Natural History of the Ornate Box Turtle, Terrapene ornata ornata AgassizLegler, John M.
Science
Natural History of the Ornate Box Turtle, Terrapene ornata ornata Agassiz
Legler, John M.
Ornate box turtle
Of the 194 turtles marked at the Damm Farm, 103 (53 per cent) were
adult or subadult females, 61 (31 per cent) were mature males, and 30
(16 per cent) were juveniles of undetermined sex. The ratio of males
to females was then, 1.00 to 1.69, and the ratio of juveniles to
adults was, 1.00 to 6.47. Eighteen of the 194 individuals were
juveniles less than 90 millimeters in plastral length and only six had
plastra less than 60 millimeters long (Fig. 25). The unbalanced ratio
between males and females may result, in part, from sexual differences
in habits. The studies of Carr (1952:9), Fitch (1954:140), Forbes
(1940:132), Legler (1954:138), and Risley (1933:690), have shown,
however, that unbalanced sex ratios, with females outnumbering males,
are found in several species of reptiles, especially in turtles.
Records for 540 adult _T. ornata_ collected at the Damm Farm, the
Reservation, and on roads in eastern Kansas, show that females
outnumber males just before and during the nesting season and again in
late autumn (Fig. 26). The high incidence of females in May, June, and
July, can be explained by their more extensive movements associated
with nesting in these months. I have no explanation for the increased
number of females captured in late autumn. In April and August, the
only two months in which males were more abundant than females, the
samples were small. The number of juveniles collected was too small to
allow any trustworthy conclusions concerning their seasonal incidence;
a few juveniles were taken in nearly all the periods in which adults
were active.
Risley (1933:690), studying _Sternotherus odoratus_ in Michigan, found
an over-all sex ratio of 1.0 male to 2.3 females; the percentage of
females in collections ranged from 50 to 71 per cent in April and most
of May and rose to 83 and 85 per cent in late May and mid-June,
respectively.
The infrequency with which hatchlings and small juveniles of ornate
box turtles are observed is well known to naturalists. Several of my
colleagues who are expert field observers and who have lived in areas
where ornate box turtles are abundant, have never seen hatchlings;
many other persons have seen only one or two. Rodeck (1949:33), noting
the abundance of coleopterous insects in the scats of captives and the
rarity of individuals of all age groups during dry periods in
Colorado, commented, "It is possible that the young are even more
subterranean than the adults. Perhaps they spend their early years in
rodent or other burrows where there is a fairly abundant insect fauna.
Increasing size might force them to the surface for feeding, with a
daily return to a burrow for resting and protection."
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