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Idaho Fish and Game


Mountain Goat Gender Identification


It is difficult to distinguish between male (billy) and female (nanny) mountain goats. There is no regulation requiring hunters to take only billies. However, female mountain goats accompanied by kids may NOT be taken.

Hunters are strongly encouraged to select a male for harvest because excessive harvest of nannies over time can lead to reductions in productivity and herd size, which in turn limits permit levels. Hunt areas in Idaho have been closed or allocated fewer permits because of high levels of nanny harvest.

Physical traits to distinguish males from females

  1. Observe urination posture.
    • Females squat while urinating (like a female dog)
    • Males lean forward to urinate (like a male horse)
  2. Through a spotting scope or high-power binoculars, look for scrotum/testicles. The presence of testicles is a reliable means of identifying males but it is often very difficult to see them.
  3. There are two characteristics of horn shape that differ between males and females. Horn characteristics are difficult to judge, even at close range, so hunters should consider all criteria when identifying male and female mountain goats.
    • Horns of billies tend to be thicker at the bases and sweep back in a uniform curve.
    • A nanny’s horns are thinner at the base and tend to grow up straighter before curving back at the last few inches of the horn.
  4. Lack of kids in a group does not mean the animals are billies.

All other characteristics that you may hear about are quite variable in nature (body size, hair coloration/staining, solitary animals, etc.) and are not useful for positively identifying a goat’s sex.

Is it a Billy or a Nanny?