Birds of America By John James Audubon,
BUFFEL-HEADED DUCK. [Bufflehead.]
FULIGULA ALBEOLA, Linn. [Bucephala albeola.]
http://employeeweb.myxa.com/rrb/Audubon/VolVI/00673.html
Egg Laying Intervals And Nutrient Reserve Use Of
Breeding Female Buffleheads And Barrow's Goldeneyes
THOMPSON, JONATHAN E. Department of Zoology, Ecology and Evolution
Group, University of Western Ontario, London, Ontario, Canada N6A 5B7 and
Caesar Kleberg Wildlife Research Institute, Texas A&M University -
Kingsville, Campus Box 218, Kingsville, Texas 78363
ANKNEY, C. DAVISON. Department of Zoology, Ecology and Evolution Group,
University of Western Ontario, London, Ontario, Canada N6A 5B7
This study was conducted to investigate nutritional aspects of
reproduction in female Buffleheads (Bucephala albeola) and Barrow's
Goldeneyes (Bucephala islandica) breeding in central British Columbia in
1993 - 95. Mean egg laying interval (Ò SE) for Buffleheads was 48.36 Ò
2.35 hr, which was similar to that of Barrow's Goldeneyes that laid, on
average, every 45.32 Ò 1.40 hr. As a consequence of slower rates of egg
production, daily energetic costs of reproduction in female Buffleheads
and Barrow's Goldeneyes, evaluated relative to their basal metabolic
requirements, are among the lowest documented for ducks. Patterns of
lipogenesis differed between female Buffleheads and Barrow's Goldeneyes,
but both species catabolized somatic fat during egg production.
Buffleheads maintained stable body protein during reproduction, and thus
relied exclusively on dietary protein for clutch formation, whereas
Goldeneyes catabolized small amounts of somatic protein to produce egg
protein during the 1993 breeding season. Use of body protein by a
primarily carnivorous duck suggests that protein availability, i.e.,
invertebrate abundance, in breeding habitats used by Goldeneyes was
periodically deficient. Somatic mineral supplied approximately 8% of
clutch minerals in Buffleheads and 3% of clutch minerals in Goldeneyes
during the 1993 breeding season, but neither species used endogenous
minerals for eggshell production in 1994. Size of somatic lipid and
protein reserves apparently did not limit clutch size in either
Buffleheads or Barrow's Goldeneyes. Furthermore, clutch size was
apparently not constrained by size of somatic mineral reserves in
Buffleheads. However, body mineral mass was positively related to clutch
size in Barrow's Goldeneyes. Thus, from a nutritional perspective, our
data suggest that size of mineral reserves may limit clutch size in
Barrow' Goldeneyes, whereas relatively low rates of nutrient reserve use
indicate that clutch size in Buffleheads may not be constained by size of
these reserves. |