Tuleyome's Science Corner - Black-tailed Deer
Black-tailed deer (Odocoileus hemionus columbianus) are very common in Berryessa Snow Mountain National Monument. These mammals are crepuscular meaning that they are most active and dawn and dusk, therefore, you will likely see their tracks or scat more often than the animal itself. They eat leaves, grasses, lichen, flowers, fruit, and berries. They even eat poison oak berries!
Baby deer, fawns, are usually twins and are born between May and July. A doe will give birth every other year, allowing her babies to stay with her for about two years. Newborn fawns have no scent at all during the first seven to ten days and lose their spots after three to four months.
Males start to grow their first “rack” of antlers when they are at least two years old – males less than two years old have single-prong antlers. Antlers start to grow in the summer and are covered with specialized hair called “velvet”. The velvet is covered with a webbing of blood vessels and is shed right before the rut, the breeding season, in the fall.
Because a deer’s pupil 10 times larger than a human’s pupil and they can see into the ultraviolet spectrum, deer have excellent low-light vision. Their eyes are placed in such a way that they have a visual range of about 310-degrees (humans have a range of about 180 degrees). In addition to their eyesight, their ears can move independently to help pinpoint where the sound is coming from. Ever seen a herd of deer scatter at the exact same time? Deer have a special gland on the outside of the lower part of the rear legs that produces a scent to communicate danger to the rest of the group.
Deer are one of the most frequently reported human-wildlife conflict species in the state. Here are some ways to limit your impact and interaction with deer:
- Remove fallen fruit in a timely manner.
- Clean bird feeders regularly and remove them if deer begin feeding under hanging feeders.
- Do not feed deer. Feeding deer can attract predators. (Please be aware, if there are deer, there may be a mountain lion – even in Los Angeles!)
- Leash pets when hiking or walking.
- Keep a safe distance when you encounter a deer.
- Slow down and be diligent when driving.
-Nate Lillge (nlillge@tuleyome.org)
Tuleyome Adventures and Engagement Director
Certified California Naturalist
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