Urine fractions that release flehmen in black-tailed deer,Odocoileus hemionus columbianus.

Flehmen (or "lipcurl") is a response of male mammals primarily to female urine, performed primarily during the reproductive season. To elucidate the components of female urine that release the Flehmen, urine of black-tailed deer (Odocoileus hemionus columbianus) was fractionated, and the fractions were presented to captive male conspecifics during three rutting seasons. The active principle (one or more compounds) is watersoluble, of low volatility, not readily extractable with organic solvents, and between 200 and 12,000 daltons in molecular weight. Several urine components were identified, but none of these showed activity.