Urban Animals - Art Gallery of Alberta

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The Alberta Foundation for the Arts Travelling Exhibition Program Animal Studies: Beaver The beaver is the second largest rodent in the world. Beavers are large, primarily nocturnal and semi-aquatic rodents. Beavers are closely related to squirrels and there are two living species: the North American Beaver and the Eurasian Beaver. The word beaver in English is probably either borrowed from the Old French bièvre or both came directly from the Celtic befros. The North American beaver population was once more than 60 million, but as of 1988 was 6-12 million. This population decline is due to extensive hunting. Jason Carter The Beaver, 2012 Acrylic on canvas Collection of the artist Genetic research has shown that the European and North American beavers are distinct species and that hybridization is unlikely. Although superficially similar to each other, there are several important differences between the two. Eurasian beavers tend to be bigger, with larger, less rounded heads, longer, narrower muzzles, thinner, shorter, and lighter underfur, narrower and less oval-shaped tails, and shorter shin bones. Fur colour is also different. Overall, 66 % of Eurasian beavers have pale brown or beige fur, 20 % have reddish brown fur, 8 % are brown, and only 4 % have blackish coats. In North American beavers, 50 % have pale brown fur, 25 % are reddish brown, 20 % are brown, and 6 % are blackish. Finally, North American beavers have 40 chromosomes while Eurasian beavers have 48. Beavers have webbed hind-feet, and a broad, scaly tail. They have poor eyesight, but keen senses of hearing, smell, and touch. Beavers continue to grow throughout their lives. Adult specimens weighing over 25 kg (55 lb) are not uncommon. Females are as large or larger than males of the same age, which is uncommon among mammals. Beavers live up to 24 years of age in the wild. Beavers are herbivores, and prefer the wood of quaking aspen, cottonwood, willow, alder, birch, maple and cherry trees. The North American beaver’s preferred food is the water-lily. Beavers also gnaw the bark of birch, poplar, and willow trees; but during the summer a more varied herbage, with the addition of berries, is consumed. A beaver’s teeth grow continuously so that they will not be worn down by chewing on wood. Their four incisors are composed of hard orange enamel on the front and a softer dentin on the back. The chisel-like ends of incisors are maintained by their self-sharpening wear pattern. AFA Travelling Exhibition Program, Edmonton, AB. Ph: 780.428.3830 Fax: 780.421.0479 youraga.ca
The Alberta Foundation for the Arts Travelling Exhibition Program Animal Studies: Beaver continued The habitat of the beaver is the riparian zone, inclusive of stream beds. The actions of beavers for hundreds of thousands of years in the Northern Hemisphere have kept these watery systems healthy and in good repair. The beaver works as a keystone species in an ecosystem by creating wetlands that are used by many other species. Next to humans, no other animal appears to do more to shape its landscape. Beavers fell trees for several reasons. They fell large, mature trees, usually in strategic locations, to form the basis of a dam. Beavers fell small trees, especially young second-growth trees, for food. Beaver dams are created as a protection against predators, such as coyotes, wolves and bears, and to provide easy access to food during winter. Beavers always work at night and are prolific builders, carrying mud and stones with their fore-paws and timber between their teeth. The ponds, created by well-maintained dams, help isolate the beavers’ homes. Beaver lodges are created from severed branches and mud. The beavers cover their lodges late every autumn with fresh mud, which freezes when the frost sets in. The mud becomes almost as hard as stone, and neither wolves nor wolverines can penetrate it. The lodge has underwater entrances to make entry nearly impossible for any other animals. A very small amount of the lodge is actually used as a living area. The basic social unit of beavers are families consisting of an adult male and adult female in a monogamous pair and their kits and yearlings. Beaver families can have as many as ten members in addition to the monogamous pair. Beaver pairs mate for life: however, if a beaver’s mate dies, it will partner with another one. In addition to being monogamous, both the male and female take part in raising offspring. When young are born they spend their first month in the lodge and their mother is the primary caretaker while their father maintains the territory. After the young leave the lodge for the first time yearlings will help their parents build food caches in the fall and repair dams and lodges. Older offspring, which are around two years old, may also live in families and help their parents. In addition to helping build food caches and repairing the dam, two-year olds will also help in feeding and grooming and guarding the younger offspring. Beavers maintain and defend territories, which are areas for feeding, nesting and mating. They mark their territories by constructing scent mounds made of mud, debris and castoreum, a urine based substance excreted through the beaver’s castor sacs between the pelvis and the base of the tail. These scent mounds are established on the border of the territory. Because they invest so much energy in their territories beavers are intolerant of intruders and the holder of the territory is more likely to escalate an aggressive encounter. AFA Travelling Exhibition Program, Edmonton, AB. Ph: 780.428.3830 Fax: 780.421.0479 youraga.ca
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Urban Animals - Art Gallery of Alberta

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