Iowa State University Veterinarian Records, RS 22/6/0/9, University Archives, Special Collections Department, Iowa State University, http://www.add.lib.iastate.edu/spcl/arch/rgrp/22-6-0-9.html
The techniques available for sex determination of birds are the museum technique of measurements and weights, cloaca examination, laparotomy, fiber optic endoscopy, fecal and plasma steroid hormone analysis, and karyotyping. The procedure found most practical for the average veterinarian is the laparotomy. In this article the laparotomy procedure will be described, and its advantages and disadvantages discussed.
Elliott, Linda R.
"Sex Determination of Birds,"
Iowa State University Veterinarian: Vol. 40
, Article 4.
Available at: http://lib.dr.iastate.edu/iowastate_veterinarian/vol40/iss3/4