SURVIVAL OF RADIO-MARKED MALLARD DUCKLINGS IN NORTHEASTERN CALIFORNIA

Estimates of duckling survival are necessary to accurately assess recr uitment of mallards (Anas platyrhynchos), yet few reliable estimates e xist. During 1988-90, we estimated survival rates for 127 radio-marked mallard ducklings from 64 broods on Lower Klamath National Wildlife R efuge, California. In 1988, we restricted the survival estimate to the first 10 days post-hatch (S = 0.18, SE = 0.07). Survival from hatchin g to 50 days was 0.37 (SE = 0.09) in 1989 and 0.34 (SE = 0.07) in 1990 . Total brood loss differed among years (P < 0.05); 81.2% in 1988 (n = 16), 36.8% in 1989 (n = 19), and 37.5% in 1990 (n = 24). Ninety-three percent of mortality occurred during the first 10 days of life. We de tected no differences in the proportion of radio-marked ducklings fled ged from early-hatched versus late-hatched nests (P = 0.74). During 19 89-90, 16 females appeared to lose their entire brood; however, 3 radi o-marked ducklings from 2 of these broods were fledged by other brood hens. Of 29 radio-marked ducklings that reached 44 days of life, 6 (20 .7%) joined other broods. Habitat enhancement is the key to improving duckling survival because the large number of predator species that co nsume ducklings makes predator control difficult.