The three age groups seem to be natural ones, and each has its own methods and activities.
Age groups for opossums caught in the three seasons are shown in the following tabular fashion.
This species appears to stay in age groups when it flocks, as evidenced by the large flocks of young in first-year plumage.
Four age groups, based on characters of the dentition and skull, have been recognized.
Saupe observed a strong "herd instinct" in all age groups of Blaberus craniifer.
The three age groups seem to be natural ones and each has its own methods and activities.
Since there is a brief annual breeding season, any local population of racers consists of a series of discrete annual age groups.
A study of the age groups in each month's population revealed a differential survival based on the season of birth.