Journal of Mammalogy

August, Peter, V.;Ayvazian, Suzanne, G.;Anderson, John G., T.

doi: 10.2307/1381663pmid: N/A

Abstract We displaced white-footed mice (Peromyscus leucopus) 40 m away from their home areas and released them in a circular arena. Mice concentrated their exploratory and escape activity in the portion of the arena corresponding to home direction. In another group of mice, we reversed the horizontal component of the geomagnetic field surrounding them during displacement. These individuals concentrated their activity in areas of the circular arena opposite home direction. Mice were not likely using visual, chemical, or kinesthetic cues to establish home direction. Tissues of P. leucopus exhibit strong isothermal remanent magnetization and may contain biogenic ferrimagnetic material. Our results suggest that white-footed mice have a magnetic sense and use the geomagnetic field as a compass cue. This content is only available as a PDF. © 1989 The American Society of Mammalogists

Gregory, Michael, J.;Cameron, Guy, N.

doi: 10.2307/1381664pmid: N/A

Abstract Olfactory communication of dominance status in the hispid cotton rat (Sigmodon hispidus) was evaluated by examining the relationship between dominance of individuals and their urinary- and fecal-marking patterns. Their response to presence of urine or feces of con-specifics also was examined. Dominant males, but not females, marked more with urine than did subordinates. Dominance was not associated with fecal marking by either sex. Marking response by males and nonreproductive females to feces of a same-sex opponent was associated with dominance status of the fecal donor. Male response to urine from males also was associated with dominance status of the urine donor. These results indicate that dominance status is communicated by urinary and fecal odors. Marking by nonreproductive females decreased whereas marking by reproductive females increased when exposed to urine from males. Response of reproductive females to feces of either sex was dependent on the dominance status of the female. This content is only available as a PDF. © 1989 The American Society of Mammalogists

Johnson, Christopher, N.

doi: 10.2307/1381665pmid: N/A

Abstract Red-necked wallabies, Macropus rufogriseus banksianus, spent most of their time alone, and their groups generally were small and unstable. Average group size varied seasonally, but was not influenced by population density. Groups were least stable in winter when rates of movement of feeding wallabies were highest. Individuals were no less alert when in groups than when alone, but rates of movement of grouped individuals were unusually high. Mothers and their independent offspring (subadult sons, and subadult and adult daughters) spent more time together than expected from the degrees to which their home ranges overlapped. Females that associated regularly tended also to breed in synchrony. Males spent more time than expected with other males of their own body sizes. It appears that, despite their relative solitariness and the fluidity of many of their associations, red-necked wallabies have a social organization similar in form to that of many species of more gregarious mammals. This content is only available as a PDF. Author notes Present address: Queensland National Parks and Wildlife Service, Central Region, P.O. Box 1395, Rockhampton, Queensland 4700, Australia © 1989 The American Society of Mammalogists

Jones, W., Thomas

doi: 10.2307/1381666pmid: N/A

Abstract Lifetime dispersal distances in Merriam's kangaroo rat, Dipodomys merriami, ranged from 0 to 265 m in males and from 0 to 158 m in females. Radiotelemetry data on nightly movements detected males ≤146 m and females ≤123 m from home-range centers. Eighty-nine percent of lifetime dispersal distances and 96% of moves between consecutive censuses were within the radii of familiarity indicated by radiotelemetry. Most effective “dispersal” appears to occur as a series of shifts in centers of activity within familiar areas. Occasional excursions beyond the usual area of activity and frequent moves to new burrows may contribute to the ability of the D. merriami to shift home ranges. The traditional view of dispersal as high-risk movement into unfamiliar areas does not apply to effective dispersal in D. merriami. Neither is dispersal in this species described precisely by models in which investigators assumed that individuals move to the nearest vacant site at a particular age or season. This content is only available as a PDF. © 1989 The American Society of Mammalogists

Briggs, John, M.;Smith, Kimberly, G.

