Proposal for the use of morphometry as a sexing method for psittacine species Amazona amazonica,Amazona aestiva,Ara chloropterus,Anodorhynchus hyacinthinus,and Ara ararauna

Abstract

Psittacides are birds characterized by a curved beak, zygodactyl feet and colorful feathers, with species varying in size and without apparent sexual dimorphism. They are among the birds most threatened with extinction, with around 31% of species in the Neotropical region in this condition. Reproduction of these birds in captivity is crucial for the maintenance and recovery of populations, with sex identification being essential in this process. Given the difficulty of differentiating between males and females, it is proposed to use external morphometry to determine sex in a population of parrots, correlating it with the measurement of five parameters: length of the culmen, tomium, depth of the beak, length of the head and cloaca opening. Sex was determined by DNA testing, where females presented two copies of genes amplified by PCR (one from each chromosome, W and Z) and males presented only one copy (Z chromosome). 40 parrot specimens of different species were used: 7 Amazona amazonica, 8 Amazona aestiva, 9 Ara chloropterus, 5 Anodorhynchus hyacinthinus, 11 Ara ararauna. Of the total, 55% (22/40) were males and 45% (18/40) were females. Among the parameters evaluated, there were no significant variances between the sexes of the species studied, with the exception of one variable vent opening of one species Ara ararauna. Additionally, the lack of information about the age range of the animals meant that some individuals showed similarities, as in the case of A. amazonica, possibly linked to the stage of development. Thus, in addition to verifying that not all species can be subjected to the morphometric technique, the development phase also interferes with its use. It is concluded that among the species studied, only Ara ararauna is possible to determine the sex by measuring the cloaca opening, which showed significant differences, with no divergence from other biometric parameters.