Monthly Archives: October 2016

Reindeer/Caribou (Rangifer tarandus)

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The U.S. State Department introduced thirty-two Siberian reindeer to the south end of Kodiak Island in 1921 when they were granted to the native peoples to herd and raise.

Reindeer and caribou belong to the same genus and species (Rangifer tarandus). Both wild and domesticated animals in this species are referred to as reindeer in Europe and Asia, but in North America, the term reindeer is reserved for semi-domesticated animals, while their wild cousins are called caribou. There are many subspecies of both reindeer and caribou in Alaska.

Reindeer and caribou are members of the deer family, and they are the only species in the deer family in which both males and females grow antlers. The antlers of female reindeer are larger than those of female caribou. This difference, as well as many of the other differences between caribou and reindeer, are probably the result of domestication and breeding. Caribou have longer legs, while reindeer are shorter and rounder. Reindeer bulls are smaller than caribou bulls, but reindeer and caribou cows are about the same size. Reindeer have thicker fur than caribou, and they breed two to four weeks earlier than caribou.

Biologists believe reindeer were one of the first domesticated animals. A 9th-century letter from King Ottar, the king of Norway, to Alfred the Great mentions his herd of over 600 reindeer. Reindeer herding began in Alaska more than a century ago when 1300 reindeer were imported from Siberia. By the 1930s, 600,000 domestic reindeer lived in Alaska, but much of the reindeer industry in the state collapsed during the Great Depression.

After reindeer were introduced to Kodiak in 1921, The Alitak Native Reindeer Corporation was formed, and residents of the village of Ahkiok managed the herd. The herd grew throughout the 1940s and reached approximately 3000 animals by 1950. A wildfire in the early 1950s wiped out much of the reindeer range, and approximately 1200 reindeer escaped into the wild. Active management of the herd ended in 1961, and federal grazing leases expired in 1964. The State of Alaska declared the reindeer to be feral and soon established an open hunting season with no bag limit on reindeer. In 2010, the State of Alaska restricted the reindeer hunting season on Kodiak to six months and limited the annual take to one reindeer per hunter. The state also reclassified reindeer on Kodiak as “caribou.”

A reindeer has a thick coat that is brown in the summer and gray during the winter. Its chest and belly are pale, and it has a white rump and tail. A male’s antlers are larger and more complex than those of a female. A male usually sheds his antlers in the fall after the mating season, while a female keeps her antlers until spring. A reindeer has hooves that adapt to the season and environment. In the summer, its footpads are spongy, providing it with extra traction on the soft, wet tundra. In the winter, the foot pads shrink and tighten, exposing the rim of the hoof which cuts into the ice and snow and prevents the reindeer from slipping and falling.

Reindeer can run as fast as 50 mph (80 km/hr) and are excellent swimmers. They feed on herbs sedges, mosses, and lichens in the summer but mainly feed on lichens in the winter, often digging through the snow with their hooves to expose the lichens.

Reindeer breed in October, and after a gestation of 210 to 240 days, females give birth to a single calf weighing 6.6 to 26.5 lbs. (3-12 kgs). One hour after it is born, a calf can follow its mother, and at one-day old, it can run at fast speeds. Calves are weaned when they are one-month old, and reindeer reach sexual maturity when they are one to three years old.

The caribou population on Kodiak has remained stable over the past several years, and biologists estimate there are 250 to 300 caribou on the island.

Mountain Goats (Oreamnos americanus)

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It is estimated that 100,000 mountain goats live in North America. They occupy steep mountain ranges from the Cascade and the Rocky Mountains to Southcentral Alaska. Mountain goats occur naturally in the Southeast Panhandle and north and west to Cook Inlet. In Southcentral Alaska, goats can be found in the Chugach and Wrangell Mountains. Mountain goats have been successfully introduced to Baranof Island and Kodiak Island.

From 1952 to 1953, eleven female and seven male goats were transplanted from the Kenai Peninsula to Hidden Basin near the head of Ugak Bay, approximately 30 miles from the town of Kodiak. After a few severe winters, it was uncertain whether any of the transplanted goats had survived, but a 1964 aerial survey counted 26 goats. By 1972, biologists estimated that 100 goats lived on the island. By 2004, the population was estimated at 1560 goats, and by 2013, it had increased to 2500 animals. Goats now occupy every suitable habitat on Kodiak, and biologists are concerned that there are too many goats for the habitat to sustain.

While steep mountain cliffs are barriers to most animals, they are the preferred habitat of goats. Forested valleys, on the other hand, tend to be barriers to goats, because goats live not only where they can find an adequate food supply but also where they can quickly and easily escape predators such as bears. The steep slopes where goats live are easy for them to maneuver but are inaccessible to predators.

