Sorex Arcticus Research Articles

Habitat preferences of Arctic shrew in central and southern Alberta

Habitat preferences of Arctic shrew in central and southern Alberta

New Records for the Arctic Shrew, <em>Sorex arcticus</em> and the Newly Recognized Maritime Shrew, <em>Sorex maritimensis</em>

We report the first record for the Arctic Shrew (Sorex arcticus) in the state of Montana, USA. We also report range extensions for the closely related Maritime Shrew (Sorex maritimensis) in New Brunswick and Nova Scotia, Canada. These collections augment our limited knowledge of the ranges and habitat associations of these rarely collected shrews, and highlight the need for a careful assessment of the status of S. maritimensis in Canada.

The maritime shrew, Sorex maritimensis (Insectivora: Soricidae): a newly recognized Canadian endemic

Previous morphological and cytological analyses have suggested that the arctic shrew (Sorex arcticus) as currently recognized may be two distinct species. Specifically, those studies demonstrated considerable differentiation between the putative subspecies S. a. maritimensis and one or both of the other two subspecies, S. a. arcticus and S. a. laricorum. Phylogenetic analysis of 546 base pairs of cytochrome b sequence data from 10 arctic shrews from across Canada indicates that maritimensis is the sister-group to arcticus + laricorum. Furthermore, there is considerable genetic divergence between maritimensis and the other two putative subspecies (~8–9%; Kimura's two-parameter distance). Given that maritimensis and arcticus + laricorum appear to be reciprocally monophyletic clades with considerable genetic divergence (i.e., greater than that between other recognized pairs of sister-species within the S. araneus–arcticus group), we propose that S. maritimensis be recognized as a distinct species. The proportion of third-position transversion substitutions between S. arcticus and S. maritimensis suggests that these two species shared a common ancestor approximately 2.4 million years ago.

Range extension and first Holocene record of the Arctic Shrew, Sorex arcticus, from the Driftless Area, southeastern Minnesota

Range extension and first Holocene record of the Arctic Shrew, Sorex arcticus, from the Driftless Area, southeastern Minnesota

The karyotype of Sorex arcticus maritimensis (Insectivora, Soricidae) and its systematic implications

The chromosomes of Sorex arcticus maritimensis are described for the first time and their banding pattern (R- and C-bands) compared with those of Sorex araneus. The results provide further evidence for the monophyletic origin of the araneus–arcticus group and clearly indicate that the primary mechanisms of chromosomal reorganization in this group have been Robertsonian and tandem translocations. The basic karyotype of S. a. maritimensis was found to differ from that of S. a. arcticus in having a different fundamental number (34 vs. 38) but the same diploid number. A full understanding of the karyotypic differences between these taxa requires further work. Whatever the exact nature of the differences, they increase the likelihood of an independent specific status for S. a. maritimensis as suggested by the results of an earlier morphometric analysis.

Reproduction in the Arctic Shrew, Sorex arcticus

Reproduction in the Arctic Shrew, Sorex arcticus

Ecological Notes on Animals of the Churchill Region of Hudson Bay

The distribution and ecology of 26 mammals, 6 birds, and 1 amphibian are described. Northern range extensions are recorded for the pygmy shrew, arctic shrew, muskrat, heather vole, northern bog lemming and wood frog. A southern range extension of the arctic ground squirrel is noted following its being observed for the first time in Manitoba. Observation of a great blue heron at Churchill, far from its usual range in southern Manitoba, is also recorded. The number of species of small mammals on two-hectare quadrats in marsh, prairie, shrub, and savanna along the grassland-coniferous forest transition in southern Manitoba was 1.8 to 3.0 times greater than in beach-meadow, tundra, shrub, and open-forest quadrats along the coniferous forest-tundra transition of northern Manitoba, while the total population was 1.8 to 3.4 times greater.

External Parasites of Arctic Shrews (Sorex arcticus) Taken in Minnesota

External Parasites of Arctic Shrews (Sorex arcticus) Taken in Minnesota

Small-Mammal Distributions Across the Prairie-Forest Transition of Minnesota and North Dakota

Thirteen taxa of small mammals were collected in the continuous forest, aspen groves, riparian woodland and prairie areas of the prairie-forest transition. Mammals captured were placed in three groups on the basis of habitat selection. Of the forest species, Peromyscus maniculatus gracilis was the most restricted and occurred only in or near conifer forest. P. leucopus noveboracensis was found in coniferous, deciduous and river-bottom forests and in large aspen groves. Clethrionomys gap peri had a similar distribution, but was also found in some small aspen groves with grassy ground cover. Tamias striatus was collected in the continuous forest and nearby large groves. Eutamias minimus and Synaptomys cooperi were collected only in the continuous forest. The prairie species, P. m. bairdii, Onychomys leucogaster and Microtus pennsylvanicus, were found essentially in grassland situations. P. m. bairdii also occurs in aspen groves and river-bottom forests where P. 1. noveboracensis is absent. M. pennsylvanicus appears to be a permanent resident in young groves with a grassy undercover. The nonselective species, Sorex cinereus, Blarina brevicauda and Zapus hudsonius, were found throughout the area in all habitats trapped. Sorex arcticus may also be present in moister habitats throughout the transition. The small-mammal fauna of the prairie-forest ecotone includes fragments of both prairie and forest faunas and reflects the state of flux in the plant associations.

