Percentage recovery of radioactive hormones added to plasma 
The recovery of radioactive testosterone added to male plasma was 38.8 
percent, and that of radioactive B-estradiol added to female plasma was 15.5 
gprcene (table 1). Less than 0.2 percent 14¢_-testosterone and 3.2 percent 
4c_8-estradiol was found on each of the remaining portions of the respective 
columns, indicating practically all of the testosterone or 8-estradiol were 
localized in one band on each of the columns. 
Steroid Hormone Unknowns 
Avian species examined 
Thus far these methods have been used to sucessfully distinguish the 
sexes of immature and mature bald eagles, mature barn owls, immature and 
mature black-crowned night herons, and a Louisiana heron. Prior to sexing a 
series of these species, a "blind trial" with known-sex pairs was conducted. 
Additional "blind trials' were conducted with known-sex pairs of mature 
Japanese quail, mature mallard ducks, and mature and immature American kes- 
trels. In all of these trials, the determination of sex was correct. 
Identification of steroid hormone components from males and females 
Staining with iodine.-- In all instances chromatograms of extracts from 
male birds showed five distinct bands when stained with iodine, and those from 
females usually two, and sometimes three. 
Charring with sulfuric acid.-- In extracts from birds identified as males, 
a band corresponding to authentic testosterone was visualized with iodine, but 
did not char with sulfuric acid. A band that chromatographed just above cho- 
lesterol and was not distinctly separated from it, charred a reddish-purple. 
In extracts from birds identified as females, a band corresponding to the f- 
estradiol standard was visualized with iodine, ran above cholesterol, and was 
distinctly separated from cholesterol; it charred a brilliant red like authen- 
tic B-estradiol. The most intensely stained band in both males and females 
corresponded to authentic cholesterol and charred a rust color like the 
standard. 
Emission of fluorescence under ultraviolet light.-- When viewed under 
ultraviolet light after charring, the band corresponding to B-estradiol 
appeared red and cholesterol pink, but neither fluoresced. The reddish-purple 
band in extracts from males emitted a brilliant, blue fluorescence under 
ultraviolet light. 
DISCUSSION 
Recommendations for Analyses of Steroid Hormone Unknowns 
The methods outlined for sex determination are very sensitive, relatively 
rapid, and require only a small plasma sample that may be frozen until 
analyzed. It is recommended that a known-sex pair of any given species always 
