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Annexe IV
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Performance measures
Trials were performed on one-month-old juveniles, in a wooden box containing nine open
areas (9 cm long × 9 cm wide ×6 cm high) that were aligned in three rows of three. Each open
area was considered as an independent unit. Trials were performed at an ambient temperature
of approximately 28°C. Turtles were randomly distributed into groups of nine individuals.
Each group of nine turtles was tested twice before and twice after feeding. The two replicate
trials per nutritional status were performed alternatively during the morning and the
afternoon, at least two days apart. Trials were videotaped with a numerical camera, to prevent
experimenter-linked inconvenience effect during trial. The videotaped record began when all
turtles were placed upside down and was stopped after a maximal duration of 30 minutes. The
data were collected a posteriori from the videotapes.
We studied two different and independent measures revealing different components in the
righting response of the turtles: (1) the Latency time, defined as the time at the first movement
of the turtle since it was placed upside down, and (2) the Time to right, defined as the time for
a turtle to right itself since it started to move.
The juvenile growth rate was defined as:
Growth, survival and sex identification
Growth rate
=
ln(weight ) - ln(weight )
t t 0
t-t
0
weight t = juvenile weight at time of experiment
weight t0 = juvenile weight at birth
t-t 0 = age of juvenile at time of experiment
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