Growth and reproduction trade-offs can estimate previous reproductive history in alpine ungulates

1. Life-history theory predicts energy allocation trade-offs between traits when resources are limited. If females reduce allocation to growth when they reproduce, annual growth could reveal past reproductive effort, which would be useful to assess population dynamics and harvest sustainability. The potential and accuracy of growth measures for predicting reproductive success have rarely been evaluated with individuals with known reproductive history.

2. We used long-term monitoring of annual growth and reproduction of marked female bighorn sheep and mountain goats, two species in which primiparity normally occurs well before growth completion, to evaluate growth vs. reproduction trade-offs and their potential for predicting reproductive history of young females using mixed models and 10-fold block cross-validation.

3. We documented a significant reduction in mass gain and horn growth in young reproducing females of both species. This trade-off was affected by individual differenc...