Mountain goats are both grazers and browsers. They eat sedges, ferns, mosses, and lichens. They spend their summers in the high alpine meadows where they consume sedges, forbs, and shrubs. During the winter when there is less food available, goats eat whatever they can find, including blueberry, hemlock, and lichens. Recent research on Kodiak indicates that fern rhizomes are an important part of the goats’ diet in early summer before and during vegetative green-up, but as the summer progresses, goats switch from ferns to sedges and forbs. Goats particularly seem to favor feeding sites with abundant long-awned sedge.

Mountain goats live an average of twelve years but may live as long as eighteen years. They inhabit an extreme environment that harbors a number of threats. Some of the main causes of death for goats include malnutrition, bear and wolf predation (although on Kodiak, there are no wolves), avalanches, falling, and human hunters. The ability to survive the winter depends on the goat’s body condition in the fall and the winter food supply. Mortality spikes in October during the first snowfalls and biologists surmise this is probably due to avalanches and the risks of traveling between summer and winter ranges, possibly through bear habitat. There is an even larger spike in mortality in late winter when malnutrition becomes a greater threat. Mortality also tends to be higher after a hot summer, and this may be because the most nutritious forage occurs at the edges of snow patches. If it is cooler and the snow recedes more slowly, the period of early-growth sprouting lasts longer than it does when the temperatures are warmer, and all the snow melts at once. Warm summers also cause heat stress.

The goat population on Kodiak continues to grow, and mountain goats have dramatically expanded their range in recent years. Introduced species like mountain goats can have negative impacts on native plants and animals, and biologists are concerned that a high density of mountain goats could adversely impact alpine areas where the slopes are steep, and there is not much soil. There is very little vegetation in this habitat, and goats could easily over-graze the plants that are there. Not only could over-grazing be irreversibly detrimental to the habitat, but it could and probably would cause a crash in the goat population. Researchers are trying to determine how many goats the alpine habitat on Kodiak can support, or in scientific terms, they want to find the carrying capacity for mountain goats on Kodiak. Biologists are concerned that mountain goats may have already exceeded their carrying capacity on the island, and current ongoing research by the U.S. Fish and Wildlife Service and the Alaska Department of Fish and Game is focused on better understanding exactly what and how much a goat eats over the course of a year.

 

 

 

 

 

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.

 

Mammals Introduced to Kodiak Island

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

Man has introduced every mammal species on Kodiak Island other than the six endemic species (Kodiak bear, red fox, river otter, short-tailed weasel, little brown bat, and tundra vole). We humans have a sketchy history of introducing mammals into ecosystems where they did not evolve. Sometimes these introductions are harmless, but often, they are not. Ecosystems are complicated, and it is impossible for us to fully understand how the plants and animals in a particular habitat have worked together to survive over thousands of years. When we introduce mammals not native to that environment, we change the balance.

It is tricky to introduce a mammal into a habitat where it did not evolve. For example, if an island has birds that nest on the ground and man introduces an egg-eating or chick-eating predator to this habitat, the predator will soon wipe out the ground-nesting birds. Of course, most introductions do not cause such an obvious impact, but the harm is often subtle and occurs slowly over time.

New Zealanders have waged an all-out war on introduced mammals in their country. New Zealand has lost 42% of its terrestrial birds since humans settled the country 700 years ago. Many of these birds were flightless and provided easy prey for introduced mammals such as rats, stoats (weasels), and dogs. New Zealanders are trying very hard to save the few species of flightless birds they have left, including kiwis and penguins, but at this point, it is an uphill battle.

While the mammal introductions to Kodiak Island have not had the disastrous consequences of those in New Zealand, introduced mammals have had an impact on the habitat here. Beavers have altered some watersheds on the island. Their dams can divert rivers and block salmon-spawning streams. In areas where beavers are native, their activity may be beneficial to other wildlife, but in an ecosystem where beavers did not originally exist, they can have a negative effect on riparian habitat. If beavers construct a dam on a small salmon stream, they can destroy the salmon-spawning grounds in that stream.DSC_53

Mountain goats on Kodiak are over-grazing their alpine habitat, and these impacts are now being studied. Sitka black-tailed deer have nearly decimated high-bush cranberries, a species that was abundant before deer were introduced to Kodiak. Other introduced mammals have also impacted the endemic flora and fauna of the island, but most mammals were introduced in the first half of the twentieth century, and those species that survived their initial introduction, are now thriving and are considered part of the complex ecosystem of the Kodiak Island Archipelago.

Over the next few weeks, I will write about several of the introduced wild mammal species on Kodiak Island. These include Sitka black-tailed deer, mountain goats, Roosevelt elk on Afognak Island, reindeer, beavers, and snowshoe hare. I will discuss how the species are doing and how their introductions have impacted the island.

