Morphometric and Molecular Techniques for Sex Identification in Greater Coucal (Centropus sinensis intermedius)

Abstract

Accurate gender recognition in birds is crucial for research and conservation. Nevertheless, distinguishing sexes in weakly dimorphic birds poses challenges for conservationists, hindering efforts to boost endangered populations. Greater coucal exhibits weak Sexual Size Dimorphism (SSD) and lacks established criteria or methodology for morphometric sexing. Therefore, this study aimed to determine the sex of a weakly dimorphic bird by amplifying the CHDZ and CHDW genes, examining seven (7) morphological characters for standardisation of morphometric analysis using discriminant function analysis (DFA). Freshly plucked feathers from 66 Greater Coucals were used in Touchdown Polymerase Chain Reaction (tPCR), amplified a single Z band in males and both Z and W bands in females. Amplification of the
300-400 bp segment of the CHD1-Z gene and a 200-300 bp segment of CHD1-W using the 2550F/2718R primer set gene can be used to distinguish the sex of adult Greater coucal (males 30: females 36). The established function is (D = (-61.74) + (0.29) bill culmen length + (0.50) total head length + (0.60) bill depth) allowed for 100% correct
classification where female if D > 0 and male if D < 0. Thus, the formulated function equation, intended for practical application in the field, emphasises the potential for gaining valuable insights into diverse facets of the biology, behaviour, and ecology of monogamous bird species by exploring size differences. This first field-based, cost-effective study of sexual dimorphism in birds provides valuable resources for future
coucal management while offering important genetic and morphological data in Malaysia. It also provides the groundwork for more effective conservation and breeding programs, where accurate sex identification is crucial in decision-making.