Duckling survival among broods reared by 8 radio-marked and 28 unmarked black ducks (Anas rubripes) was studied in Maine during 1977-80. The mean class III brood size of 5.26 yielded an apparent survival rate of 0.6152 from hatching to fledging. However, by using the method described by Mayfield (1961, 1975), survival was estimated as 0.4244, indicating that average class III brood size overestimated recruitment by 45%. Young ducklings (class Ia-IIa) had a survival rate of 0.6073, which was significantly lower than the 0.6988 rate for older ducklings. At least 1 unmarked and 5 radio-marked hens lost all their ducklings. Total-brood survival was estimated at 81%. The lower survival of ducklings of radio-marked hens (0.9517/day) compared with those from unmarked females (0.9895/day) was attributed to better documentation of total-brood loss for radio-equipped birds. Ducklings hatched after 14 June had lower survival (0.1007) than did young from earlier nests (0.3713). Our study showed a lower survival rate than usually is attributed to this species, with productivity approaching the low levels reported for black ducks breeding in estuarine habitats of the St. Lawrence River.
Additional publication details
Survival of juvenile black ducks during brood rearing