EFFECTS OF TRANSMITTERS ON REPRODUCTION AND SURVIVAL OF WILD MALLARDS

Radiotelemetry is an important tool in many studies of waterfowl ecolo gy and management, but some studies have indicated that harnessed-radi opackages affected the behavior and survival of marked birds. Transmit ters attached mid-dorsally with sutures, glue, and a subcutaneous, sta inless steel anchor-shaped wire (hereafter anchored backpacks) may eli minate such problems. Therefore, we compared various measures of repro duction and survival rates of wild mallards (Anas platyrhynchos) radio marked with abdominal implants and anchored backpacks at 5 study sites located in the aspen-parkland biome of the Prairie Pothole Region of Canada. We also compared our tracking ability between abdominal implan ts and anchored backpacks and determined retention time of anchored ba ckpacks. Females with anchored backpacks devoted significantly fewer d ays to egg laying and incubation and initiated fewer nests than did fe males with implants. At one site, females with backpacks had significa ntly lower survival rates than females with implants. At 3 of the rema ining 4 sites, females with anchored backpacks had lower survival rate s than females with implants, but these results were not significant. We detected no difference in our tracking ability between anchored bac kpacks and abdominal implants (63 of 136 [46%] with anchored backpacks , and 140 of 319 [43%] with implants were monitored successfully from the time they were trapped to 30 June at each site). Two anchored back packs were known to have fallen off and 11 were suspected to have fall en off, out of 198 backpacks (average retention time for anchored back packs was 43 +/- 5.8 days for those that lost their transmitter). Our results suggest that anchored backpacks may have negatively affected r eproduction and survival rates of wild mallards.