Systematics and Zoogeography of Sorex in the Bering Strait Area

Shrew populations on the islands in the Bering Strait region (Sorex pribilofensis, S. jacksoni, S. hydrodromus) were regarded as related to Sorex arcticus of the Alaskan mainland. Our data indicate that S. pribilofensis and S. jacksoni are members of the S. (Otiosorex) cinereus group, which occurs both in Alaska and eastern Siberia. Sorex hydrodromus apparently does not exist on Unalaska Island, and is a synonym of S. pribilofensis. The Holarctic evolution of the S. cinereus and S. arcticus-S. araneus groups, and their occurrence on the Bering land connection in the late Pleistocene, is discussed. Changes in sea-level in the Bering Strait area during the Cenozoic, and particularly the Pleistocene, from time to time produced a broad land connection between northeastern Siberia and Alaska (Fig. 1), whose importance to mammal distribution has been appreciated for some time (Gilmore, 1943, 1946; Simpson, 1947). The extent of this land connection directly varied with the amount of water withdrawn from the world ocean by glaciers, and was greater in the Riss (Illinoian) glaciation than in the last glacial episode, the Wurm (Wisconsin), which followed it (Hopkins, 1959; Saidova, 1961). The Riss (Illinoian) land connection existed about 100,000 years ago; the Wurm (Wisconsin) dates from 70,000 to 10,000 years ago (Pewe, et al., 1965). The connection was broken, and Bering Strait most recently formed, to the west of St. Lawrence Island about 12,000 years ago (Creager and McManus, 1965). The land connection was continuous with adjacent unglaciated areas in eastern Siberia and the Alaska-Yukon, but was isolated from other unglaciated areas of North America by continental and Cordilleran ice-sheets (Fig. 1), and semi-isolated from the unglaciated areas of Siberia by extensive montane glaciers on the eastern Siberian mountain ranges (Moreau, 1955; Rand, 1954). This ice-free refugium has been called Beringia (Hulten, 1.937) or Amerasia (Gilmore, 1943). The environment of the land-bridge portion of Beringia during the last two glacial periods was one of tundra (Colinvaux, 1964); hence only species adapted to, or tolerant of, tundra or to other cold open habitats such as loess steppe, could occupy the land connection. Thus, only such species might be expected to occur on both the Eurasian and North American sides of Bering Strait. LATE-WISCONSIN AND POST-PLEISTOCENE

Populations and Ecological Relationships of Shrews in Tamarack Bogs of Southeastern Manitoba

Shrew populations were measured by recapture techniques at monthly intervals between May and October from 1952 to 1957 on two of three plots in southeastern Manitoba, and from 1952 to 1958 on the third. Annual populations per acre varied from 0.4 to 9.3 for Sorex cinereus , 0 to 4.1 for Sorex arcticus , and 0 to 1.8 for Blarina brevicauda . Populations of S. cinereus varied inversely with those of S. arcticus where the two species occurred together. The population turnover appeared to be about two generations a year for the two species of Sorex and one per year for B. brevicauda . An exceptional population peak of S. cinereus is described. The breeding season was from May to August, except in a particularly high population of S. cinereus when breeding extended into October. Breeding began at about 4 months of age or earlier in Sorex and at about 10 months in Blarina . The average number of embryos was 6.5 for all species except at the highest population of S. cinereus when the average for this species dropped to 3.0. Several litters may be produced per season by all these species. Mortality was greatest in the first 2 months after birth, after which it declined gradually. One S. cinereus lived for at least 23 months, and one S. arcticus 18 months. Population levels of S. arcticus were correlated with the depth of the water table below ground surface—the drier the site, the higher the population. Nesting S. cinereus appeared to be advsersely affected by rainfall. The rate of mortality was markedly lower in winter than in summer. Observations failed to implicate parasites or predators as important factors in the population dynamics of shrews. Immigration and emigration may be the chief causes of apparent fluctuations in populations in spring.

