Costs of reproduction in female moose ( Alces alces ) as measured by means of phenotypic correlations

• Published in: Canadian Journal of Zoology
• Main Author: Sand, Håkan
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1998
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Alces alces
• Online Access: http://dx.doi.org/10.1139/z97-181; http://www.nrcresearchpress.com/doi/pdf/10.1139/z97-181

The costs of pregnancy and lactation in terms of subsequent body growth and fecundity were studied by comparing different reproductive categories of Swedish female moose (Alces alces) during 1989-1992. Non-reproducing females and females that experienced gestation but not lactation were significantly heavier than females in the same reproductive category prior to reproduction. Production of one offspring and subsequent lactation during the summer and early autumn were also associated with an average annual increase in carcass mass, although this was less pronounced than in females that only experienced gestation. By contrast, production of two offspring and successful rearing of both to the autumn resulted, on average, in a reduction of carcass mass (7%) relative to that of females in the same reproductive category prior to reproduction. In female moose, while body growth was affected by the costs of lactation, future fecundity was not. Instead, future fecundity was related most strongly to the number of offspring produced during the current year. This positive association could not be attributed to variation in individual quality in terms of age or carcass mass. The ultimate consequences of reproduction in female moose seem to strongly influence the patterns of growth: adult females will alternate between gain and loss of body mass among years, depending on the number of offspring produced and successfully reared through the lactation phase.