Monthly Archives: September 2016

Tundra Vole (Microtus oeconomus)

Kodiak Wildlife, , , ,

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Tundra Voles are one of the six mammal species endemic to Kodiak Island. Seven species of voles live in Alaska. Two belong to the genus Muridae, and the other five belong to the genus Microtus. The name Microtus means “small ear,” referring to the tiny ears that are nearly hidden in the fur. The tundra vole or root vole, (Microtus oeconomus) is the only species of vole that lives on Kodiak Island. Microtus oeconomus has the northernmost distribution of any Microtus species and exists on all northern continents. In North America, tundra voles are only found in Alaska and northwest Canada.

Tundra voles live in colonies of a few to as many as 300 individuals. They live in a variety of habitats from tundra to sedge meadows, but they favor areas with abundant cover. In grassy meadows, they build distinctive runways that crisscross the ground. They also dig burrows, complete with food and nesting chambers. Tundra voles do not hibernate and are active all winter. In areas covered with snow, voles make extensive tunnel systems, sometimes hundreds of meters long, under the snow where they feed on snow-flattened grass and plants. Research has shown that they memorize their tunnel routes and become so accustomed to them that if a rock is placed in the middle of a tunnel, the vole will probably run into the rock.

Voles are highly dependent on their sense of smell, and scents are probably used to identify individuals or to determine age, sex, and reproductive condition of other voles. Voles have scent glands and display common scent-marking behaviors such as scratching or rubbing. Tundra voles also have a well-developed sense of hearing, and it is believed that they may use vocalizations for communicating.

Tundra voles breed from late April through September. The gestation period lasts 20 to 21 days, and females can produce three litters a year. Females give birth to between four and eight offspring, and when they are born, the babies are naked and blind. After five days, the young are covered with hair, and they open their eyes 11 to 13 days after birth. The young develop quickly and are weaned after 18 days. They attain their maximum size approximately two months after they are weaned. Females reach sexual maturity at an age of only three weeks, but males are not sexually mature for six to eight weeks. Biologists think this delay in sexual maturation for males guards against inbreeding since females are usually fertilized before their males siblings are ready to mate. Tundra voles may live as long as two years but rarely live longer than one year in the wild.

Tundra voles are vegetarians and eat sedges, grasses, mosses, lichens, small woody shrubs, and other plants. Voles play a critical role in the food chain in Alaska. They are the primary food source for many small mammals and birds, including weasels and foxes. Even bears will sometimes eat voles. Vole populations cycle through boom and bust periods. During the high point of a cycle, the vole population may be 50 to 100 times higher than it is at the low point of the cycle. These boom times occur every four to five years, and predators that depend on voles for food also cycle in response to the size of the vole population.

Next week, my post will be about the little brown bat, another mammal endemic to Kodiak Island. Don’t forget to sign up for my free monthly mystery newsletter to read about true crime in Alaska.

 

End of Summer

Kodiak Wildlife, Living in the wilderness on Kodiak Island, , , , , ,

 

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Our summer wildlife-viewing and sport-fishing trips ended three days ago. It was time for them to end because summer is over here on Kodiak Island, and a fall storm broadsided us with our last group of bear viewers. They were good sports as we fought through the wind and rain to watch bears. The bears didn’t seem to mind the weather and put on a fantastic show, and while our guests loved watching sows chase salmon while their cubs played, we were all very wet by the end of the day. I love our September bear-watching trips, but I am tired of fighting boats in the wind, and I admit I am ready for a break. It is time to let my bruises heal and curl up with a blanket on a rainy, windy day instead of pulling on my foul-weather gear and heading out on a boat. dsc_0590b

We had a great season this year. No two days of our summer trips are ever the same, and every minute is as much of an adventure for us as it is for our guests. In July, we enjoyed great salmon fishing, and halibut fishing was good most of the summer. We saw bears in July, but they weren’t concentrated in any one place. As the summer progressed, the bear viewing steadily improved, and by September, we enjoyed phenomenal bear viewing every day. We watched several sets of sows and cubs this summer, and while our guests crouched behind fallen trees on a riverbank, they were thrilled by bears that fished only a few feet from them. They were so close; they could hear bones snap when a bear bit into a salmon.dsc_0204-2

We saw whales nearly every day of our summer season. Huge fin whales surfaced beside our boat, while humpbacks raised their flukes in the air. We saw killer whales a few times, and once, they swam over to us when we were in our 19-foot whaler, jumping beside the boat and playing in our wake. We saw dozens of sea otters and countless bald eagles every day, and we watched Sitka black-tailed deer prance along the beach while red foxes dug for clams.dsc_0287-2

On the sport-fishing front, our guests caught 17 halibut over 40 lbs. (that’s what it takes to make the Munsey’s Bear Camp halibut club) and many more halibut between 20 and 40 lbs. The largest halibut of the summer weighed 128 lbs. We enjoyed great pink salmon fishing in July, but we had a poor silver salmon run.

