Monthly Archives: November 2016

Kodiak Birds

Bald Eagle, Birds, Kodiak Wildlife, , , , , , ,
Pine Grosbeak
Pine Grosbeak

More than 240 species of birds have been identified in the Kodiak Island Archipelago. Kodiak is not on a major flyway, but many species migrate to Kodiak in either the summer or winter, and many other species are year-round residents. Common species include golden-crowned sparrows, Wilson’s warblers, fox sparrows, black-capped chickadees, hermit thrushes, and winter wrens.

Varied Thrush
Varied Thrush

Due to its mild maritime climate in the winter, wide variety of habitats, and plentiful food supply, the Kodiak Archipelago is a winter home to more species and numbers of birds than anywhere else in Alaska. Over a million sea ducks and other aquatic migratory birds flock to Kodiak in the winter. Sea ducks commonly seen in the archipelago in the fall and winter include harlequins, surf scoters, buffleheads, Barrow’s Goldeneye, oldsquaws, and mergansers.

In the spring, Arctic terns arrive from as far away as Antarctica, and bank swallows return from South America. Horned and tufted puffins fly from their winter home on the deep North Pacific Ocean to the rocky cliffs of the archipelago where they nest.

Tufted Puffin
Tufted Puffin

Without question, the bald eagle is Kodiak’s most noticeable bird, and with 600 nesting pairs on the archipelago, biologists believe the nesting real estate is saturated, and many adult eagles here may never mate. In the winter, hundreds of eagles congregate near the town of Kodiak where they feed on cannery effluent and scraps of fish from boats when the fishermen offload their catch. Many of these eagles seen near town in the winter are seasonal migrants from the mainland.

Over the next few weeks, I will cover a few of these bird species in more detail, including bald eagles, tufted and horned puffins, Arctic terns, and oystercatchers.

Bald Eagle
Bald Eagle

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Snowshoe Hare (Lepus americanus)

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Snowshoe hares (Lepus americanus) are found throughout Canada and in the northernmost United States. Their range extends south to the Sierras, Rockies, and Appalachian mountains.[1] They are common in Alaska and can be found throughout the state except for the lower Kuskokwim Delta, the Alaska Peninsula, and the area north of the Brooks Ranges.[2] They are not native to Kodiak Island but were introduced to Kodiak in 1934.[3]

Snowshoe hares average between 18 and 20 inches (.5 m) in total length and weigh 3 to 4 pounds (1.4– .8 kg).[2] Males are slightly smaller than females.[1] Their summer coat is yellowish to grayish-brown with buff-colored flanks and a white belly. The ears are light brown with black tips and creamy borders, and the face and legs are cinnamon brown. Their winter coat is snowy white, except for their black eyelids and the black tips of their ears.[1,2 ] The start of the molt from their summer to winter coat is regulated by daylength and takes approximately 72 days to complete. Two different sets of hair follicles give rise to the white and brown hairs.[1] Snowshoe hares have large hind feet that are well-furred, allowing them to maneuver on deep snow and giving them their common name.[2]

Snowshoes are mostly vegetarians and eat a variety of plant materials, including grasses, buds, twigs, and leaves in the summer and twigs, spruce needles, barks, and buds in the winter.[1] They are also known to cannibalize the remains of other hares that have died, and they will eat fecal pellets to extract more nutrients.[1]

Snowshoe hares breed when they are one year old, and in Alaska, they have two to three litters per year. Breeding takes place from mid-May until August, and both males and females have multiple mates.[2] When the time nears for a pregnant female to give birth, she becomes highly intolerant of and aggressive toward males.[1] The gestation period lasts 36 to 37 days, and the first litter of the year averages four young, called leverets. The second litter of the year often averages six leverets, and there is sometimes a third litter.[2] Research suggests that the female may be able to breed even a day or two before she gives birth to her current litter.[1]

Leverets are born in a natural, unlined depression in the ground. They weigh 2 ounces (57 g) at birth, and they can walk by the time their fur dries. One of the main features that differentiates hares from rabbits is that hares are born with a full coat of fur, while rabbits are born with no fur. Hares also have open eyes and ears at birth, and in less than two weeks after they are born, they are already able to eat green vegetation. They continue to nurse for a month before they leave the nest for good.[2] Young hares reach sexual maturity within a year, but 85% of snowshoe hares live less than one year. Those that do survive may live up to five years in the wild.[1]

