Yellowstone Science – Motherhood

For many of Yellowstone’s species, spring’s arrival not only brings relief from winter’s challenges, but also resets the biological calendar that governs individuals’ lives. As April’s temperatures rise and its expanding daylight weakens the veneer of snow and ice, many animals enter a new phase of their life history through the process of birth. The female raven at her cliff ledge nest, a cow bison on the big sage flats, and a mother wolf down inside a boulder den—all share in the culmination of their reproductive efforts from the previous months. There are many challenges for animals of any sex and age to simply survive from one life stage to the next. For a mother charged with the great expense of gestation, birthing, lactation, and successful raising of offspring, the costs are extraordinary. Because of certain individual traits, or social and environmental conditions, some mothers are more successful than others. While awe and admiration is deserved for all who become mothers, a biologist studying animal reproduction is particularly interested in asking: What are the qualities of a great mother? What factors play most significantly in shaping success at this key life-history stage?