MICE, VOLES, MUSKRAT, AND LEMMINGS

Red-backed vole Clethrionomys rutilus

Found throughout the Yukon, red-backed voles have been reported from Rampart House and Lapierre House, from near the mouth of Johnson Creek, from the Old Crow River at Timber Creek and Black Fox Creek within Vuntut National Park, and from Blow River, Joe Creek, and the Firth River in Ivvavik National Park (Youngman 1975). Red-backed voles have the widest range of any species in the Yukon, having been collected from all habitats, from dry arctic tundra to floating bog, and from near sea level up to 1800 m in elevation (Youngman 1975). They reach their greatest population density in overgrown talus slopes or in stands of dwarf willow, alder, and dwarf birch. When Youngman was collecting voles, the greatest number of pregnant females were taken in July and August and the average number of embryos in 47 pregnant females was 5.4 (Youngman 1975).

Meadow vole Microtus pennsylvanicus

The meadow vole is found across much of northern North America and throughout most of the Yukon. The northernmost museum specimens are from the Old Crow River at Timber Creek, near the mouth of Johnson Creek, and 30 km north of Old Crow (Youngman 1975). The meadow vole has a large breeding potential with an average of over three litters a year, and is known for dramatic population peaks and fluctuations (Banfield 1974). Partly due to these population fluctuations, the meadow vole is an important food for many different predators.

Northern vole Microtus oeconomus

In contrast to the meadow vole, the northern vole has a North American range restricted to the northwest corner, though it is found throughout much of northern Asia (Youngman 1975). Its range in the Yukon extends north to the arctic coast and Herschel Island. Museum specimens fromVuntut National Park are from the Old Crow River; 22 and 100 km above Timber Creek and Black Fox Creek. In Alaska's Arctic National Wildlife Refuge, the northern vole was the most commonly captured species during small mammal trapping (Babcock 1986). There the preferred habitats included wet grassy troughs of tundra polygons. In general, the northern vole is most often found in damp tundra areas around lakes, streams, and sedge marshes (Banfield 1974). This vole has a similar life-history pattern to the meadow vole and may occur in the same area and even use the same runways and burrows.

Long-tailed vole Microtus longicaudus

With a range extending along the western side of North America north of Mexico, the long-tailed vole is found as far north as the southern edge of the arctic coastal plain (Youngman 1975). The only records from the Old Crow Basin are from Rampart House and Lapierre House.

Long-tailed voles are most commonly found in rocky situations on mountainsides but are also found in a wide range of habitats from low, wet, spruce woodland to high mountains (Youngman 1975). Youngman notes that pregnant females have been collected in June, July, and August, and that nine pregnant females had an average of 3.7 (2-5) embryos.

Chestnut-cheeked vole Microtus xanthognatus

Found throughout the northern half of the Yukon, this large 190-mm colonial vole ( Figure 12.1b) is known for extreme changes in its population size (Youngman 1975). When Youngman described this vole to Old Crow residents in 1964, people suggested that vole populations "irrupt" every 20 years or so, ruining muskrat sets, and that at times they became so numerous that dogs became sick from eating them. Peter Lord reported seeing them in early spring at Little Crow Flats and at Cadzow Lake where they "swam like little muskrats." The last irruption that Peter Lord recalled was in 1945 (Youngman 1975). In 1965, Abraham Peter of Old Crow reported high numbers of this vole at Hungry Lake and urged Youngman to visit the locality.

At Hungry Lake Chestnut-cheeked voles were most numerous in wet habitats along a small stream where surface runways and burrows "abounded" in the thick sphagnum moss. Large mounds of earth with networks of underground passages and a nesting chamber with dried sedges were associated with some burrows.

Singing vole Microtus miurus

With a world range restricted to mountainous areas of the Yukon and Alaska, the presence of singing vole is documented only in the extreme southwestern portion of the Yukon and in the British and Ogilvie mountains in the north (Youngman 1975). The singing vole was considered common in the foothills and mountains near the Kongakut River area of Alaska in the 1980s (Babcock 1986). The nearest specimen localities to Vuntut National Park are the Firth River in the vicinity of Joe Creek. The range of the singing vole in the Park area is likely to be along the northern and northeastern boundaries. Parks Canada staff heard characteristic vocalizations and saw voles similar to singing voles in small colonies along the central portion of Thomas Creek in June 1999 (Henry pers. comm. 1999). Youngman found this vole to be the predominant species at his collecting site on the Firth River where it was found in association with the northern vole, red-backed vole, and tundra shrew. Singing voles were found on a well-drained knoll in otherwise moist habitat several hundred metres from the Firth River. This vole, like the pika, gathers food plants into small piles to dry on rocks. These hay piles were first noted on 6 August on the Firth River and contained plants of bear roots (trih), also known as Eskimo potato (Hedysarum sp.). Singing voles are colonial and burrow entrances may be close to one another. The name is derived from this vole's habit of producing a high-pitched pulsating squeak or trill, especially when an intruder was in the colony.

Muskrat (Rat) Dzun (Ondatra zibethicus)

Distribution

Muskrats are found throughout North America except in tundra and desert areas and probably occur north to the arctic coast in the Yukon (Youngman 1975). The northernmost museum specimens come from the Old Crow Flats; at the International Boundary 100 km north of the Porcupine River, and along the Old Crow River near Timber Creek. Muskrats have been collected between 220 m and 1800 m altitude in the Yukon.

