DIAMOND-BACK TERRAPIN CULTURE 
43 
confined. On the other hand, some of them probably already were very old. The 
shells of some of these old animals have been worn smooth, leaving no trace of growth 
rings, which are prominent in younger terrapins. The writer does not care to venture 
to make an analysis of the age 10 of these terrapins. A conservative estimate, in the 
opinion of our terrapin culturist and the writer, is that the ages range from 25 to 
possibly 40 years or more. It is pointed out in the section of this report dealing with 
egg production that there is as yet no conclusive evidence indicating that these 
animals are declining in egg production because of old age ; nor is the death rate such 
(only two deaths having occurred during the past four years) as to suggest old age. 
The span of life of a diamond-back terrapin, therefore, remains undetermined. 
Table 16. — -Percentage of deaths caused by sores and other causes among winter-fed terrapins 
Brood 
Animals 
fed 
Per'cent 
of deaths 
due to 
sores 
Per cent 
of deaths 
due to 
other 
causes, 
prin- 
cipally 
soft shell 
1920 
2,502 
1 4.9 
14.7 
1921 
2,395 
3.7 
10.3 
1922 
2,787 
3.7 
21.4 
1923 
2,427 
2.3 
12.7 
Brood 
Animals 
fed 
Per cent 
of deaths 
due to 
sores 
Per cent 
of deaths 
due to 
other 
causes, 
prin- 
cipally 
soft shell 
1924_ 
2,407 
2, 391 
2,936 
3, 720 
6.3 
23.0 
1925 
2.0 
13. 2 
1926 
2.4 
20,8 
15.0 
1927... 
13.4 
1 The combined percentages of deaths due to sores and all other causes do not quite equal the percentages of loss shown in Table 
17, because each year a small number of animals is missing and in the table showing survival such animals are counted as dead. 
Table 17. — Survival of young terrapin during their first winter ° 
Year 
Terra- 
pins 
fed in 
nursery 
house 
Per 
cent 
sur- 
vived 
Ani- 
mals 
hiber- 
nated 
Per 
cent 
sur- 
vived 
Year 
Terra- 
pins 
fed in 
nursery 
house 
Per 
cent 
sur- 
vived 
Ani- 
mals 
hiber- 
nated 
Per 
cent 
sur- 
vived 
Year 
Terra- 
pins 
fed in 
nursery 
house 
Per 
cent 
sur- 
vived 
Ani- 
mals 
hiber- 
nated 
Per 
cent 
sur- 
vived 
1912 ».. 
500 
92.6 
480 
95.0 
1917... 
1, 481 
82.5 
735 
99.9 
1923... 
2, 427 
85.0 
993 
93.8 
1913... 
525 
96.0 
716 
99.7 
1919... 
2, 937 
82.0 
1, 590 
70. 6 
1924... 
2, 407 
68.6 
1, 163 
99.0 
1914. .. 
1,349 
53.9 
254 
82.2 
1920... 
2, 502 
79.6 
1, 404 
99.5 
1925... 
2,391 
85. 0 
1, 066 
81.3 
1915... 
1, 306 
97.6 
736 
87.2 
1921... 
2,395 
87.7 
231 
82.2 
1926... 
2, 936 
74.2 
1,627 
99. y 
1916... 
1,906 
89.7 
636 
90.2 
1922... 
2, 820 
75.6 
789 
44.7 
1927... 
3, 720 
69.4 
3, 192 
89.2 
« The percentages of survival of the winter-fed and hibernating terrapins are not directly comparable because the hibernating 
terrapins were taken from the hibernating boxes and counted late in March or early in April, whereas the winter-fed terrapins were 
counted when removed from the nursery house at least 1 month later. The death rate among hibernating animals during the first 
month after emerging from hibernation usually is large and generally much greater than among winter-fed animals. 
i> It must not be assumed that the sum of tho winter-fed and the hibernating lots of each year equals the total hatch. All the 
young animals rarely are found in the autumn, and frequently there is a considerable addition in the spring. Such animals, of course, 
are not included in this table. 
10 Barney (1922, pp. 93 and 94) has attempted to analyze the age of the wild brood stock on hand at this station. He estimated 
that their average age in 1921 was 28 years. If that be true, they would now (1928) be about 35 years old. 
