Improving the Adaptability of Animals by Selection - Genetics and the Behavior of Domestic Animals - page 305

The treadmill and time budget tests did not permit the expression of
aggression because the two birds were separated from one another by a wire
mesh partition. Under these conditions, these differences between adult high
SR and low SR quail. In the open-field test, aggression can be expressed
because there is no barrier between birds, and adult interindividual distances
are identical in high SR and low SR lines. To test for differences in aggres-
siveness, paired encounters were staged between low SR and high SR pairs
of adult birds. High SR line birds showed more aggression (particularly
attack) than the low SR line birds ( Magnolon, 1994 ; Francis, unpublished
data).
Another situation in which social motivation can be measured is tests of
social facilitation. In many species, social facilitation influences feeding
behavior. In quail, social facilitation occurs when one bird sees another bird
doing something and then imitates or increases its own expression of that
behavior. To test social motivation in each of the four selected lines, groups
of three quail were presented with a novel (colored) food, either within sight
of birds called teachers, or in their absence. Teacher birds were preadapted
to the colored food and readily consumed it. The birds being tested were
also familiar with the teacher birds and control tests were run using the nor-
mal food of the test birds. There were no differences in the four lines in the
control situation (normal food in the presence or absence of teachers), in
time elapsed to start eating, nor in the time spent at the feeder. In the novel
food without teachers situation, significant differences were found between
the long TI and short TI lines ( Figure 8.18 ). Long TI (high fear) birds took
longer to eat. The longer latency to begin eating the colored food in the high
tonic immobility chicks is possibly explained by higher neophobia (fear of
novelty) in this line. In the novel food with teachers present test, the high SR
and low SR lines differed. The low social reinstatement line had longer
(latency) times to start eating and spent less time at the feeder. In this social
situation, high SR line chicks appeared to learn from the teachers whereas
the low SR line chicks did not.
STRESS REACTIONS
Stress reactions can also be induced by frightening stimuli ( Toates, 1995 ), or
by modifications of the social environment ( Gross and Siegel, 1985; Jones
and Harvey, 1987 ). In the four genetically selected lines of quail, the birds
selected for high and low levels of fear and the birds selected for high and
low levels of social reinstatement tendencies should, theoretically, react in
different ways to different types of stress-inducing stimuli. If this model has
validity, two predictions can be made: (1) the long tonic immobility (high
fear) line is likely to be the most reactive to novelty or frightening manipula-
tion of the test environment, and (2) the high SR lines will be more reactive
to manipulations of the social environment.