Michael Acela and his 128-lb. halibut
Michael Acela and his 128-lb. halibut

As always, we had guests from around the world, and we shared many laughs on ouradventures with them. Summer always seems to fly by too quickly. Sure, by mid-September I’m tired, but come next June, I’ll be excited for our summer season to begin again.

Visit our Munsey’s Bear Camp website for more information about our summer trips. If you haven’t signed up for my free Mystery Newsletter yet, head over to my home page and do that now. My newsletters chronicle true crime stories from Alaska.

Gordy Sexton with his 87-lb. halibut
Gordy Sexton with his 87-lb. halibut

Kodiak Short-tailed Weasel (Mustela ermine kadiacensis)

Kodiak Wildlife, , , , , ,

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Short-tailed weasels are one of the six mammals native to Kodiak Island.  Weasels are known by three common names. In their summer phase in the U.S., they are called weasels, but in their white, winter phase, they are known as ermine, and in many other countries, the same animal is called a stoat.  Two species of weasels exist in Alaska: the short-tailed weasel or ermine (Mustela ermine) and the least weasel (Mustela rixosa). The least weasel does not occur on the Kodiak Archipelago. Seven subspecies of Mustela ermine can be found in Alaska, and six of these are endemic to the state, including Mustela ermine kadiacensis, which is only found on the Kodiak Archipelago.  Weasels belong to the family Mustelidae.  Other Alaskan mustelids include river otters, sea otters, mink, marten, and wolverines.

Short-tailed weasels are found in North America, Europe, Siberia, Greenland, and Canada and have been introduced to other parts of the world.  In North America, they range from Alaska and Canada south to central California, northern Arizona, northern New Mexico, Iowa, the Great Lakes, Pennsylvania, and northern Virginia.  Short-tailed weasels occur throughout most of Alaska, except on the offshore islands of the Bering Sea and the Aleutian Islands west of Unimak Island.ermin

A Short-tailed weasel has an elongated body, short legs, a long neck, and a triangular head with long whiskers and round ears.  In the summer, a weasel’s fur is reddish-brown on the back and creamy white on the stomach, but in the winter, the fur is completely white except for the tip of the tail, which remains black all year.  A short-tailed weasel can reach 15 inches (38 cm) in length and weigh seven ounces (198 g). A weasel’s long narrow skull and slender body allow it to squeeze into vole tunnels to chase its prey of choice.

Weasels mate in mid- to late summer in Alaska, and a female may breed with more than one male.  In the southern part of their range a female produces three litters per year, but in Alaska, females give birth to only one litter a year.  Like many other animals, weasels experience delayed implantation.  After an egg is fertilized, it does not implant on the uterine wall for six to seven months.  Once it does implant, the remaining gestation period lasts only four weeks. Females give birth from early May through June to litters of three to ten young.

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Weasels nest under old buildings, in stumps, in rock outcroppings, or in rodent burrows.  They often line their nests with mouse or vole fur.  Young weasels remain in the den for 30 to 45 days after they are born, and after they first emerge, they stay near the den for a week or two before following their mother on foraging trips.  They are full grown in the early fall when they are 80 to 85 days old, and at this time, they leave their mother.  Weasels reach sexual maturity when they are one year old.  Female weasels may survive three years, but males usually do not live that long.

Weasels eat a variety of animals, including birds, insects, fish and young rabbits, but rodents, especially mice and voles, are their food of choice.  On Kodiak Island, weasels mainly eat tundra voles (Microtus oeconomus).  Weasels have a very high metabolic rate and must eat at least 40% of their body weight every day.  A pregnant female consumes an average of four voles per day.  Weasels do not hibernate but hunt all year long.  Their white fur provides them camouflage against the snow in northern climates, allowing them to sneak up on prey more easily.  They hunt both night and day, and they locate their prey mainly by scent. A weasel usually pounces on its prey with its forefeet and then kills it by biting the back of its neck.

