THERMOREGULATORY EFFECTS OF RADIOTELEMETRY TRANSMITTERS ON MALLARD DUCKLINGS

Many telemetry transmitter attachments disrupt downy insulation, and m ay bias survival studies during cold weather by making ducklings more susceptible to chilling. We compared thermal responses of untreated 1- day-old mallards (Anas platyrhynchos) to ducklings carrying external s utured backpack or subcutaneously implanted transmitters. Ducklings ca rrying external transmitters showed areas of increased surface tempera ture in thermographic images. However, open-circuit respirometry studi es at 5, 10, 15, 20, and 25 C and wind speeds of 0.1, 0.2, 0.5, and 1 m/s indicated no biologically significant differences in total heat pr oduction, net heat production, or short-term body mass loss. These res ults do not exclude the possibility of other negative effects of trans mitters on duckling behavior and survival.