Morphological changes related to the growth of red junglefowl Gallus gallus spadiceus in captivity at Huai Kha Khaeng Wildlife Breeding Station

Morphological changes related to the growth of the Red Junglefowl, Gallus gallus spadiceus, were studied using 19 descriptive and 13 morphometrical characteristics on a captive bred population during their first year of development. The results showed that the descriptive characteristics can be used for age classification, especially at the first (0-7 day old) and second (2-20 weeks old) growth periods, whilst the morphometrical characteristics were valid for age estimation in all three growth periods over the first year of life, but were more accurate in the second and the third (6-12 months old) periods. During the first growth period, the morphological characteristics changed rapidly. At the first molting the natal plumages changed to juvenile plumage during the second growth period and the sexes could be differentiated by the color pattern of the feathers and the comb. The second molting occurred when the chicks were twenty weeks old, when their juvenile plumage changed to that of the prenuptial plumage. In the third growth period, chicks began their third molting, changing from the prenuptial plumage to that of the nuptial plumage, and at this stage males become more colorful with a brighter color and more glossy plumage feathers at the neck, wing covert, back and tail. In addition, the male’s red fleshy comb becomes enlarged in size, whilst in females, most of the plumage changed into a yellowish brown with mottled brown color, except for the neck feathers that have a dark brown or black strip. The 13 morphometrical characteristics were all significantly different (p<0.05) between age cohorts in both males and females, and were found to be positively correlated to the growth by nonlinear regression. This method can predict the age cohort in Red Junglefowls with 95-98% accuracy. Analysis of the tarsal growth rate revealed three distinct growth periods over the year. In first period (1-10 weeks old) the tarsal growth rate increased rapidly, but it fluctuated in the second period (11-24 weeks old), and became stable in the last period (24-40 weeks old.)