Hi All I was watching a show about reptiles and the sex of babies several varieties of reptiles and birds is determined by temp. I was wondering if anyone has tried this with chickens by using lower temps or higher temps at the critical stage to see if there is any difference in percentage of males to females. I found the following on WIKIPEDIA Temperature-dependent sex determination (TSD) is a system in which the temperature the eggs experience determine the sexes of the organisms that hatch. It is most prevalent and common among amniote vertebrates that are classified under the reptile class, but is also used among some birds, such as the Australian Brush-turkey. It differs from the chromosomal sex-determination systems common among vertebrates. It is a type of environmental sex determination (ESD); in other ESD systems, some factors such as population determine the sex of organisms (see Polyphenism). The eggs are affected by the temperature at which they are incubated during the middle one-third of embryonic development. This critical period of incubation is known as the thermosensitive period (TSP). The specific time of sex-commitment is known due to several authors resolving histological chronology of sex differentiation in the gonads of turtles with TSD.