Natural History

The demographic and reproductive characteristics of the Old Crow Flats muskrat population was studied between 1984 and 1986 (Simpson et al. 1989) in order to provide information necessary for future harvest management for the Fish and Wildlife Branch of the Renewable Resources department of the Yukon Government. In testing the accuracy of aerial surveys it was concluded that counting of muskrat pushups alone was not a reliable census technique (Simpson et al. 1989). The effect of harvesting muskrats on the populations of the Flats was that other adults migrated into the areas where populations had been depleted. The total spring population of the entire Flats area, including Vuntut National Park and the Old Crow Special Management Area, was estimated at 490,000 (+/- 164,000). Spring muskrat densities varied from 0.93 muskrats per hectare to 4.46 muskrats per hectare. Bryant (1957) examined muskrat carcasses obtained from trappers in the Old Crow Flats for the presence of a liver parasite. As well as giving the number of cysts found in livers, Bryant's work provides information on sexes and ages of trapped muskrats, compares frequency of parasites, age and sex ratio with Mackenzie Delta.

Studies of muskrat ecology conducted in 1972 in association with the proposed gas pipeline routes in the Yukon (for Canadian Arctic Gas Study Ltd.) describe the characteristics of lakes, ice, water flow, fluctuations in water level, vegetation, and the role of beavers in waterbodies in the area of the Old Crow Flats, south and east of Schaeffer Creek, and east to Zelma Lake. This study presents information on numbers, use of dens and pushups, sex ratios, ages, timing of reproduction, litter sizes, growth, survival, predators, parasites, and harvest (Ruttan 1974).

The muskrat ecology studies of 1985-86 indicated that breeding began in early June in the Flats, with females producing only one litter with an average litter size of 7.75 young. In the three years of the study juveniles first appeared in livetraps between the 6th and 11th of August (Simpson et al. 1986).

Utilization

"If there was no game they had to rush back to Crow Flats for rats. And this is the way they hunted rats in the wintertime. They had a bone chisel and they went along the shore of the lake and tapped. There was a sound - that means that was a rat runway under the lake. They opened that place up and they put a net made out of roots or babiche down in the runway. So, they had a little stick in front. If the rat touched that stick, it [the net] was pulled out. They'd get quite a few rats in one night." Neil McDonald, Old Crow (McClellan 1987).

CWS studies in the early 1950s presents the average catch of muskrat and value of pelts from the Old Crow area from 1951-52 to 1954-55 (Bryant 1957). Stager (1974) provides harvest data from the 1960s and 1970s indicating that the annual average number of muskrats trapped out of Old Crow was over 14,000. The data were not presented by geographic area. Trapping areas for muskrat within Vuntut National Park and the SMA are shown in Figure 12.4). Harvest figures from 1977 to 1988 are presented in Simpson et al. 1989. In the years between 1980 and 1993, up to 18,639 muskrats were harvested per year in the Old Crow Group Trapping Area, for a total of 82,189 muskrats (Government of Yukon 1993). The annual total has decreased from 5,000 in the mid 1980s to less than 500 between 1990 and 1993.

"We hunt for muskrat every year. That is why there are lots of them. If we don't trap or hunt the muskrat they will multiply. It will eat all its food, and eventually die off. They will be almost extinct for three years. The beaver is the same way" Alfred Charlie (Sherry and Vuntut Gwitchin First Nation 1999).

Siberian (or brown) lemming Lemmus sibiricus

The Siberian or brown lemming is found throughout the Yukon except for the extreme southwestern corner, and northern British Columbia. This lemming is also found along the northern coast of Siberia (Russia), the Canadian arctic mainland and on the southernmost arctic islands. Wet tundra areas are the preferred habitats. Youngman (1975) follows the taxonomists who have suggested that Siberian and North American forms of this lemming are all of the same species, hence his use of "Siberian" rather than "brown" for the common name of this species. Specimens from the Old Crow Basin include Old Crow River, Timber Creek, Johnson Creek and Old Crow Mountains. The Siberian lemming is well known for dramatic and cyclical fluctuations in populations featuring an excessive population high and a diminishing food supply, and a correlated high number of predators. At two study sites in the Arctic National Wildlife Refuge in 1985, Babcock (1986) documented an increase in Siberian lemming densities and a correspondingly high diversity of lemming predators.

Northern bog lemming Synaptomys borealis

Disributed across most of the wooded areas (taiga) of Canada, the range of the northern bog lemming probably occurs throughout the forested part of the Yukon (Youngman 1975). This lemming has been collected in the Yukon mostly in bogs and marshes from 180 m to 1800 m elevation. Its range in the Old Crow Basin area probably coincides with the treeline, however, there are no records of this species from within Vuntut National Park or the Special Management Area. Youngman records specimens of northern bog lemming from Old Crow, Rampart House and Lapierre House.

Varying lemming Dicrostonyx torquatus

The varying lemming is found in tundra areas of northern Canada including the arctic islands, Alaska and Russia. In the Yukon this lemming is found in two separate areas (as two different subspecies); in the northern Yukon extending from the arctic coast to the British and Richardson Mountains, and in the north-central Yukon in the Ogilvie Mountains (Youngman 1975). The suggested range covers the Old Crow Basin north of the Porcupine River. However, specimens are known only from Herschel Island and a location 32 km southeast of Joe Creek, near the northern boundary of Vuntut National Park. At the location in the British Mountains, at an elevation of about 800 m, the varying lemmings occurred in a sparsely vegetated dry heath on a barren, rock-strewn mountainside, but not in the adjacent low tundra. In the Richardson Mountains at Horn Lake, NWT, near the Yukon border, they were found in low, poorly drained cottongrass meadows and not in the adjacent alpine tundra (Youngman 1975).

Youngman (1975) noted that in both the British and Ogilvie Mountains, where varying lemmings were confined to alpine heath, the singing vole was the dominant species occupying the low hillsides. This observation suggests the possibility of competition between the two species to explain the two different ecotypes occupied by varying lemmings (Youngman 1975).