40 
BULLETIN OF THE BUREAU OF FISHERIES 
rarely it occurs in animals that have fed and have gained some growth. Animals 
that fail to take food are inactive, and they seldom enter the water but seek the sun 
and heat. Many of these animals die, but others often suddenly begin to feed, and 
a rather rapid recovery (for a terrapin) takes place. For example, 200 soft-shell 
terrapins (the very poorest) were selected late in May, 1927, from 2,180 winter-fed 
terrapins of the 1926 brood. Of the 200 animals selected, 74 were living on August 
15, 1927, when they were liberated. All had gained some growth, the shells had 
become hard, and, with the exception of 1 animal that had a tail lesion, all gave the 
appearance of being healthy and sound. 
Soft shell, except possibly during 1914, when a severe epidemic of sores existed, 
has caused the greatest loss among winter-fed terrapins. The loss from this source, 
combined with minor losses from limber neck, etc., for the several broods (1920 to 
1927) for which fairly accurate data are available has ranged from 10.3 per cent 
(1921 brood) to 23 per cent (1924 brood). Table 16 shows in detail the percentage 
of deaths among winter-fed animals ascribed principally to soft shell and those due to 
sores. Soft shell, too, appears to be the chief cause, during their first summer, of 
the heavy mortality among terrapins that hibernated. 
Limber neck apparently is a form of paralysis, which most frequently causes 
the animal to lose the use of the muscles in the neck and fore limbs, but occasionally it 
affects only the hind limbs or the control of all muscles may be lost. Few recoveries 
have been noticed. No definite records of the death rate caused by this disease are 
available, but it quite certainly has never exceeded one-half of 1 per cent and, there- 
fore, is quite negligible. 
The cause or causes of the great fluctuations in the death rate of hibernating 
terrapins is much more difficult to find. Since the animals do not feed during the 
hibernation period, nor have fed previously, and since they do not expose themselves 
to light but lie buried underneath sand, sod, or debris, food and light appear to be 
eliminated as factors influencing survival. Weather conditions — that is, tempera- 
ture and precipitation — appear to be the most plausible influences to consider. 
Precipitation is of little importance, however, as the hibernating animals are pro- 
vided with covered quarters, 9 into which little rain can enter, and moisture is provided 
artificially. Therefore, rainfall appears to be of little importance. A careful study 
of temperature records has revealed nothing. The greatest mortality that has 
occurred during the course of the experiments, as shown by Table 17, took place 
in the brood of 1922. In the 1926 brood it was negligible. 
In view of the contrast in the death rate of young hibernating terrapins, tem- 
perature records (kept at this station in cooperation with the United States Weather 
Bureau) were carefully compared for the months during which the 1922 and the 1926 
broods were in hibernation. Comparing temperatures, month by month, for the 
two seasons, the greatest difference occurs in February, for the average maximum 
and mini mum temperatures each were 9.5° F. higher in 1927 than in 1923. The 
highest temperature on any one day during February, 1927, was 74° and the lowest 
• A description of the winter quarters provided for hibernating terrapins is given in Bureau of Fisheries Economic Circular 
No. 60, 1926, p. 16. 
