Tag Archives: Introduced mammals to Kodiak Island

Red Squirrel (Tamiasciurus hudsonicus)

Photo by Tony Ross

Two species of squirrels live on the islands of the Kodiak Archipelago. The Arctic ground squirrel (Spermophilus parryii) was introduced a few hundred years ago[1], and the more common red squirrel (Tamiasciurus hudsonicus) was introduced in 1952.[2] The red squirrel population is slowly spreading across Kodiak Island, and biologists estimate at least 10,000 to 15,000 red squirrels now live on Kodiak.[2]

Red squirrels range across Canada and Alaska and south into the North Central and Northeastern United States, west to the Rocky Mountains.[3] Their range in Alaska extends through most of the forested areas, from the Brooks Range through south central and southeast Alaska.[4]

Red squirrels are members of the rodent family, and the species Tamiasciurus hudsonicus has been divided into 25 subspecies.[3] A red squirrel is small, measuring approximately 12 inches (30 cm) in length, with its long, bushy tail accounting for a third of the total length. A large adult may weigh 8.4 ounces (240 g).[5] In the summer, it has a pale red to olive-gray coat with a black line along each side. It is creamy white or buff-colored on its underside. In the winter, it has reddish-brown ear tufts and a bright rusty red strip along the back, while the black stripes along the side fade or disappear. In all seasons, a red squirrel has a white ring around each eye.[5]

Red squirrels are territorial and vigorously defend their territories.[3] A squirrel’s territory can range in size one-half acre to six acres, and each squirrel knows its territory well and may have several nests and food caches within the boundaries of its territory.[4] Red squirrels build their nests in trees. The nests are usually between 10 to 60 ft. (3-18 m) above the ground and are either constructed inside a tree cavity or out of a mass of twigs, leaves, moss, and lichens inside the dense foliage of a branch.[4,5}

Red squirrels mainly eat the seeds of conifer cones.[5] A spruce forest covers the north side of Kodiak Island, and the squirrels living in this forest eat the seeds of spruce cones. Since few spruce trees grow on the rest of the island, though, squirrels in other areas eat and cache alder cones. When collecting cones, a red squirrel cuts green cones from a tree and allows them to fall to the ground. The squirrel then gathers the fallen cones and buries them in one or several caches in its territory. By collecting only green cones, the squirrel knows the seeds are still in the cones.[5]

A squirrel may collect several bushels of cones in a cache, and a cache may be as big as 15 by 18 ft. with a depth of 3 ft. (5 x 6 x 1 m). In addition to one large cache, a squirrel often has several smaller caches in its territory.[4] Besides seeds, red squirrels also eat berries, buds, fungi, insects and bird eggs.[4] They do most of their food collecting during the day but may also be active on moonlit nights.[4] Red squirrels do not hibernate but instead depend on their stored food caches to make it through the winter. In regions with heavy snow, they may dig elaborate snow tunnels to reach their caches.[5]

Photo by Tony Ross

Red squirrels can climb trees with ease. They run up and down the trunks and along branches and can jump as far as 8 ft. (2.4 m) from one branch to another. On the ground, they walk or run and can run as fast as 14 mph (22.5 km/hr) over short distances.[5]

Red squirrels are solitary animals except during the breeding season, when males leave their territories, and females allow males to enter their territories.[4] A female has a one-day estrous period, and one to ten males may pursue her during that time. The dominant male will approach the female while uttering quiet vocalizations. Copulation is brief but may be repeated several times until the female becomes aggressive.[5] After a gestation of 36 to 40 days, the female gives birth to three to seven young. The young are blind and hairless at birth and weigh only ¼ oz. (7 g).[4] The young develop slowly and do not open their eyes until they are 27 days old. By 30 days of age, they are fully furred and begin to leave the nest. When young red squirrels are 9 to 11 weeks old, they begin to establish their territories.[5]

A red squirrel will emit a long rattling buzz when another squirrel enters its territory, and this call is often accompanied by tail-jerking and foot stamping. Neighboring squirrels may respond with similar calls. A slowly repeated “whuuk” call is an alarm call announcing the approach of a predator.[5] Biologists have noted red squirrels often produce a high-frequency alarm call when they detect an avian predator and a low, barking call when they sense the approach of a land predator.[4] In addition to vocalizations, red squirrels use posturing and chemical signals to communicate.[5]                                                                                                                                  

Red squirrels have a high mortality rate, and only 22% survive to one year of age. Females that survive their first year have a life expectancy of 2.3 years and a maximum lifespan of 8 years.[3] Red squirrels may be preyed upon by hawks, owls, eagles, bobcats, coyotes, weasels, minks, foxes, raccoons, and fishers. In the long term, habitat loss is the biggest threat to red squirrels.[4,5}

Beginning next week, I’ll write a few posts about bald eagles.  As always, I appreciate you stopping by to read my blog and would love hearing from you.  Please leave a comment!







Snowshoe Hare (Lepus americanus)

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