We used known-fate analysis in Program MARK to estimate retention rates for radio collars equipped with leather spacers on American black bears (Ursus americanus). We radio collared 72 bears 81 times in the Upper Coastal Plain of middle Georgia along the Ocmulgee River. For the 59 spacers that broke, they lasted an average of 365.5 days (SE = 31.3, 38-782) for males and 519.2 days (SE = 63.4, 139-1482) for females. Retention rate for leather spacers varied by month and sex (x- = 0.8736, SE = 0.0390, n = 50 for males and x- = 0.9391, SE = 0.0231, n = 50 for females). Leather spacers did not last as long on males, averaging 1 year but broke early enough to avoid injuries. Females tended to retain spacers for longer periods, allowing researchers to obtain greater data without having to re-collar them annually.