11.|Female | | | | |April 26, 1950| 50-1/2 | 78-1/2 | 2.7 |This skink had attained |May 24, 1951| 74 | 87 | .... | maximum female size |April 28, 1952| 78 | 72 + 21 | 8.5 | when she was a little |April 23, 1953| 80 | 73 + 20 | .... | less than four years old. -------+------------------+----------+---------------------+------+---------------------------- Differences in their growth rates therefore reflect differences in sex, individual vigor, and local situation, in individuals living at the same time and within the same general environment. Changing weather, and other factors that vary from year to year cause marked differences in the dates of important events in the annual cycle, and in the stage of development at any given date. Data are available for five successive annual broods of young, those of 1948, 1949, 1950, 1951, and 1952, and each brood differs from the others to some extent, as shown in Figures 11 to 13. In 1949, for instance, young hatched relatively early, and probably most of them were active by the middle of July. They made rapid growth in August, averaging larger than young hatched in other years on any given date in late summer. However, they retired into dormancy early in the fall. Cool and dry weather in early September ended their activity for the season. In 1950, young hatched, on the average, at least three weeks later, about the first of August, but they remained active until late in September, and by hibernation time had partly caught up to the stage of development attained by the young of 1949. Most young of 1951 hatched late in the first half of August, and at first were smaller than those of 1950 and much smaller than those of 1949 on corresponding dates, but favorable weather in the early fall hastened their development. By early September they had caught up and passed the stage of development of young of 1950 and by the time they retired to dormancy in late September, they had reduced by half the size-advantage of the young of 1949 at the time these latter retired into hibernation. The young of 1951 appeared to be few in numbers, and a lack of competition may have been a factor in their rapid early development. [Illustration: FIG. 15. Records of growth in another group of recaptured young that grew less rapidly than those of Fig. 14.]