SURGERY PERFORMED TO INSTRUMENT
SURF AND BLACK SCOTERS
FOR SATELLITE TELEMETRY
Satellite telemetry is being used in the Atlantic Seaduck Project to learn more about the breeding and molting areas of scoters in northern Canada. Scoters were captured on wintering grounds of Chesapeake Bay, Maryland, USA and migrational staging areas on the Restigouche River, New Brunswick, Canada. Scoters captured in the Chesapeake Bay were transported in small plastic animal transport crates to the veterinary hospital at the USGS-Patuxent Wildlife Research Center, Laurel, MD, USA. Ducks caught in New Brunswick were transported in the same type of animal transport crates to a local veterinary clinic for surgery.
A PTT100 transmitter manufactured by Microwave Telemetry, Inc. (Columbia, MD, USA) was surgically implanted in the duck's abdominal cavity following general anesthesia using isoflurane (Isoflo, Abbott Laboratories, North Chicago, IL, USA) for both induction and maintenance. Transmitters measured approximately 5 x 3.8 x 0.6 cm and have a nominal weight of 39 grams. This weight is slightly heavier than normal because of potting required to allow the transmitters to withstand pressures accompanying diving to depths of 30 m.
The transmitter's 20 cm antenna exited the skin lateral to the sacral vertebrae. Because of recent problems with extrusion of cylindrically-shaped implant transmitters through the antenna perforation, transmitters used in this study were wide-bodied with no abrupt edges. Initially, ducks were given butorphenol tartrate (Torbugesic, Fort Dodge Animal Health, Fort Dodge, IA, USA) as an analgesic. However, this was stopped when we observed that the analgesic made the ducks lethargic and slowed the preening process post surgery.
Ducks were also initially given an avian nutritional maintenance diet (Emeraid II, Lafeber Company, Cornell, IL, USA) by gastric tube to reduce weight loss in captivity due to the cessation of normal feeding. This was curtailed when two ducks died from regurgitation and inhalation of the liquid food supplement. Blood samples for CBC and serum chemistries were taken from a sample of the ducks to obtain background information of each species. All ducks received an injection of fluids (Lactated Ringers Solution, Baxter Healthcare Corporation, Deerfield, IL, USA) to replace fluids lost in surgery. Most ducks were radiographed to determine the position of the transmitter. It was learned while examining the radiographs that 45% of the ducks were carrying embedded shot from previous exposure to hunting.
Ducks were held post-surgery for periods of 1-9 days, banded, and then released at the site of capture. This study determined that one of the critical factors for survival of instrumented scoters is to assure that feathers are properly preened and dry before release to the wild. This preening process was delayed with some scoters because of the use of a pain reducing narcotic that appeared to make the ducks lethargic. We recommend only using essential medication and minimal handling with a return to the wild as soon as possible.
The current techniques used to instrument scoters have been modified and improved during the study. This technique has now minimized mortality to levels similar to other conventional implant telemetry procedures. These procedures will greatly aid the conservation effort for seaducks presently being conducted throughout the world.