Survival of Adult Female Northern Pintails in Sacramento Valley, California

North American populations of northern pintails (Anas acuta) declined between 1979 and the early 1990s. To determine if low survival during winter contributed to declines, we estimated winter (last week of Aug-Feb 1987-90) survival for 190 adult (after hatching yr [AHY]) female radio-tagged pintails...

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Bibliographic Details
Published in:The Journal of wildlife management 1995-07, Vol.59 (3), p.478-486
Main Authors: Miller, Michael R., Fleskes, Joseph P., Orthmeyer, Dennis L., Newton, Wesley E., Gilmer, David S.
Format: Article
Language:English
Subjects:
Anas acuta
Animal and plant ecology
Animal reproduction
Animal, plant and microbial ecology
Animals
Aves
Biological and medical sciences
Birds
Demecology
Ducks
Female animals
Freshwater
Fundamental and applied biological sciences. Psychology
Hunting
Hunting seasons
Mortality
Overwintering
Predators
Radio transmitters
Survival rates
Vertebrata
Waterfowl
Wildlife management
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Summary:North American populations of northern pintails (Anas acuta) declined between 1979 and the early 1990s. To determine if low survival during winter contributed to declines, we estimated winter (last week of Aug-Feb 1987-90) survival for 190 adult (after hatching yr [AHY]) female radio-tagged pintails in late summer in Sacramento Valley (SACV), California. Survival rates did not vary by winter (P = 0.808), among preseason, hunting season, or postseason intervals (P = 0.579), or by body mass at time of capture (P = 0.127). Premolt (wing) pintails (n = 10) tended to survive at a lower rate (0.622, SE = 0.178) than pintails that had already replaced flight feathers (0.887, SE = 0.030) (P = 0.091). The pooled survival (all years) estimate for the 180-day winter was 0.874 (SE = 0.031). Hunting mortality rate (0.041-0.087) and nonhunting mortality rate (0.013-0.076) did not differ among years (P = 0.332) or within years (all P > 0.149). Legal hunting (n = 7), predation (n = 4), cholera (n = 2), illegal shooting (n = 2), botulism (n = 1), and unknown cause (n = 1) accounted for all mortality. Nonwintering survival (annu. survival/winter survival = 0.748) was lower than winter survival; thus, if gains in annual survival are desired for this population, managers should first examine the breeding-migration period for opportunities to achieve increases.
ISSN:0022-541X
1937-2817
DOI:10.2307/3802454