Journal Article

Reproductive Effort and Reproductive Nutrition of Female Desert Tortoises: Essential Field Methods1

Brian Thomas Henen

in Integrative and Comparative Biology

Published on behalf of The Society for Integrative and Comparative Biology

Volume 42, issue 1, pages 43-50
Published in print February 2002 | ISSN: 1540-7063
Published online February 2002 | e-ISSN: 1557-7023 | DOI:

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I used three innovative, nondestructive field methods (gas dilution, doubly labeled water and radiography) to measure individual energy and water budgets of wild, female desert tortoises (Gopherus agassizii). With these budgets, I evaluated whether body reserves help females produce eggs independent of rainfall and food availability. Female desert tortoises used large seasonal and annual changes in metabolism and body water, protein and energy reserves to survive and produce eggs. Although lipid reserves are important to female desert tortoises, nitrogen or crude protein appears to be the primary limiting resource for producing eggs. By reducing metabolic rates 90%, females conserved enough body reserves to produce eggs during extreme drought conditions; this is an effective bet-hedging reproductive pattern in an extreme and unpredictable environment.

Journal Article.  5599 words.  Illustrated.

Subjects: Biological Sciences