Early and Noninvasive Bird Gender Identification by ATR-FTIR Spectra Coupled with a Randon Forest Algorithm

The early identification of sex in birds is essential for reproduction, breeding programs, and commercialization and plays a crucial role in wildlife management and environmental law enforcement. The DNA-based molecular techniques, known for their accuracy and noninvasive nature, are the primary methods for sex determination. However, these techniques are time-consuming and expensive and require specialized laboratories. This study explores the use of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) combined with the Random Forest algorithm as a noninvasive, cost-effective, and precise alternative for early gender determination in birds. Measurements were performed on the feather region, known as the vexillum, of four bird species: <i>Oryzoborus maximiliani</i> (Bicudo), <i>Nymphicus hollandicus</i> (Cockatiel), <i>Oryzoborus angolensis</i> (Curio), and <i>Psittacula krameri</i> (Ring-necked Parakeet). The bird's sex was confirmed by DNA analysis. The ATR-FTIR spectra in the range of 3800-800 cm^-1 were processed using standard normal variate (SNV) and analyzed with principal component analysis (PCA) to reduce dimensionality and highlight significant transitions. Processing ATR-FTIR spectra by the Random Forest classifier yielded promising results, with accuracy rates in an external validation of 94.4% for Bicudo and Curio, 77.8% for Cockatiel, and 72.2% for the Ring-necked Parakeet. These findings highlight the potential of ATR-FTIR as a viable technique for the early identification of gender in birds.