Bareheaded Bucks and a Springtime Quiz

Seven bucks in formal antler attire, Dipper Ranch sunset, Christmas 2011

It's the bareheaded season for bucks - by March they should have dropped their antlers. So far this winter, I haven't seen any brown and therefore recently-shed antlers on the ground. On the other hand, all the deer I see right now are antler-less. I play this game in late winter and spring - I try to figure out which are the does and which are the bucks by their body shapes and behavior. If I see a group of deer that are of mixed sizes, I assume it is the matriarch doe with her last two generations of daughters.  If I see a large single deer, I assume it is a lone buck. But I'm not sure, so the guessing game is actually quite fun for the next month or so.

The Columbian black-tailed buck grows and sheds its antlers every year. The antler calendar goes something like this:

June 2009 - small bumps on a young buck.

April - bumps appear on top of the head as increased blood supply to this area starts the growth of bone which forms the antlers.

May 2011- look closely to see the long blood vessels under the velvet cover of this buck's growing antlers.
You can see a larger version of any photo on this blogsite by clicking the photo.

May through July - antlers grow and branch with a velvety cover. The velvet contains blood vessels which nourish the rapid growth of antler bone.

late July through early August - velvet sheds off antlers due to constriction of the blood vessels at the base of the antlers. Bucks rub antlers on tree trunks and shrubs.

October 2011 - bigger buck pushing other buck back from doe herd.  No actual sparring, just a series of face-offs and the buck with the smaller rack in the background gradually browsed further and further away from the fence which separated him from the does.

October - coastal deer generally enter the rut.  Bucks use their antlers to demonstrate status when competing for access to does, only sometimes are antlers actually used in fights.

April 2011 - recently shed antlers usually still have some brown color to them.

mid-December through February - antlers fall off as the bone at their base is resorbed.

January 29, 2012 - taken by a wildlife camera at the Newt Spring, this was the last evidence of attached antlers on a buck at the Dipper Ranch in the 2011-2012 season.

January - March - no antlers, but if you look closely, you may see the pedicels, the raised circular base of the antlers, on the buck's head.

Those are the months reported for black-tail deer in Lake County, California (Taber and Dasmann, 1958), so it may vary somewhat in other regions.

A spike buck skull I found in a forest with lots of vertebrae. 

If you find a deer skull, you can tell whether it was a buck by the presence of antlers.  If just the pedicels are present, that means the buck died during late winter. Last summer, while working with volunteers at Los Trancos Open Space Preserve, I reached under a coyote brush to pull out a yellow starthistle plant, when I spotted a deer skull with pedicel stumps - a buck died there a few months earlier.  Then in the tall grass nearby I found another skull that was smooth behind the eye sockets indicating it was a doe. It was fun comparing the two skulls as a break from our hot work, but then we started imagining what large predator frequented the area.  I try hard to make volunteer projects fun and interesting, and signs of mountain lion predation really add excitement to weeding.

December 2011 -typical signs of antler rubbing on a willow, although a little late for the usual rutting season.

I start seeing skinned-up willows in late summer and then I know the rutting season for black-tailed deer is coming up. The buck's purpose for rubbing his antlers on branches is to advertise his vigorous presence through scent and the bright color of the freshly debarked wood. The buck is rubbing the scent from glands on his head and face onto the tree, and then as he further spars with the brush, that scent is transferred onto his antlers which he waves throughout the forest and glen as he trots away.  I used to think bucks were rubbing their antlers to relieve itching from the shedding velvet (like when our skin peels after sunburn), but Mark Elbroch says that may be secondary to the buck sending out waves of his own personal, powerful scent.  As humans, we are so dependent on our visual senses, we don't always realize how primary the olfactory senses are to many animals.

December 2011 - a thoroughly thrashed willow branch.
Imagine what the message was if you could smell it too.

Bucks don't pick big trees for rubbing.  They tend to go for branches that have a little give to them.  One fall, I was setting up an ecological restoration workshop in Yosemite National Park and the biological staff told me the bucks preferred the flexible stakes they installed with protective plastic screens around saplings planted along the Merced River.  Soon there were bucks running around the valley floor with bright yellow netting hanging from their racks.  That was the last time the park staff used that technique.

December 2011 - out-of-season antler rubbing on recently planted alder.

Recently, I have been finding what looks like antler rub at a time outside of the rutting season.  We took out an old road on the Dipper Ranch, restored a creek to its original banks, and planted alder and willow saplings in mid-November.  By the end of December, almost ever planted alder had its bark scraped.  I think it is because we put the young trees at a location where a buck frequently travels and he decided to mark these new intruders along his route.

August 2011 -  wildlife camera catches photo of buck from backside revealing genitalia hanging between legs.

I've asked my hunter friends if there was a way to tell the difference between a buck and a doe during the antlerless season. They described differences in size, the curve of the neck, the shape of the chest, and one friend even said mature does are shaped like a bread box.  I'm not good at picking out those features yet, and really, does anyone even know what a bread box looks like anymore?

May 2011 - It's a buck.  Probably not usually this obvious.

Last spring, a big buck was hanging out in my yard for a few weeks and gave me some very good views through my kitchen window. I realized that at the right angle, you can spot a buck even if he doesn't have antlers. You don't want to get that close to a buck, so binoculars or the zoom function of your camera are useful tools. I figured if I had that question, some of you do too, so I thought I would share.  We are all biologists here, right?

Now you try it.  See if you can tell if these deer are bucks or does.

March 4, 2012 - adult deer in center of photo followed by yearling

March 4, 2012 - the same yearling from behind.

March 4, 2012 - same yearling from the front.

January 8, 2011 - was this skull from a doe or a buck?

March 4, 2012 - sporting their little black accessory. 

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See also:

Columbian black-tailed deer, Odocoileus hemioanus columbianus

Richard D. Taber and Raymond F. Dasmann, The Black-tailed deer of the Chaparral: Its Life History and Management in the North Coast Range of California, California Department of Fish and Game, 1958.

Mark Elbroch. Mammal Tracks and Signs. Stackpole Books. 2003.