Does "Headstarting" Help?
The concept of "headstarting" is simple. Eggs are protected and hatchlings are reared to the point where they are no longer as vulnerable to predators. Hatchlings can be eaten by just about any animal from a chipmunk or starling up in size. Juveniles are safe from a wider variety of predators, and the adults are relatively safe from all predators. Thus, any increase in size before the turtles are exposed to predators will increase the overall chance of survival.
While the idea is simple, the execution is not. There are a number of questions - how long to keep the hatchlings, whether or not to hibernate them, how to ensure proper development of the shell, etc. Julie Zickefoose and I are doing some experiments to try to get some answers. In 2003, Julie took 3 hatchlings (Riker, Data and Worf), fed them for a short while, and then hibernated them indoors over the winter. Meanwhile, I took 2 hatchlings (Picard and Geordi) and fed them over the winter without hibernation. On March 27th, 2004, my wife Ann was working in the turtle garden when she discovered a 6th hatchling, which we named Winter. This hatchling must have been from a second, undiscovered nest, laid by the other female (either Terry or Carol laid the eggs which produced Picard et al., there were no other eggs in that nest, so Winter must have come from a nest laid by the other female). The chart below shows hatchling growth; it will be updated periodically. You can see that Picard and Geordi grew exponentially and ended up much ahead of where they would have been on their own (as Winter was). Note also that Winter apparently was born smaller to begin with (this has nothing to do with headstarting). Riker and Worf were brought in by Julie on March 30th to be measured and weighed, and they did not grow much at all over the winter, although both had eaten a little in the fall and Riker had been eating for a day or so before being measured. The red circle in the graph below encompasses the length measurements of the 3 turtles not fed over the winter; the blue circle surrounds the weights of those turtles. Clearly both fall well below the length and weight measurements of Picard and Geordi, who had been eating all winter.
Above - Graph of Box Turtle Growth
Below: View of Picard, Geordi and Winter showing the effect of feeding the hatchlings through a winter. Picard and Geordi were fed; Winter was left outside and presumably only emerged from the egg a few days before being found on March 27, 2004.
It is obvious that feeding them over the winter increases their size; what we don't know is if there are any long-term effects. Will the turtles learn to go into hibernation on their own, for instance? Quasi, who was raised from a hatchling to an adult over 18 years in captivity, has a badly malformed shell and doesn't seem to know when to go into hibernation. Was this the effect of being raised in captivity - or simply from being raised in captivity for so long? Also, will the turtles that hibernated catch up?
Below - 5 hatchlings; Picard and Geordi on the left were fed over the winter, Riker and Worf were hibernated after feeding some in the fall, and Winter overwintered outside.
Current plans are to get Daisy and Dylan outside under more natural conditions this summer and to continue to protect all the 2003 hatchlings (Picard, Riker, Data, Geordi, Worf and Winter) and feed them over the summer of 2004.
Update: In the early summer of 2007, an unknown cat-sized animal raided the enclosure and killed 2 of the small turtles after they had reached a length of several inches long at the plastron.
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