I would love to hear your comments and opinions about mammal introductions. Are they good, bad, or a little of both?

 

 

Little Brown Bat (Myotis lucifugus)

Kodiak Wildlife, , , , , ,

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The little brown bat (Myotis lucifugus) is one of the six species of mammals endemic to Kodiak Island. The species ranges from Alaska to Labrador and south into central Mexico. It is more prevalent in the northern part of its range and is absent from much of Florida and Texas. It is the most common and widespread bat species in Alaska and lives in a variety of habitats, from the temperate rainforests of southeastern Alaska to the spruce/birch forests of the interior to treeless areas dominated by shrubs in western Alaska. While four other bat species are found in Southeast Alaska, the little brown bat is the only species of bat that lives in the Interior and South Central Alaska, and it is the only species that exists on Kodiak Island.

As their name implies, little brown bats are small mammals. They weigh between .18 and .32 ounces (5-9 grams) and are 3-4.5 inches (7.62-11.43 cm) in length. Their wingspan is 8 to 9 inches (20.32-22.86 cm) wide. They have cinnamon to dark brown fur on their backs, while their undersides are buff to pale gray. The hairs on their backs have long, glossy tips. The tragus, a fleshy projection that covers the ear canal, aids bats in echolocation. The shape and length of the tragus are sometimes used to identify bat species. In little brown bats, the tragus is half as long as the ear and has a blunt tip.

Little brown bats are efficient in the air and can fly at speeds ranging from 4 to 21 mph (6-34km/h). At an intermediate rate of speed, their wings make 15 strokes per second. They are most active at night, and their flight patterns are erratic. If knocked to the ground, they are clumsy crawlers, but if they land on the water, they can flap across the water for several hundred feet before getting tired. When roosting, bats hang upside down, and they achieve this position by flying up to a perch and grasping it with the long, clawed toes on their hind feet.

Little brown bats in Alaska mate between August and October, but fertilization is delayed until spring. After a gestation of 50 to 60 days, a female gives birth to a single pup. It is unusual for a small mammal to have only one baby at a time. Voles and mice give birth to large litters, and sometimes produce many litters per year. Voles and mice only live for one or two years, though, while bats may live 10 to 20 years. Pregnant or nursing females congregate together in maternity roosts. This clustering helps raise the temperature in the roost, speeding growth and development of the young. While bats normally hang with their heads down, a female gives birth with her head up, allowing her to catch the newly born pup with her tail membrane. A baby is born with deciduous incisors that along with its thumb and hind feet, allow it to cling to its mother. Pups are naked and blind at birth. They are weaned and able to fly on their own when they are three weeks old.

Little brown bats eat insects and feed at night, and this can be a problem in Alaska where the short amount of darkness at high latitudes in the summer reduces the amount of time bats can spend feeding. Bats use echolocation to find and capture prey, and they often hunt over lakes, ponds, and slow-moving streams and rivers. Bats drink while flying near the surface of the water. In Alaska, little brown bats eat moths, mosquitos, beetles, a variety of flies, and even spiders. They capture prey with their teeth, by netting them with their tail membrane, or by batting an insect with the tip of a wing and deflecting it into the tail membrane. They can then transfer prey from their tail membrane to their mouth while still in flight. During the day when not feeding, bats rest in roosts, and they conserve energy while roosting by going into torpor. A torpid bat reduces its metabolic rate and temperature, thereby decreasing its energy demands.

Little brown bats communicate with chemical signals produced by the nasal gland. These glands enlarge during the breeding season. Bats also use tactile signals when mating, and while they produce few vocalizations, they do make a honking sound, which may help to prevent mid-air collisions when foraging. Echolocation calls probably help bats locate roosts and hibernation sites.

It is not known how many little brown bats live in Alaska, and not much is known about where they hibernate, or if bats in the interior and far north migrate to warmer coastal areas before hibernating. Biologists hope to learn more about the migration and hibernation of bats in Alaska through ongoing research and bat-monitoring programs.

Bats face many threats, including wind farms. For some reason, bats are more susceptible than birds to being hit by windmill blades. Pesticides are bad for bats for two reasons. They can directly poison bats, and they reduce the number of insects that bats depend on for food. Habitat loss and disturbance can also affect bats, but at present, the greatest threat to bats, especially little brown bats, is a disease called white-nose syndrome. This disease is caused by a fungus that appears white around the nose and on the wing membranes. Biologists believe this fungus, or something associated with the fungus, causes bats to wake and move around when they should be hibernating, forcing the bats to use up all their stored energy and causing them to starve to death. White-nose syndrome has killed more than six million bats in northeastern North America since 2006, and the disease is slowly moving westward.

I have now written posts about the six mammal species endemic to Kodiak Island, and next week, I will begin a series of posts about some of the mammals that have been introduced to Kodiak.

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