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Saturday, April 23, 2011

Signs of Spring: Antlers starting to "bloom"

I put a camera out in a new spot on Thursday and was excited to check it today. Imagine my disappointment when I checked it this evening only to find I had left it on "test" so it took no photos. Since I was so in the mood to post a photo, I went into the archives to pull out this buck photo from two years ago.

One way that antlers differ from horns is that antlers are shed and regrown each year. As you can see from the photo, they are just starting to pop out at this time of year. Only deer grow antlers and typically only males grow antlers. Exceptions include caribou where the females routinely grow smaller versions of the massive antlers the males sprout and any female of any deer species that has high amounts of testosterone.

Antlers beginning to grow (Seneca Falls, NY 4/09)

Throughout the summer, the antlers continue to grow. They are covered in a soft tissue called "velvet". They are soft during growth and filled with blood vessels to provide the nutrients necessary to maintain the extremely fast growth. How fast? Antlers are the fastest growing tissue in an adult mammal. Only a fetus grows faster... By the fall, the antlers have reached their full size for the season. Below is the latest I have ever seen a deer in velvet.

Deer still in velvet (Seneca Falls, 9/09)

It is a common misconception that you can tell the age of a deer by the number of points he has (I should also add that here in the Eastern US we count all points, while in the West they only refer to the points on one side of a rack. So our 8 pointer is their 4 pointer). A much more accurate measure of age is the width of the rack as well as the diameter of the beam. About 90% of white-tailed deer have a first rack that is narrower than the width of their ears. Likewise, the beam is thin. As the deer gets older, it gets larger overall as well as in thickness of the actual antler. Since antlers are grown and shed every year, a buck's best antlers are grown when he is at his peak. Horns are not shed so that an animal with horns, like a bighorn sheep, will have his largest headgear when he is oldest. Deer will actually show a decline in their antler size after they have reached their physical peak for at least two reasons: As they are older, their teeth wear down and they will have less nutrition to grow antlers. Secondly, it is possible that an older deer will be pushed to more marginal habitat by younger ones, further decreasing their available nutrition. But let's look at a buck in his prime:

Mature white-tailed deer (Seneca Falls, NY 11/09)

Impressive? My neighbor thought so and this deer hangs as a trophy on his wall. Before I show the last photo we ought to visit the purpose of antlers. Many people believe they are to fight predators. Certainly an antlered deer COULD defend itself with those tines, but that is not the main purpose of antlers. Think about it: If antlers were so good as a means of defense, why do only the males of them and even then, they are useless for defense until they are hard. Antlers are for breeding (Our first clue to that was the fact that only males have them). They announce their owners' health to females and potential male competitors as well. Males will spar with their antlers but these are most often pushing matches. Only rarely do these battles for dominance end in injury to either combatant. So each year, after the breeding season, the antlers loosen and fall off. This can happen as early as December. But as the photo below shows, it can happen as late as the end of March (although that is unusually late). That doesn't give him too much time until he needs to grow his next pair. And camera traps help tell each chapter of the story.....

White-tailed deer with antlers in late March (Seneca Falls, NY 3/09)

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