Northern Prairie Wildlife Research Center
John H. Schulz, Missouri Department of Conservation, Fish and Wildlife Research Center, 1110 S. College Ave., Columbia, MO 65201 USA, Alex J. Bermudez, University of Missouri, Veterinary Medicine Diagnostic Laboratory, Columbia, MO 65201 USA, James L. Tomlinson, University of Missouri, Veterinary Medical Teaching Hospital, Columbia, MO 65201 USA, and Jeffre D. Firman, University of Missouri, Animal Sciences Research Center, Columbia, MO 65201 USA
To help wildlife managers learn more about mourning dove biology and management, we developed and evaluated the physiological and pathological effects of implanted radio transmitters in mourning doves. In past mourning dove telemetry research projects, small radio transmitters (usually 3-6 g) were either glued or attached with harnesses to the back of mourning doves. External transmitter attachment techniques used in these past studies may have affected the birds more than previously thought.
To develop and evaluate the surgical procedures needed to implant radio transmitters with external antennas, we maintained 200 wild doves in captivity in individual cages. Two surgical procedures were tested for placement of the internal transmitters; subcutaneous (under the skin at the base of the neck) and intra-abdominal (in the abdominal cavity). The subcutaneous transmitters had a flattened shape and the intra-abdominal transmitters were cylindrical to fit more easily in the abdominal cavity. Each transmitter weighed <3 g; one half of each transmitter type were functioning transmitters and the other half were dummy facsimiles. Both subcutaneous and intra-abdominal transmitters had external antennas that passed through the skin or body wall.
Out of the 200 captive doves, 40 doves were fitted with subcutaneous transmitters, 40 with intra-abdominal transmitters, 40 had only the subcutaneous surgery, 40 had only the intra-abdominal surgery, and 40 were control birds. Treatments were assigned in a randomized block design. Average surgery times for subcutaneous surgeries were 3.6-4.4 min and 3.0-3.6 min for the intra-abdominal surgeries. Recovery times of the doves from the effects of the anesthesia ranged from 7.8 to 9.2 min. Total time of the entire procedure was approximately 14-16 min. For comparison, it takes roughly 20-25 min to properly attach transmitters with super-glue and 10-15 min to attach transmitters with harnesses.
Both pathological and physiological factors were measured to test for effects of the implanted transmitters. Blood was collected 4 times (10 weeks pre-surgery; <7 days pre-surgery; <6 days post-surgery; 10 weeks post-surgery) to monitor heterophyl:lymphocyte ratios. Blood smears are still being read and summarized. Total blood serum chemistry analyses were conducted from blood collected at necropsies. Serum chemistry tests included measures of glucose, sodium, potassium, chloride, enzymatic CO2, albumin, total protein, globulin, calcium, phosphorus, cholesterol, magnesium, aspartate aminotransferase (AST), alkaline phosphatase (ALKP), gamma glutamyl transferase (GGT), lactate dehydrogenase (LDH), and uric acid. Preliminary analysis of 17 blood chemistries showed no difference (P > 0.05) between males and females within treatments, or among the treatments overall.
At 4-days post-surgery, 153 of 160 birds with surgical treatments demonstrated closed and healed surgical sites with no complications. Seven doves had visible complications (4 subcutaneous, 2 intra-abdominal, 1 sham intra-abdominal surgery; 1 dove was euthanized). By 14 days post-surgery, 5 of the 7 birds still showed some complications but were acting "normally" and showed secondary healing around surgical site. Gross necropsy findings at 70 days post-surgery for 36 of 39 subcutaneous implants showed no to little immune response to the transmitter implant (e.g., ≤6 fibrin patches ≤1 mm on transmitters or <2 cm of fibrin along subcutaneous antenna tract). Intra-abdominal implants also showed 36 of 39 with no to little immune response at 70 days post-surgery. Many complications with the implants observed during necropsies appear to have resulted from leaking batteries in the dummy transmitter implants; histology results are pending.
These results are based on preliminary information and may change after all the data are available. Also, a follow up study is scheduled in 1998 to compare implants to conventional external attachment techniques using glues and harnesses. Hopefully, this work will show that implanted transmitters with external antennas have the potential to become a common field research tool of the future.