Snowshoe-hare density in an area is often high, but hares are solitary animals. They are most active at low light levels, so they are usually seen at dusk and dawn. They are also active at night and on cloudy days.[1] Most of their traveling takes place on well-known, trampled pathways through the vegetation, and these trails make deep grooves in the winter snow.[2] During the day, hares take short naps and spend a large amount of time grooming themselves. They also take dust baths to remove ectoparasites from their fur.[1]

Snowshoes can travel as fast as 27 mph (43.45 km/h) and can jump 10 ft. (3 m) in a single hop. They can change directions quickly and make vertical leaps, and both of these maneuvers aid them in avoiding predators. Hares are also good swimmers and will jump into a lake or a river to flee a predator. Young hares often attempt to escape predation by freezing in their tracks and blending into the background. If the hare remains immobile, the predator may not be able to see him when he is camouflaged.[1]

Snowshoe hares have excellent hearing that helps them identify approaching predators, but they are not very vocal. They make loud, squealing sounds when captured and may hiss and snort when approached by a predator, but hares communicate among themselves by thumping their hind feet on the ground.[1]

Populations of snowshoe hares cycle from periods of high abundance to periods of only a few animals. The population in an area will grow and then suddenly crash to a low level. When the population peaks, there may be as many as 600 hares per square mile (230/km2). Biologists are unsure why hare populations suddenly decline, but they suspect it may be due to a depletion of their food supply, predators, disease due to stress and parasites, or a combination of these causes.[2] It is difficult to determine the size of a hare population, but biologists estimate approximately 100,000 snowshoe hares live on Kodiak Island.[3]

Happy Thanksgiving to my U.S. readers!  If you haven’t already signed up for my free Mystery Newsletter, this would be a good time to do that.  This month I wrote about Israel Keyes, a monster that experts consider to be one of the top three most organized and intelligent serial killers ever.  You can sign up for my newsletter here. 

 

 

 

The Common or True Beaver (Castor canadensis)

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, True Beaver, Beavers in Alaska, Beavers on Kodiak Island, Wildlife of Kodiak Island, Mammals introduced to Kodiak Island

The common beaver or true beaver (Castor canadensis) is native to North America and is found in most areas from the Arctic to northern Mexico. C. canadensis is absent from Southern California, Nevada, most of Florida, and parts of Alaska. Beavers are not native to Kodiak Island but were introduced to Kodiak in 1925.

Description

The true beaver is the largest rodent in North America and the second-largest rodent in the world. The South American capybara is the largest. Beavers continue to grow  throughout their lives and may reach a length of 3 to 4 feet (0.9-1.2 m), including the tail. Most adults weigh between 40 and 70 lbs. (17-32 kg), but they can weigh as much as 100 lbs. (45 kg).

A beaver has a heavy, thick, chestnut-brown coat and a warm, soft underfur that keeps it comfortable in all temperatures on land and in the water. This warm, soft fur was in such high demand by humans in the late 1800s and early 1900s that by 1930, beavers had been trapped nearly to extinction in many areas.

The beaver’s scientific name is derived from castoreum, a strong smelling, oily substance secreted by castor glands at the base its tail. A beaver uses its feet to comb this oil through its fur to provide a waterproof barrier that keep its skin dry underwater. It also has a thick layer of fat beneath its skin to insulate it in cold water.

A beaver’s body is adapted to a life spent mostly in the water. In addition to the castoreum which keeps its skin dry underwater, it has nictitating membranes that protect its eyes underwater and nose and ear valves that close when it submerges. It can cut and carry wood underwater without getting water in its mouth by tightly closing its loose lips behind its protruding front teeth. A beaver has large, webbed feet and a broad, black tail that is approximately 10 inches (25 cm) long and 6 inches (15 cm) wide that it uses as a rudder when swimming. It also uses its tail as a warning signal when it slaps it against the water. When it stands on its hind legs to cut down a tree, the tail serves as a fifth leg and helps to balance the animal. A beaver can stay underwater for fifteen minutes, and it can swim up to 5 mph (8 km/h). It propels itself through the water with its webbed hind feet while holding its front feet against its body. When swimming at the surface, only its head is visible above water. On land, a beaver moves with a waddling gait and can run between 6 and 8 mph (9.7-12.9 km/h).

