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(a)
800
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0
0
New
Control
New
Control
Food
Food
(b)
800
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New
Control
New
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Food
Food
FIGURE 8.18
Feeding latency and time at the feeder during the first contact with familiar or
novel food in the presence or absence of animals acquainted with the food tested in lines of
quails selected for long or short duration of tonic immobility and for high or low levels of social
reinstatement behavior over 14 generations. (
'
) STI, (
&
) LTI, (
) LSR, (
) HSR. (a) Without
teachers, (b) with teachers.
To test these hypotheses, birds from the four lines were subjected to three
potentially stressful situations and plasma corticosterone (stress hormone)
levels of each animal were measured. The tests were: (1) the introduction of
a novel stimulus (an inflated balloon into the home cage), (2) restraint in a
crush cage, and (3) isolation in a novel environment (
Figure 8.20
). The intro-
duction of the balloon into the home cage (
Figure 8.19
) induced a significant
increase in plasma corticosterone levels only in the long TI line (
Launay,
1993
). Presumably, the more stressful experience of restraint in a crush cage
as described by
Satterlee and Johnson (1988)
induced different behavioral
and physiological reactions in the long TI and short TI lines (
Jones et al.,
1994
). During restraint in the crush cage for a period of 15 minutes, the short
TI (low fear) birds showed more active struggling reactions (55.7) compared
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