Assessing age in the desert tortoise Gopherus agassizii: testing skeletochronology with individuals of known age

Abstract

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 5:21-27 (2008) - DOI: https://doi.org/10.3354/esr00108 Assessing age in the desert tortoise Gopherus agassizii: testing skeletochronology with individuals of known age Amanda J. Curtin1,4, George R. Zug2,*, Philip A. Medica3, James R. Spotila1 1Department of Bioscience and Biotechnology, Drexel University, 3141 Chestnut St., Pennsylvania 19104, USA 2Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, PO Box 37012, Washington, DC 20013-7012, USA 3USGS-Biological Resources Division, Western Ecological Science Center, 160 N. Stephanie St., Henderson, Nevada 89074, USA 4Present address: Academic Resource Center, Duke University, PO Box 90694, Durham, North Carolina 27708, USA *Corresponding author: Email: zugg@si.edu ABSTRACT: Eight desert tortoises Gopherus agassizii from a long-term mark–recapture study in the Mojave Desert, Nevada, USA, afforded an opportunity to examine the accuracy of skeletochronological age estimation on tortoises from a seasonal, yet environmentally erratic environment. These 8 tortoises were marked as hatchlings or within the first 2 yr of life, and their carcasses were salvaged from predator kills. Using a blind protocol, 2 skeletochronological protocols (correction-factor and ranking) provided age estimates for a set of 4 bony elements (humerus, scapula, femur, ilium) from these tortoises of known age. The age at death of the tortoises ranged from 15 to 50 yr. The most accurate protocol—ranking using the growth layers within each of the 4 elements—provided estimates from 21 to 47 yr, with the highest accuracy from the ilia. The results indicate that skeletochronological age estimation provides a reasonably accurate method for assessing the age at death of desert tortoises and, if used with a large sample of individuals, will provide a valuable tool for examining age-related mortality parameters in desert tortoise and likely in other gopher tortoises (Gopherus). KEY WORDS: Age · Sexual maturity · Skeletochronology · Testudines · Mojave Desert ·North America Full text in pdf format PreviousNextCite this article as: Curtin AJ, Zug GR, Medica PA, Spotila JR (2008) Assessing age in the desert tortoise Gopherus agassizii: testing skeletochronology with individuals of known age. Endang Species Res 5:21-27. https://doi.org/10.3354/esr00108 Export citation Mail this link - Contents Mailing Lists - RSS Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 5, No. 1. Online publication date: July 22, 2008 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2008 Inter-Research.