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RESEARCH ARTICLE
Contents Vol 46(1)

Estimating age of wild eastern grey kangaroos through molar progression

Wendy J. King https://orcid.org/0000-0002-5832-0088 A B * and Graeme Coulson https://orcid.org/0000-0001-9873-8203 C
+ Author Affiliations
- Author Affiliations

A Département de Biologie, Université de Sherbrooke, 2500 boulevard de l’Université, Sherbrooke, QC J1K 2R1, Canada.

B Research School of Biology, The Australian National University, 46 Sullivans Creek Road, Acton, ACT 2601, Australia.

C School of BioSciences, The University of Melbourne, Parkville Campus, VIC 3010, Australia.

* Correspondence to: w.king@usherbrooke.ca

Handling Editor: Stuart Cairns

Australian Mammalogy 46, AM22043 https://doi.org/10.1071/AM23043
Submitted: 7 October 2023  Accepted: 22 November 2023  Published: 14 December 2023

© 2024 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of the Australian Mammal Society.

Abstract

Age is an essential attribute in studies of animal development, survival and reproduction. Here we evaluate the age estimation technique of molar progression devised for kangaroos in 1965. We used 71 wild eastern grey kangaroos (Macropus giganteus) that were first captured and aged as pouch young at Wilsons Promontory National Park, Victoria, and subsequently found dead between the ages of 1 and 14 years. We expected that the original equation, derived from captive kangaroos in Queensland, would not estimate age correctly due to differences in diet and/or clinal variation in skull morphology. We found no difference in rate of molar progression between males (n = 44) and females (n = 27). Our overall regression of age on molar index (MI) was log10 (age, days) = 0.284 (MI) + 2.511, r2 = 0.97. The slope of this equation was indistinguishable from that of the original one, meaning that molar progression in the wild was equivalent to that originally developed on captive kangaroos, despite likely differences in diet and morphology.

Keywords: ageing, chewing, estimating age, macropodid, molar progression, skull landmark, teeth, tooth movement, wild eastern grey kangaroos.

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