Weasels have few natural enemies; their speed and ability to squeeze into narrow spaces help them avoid most predators.  Humans sometimes trap weasels in their white, winter phase and use this “ermine fur” as a trim on parkas and other clothing.  In some western societies, ermine fur was once considered a badge of royalty.  In Alaska, not many weasels are trapped, and only about 300-500 weasel pelts enter the fur market every year.

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Kodiak River Otter ( Lontra canadensis kodiacensis)

River Otter, Uncategorized, , , , ,

The Kodiak river otter (Lontra canadensis kodiacensis) is a sub species of the North American river otter and is found only on the Kodiak Archipelago. North American river otters range throughout much of Canada and the United States.

River otters are stocky, with short legs, webbed hind feet, a thick neck, a flattened head, small ears, and a muscular body. A strong tail that is more than one-third as long as the head and body helps propel them through the water when they swim. Adult river otters weigh 15 to 35 lbs. (6.8-15kg) and are 40 to 60 inches (102-152 cm) long. Females are usually about 25% smaller than males. An otter’s fur is black-brown in color on the legs and back fading to a slightly lighter shade on the belly. The chin and throat are gray. The fur consists of a dense undercoat and longer guard hairs. Several sets of strong whiskers sprout from beneath the nose.

A river otter is well adapted for living both on land and in the water. Its thick fur helps keep it warm when swimming in cold water, and its webbed hind feet, narrow body, and flattened head allow for streamlined movement through the water. An otter swims by paddling or vertically flexing its hindquarters and strong tail. It can swim 6 mph (9.7 km/hr) and even faster over short distances by “porpoising.” An otter can dive at least as deep as 60 ft. (18 m) and stay underwater for as long as eight minutes. On land, an otter can run up to 15 mph (24 km/hr).

River otters have well-developed senses of smell and hearing. Their vision on land is not good, but they may see better under water. An otter uses its whiskers to detect prey in murky or dark water, aid in navigation, and to avoid obstructions.

River otters can live in any water habitat, including ponds, marshes, lakes, rivers, estuaries and coastal areas. They can tolerate both cold and warm environments and can live at any elevation as long as the habitat provides an adequate food source. On Kodiak, river otters live in timbered habitat next to the coast. They often travel long distances overland between bodies of water and use the same trails year after year. While more common at sea level, river otters on Kodiak are sometimes found high in the mountains.

River otters reach sexual maturity at age two, and females produce one litter per year. In Alaska, otters breed in the spring, and breeding can take place in or out of the water. A female may give birth to as many as six pups, but two or three are more common. Due to delayed implantation of the fertilized egg in the uterine wall, pups may be born from late January to June after a gestation of nine to thirteen months.

Pups are born in a den, and at birth, they are toothless and blind. They open their eyes when they are seven weeks old, and at two months of age, they begin to leave the den and start to swim and eat solid food. Pups do not innately know how to swim but must be taught by their mother who sometimes has to force and even drag them into the water. Pups are weaned when they are five months old, but they stay with their mother until just before her next litter is born.

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River otters are usually found in groups. Often these groups are related individuals, such as a mother and her pups, with or without an adult male. The female is normally the dominate member of such a group and will drive other animals away from the area around her den. Other groups may consist of siblings who have left their mother, a male and female otter, or a group of bachelor males. While otters live together in social units, they do not hunt together or share their catch with other members of their group. River otters may live for more than twenty years, but a lifespan of eight to nine years is more common.

In Alaska, river otters hunt on land and in fresh and salt water. They are opportunistic feeders and eat mussels, clams, sea urchins, snails, crabs, shrimp, octopi, fish, insects, birds, small mammals, and even plants. Otters normally eat their aquatic organisms on shore, and it is not unusual for us to find the remains of a river otter’s breakfast on our dock. If an otter catches a fish or other organism that is too big to eat in one meal, it eats what it can and abandons the rest of the food. River otters have a high metabolism and must eat often.

River otters spend half of their time sleeping. Both adults and pups are playful and like to slide on snow and mud. They wrestle, chase their tails, dunk each other in the water, and play with rocks and sticks. This playful behavior strengthens social bonds and aids pups in learning how to hunt.

River otters communicate with each other in a variety of ways. They use several vocalizations, including whistles, yelps, growls, and screams. When they are alarmed or upset, they emit a loud “hah” sound, and when two or more otters are together, they may mumble to each other as if in conversation. They chirp like a bird to express anxiety, and this sound is often heard when members of a group become separated from each other.[3] Otters also communicate by body posturing and by touch. They use the scent produced by the glands at the base of their tail to mark their territories or to create scent trails to communicate where they have been.