By Sharon Wootton
Herald Columnist
A tram ride through the wildlife park Northwest Trek got me to thinking about antlers and horns, of which there were many to be seen a couple of weeks ago, sitting atop woodland caribou, Roosevelt elk, bighorn sheep, white-tailed deer, mountain goats and moose.
Spikes, racks and curls were evident. Horns (mountain goats, bighorn sheep) grow continuously and are never shed; antlers (deer, elk, moose, caribou) are shed and regrown each year.
The animals weren't yet engaged in the fall sport of butting heads or wrestling with their racks, the standard this-female-is-mine action. Still, the antlers were interesting.
Because the tram offers a close-up view of many of the animals, often drawn to the side of the road with grain, it was easy to see the fast-growing antlers were covered in velvet.
The fuzzy brown velvet is a blood-vessel-rich skin that supplies blood and minerals to the connective tissues undergoing explosive growth that will turn into bone.
The antlers, especially when just starting, are soft and can be easily damaged. The antlers are fully formed and mineralized into bone in 12-16 weeks, usually in August.
As the growing antlers turn to bone, they need calcium, not easy to find in large quantities if you're a vegetarian. Biologists believe that one place deer may get some of that calcium is by drawing it out from other bones, particularly the rib cage.
Eventually the blood vessels at the base of the antlers dry up and the velvet dies. The deer rubs the tines on tree trunks to scrape off the velvet, and then may eat the skin, probably because it has minerals that plants may not provide.
The size of antlers can indicate an animal's health, important, since the strongest males win the right to breed with females. Hunters believe that the largest antlers are usually paired with the toughest temperaments and both are used to a dominating male's advantage.
The downside is that constantly battling challengers to the females consumes energy that is needed to survive the winter, ironically lessening the champion's chances of surviving.
In most species with antlers, only males grow them to fight during rut. Both male and female caribou have antlers, but the males grow them in the summer to compete for females; the females grow short spike antlers after the rut.
The spikes give pregnant females a much-needed advantage when it comes to competing for scarce winter forage, enough to feed two.
Horns are similar to hooves because the outer surface is made of keratin, the main protein of skin, hair and nails; antlers are bone. Bighorn sheep and mountain goats have horns that can't be replaced and that grow throughout their lives.
Bighorn sheep have massive horns that curve backward, down and forward. Females have smaller horns that only do a half-curl. Mountain goats have spike-like horns that curve backward for up to a foot and both sexes have horns.
While horn-wearers do not shed their horns, deer shed antlers by the end of December; elk not until spring. So why don't backcountry hikers come across more antlers?
The rodent population considers antlers a valuable source of calcium and by hiking season, the antlers are usually gone.
What happens to the antlers at Northwest Trek? Samples of different species' antlers are shown, identified and discussed with passengers lined up for a tram ride.
Otherwise Northwest Trek lets nature take its course with the rest.
"We leave them in the free-roaming area," said spokeswoman Cherilyn Williams. "Smaller critters chew on the antlers. They're public property so we can't give them away."
To see antlers and horns up close and personal, check out Northwest Trek near Eatonville (360-832-6117).
Beware the jellyfish: The Explorer series returns to the National Geographic Channel at 8 p.m. Wednesday with a terrific show, "Explorer: Jellyfish Invasion." Once past the doomsday tone of voice, the coverage of a jellyfish population explosion delivers facts, theories and fine photography.
On the book shelf: Bill Thorness' "Biking Puget Sound: 50 Rides from Olympia to the San Juans" ($17, Mountaineers Books) will bikers plenty of options for the rest of the season.
"Biking" includes good maps, mileage logs, useful elevation graphs, photographs and five rides in Snohomish County.
Columnist Sharon Wootton can be reached at 360-468-3964 or www.songandword.com.
