INFLUENCE OF BROOD REARING ON FEMALE MALLARD SURVIVAL AND EFFECTS OF HARNESS-TYPE TRANSMITTERS

A total of 62 Mallard (Anas platyrhynchos) females were captured at th eir nests in eastern South Dakota during 1990 and 1991. Females were c aptured on an island, a peninsula cut off from the mainland by excavat ion, and a peninsula protected by an electric fence that deters mammal s. Loop harnesses were used to attach radio transmitters to females to evaluate possible effects of marking females on survival of their duc klings and to determine the influence of brood rearing on female survi val. No difference was found in duckling (P = 0.999) or brood (P = 0.4 58) (e.g., one or more ducklings alive in brood) survival to 7 d for f emales marked from 1 d prior to hatch to immediately post hatch (still in nest) compared with those marked at 3-9 d before hatch (P = 0.081) . There also were no differences in survival by age class between mark ed broods that did not suffer total mortality and unmarked broods (P > 0.05). If survival of broods was influenced by harness attachments on females, it likely occurred in females suffering total brood loss ear ly in brood rearing. Marked females with broods had poorer survival to 21 d than marked females that had lost or abandoned their clutches or broods (73.5% vs. 100%, P < 0.001).