METABOLISM, FOOD CAPACITY, AND FEEDING BEHAVIOR IN FOUR SPECIES OF SHREWS

The metabolic rates of Sorex cinereus, Sorex arcticus, Microsorex hoyi, and Blarina brevicauda were calculated from oxygen consumption, carbon dioxide production, and urinary nitrogen excretion and found to be 6.1, 6.9, 67, and 9.7 Calories per animal per day respectively. The resting rate of oxygen consumption was lower for S. cinereus than values reported by previous authors and was probably close to the basal level. Respiratory quotients were higher than expected for carnivorous animals, averaging 0.83 for all species. Protein catabolism accounted for about half the daily caloric output. Metabolic rate increased with increasing population densities.The minimum numbers of larch sawfly eonymphs required to support the daily metabolic requirements, including fecal wastage, for S. cinereus, S. arcticus, M. hoyi, and B. brevicauda were 87, 123, 98, and 150 respectively. Because of digestive inefficiency and wasteful feeding habits the approximate numbers of eonymphs destroyed daily could be as high as 663, 570, 711, and 150, and if hoarding is considered, 833, 790, 891, and 410 respectively could be taken. Excepting B. brevicauda, the larch sawfly is a preferred food of the group and, when available in abundance, comprises over 70% of the diet. It was estimated that shrews have the capacity to consume numbers of cocoons in excess of naturally occurring populations, but the likelihood of complete destruction of populations is remote. Of the species studied, S. cinereus appeared to be the most likely to provide effective control of larch sawfly populations.

Biology of the Arctic Shrew, Sorex arcticus

A population of arctic shrews, Sorex arcticus, living in a grass-sedge marsh in southern Wisconsin, was studied for three years. Two North American Census of Small Mammal trap lines operated for 28 months revealed six other species of small mammals living in the same area. Results showed neither positive nor negative association of the different species at trapping stations. The population fluctuations of the arctic shrew appeared to be independent of those of the other small mammals. Age determination was done by measurement of tooth wear. Young arctic shrews appeared first in July and disappeared after July of the following year. Males came into breeding condition in February. Females became pregnant by mid-May at the latest. Young animals did not commonly breed in their first season. The average embryo count of four females was six. Adult animals were heavier and longer than young but had similar skull measurements. The dull coat pattern of the young was replaced by the tricolor in the fall and this tricolor coat pattern was retained by the adults in the following summer. The rate of shrew capture in live traps was slightly lower in early morning than at other times of day and night. The behavior of the arctic shrew in captivity is described with notes on feeding habits and interactions with meadow voles.

Arctic Shrew in Southern Wisconsin

Arctic Shrew in Southern Wisconsin

STRATIGRAPHY AND PALEONTOLOGY OF A LATE PLEISTOCENE BASIN, HARPER COUNTY, OKLAHOMA

Pleistocene (Illinoian) lake deposits are exposed in the Doby Springs area, Harper County, Oklahoma. The collapse basin in which these beds were deposited resulted from solution of salt or anhydrite in the underlying Permian strata. The rim of the basin is made up of the Permian Whitehorse group, the Pliocene Ogallala formation, and the Pleistocene (Kansan to Yarmouth) Crooked Creek formation. In Kansan time a southeastward-flowing stream cut through the Ogallala formation into the Permian strata. This stream deposited the gravels, sands, and silts of the Crooked Creek formation in its valley. During Yarmouth time a caliche formed in the top of the formation. In Illinoian time a collapse basin formed in the Doby Springs area. Lake sediments containing the Doby Springs local fauna were deposited in this basin. Settling and collapse along the southern edge imparted the present dip to the lake beds. In Sangamon time the area was drained, and a caliche formed in the upper part of the lake sediments; later, further collapse occurred to the north and imparted the northward dip to the northern part of the initial basin deposits. The present outward radial drainage results from the collapse on the margins of the initial basin. The alluvial deposits along the modern streams are of Wisconsin and Recent age. The Doby Springs local fauna contained in the Illinoian lake deposits consists of the remains of ostracods, mollusks, fishes, amphibians, reptiles, birds, and mammals. The seven fishes (white sucker, creek chub, flathead chub, fathead minnow, black bullhead, green sunfish, and yellow perch) indicate a cool, upstream, lake environment with smaller streams running into the lake. Twenty-four forms of mammals from the Doby Springs local fauna are discussed, and a new species of the mammalian genus, Peromyscus, is described. The following extant small mammals indicate a marsh environment with surrounding lowland meadows and some trees: arctic shrew, masked shrew, northern water shrew, shorttail shrew, muskrat, meadow vole, and jumping mouse. The climate in the area is determined by plotting the present-day distribution of the living forms and arriving at an area of overlap. This area of overlap for the species recorded in the Doby Springs local fauna lies in southeastern North Dakota and northeastern South Dakota. The climate in Oklahoma during Illinoian time was probably similar to that in the area of overlap today. Lower summer temperatures and more effective moisture are indicated. The Doby Springs local fauna is correlated with the Berends local fauna, Beaver County, Oklahoma, and the Butler Spring local fauna, Meade County, Kansas.

Sorex arcticus at Maugerville, New Brunswick

Sorex arcticus at Maugerville, New Brunswick

A Record of Sorex arcticus for New Brunswick

Although there are two published records of the saddle-backed shrew, Sorex arcticus , in New Brunswick, neither seems to be supported by extant specimens, and it therefore seems desirable to place on record the recent acquisition, by the Canadian Museum of Natural History, of a specimen collected near Sackville in 1949. Cox in 1896 (Bull. Nat. Hist. Soc, …

A New Race of Sorex arcticus from Nova Scotia

A New Race of Sorex arcticus from Nova Scotia