Effects of Transmitters on Reproduction and Survival of Wild Mallards

Abstract

Radiotelemetry is an important tool in many studies of waterfowl ecology and management, but some studies have indicated that harnessed-radiopackages affected the behavior and survival of marked birds. Transmitters attached mid-dorsally with sutures, glue, and a subcutaneous, stainless steel anchor-shaped wire (hereafter anchored backpacks) may eliminate such problems. Therefore, we compared various measures of reproduction and survival rates of wild mallards (Anas platyrhynchos) radiomarked 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 implants and anchored backpacks and determined retention time of anchored backpacks. Females with anchored backpacks devoted significantly fewer days to egg laying and incubation and initiated fewer nests than did females with implants. At one site, females with backpacks had significantly lower survival rates than females with implants. At 3 of the remaining 4 sites, females with anchored backpacks had lower survival rates than females with implants, but these results were not significant. We detected no difference in our tracking ability between anchored backpacks 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 backpacks were known to have fallen off and 11 were suspected to have fallen off, out of 198 backpacks (average retention time for anchored backpacks was 43 ± 5.8 days for those that lost their transmitter). Our results suggest that anchored backpacks may have negatively affected reproduction and survival rates of wild mallards.