Dams

Beavers are second only to humans in their ability to alter the environment for their own needs. Beavers spend part of their time on land of the rest of their time in the water. They must build their dens in an area that provides 2 to 3 feet (0.6-0.9 m) of water year-round to ensure that ice does not block the underwater entrance to their lodge or den in the winter. In areas where the natural water level is less than 2 ft. (0.6 m), beavers construct dams to increase the height of the water level. The height of an average dam is 6 ft. (1.8 m), producing an average water depth of 4 to 6 ft. (1.2 to 1.8 m). Beavers construct the dam by first diverting the stream to reduce the flow of water at their building site. Next, they drive branches and logs into the mud of the stream bed for the base. They then use whatever they can find, including sticks, bark, rocks, mud, and grasses to build the superstructure of the dam. They even include spillways and passageways in the dam structure to allow excess water to drain off the dam without damaging it. A beaver can move building materials that weigh as much as it does, and it can cut down a tree with a 6-inch-diameter (15.2 cm) trunk in 20 minutes. It may work alone to build a dam, or several family members may work together on the project.

Dens

Beavers build two different styles of dens, depending on the current and water level of the river. Both types of dens have at least one exit to deep water that will remain free of ice in the winter. In a swiftly flowing river with a year-round water level deep enough so that a dam is not required, beavers build simple bank dens into the side of the riverbank. They cover the top of a bank den with sticks, mud, and other debris. Bank dens usually have several entry tunnels. The interior of a bank den has one chamber that is approximately 2 ft. (.61 m) wide by 3 ft. (.9 m) long by 3 ft. (.9 m) high.

The second type of beaver den is called a “lodge.” A lodge is dome-shaped and is about 10 ft. (3 m) high by 19.6 ft. (6 m) wide at the base. Beavers build lodges in slow-moving water and use the same construction techniques they employ when building a dam. The lodge consists of an entry tunnel and two chambers. The entry tunnel is below the water level, and the floor of the first chamber is a few inches above the water line. The first chamber is used as an eating area and a place to dry off after getting out of the water. The floor of the second chamber is above the first chamber, and this area is used for sleeping and caring for the kits. Beavers cover the floor of this chamber with shredded wood or vegetation. A single family group, including an adult pair, this year’s kits, and the young from the previous year, occupy a lodge. The older offspring assist their parents in maintaining the lodge and the dam.

Beavers use the same lodge for many years, and since they add material to the lodge every year, the lodge grows over time. Beavers do no hibernate in the winter but stay active in their lodges. Since the only entrance to the lodge is underwater, they are frozen in the lodge or under the surface of the water if the river develops an ice layer. To prepare for winter, they store enough food to make it until spring. The walls of the lodge freeze in the winter, helping to insulate the interior and protecting them from predators.

Diet

Beavers do not eat wood, they eat the cambium, a soft tissue near the surface of the tree from which new wood and bark grow. They also eat aquatic plants and roots and grasses. During the winter, they mainly depend on woody material such and shrubs and branches, which they plant underwater close to the lodge entrance. When they deplete the food supply near their den, they must forage further from home for food, and this increases their risk from predators. When they no longer have a good supply of food near their den, they migrate to a new home.

Behavior

Beavers are mostly nocturnal. They sleep during the day and forage for food and build their dams and dens at night. They communicate mainly by posturing and scent marking. They use their paddle-like tail to slap the water as a warning and to communicate other emotions. They build small, dome-shaped mounds and rub castoreum, the oily substance secreted by their castor glands, on the mounds to mark their territory. Young beavers make a sound like a quacking duck, and adult beavers sometimes grunt when they work.

