Many terrestrial mammals scent mark in areas containing the scent marks of conspecifics, and thus, may deposit their own scent marks on top of those that were deposited previously by conspecifics. This phenomenon, known as over-marking appears to play a role in same-sex competition or mate attraction. The present study determines whether meadow and prairie voles avoid over-marking the scent marks of conspecifics, target the scent marks of conspecifics and over-mark them, or randomly over-mark the scent marks of conspecifics. The data show that meadow and prairie voles adjust the number and location of scent marks that they deposit in areas marked previously by particular conspecifics. Male and female meadow and prairie voles target the scent marks of opposite-sex conspecifics and over-mark them. Female meadow and prairie voles also target the scent marks of female conspecifics. In contrast, male meadow and prairie voles over-mark the scent marks of male conspecifics in a random manner. By differentially overmarking the scent marks of conspecifics, voles may be able to communicate particular information to a variety of conspecifics.

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Purpose Male partner engagement in family planning can influence women's contraceptive behaviors and risk of unintended pregnancy. We identified factors associated with self-reported expectations for future contraceptive use among a nationally-representative sample of young men. Materials and Methods The National Survey of Reproductive and Contraceptive Knowledge asked unmarried, sexually active men (ages, 18–29 y), who were neither involved in nor trying for a pregnancy, about their likelihood of having sex without contraception in the following three months. Demographics, social factors, and contraceptive awareness and attitudes were examined for potential associations using weighted analyses. Results Of 903 men surveyed, nearly 600 were sexually active and expected to have sex in the following 3 months; nearly half (43%) reported at least some likelihood (23% slightly, 7% very, 13% extreme likely) that they would have sex without any contraception. Factors independently associated with sex without contraception included: not completing high school, not being in school full-time, not receiving sex education, limited awareness of contraceptive methods, multiple sexual partners, and friends with unintended pregnancies. Conclusions Despite not wanting a pregnancy, many young men report they will have sex without contraception. While comprehensive sex education may increase contraceptive use, interpersonal and social factors also influence men's expected use of contraception.