JOURNAL OF WILDLIFE MANAGEMENT 72(6):1388–1393; 2008)
Breeding propensity, the proportion of sexually mature females that initiate egg production,
can be an important demographic trait when considering reproductive performance and,
subsequently, population dynamics in birds. We measured egg production using yolk
precursor (vitellogenin and very-low-density lipoprotein) analyses and we measured nesting using radiotelemetry to quantify breeding propensity of adult female harlequin ducks (Histrionicus
histrionicus) in British Columbia, Canada, in 2003 and 2004. Using both methodscombined,
and accounting for error rates of each, we estimated that breeding propensity of adult females
that migrated to breeding streams was 92%. These data suggest that, despite speculation that
harlequin ducks have low breeding propensity, almost all adult females on our study site were
not constrained in their ability to produce eggs and that influences on reproductive performance
at later stages likely have much stronger effects on population dynamics.
KEY WORDS breeding propensity, Histrionicus histrionicus, nonbreeders, radiotelemetry, vitellogenin, yolk precursors.