The effect of photoperiod on reproduction of Chinese quail, Coturnix chinensis (Linnaeus) : A dissertation submitted in partial fulfilment of the requirements for the Degree of Bachelor of Agricultural Science with Honours in the University of Canterbury

Abstract

Reproduction in most birds is restricted to certain times of the year when conditions are most favourable for the rearing of young. In order that the birds be physiologically prepared for the onset of this favourable period, certain factors must exist to predict the time of its arrival. Changes in photoperiod provide the predictive information in many birds, especially those inhabiting temperate regions. In such regions, annual fluctuations in photoperiod are large and the breeding season is restricted to a specific and fairly short period of time. In tropical regions, where annual variations in photoperiod are slight and are of little use for predicting the most favourable time for breeding, the predictive role is often taken over by rainfall. In general, the rainy season brings vigorous growth of the vegetation, which in turn provides opportunities for building nests and obtaining food readily. On the other hand, tropical birds which experience favourable breeding conditions all year round may not be affected by external factors at all, but may have an endogenous reproductive cycle of their own. The role of photoperiod in reproduction has been investigated for many species of birds. Species extensively studied are the Japanese quail, Coturnix coturnix japonica, {Wilson et al, 1962; Tanaka et al, 1965; Follett and Sharp, 1969; Nicholls et al, 1973; Nicholls and Follett, 1974; Gibson et al, 1975), white-crowned sparrow, Zonotrichia leucophrys garnbelii, (Farner, 1959, 1965; Stetson et al, 1973; Follett et al, 1974, 1975) and the canary, Serinus canarius, (Follett et al, 1973; Steel et al, 1975.) This project was performed with a subspecies of Chinese painted quail, Coturnix chinensis (Linnaeus). The species occupies a latitude range from about 250 N to 390 S. Thus, the species must be considered to be an inhabitant of tropical areas, although its range does include some temperature regions. This distribution pattern indicates that reproduction of the bird is probably not under the direct control of photoperiod. Species which may have photoperiodically controlled reproductive cycles in many parts of their range may respond to rainfall nearer the equator (Williamson, 1956; Orians, 1960; Marshall, 1963; Payne, 1969). It seems equally likely that the converse may apply and therefore populations of Chinese quail inhabiting temperate zones may be quite sensitive to photoperiod, although reproduction of those nearer the equator may be regulated by rainfall, an endogenous rhythm, or some other factor. The aim of this project was to investigate the role of photoperiod in reproduction of Chinese quail, and if possible to determine whether photoperiodic time measurement occurred in these birds by means of a circadian rhythm of sensitivity to light.