Endangered Species Recovery Program

Evaluation of methods for permanently
marking kangaroo rats
(Dipodomys: Heteromyidae)

Published in:

Pp. 259-271, in Life Among the Muses: Papers in Honor of James S. Findley (T.L. Yates, W.L. Gannon, and D.E. Wilson, eds.). Spec. Publ., Mus. Southwestern Biol., 3:1-290, 1997

by

Daniel F. Williams,
Walter Tordoff II
and
David J. Germano

Abstract

We analyzed the loss and failure rates, misreading errors, mortality during applying and reading marks, and relative costs of marking kangaroo rats, Dipodomys heermanni, D. ingens, and D. nitratoides, during an 8-year study. Tattooing was considered to be an unacceptable method because of the high rates of misread marks (3.9%) and mortality during handling (0.5%). Cheek-pouch tags showed unacceptable problems with infections and injuries from the tags. Ear tags were the least expensive, but had the highest rates of loss (1 - 58% for time intervals of 6 days to > 1 year) and a relatively high rate of reading errors (0.5%). Infections often were associated with tags after they had been attached for several weeks or months. Passive integrated transponders (PIT tags) had the highest equipment and supply costs, but required the least amount of time to identify marked animals. They had lower loss rates (1 - 7%) than ear tags and a very low misreading rate (0.005%). Readers that store numbers can eliminate all misreading and transcription errors. No infections or other pathology were noted for PIT tags. The rate of mortality during handling for applying and reading ear and PIT tags (most were marked by both methods) was 0.04%; all mortalities involved the smallest-sized species, D. nitratoides.