Mortality rates of canvasbacks were estimated from band-recovery records. The annual rate of mortality of immatures during the first year was 77 per cent. Annual mortality rates of adults ranged from 35 to 50 per cent. Mortality rates of females were higher than those of males. Relatively larger numbers of immatures and adult females were shot early in the hunting season, and relatively larger numbers of males were shot late in the hunting season. Hunting was estimated to account each year for more than one-half the deaths of canvasbacks of flying age. Comparisons of band-recovery rates in years of different hunting regulations showed that both season length and daily bag limit affected the hunting kill.
Additional publication details
Flexible time budgets in breeding Common Murres: Buffers against variable prey availability