There are reports in recent literature that a markedly thinner light cementum layer in the tooth section can be used to identify a year during which a female black bear successfully reared a cub(s). Since cubs are normally born on alternate years, the light cementum layers of the reproductively successful female will have an alternating thick-thin pattern. (Source: Matson's Laboratory-Montana)
Matson uses two criteria to identify the light cementum layers that have been defined as "cub years":
- thinning of the cub year, compared to the prior year, is greater than would be expected according to the age-dependent thinning pattern that is evident for the individual;
- evident thickening of the light cementum layer that follows the cub year. The combination of the two criteria appears to clearly define a cub year.
Strength of evidence supporting reconstructions. The presence of both criteria, above, is considered to be strong evidence indicating a cub year. If one of the two criteria are absent, then a "?" is reported with the questionable cub year.
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