Survival of juvenile ring-necked ducks on wetlands of different pH

Brood and duckling survival of ring-necked ducks (Aythya collaris) was examined in relation to wetland water chemistry in eastcentral Maine during 1983-85. Daily survival rates (DSR) of broods and ducklings were determined for 381 ducklings from 64 broods by counts of each brood at 6-10-day intervals during broodrearing. Twelve of 64 females lost entire broods. Only 176 of 381 (46%) ducklings survived to fledge. Brood survival for the 45-day rearing period was 0.7731; duckling survival was 0.3707. Young ducklings (<24 days) survived at a lower rate (0.9750/day) than older (>25 days) ducklings (0.9818/day) (P = 0.002). Survival rates of broods and ducklings did not differ among wetlands of high and low alkalinities. Brood survival did not differ among wetlands of different pH, but DSR of ducklings was lower (0.9763/day) on low-pH (<6.0) wetlands than on high-pH (>6.1) wetlands (0.9816/day) (P = 0.049). Class lIb-III (25-45 days old) ducklings from the lowest-pH wetlands(<5.5) had the lowest DSR (0.9752) while Class lIb-III ducklings from the highest-pH wetlands (>6.5) had the highest DSR (0.9856) (P = 0.009).