The hypothalamic-pituitary-gonadal (HPG) axis ubiquitously regulates seasonal reproduction. following the rhythmicity of a suite of environmental cues. Birds display prominent seasonal variations in gonad size regulated by two hypothalamic peptides. gonadotropin-releasing hormone-1 (GnRH-I) and gonadotropin-inhibiting hormone (GnIH). https://fitnessgravesyardes.shop/product-category/hub-assembly/