Perceptual and Motor Skills, 1975, 41, 979-985. @ Perceptual and Motor Skills 1975

EFFECT OF COLOR I N REARING A N D TESTING ENVIRONMENT O N THE BEHAVIOR OF YOUNG DOMESTIC CHICKS1 JEFFREY B. BOLTZ A N D LEE C. DRICKAMER Williams College Simmary.-Young domestic chicks were reared individually in compartments of four different colors and then tested either in a color-preference test with stationary objects ( N = 1 2 8 ) o r with a moving stimulus ( N= 1 2 8 ) . For each type of test we used four background colors in the test arena. The dependent variables included color preferences, following behavior and emotional responses of the young chicks. The results showed no significant effects of the color of the arena-background in either test situation. The color of the rearing compartment was a significant factor affecting color preferences i n the test with stationary objects. In both test sicuarions the colors red, and then green, were the most potent in affecting the color preferences and emotional responses exhibited by the chicks.

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Gottlieb (1971) has suggested that the background color of the testing arena used in imprinting could be an important variable affecting the degree of successful imprinting in studies using precocial birds. In another study Salzen, et al. (1971) found that young domestic chicks preferred different colored stimulus objects depending upon the color of the background, but red objects were preferred regardless of the background. The color of the stimulus object is also an important parameter affecting the elicitation of a following response in precocial birds. Hess and Schaefer (1959) determined the order of effectiveness for different colors eliciting following behavior to be, blue, red, green, orange, grey, black, yellow, and white. In a similar study Smith and Bird (1964) found the order of effectiveness of colors to be, red, green, yellow, white, and blue. The differences in the results of these two studies may be atcributed to strain differences in the chicks used, procedural differences, seasonal variations, or differences in the behavioral criteria used to measure the following response. Age and prior experience also affect the color preferences of young chicks (Taylor, et al., 1969; Gray, 1961). These earlier findings raise three questions: ( 1 ) Does the background color of the testing arena affect the stimulus object color preferences of young domestic chicks? ( 2 ) Does the color of che testing arena affect the following responses of the young chicks? ( 3 ) What are the effects of early rearing exposure to a particular color on the color preferences and following behavior of 'Supported in part by Sloan Foundation Discretionary Funds at Williams College. Reprint requests should be directed to Dr. Lee C. Drickamer, Biology Department, Williams College, Williamstown, Ma. 01267.

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young chicks? The two experiments presented in this paper were designed to investigate some methodological aspects of these questions.

GENERALMETHOD Subjects Test subjects were hatched from White Rock chicken eggs from Arbor Acres Farm in Williamstown, Massachusetts. Prior to incubation the eggs were refrigerated for five days at 4OC to ensure a synchronous hatch of similaraged chicks (Gottlieb, 1 9 6 3 ) The eggs were hatched in a forced air incubator at 38 + OS°C and 80 + 2% relative humidity. The eggs were incubated in darkness and were turned three times per day at 8-hr. intervals. Turning was discontinued after the first chick in the group had pipped its shell. Apparatas and Procedare Each chick was reared individually in a compartment measuring 15 cm X 15 cm by 15 cm deep, with a fitted door having a 3-cm gap at the top to allow for air circulation. Thirty-two compartments were divided into four batteries of eight. Each group of eight compartments was painted a different color using flat Latex paint; blue, green, red or white. Continuous illumination and heat (35 to 37°C) were provided by a 7-W light bulb in the upper rear walI of each compartment. Chicks were removed from the incubator at noon or midnight and assigned at random to a rearing color and comparcment. Each chick was provided with food and water at the time of introduction into the comparcment and was left undisturbed until the time of testing. The compartments were thoroughly cleaned and aired out between groups of chicks. The rooms ho~lsingthe incubator, rearing compartments, and test apparatus were windowless and were maintained at a temperature of 33 + 2OC and 50 to 70% relative humidity. The incubator and room temperatures were checked, and adjusted when necessary, each time the eggs were turned. The rooms were not sound proof and continuousIy operating ventilation fans produced a constant level of background noise.

This experiment was designed to investigate the effects of early rearing exposure to a colored environment on the color preferences and emotionality of young chicks in a simultaneous choice test with stationary objects of all four test colors present. The effects of the background color of the testing arena were also investigated by systematically varying the color of the testing arena. Apparatus and Procedure A total of 128 chicks were used in this experiment; eight birds were tested for each of the 16 possible combinations of four background colors for the

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rearing compartments and four for the test arenas. N o chick was tested under more than one set of treatment conditions. Testing was conducted in a circular arena 110 cm in diameter with wails of 54-cm high aluminum sheeting. Four separate arena linings and floors were utilized, each set painted one of the four flat colors; white, blue, green, or red. Illumination for the test arena was provided by four 100-W incandescent light bulbs equally spaced 1 m above the arena floor and positioned so that no shadows were cast on the floor or walls of the arena. The levels of illilrnination at the site of the chick were nearly the same in all four rearing environments, white and red being 15 lux and green and blue 14 lux. Levels of illumination were also similar in the four test arenas being 23 lux in red, 22 lux in white, and 21 lux in both green and blue painted erenas. Four stimulus boxes, each measuring 13 cm X 15 cm X 10 cm and painted one of the four test colors, were placed on the floor at the outer perimeter of the arena; each box was located in one of four equal-sized quadrats of the arena as delineated by lines on the floor. To avoid positional or directional biases by the chicks the arrangement of the boxes was randomized for each trial. After a 60-hr. rearing exposure with one of the test colors each chick was tested in one of the four colored arenas. The chick was placed under a darkened box in a 30-cm square starting region at the center of the arena, the box was lifted and the chick's behavior was scored for a 15-min. test period. The dependent variables measured were ( 1 ) the color of the first stimulus box approached, ( 2 ) the total time spent within 30 cm of each colored box, ( 3 ) the number of pecks directed at each colored box, (4) the frequencies of distress vocalizations given while the chick was within 30 cm of each stimulus box, and ( 5 ) rhe number of defecations within 30 cm of each stimulus box. Data on the initial approach to the colored objects were analyzed with a chi-square test, and each of the other variables was analyzed using analysis of variance with eight replicates per treatment combination. Results

Chicks approached the red colored stimulus box first more frequently than the other stimulus boxes, regardless of either the color of the rearing compartment or the arena background color (Table 1 ) . Analysis indicated significant variation in the time spent near the object matching the color of the rearing environment (F = 7.23, df 3/112, P < .01); chicks reared in red compartments spent significantly more time near the red box (Table I ) , whereas chicks reared in blue, white, or green compartments spent less time with the colored object matching the color of the rearing compartment and showed no color preferences. There were no significant effects produced by the variation in color of the arena background. Significant differences were recorded for the number of pecks delivered

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J. B. BOLTZ & L. C. DRICKAMER

Effect of color in rearing and testing environment on the behavior of young domestic chicks.

Young domestic chicks were reared individually in compartments of four different colors and then tested either in a color-preference test with station...
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