Tag Archives: deer on Kodiak Island

Interesting Facts About Sitka Black-Tailed Deer

Kodiak Wildlife, Sitka black-tailed deer, , , , , ,

While I always smile when I see a Sitka black-tailed deer, I don’t always run for my camera because I see deer nearly every day. Last week, I wrote about the three deer that hang out in our yard. The other day, I stretched out on a sunny spot in the grass and closed my eyes. I felt something touch my face, and when I casually brushed it away, I heard loud breathing and hooves stomping. I sat up abruptly and looked into the eyes of a young buck. I’m not sure which one of us was the most startled, but after we recovered, the deer resumed grazing, and I laughed.

While they may be common, deer are fascinating animals, and I thought I would share a few interesting facts about Sitka black-tailed deer.

How did deer get to Kodiak Island, and how have they survived?

The most interesting fact about the Sitka black-tailed deer on Kodiak Island is that they exist and thrive here. The deer population on Kodiak stems from a founder population of fewer than 35 animals. Twenty-five Sitka black-tailed deer were introduced to the north end of Kodiak Island in three transplants from 1924 to 1933, and another nine deer were introduced in 1934. The deer population has since spread to most areas of the Kodiak archipelago, and despite the limited gene pool, the population appears to be healthy. The size of the deer population fluctuates from year to year, depending on the harshness of the winter, but biologists estimate when the population is at its peak, approximately 70,000 deer on live on the archipelago.

How can deer eat some poisonous plants?

After a long, cold winter, deer enthusiastically graze on the first green sprouts in the spring, and they often eat skunk cabbage, despite the fact the plant contains oxalic acid, a poisonous compound. Humans who have tasted skunk cabbage claim the plant burns their mouths for hours, but it doesn’t seem to bother deer. Deer are also able to tolerate other toxic plants, and it is possible their gut bacteria can neutralize the toxins in these noxious plants.

How do deer communicate with each other?

A couple of weeks ago, I wrote about how foxes communicate with each other. One of the ways deer communicate is with the aid of pheromones produced by the scent glands located on the lower legs. A gland on the outside of the lower leg produces an “alarm” scent, a gland on the inside of the hock produces a scent to help deer recognize each other, and glands between the toes leave a scent trail when a deer walks. Deer have excellent senses of sight, smell, and hearing. Their ears move independently of each other, allowing them to pick up on signs of danger from different directions.

Why do some deer have deformed antlers?

A certain percentage of deformed antlers are common in any deer population and may be produced as the result of an injury. Research shows that leg, pedicle, and velvet injuries can all lead to deformed antlers, and these deformities may be temporary or permanent. Some deer in certain areas of Kodiak Island, particularly the Aliulik and Hepburn Peninsulas on the southern end of the island, display abnormal antlers with a bizarre shape, sharp tips, and retention of velvet well into the mating season. Research on these deer indicates they are also sterile. At first, the problem was believed to be genetically linked due to the narrow gene pool of the small founder population. This theory, however, did not explain why the deer with the mutated antlers were mostly concentrated in one area of the island, even though there was nothing confining the deer to this area. A study published in 2005 carefully analyzed all aspects of the problem and concluded the sterile deer with the malformed antlers were not the result of inbreeding. Instead, researchers think the deer living in this area of the island are ingesting something such as kelp or grass laced with estrogenic molecules that alter antler growth, transform testicular cells, and block the descent of fetal testes.

The Sitka black-tailed deer on Kodiak Island experience the best and worst of nature. In the spring and summer, they enjoy an endless supply of food in this lush environment, but winters are often harsh, and nearly the entire deer population can be wiped out by a series of cold, snowy winters.
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Robin Barefield is the author of three Alaska wilderness mystery novels, Big Game, Murder Over Kodiak, and The Fisherman’s Daughter. To download a free copy of one of her novels, watch her webinar about how she became an author and why she writes Alaska wilderness mysteries. If you like audiobooks, check out her audiobook version of Murder Over Kodiak. Also, sign up below to subscribe to her free, monthly newsletter on true murder and mystery in Alaska.

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Sitka Black-Tailed Deer (Odocoileus hemionus sitkensis)

Kodiak Wildlife, Sitka black-tailed deer, , , ,

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Twenty-five Sitka black-tailed deer were introduced to the north end of Kodiak Island in three transplants from 1924 to 1934, and another nine deer were introduced in 1934. The deer population has since spread to most areas of the Kodiak archipelago, and despite the limited gene pool from the original small herd, the population appears to be healthy. The size of the deer population fluctuates from year to year, depending on the harshness of the winter, but biologists estimate there are approximately 70,000 deer on the archipelago.

Sitka black-tailed deer are smaller, stockier, and have a shorter face than Columbia black-tails. An average adult doe weighs 80 lbs., while an average buck weighs 120 lbs. Much larger bucks weighing as much as 200 lbs. have been reported. The summer coat of a Sitka black-tail is light reddish brown, while the winter coloration is dark brownish gray. The antlers are fairly small compared to other species of deer and typically have three or four points on either side, including the eye guards. A very large buck might have five points on each side, including the eye guards.dsc_0043

During the summer, Sitka black-tailed deer feed on herbaceous vegetation and the leaves of shrubs. During the winter when there’s snow on the ground, their diet is restricted to woody browse, which is not an adequate diet to sustain the deer over a long period. During the spring on Kodiak, deer range from sea level to approximately 1500 ft., where they forage new plant growth as the snow line recedes. Deer continue to disperse into the higher altitudes as the snow melts, and they can be found anywhere from sea level to 3000 ft. in the summer. After the first frosts in mid to late September, the forage plants die, and the deer move out of the high elevations.

The breeding season, or rut, begins in mid-October and runs through November, and once again, the deer can be found from sea level to 1500 ft. Depending on snow accumulation, Sitka black-tails usually descend below 1000 ft. in the winter. During periods of heavy snow, many deer congregate on the beach or in heavily timbered areas at low elevations. Deer are good swimmers, and at any time of the year, Sitka black-tailed deer can be seen swimming across the long, narrow bays on Kodiak Island.

dsc_0030-2Does begin breeding when they are two and continue to produce fawns until they are ten to twelve years old. Does as old as fifteen normally don’t produce any offspring. Does between the ages of five and ten are in their prime and usually produce two fawns a year. Mating season on Kodiak occurs between mid-October and late November. The gestation period is six to seven months, so fawns are born from late May through June. Twins are the most common, although many young does only produce a single fawn, and triplets do sometimes occur.

Sitka black-tails have an average lifespan of ten years, and the mortality rate for fawns is between 45% and 70%. Severe winters are the number one threat deer face on Kodiak Island. During mild winters with moderate temperatures and little snow accumulation, the deer population increases, but a harsh winter can cause a dramatic population decrease. In contrast, limited, dispersed hunting pressure seems to have little effect on deer numbers in most areas.dsc_0023

Deer are often seen in the town of Kodiak, and in more remote areas of the island where they rarely see humans, it is not unusual to have a deer walk right up to you. Bears sometimes kill deer weakened by a harsh winter, but in the summer, you often see Kodiak bears and Sitka black-tailed deer standing within a few feet of each other on a stream bank. With so much other food readily available, bears do not seem interested in chasing and attacking deer, and the deer do not seem to consider the bears a threat. Nearly ninety years after Sitka black-tailed deer were first introduced to Kodiak Island the population has endured and appears to be healthy.