Effects of Harness-Style and Abdominally Implanted Transmitters on Survival and Return Rates of Mallards (Efectos de los Transmisores Tipo Arnés y de Implante Abdominal en la Supervivencia y Tasas de Retorno de Anas platyrhynchos)

We evaluated the effects of harness-style and abdominally implanted transmitters on survival of ducklings, survival of attending females during the brood-rearing period, and female return rates in Mallards (Anas platyrhynchos). Eighty-three females were captured on their nests in late incubation in eastern Saskatchewan during 1990-1993. Transmitters were attached with harnesses on 34 females and 49 females had transmitters surgically implanted into their abdominal cavity. There was no difference in duckling survival (P = 0.22 from hatch-14 d, P = 0.07 for 15-30 d) or brood survival (one or more ducklings alive in brood; P > 0.4) to 30 d after hatching between broods accompanied by females with harnesses or implants. Female survival during late incubation and brood-rearing was high in 1990-1992 when only one of 61 females was killed over the 60-d period from the time of capture until the young fledged. Survival of brood-attending females was lower in 1993 when 5 of 16 females were killed during the brood-rearing period. Adjusted return rates were lower (P < 0.025) for females with harnesses (22.6%) than those with implants (55%). These findings provide further evidence of adverse effects of harness-style transmitters. Although implanted transmitters are recommended for use in studying reproductive ecology of waterfowl, better controls are needed before the effects of transmitters and attachment procedures can be fully evaluated. /// Evaluamos los efectos de los transmisores tipo arnés y de implante abdominal en la supervivencia de crías y de hembras cuidadoras durante el período de atender las crías y en tasas de retorno de hembras de Anas platyrhynchos. Se capturaron 83 hembras en sus nidos durante el final de la incubación en Saskatchewan oriental entre 1990-1993. Se colocaron transmisores de arnés en 34 hembras y se implantaron quirurgicamente transmisores en la cavidad abdominal de 49 hembras. No se halló diferencia en la supervivencia de crías (P = 0.22 desde nacimiento a 14 días, P = 0.07 para 15 a 30 días) o en la supervivencia de camadas (una o más crías vivas en la camada; P > 0.4) a 30 días después de eclosionar entre camadas acompañadas por hembras con arneses o implantes. La supervivencia de las hembras durante la incubación tardía y la crianza de la camada fué alta entre 1990 y 1992, cuando solo una de 61 hembras murió durante los 60 días entre el tiempo de la captura hasta que las crías se desarrollaron. La supervivencia de hembras que atiende