Growth, variations and age criteria in Apodemus agrarius (Pallas, 1771)

Variation in weights of body and internal organs of the field mouse in a gradient of urban habitats

“…This formed the basis for finally distinguishing 3 groups: (1) juveniles (age class I -up to 2 months), sexually immature animals; (2) adults (age classes II and III, 3-6 months), sexually mature animals born in the given calendar year or during the winter of the preceding year; old adults (age classes from IV to VII, over 7 months),sexually mature animals born during the previous calendar year. The division accepted took into consideration generations of rodents trapped in spring and autumn, since they might have differed in respect of many properties, such as growth and development indices, rapidity of sexual maturation and also weight of internal organs (Schwarz et al, 1965;Adamczewska-Andrzejewska, 1973).…”

“…The existence of this relation has been demonstrated in papers by Schwarz (1949Schwarz ( , 1958Schwarz ( , 1975. Relative weights of internal organs have been termed by Schwarz (1960) "morphophysiological indices" and are characterized by: (1) the fact that they apply to organs carrying out important functions in the organism's life, (2) clearly react to changes in the external habitat, (3) give a reliable representation of the animal's physiological condition.…”

Craniometric variations in Central European populations of Ondatra zibethica (Linnaeus, 1766)

“…A check was made to see whether this phenomenon is connected with differences in the growth rate of seasonal generations, such as are known to occur in other rodents (Adamczewska, 1959; Schwarz et al, 1964;Adamczewska-Andrzejewska, 1971; Z e j d a, 1971 and others). Muskrats in age class II (92°/o of all individuals) were obtained during the period from September to December, and were thus animals from the early spring litters.…”

Growth of an Australian murid ( Pseudomys novaehollandiae ) in the wild

“…There must be other factors operating to suppress early maturation in some members of the population. In several European rodents it has been shown that the early-born cohorts grow more quickly than the late-born (S c h w a r z et al., 1964;Bergstedt, 1965;Martinet, 1967;Saint Girons, 1967;Martinet & Spitz, 1971;Bujalska & Gliwicz, 1972;Adamczewska-Andrzejewska, 1973). In these species, however, a large proportion of the early-born cohort often matures in the season of birth.…”