Reproduction

There are no separate names for male and female beavers, but babies are called kits. Beavers are monogamous and mate for life, but if one of the mates dies, its partner may find another mate. They breed in January and February, and females give birth to between one and nine (two to four are average) kits between late April to June, after a gestation of 105 days. Kits are covered with a soft fur at birth. They can swim when they are four-days-old, and they can dive by the time they are two-months-old. Young beavers live with their parents until they are two-years-old, and they reach adulthood in their second winter. Beavers survive in the wild for approximately 10 to 12 years, but in captivity, they have been known to live as long as 19 years.

Impact on Environment

When beavers colonize an area, they can impact the environment in both positive and negative ways. When they build a dam on a river or stream, they create ponds by flooding the area near the dam, and this increases the water table in the area and recharges aquifers. Beaver dams can also create wetlands where there were none before, providing a habitat for birds, invertebrates, fish, and mammals.   On the negative side, beaver dams can cause flooding of crops and roads, damage dams and roads built by humans, harm forests and landscaping, negatively impact plants and animals, dam irrigation canals and prevent necessary water from flowing to farmlands, and spread diseases such as Giardia to the drinking water supply. In Alaska, beaver dams sometimes cause floods during the spring ice break-up on rivers and streams, and dams that block a stream can disrupt the salmon migrating to spawn in that stream.

 

 

 

Roosevelt Elk (Cervus elaphus roosevelti)

Kodiak Wildlife, , , , , , ,

In 1928, eight yearling Roosevelt Elk (Cervus elaphus roosevelti) were introduced from the Ho Valley on the Olympic Peninsula of Washington State to Kodiak Island where they were raised for one year at the Experimental Agricultural Research Station in Kalsin Bay near the town of Kodiak. Biologists originally planned to release the elk on Kodiak Island, but ranchers on the island were concerned the elk would compete with their cattle for the limited winter food supply, so in 1929, biologists instead transplanted the elk to Afognak Island, a large island in the Kodiak Archipelago just north of Kodiak. By 1965, the herd had expanded from the original eight calves to between 1,200 and 1,500 elk, and the population had spread to nearby Raspberry Island. Several harsh winters with heavy snowfalls in the late 1960s and early 1970s caused increased mortality and reduced calf production in the herd, but by the 1980s, the herd had recovered to 1,200 animals. Today in the late 2000s, approximately 900 elk live on Afognak and Raspberry Islands. The only other elk in Alaska are Rocky Mountain Elk (Cervus elaphus nelson) that were introduced from Oregon to Etolin Island in Southeast Alaska in 1987. This herd has now expanded to Zarembo Island.

Elk are members of the deer family. They are larger than deer and caribou but smaller than moose. An elk’s body is gray to brown in color, with dark brown legs and a brown neck. A large, yellow patch covers the rump. Males have antlers that can grow very large. The antlers sweep back over the shoulders, and the spikes point forward. Bulls shed their antlers in the winter and grow new ones the following summer.

Elk give birth in late May or early June, and soon after giving birth, cow elk and their calves band together. Sometimes one cow elk will babysit the calves while the other mothers search for food. By July, the calves are still nursing but begin to eat on their own. In August, bands of elk come together to form herds, consisting of cows, calves, yearlings and sometimes a mature bull. Small bands of bulls form nearby but separate from the herd. In September, the bulls join the main herd for the mating season. During this time, bulls challenge each other by emitting high-pitched whistles or “bugles” and sometimes push and shove each other with their large antlers. By mid-October, once breeding has ended, the herds disperse into smaller bands, and the elk move into their wintering areas in the lower valleys or near the coastline where they search for food.

Elk graze from late spring to early fall when there is more food available, including grasses, forbs, and other leafy vegetation. By late fall, they mainly browse, feeding on sprouts and branches of trees and shrubs. Elk are big animals that require a large amount of food, and since they live in herds, they can quickly over-graze their food supply and decimate the native vegetation.

Biologists estimate 900 elk live in seven herds on Afognak Island and one herd on Raspberry Island. Logging on Afognak Island has impacted elk habitat there, but biologists consider the herd to be healthy.  Elk occasionally swim to Kodiak Island, but while individual elk have been seen on Kodiak, no herd has become established there.

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