite passes overhead, a PTT signal can be received and the current location information of the PTT and the animal to which it is attached is obtained. The satellites calculate the animal's location based on the Doppler effect (the shift in transmitted signal as the satellite approaches and then moves away from the PTT) and relays this information to receiving/interpreting sites on the ground. The current generation of PTTs is coordinated through the Argos Data Collection and Location System carried on Tiros-N weather satellites. The receiving systems are positioned on three National Oceanic and Atmospheric Administration polar-orbiting satellites, resulting in complete global coverage. The location signals sent from individual PTTs are relayed to ground-receiving stations in real time, and researchers can record and interpret the data from the comfort of their offices.
Satellite telemetry was first used for tracking animals in the early 1970s. Because early PTTs weighed several kilograms, however, satellite telemetry was only useful for large animals such as bears and elk. By the 1990s, improvements in PTT technology, reductions in the weight of both batteries and housing, and the use of solar cells have enabled satellite tracking of waterfowl. PTTs have now been developed that can be attached by neck-collars (geese and swans), by harnesses, and by subdermal (beneath the skin) anchoring (ducks, geese or swans). Several waterfowl species (pintail, surf scoters, Barrow's goldeneye, light-bellied brant, white-fronted geese, Canada geese, and tundra and trumpeter swans) have been successfully studied using this new technology, revealing important information regarding their ecology and migration patterns. Satellite telemetry has also been useful in tracking the long-distance migrations of albatross and otherwise elusive birds such as bald eagles, golden eagles, gyrfalcons, vultures, penguins, and various swans. With new transmitters that weigh 30 grams (slightly more than one ounce) scientists believe a transmitter must be less than 3 percent of the animal's body weight to not adversely affect its behavior and survival) and have a battery life upwards of a year, many waterfowl species can be studied.
The primary advantage of satellite telemetry is its ability to track animals over long distances and in remote areas. The best application of satellite telemetry is for studying far-ranging species such as migratory birds and marine mammals, which are difficult or impossible to track with conventional VHF radio telemetry. Satellite telemetry improves the logistics of data acquisition by circumventing many of the deficiencies encountered with conventional VHF radio telemetry. Factors such as hazardous weather conditions, darkness, international boundaries, remoteness, and extensive animal movements present hindrances to collecting VHF telemetry data but do not hinder the systematic collection of data by satellite telemetry. Under such circumstances, satellite tracking can provide data more objectively, more accurately, and more cost effectively than can conventional telemetry methods.
Satellite telemetry's greatest advantage is in tracking elusive and far-ranging species and minimizing the researcher's travel/field time requirements. Theoretically, an animal can be tracked anywhere by a researcher sitting at his or her computer. Satellite telemetry involves a one-time handling of the animal (until the PTT's battery expires), and does not require researchers to make repeated field trips. Satellites may prove to be especially useful in studies of waterfowl migrations where duck or goose movement information is desired daily, and when animals move long distances, especially at night or during inclement weather.
There are, however, some drawbacks. Satellite telemetry is far less accurate than conventional VHF radio tracking. Satellite telemetry frequently reports locations whose accuracy varies from within 150 yards to many miles. The large degree of error is tolerable when tracking far-ranging species such as migratory birds, but not for small-scale habitat analyses or animals using relatively small areas. So, the appropriateness of satellite telemetry ultimately depends on study objectives.
Satellite telemetry can also be costly. While costs are decreasing each year, a single PTT unit generally costs around $2,700-$4,500, some 10 to 20 times as much as that of a conventional VHF transmitter. Additionally, the researcher must pay for the data acquisition and processing, which can cost from $90 to $260 per month per animal. However, satellite telemetry may be cost effective in certain situations when working with remote species that are difficult to track; using satellite telemetry eliminates the cost of following the animal through nearly inaccessible terrain. Furthermore, for certain species, such as in studying animals found far offshore, satellite telemetry may be the only feasible means of tracking them.
In applications to waterfowl, recent research using satellite PTTs have helped describe spring and fall migration corridors, identify key staging areas, establish the timing of migration relative to winter climatic and habitat conditions, determine the timing of migration in relation to managed hunting seasons and hunting opportunity (see sidebar), as well as detect habitat selection by waterfowl and their movements on wintering and breeding areas.
While conventional radio telemetry has been and remains an important research tool in waterfowl studies, the combination of continued advancements in satellite telemetry, geographic information systems technology, remote sensing, and computer processing provide powerful new tools for wildlife managers and researchers that will greatly increase their ability to monitor and unravel waterfowl mysteries.
Tracking Geese From Outer Space
After a year and a half of tracking more than 30 Atlantic Canada geese via satellite PTTs, a team of scientists led by Dr. Richard Malecki of Cornell University and DU Chief Biologist Dr. Bruce Batt made several useful discoveries regarding migration habits of these birds, which have significant implications for their management. Among the most notable findings was that nearly all of the geese tracked in the study left northern Quebec during the final days of September and arrived on their wintering grounds in early October. The timing of the birds' arrival in the U.S. was later than researchers had anticipated, and gave justification to the extension of early goose seasons targeting resident giant Canada geese to the end of September in the Atlantic Flyway states.
Pinsat - Discovery for Recovery
Several years of satellite tracking of pintail in California (Tuscany Research Institute, Ducks Unlimited, U.S. Geologic Survey, and other research partners) has allowed recognition of critical staging areas that are not protected and allowed us to broaden our understanding of spring staging areas and pintail distribution patterns as they relate to nesting habitat conditions. Among the notable findings were that the southern Oregon and northern California (SONEC) region is the most important spring stopover for California wintering pintails, and that Alaska and prairie-bound hens migrate at different times. Migration data also indicated that pintails that breed in Alaska stage in SONEC for a couple of months before departing, whereas prairie-nesting pintails may leave there quickly if they use additional stopovers, or may delay their departure a month or so if they fly directly to Canada, usually Alberta. The study verified that the U.S. Fish and Wildlife Service's spring waterfowl survey often misses many pintails, which tend to inhabit unsurveyed areas, especially when the prairies are dry.
Ducks Unlimited has been involved in many of the early state-of-the-art studies using satellite technology in efforts to learn more about specific waterfowl species. To learn more about satellite tracking of specific waterfowl species, see the following Web sites:
California pintails: http://www.werc.usgs.gov/pinsat/
South Carolina pintails: http://water.dnr.state.sc.us/wild/pintails/index.htm
Atlantic Canada geese: http://www.ducks.ca/geese/index.html
Mallards: http://www.agfc.com
Surf scoters: http://wildlife.alaska.gov/index.cfm?adfg=waterfowl.main
Trumpeter swans: http://www.wesave.org/swan/
Tundra swans: http://www.bsc-eoc.org/lpbo/swans/swans.html
Light-bellied brant geese: http://www2.dmu.dk/CoastalZoneEcology/satellite/index_uk.htm
White-fronted geese: http://mercury.bio.uaf.edu/%7Eeric_rexstad/satellitegeese/
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