doi: 10.2307/1381667pmid: N/A

Abstract Acorn selection by white-footed mice (Peromyscus leucopus) was tested with mice from four different habitats and acorns from six species of oaks (Quercus). Three mice captured in white-oak (subgenus Lepidobalanus) forests in northwestern Arkansas selected acorns from the white-oak group (post [Q. stellata] and white [Q. alba] oaks) over those from the red-oak (subgenus Erthrobalanus) group (pin [Q. palustris], willow [Q. phellos], and black [Q. velutina] oaks). These mice were able to subsist for >2 months on a diet of only acorns, provided that acorns from post oaks were available. These mice developed signs of tannin poisoning when maintained on acorns only from the red-oak group. Eleven mice captured in white-oak forests in eastern Kansas also consumed more acorns from the white-oak (post, bur [Q. macrocarpa], and chinquapin [Q. muehlenbergii] oaks) than from the red-oak group (black, northern red [Q. rubra], and pin oaks). However, seven mice captured in red-oak group forest in eastern Kansas consumed more acorns from the red-oak group than from the white-oak group and showed no signs of tannin poisoning. Five mice captured in habitats without oaks consumed equal amounts of acorns from the two subgenera. These results suggest that exposure to acorns may determine acorn selection by P. leucopus independent of fat, protein, or tannin content of the acorns. Acorn selection may be labile, as seven mice captured in white-oak forests in eastern Kansas consumed equal amounts of bur and black oak acorns after being given only red-oak acorns for 9 days. This content is only available as a PDF. © 1989 The American Society of Mammalogists

Kawamichi,, Mieko

doi: 10.2307/1381668pmid: N/A

Abstract Nest use by the Siberian chipmunk (Eutamias sibiricus) was observed in an oak (Quercus) forest in northern Japan for 7 years. Nests were located in underground burrows or tree hollows and, except for mothers with young, were occupied by single animals. Tree nests were not used for hibernation or parturition. After emergence from hibernation, many individuals abandoned their spring burrows. Adult males used tree nests or spring burrows of other individuals as summer nests, whereas females either used their own spring burrows or new burrows for parturition. Most residents used the new burrows for hibernation. Frequent change of nest sites is probably an antipredator strategy. Excavation of 17 burrows revealed differences in burrow structure before and after hibernation. In the preparation period, burrows consisted of one main tunnel and one nest chamber. When the hibernation stage started, a plug of soil was made at the entrance. Usually in late November, a large amount of soil was expelled from the entrance and soil was packed tightly into the main tunnel. This soil was taken from one or two new subtunnels dug below the nest chamber. In spring a new tunnel was dug to the surface. The soil resulting from digging the new main tunnel was packed into the subtunnels. There is a relationship between burrow structure and social organization among chipmunks. E. sibiricus has a simple burrow system and does not hold individual territories, whereas Tamias striatus has an extensive burrow system and holds individual territories. This content is only available as a PDF. © 1989 The American Society of Mammalogists

Getz, Lowell, L.

doi: 10.2307/1381669pmid: N/A

Abstract Short-tailed shrew, Blarina brevicauda, populations in east-central Illinois displayed annual population cycles within bluegrass (Poa pratensis), tallgrass, and alfalfa (Medicago sativa) habitats. There was no indication of multiannual population fluctuations in any habitat. Amplitudes of annual fluctuation were relatively consistent within each habitat type. Population density was significantly higher in bluegrass than in the other two habitats, and higher in alfalfa than in tallgrass from February to July. The annual peak in tallgrass occurred 3 months later (October) than in the other two habitats (July). Males were reproductively active January–July and females, March–September. Survival was highest in bluegrass, intermediate in tallgrass, and lowest in alfalfa. January–August precipitation >24% below the mean was followed by lower peaks in B. brevicauda populations in bluegrass and alfalfa; ≥9% above-normal precipitation was followed by higher populations in alfalfa and bluegrass. There was no correlation between precipitation and population density in tallgrass. There was no correlation between summer temperatures and numbers of B. brevicauda. This content is only available as a PDF. © 1989 The American Society of Mammalogists

Patterson, Bruce, D.;Meserve, Peter, L.;Lang, Brian, K.

doi: 10.2307/1381670pmid: N/A

Abstract Assemblages of small mammals in temperate Andean rainforests of southern South America are diverse but poorly known. Herein, we describe an elevational transect through temperate rainforests in Valle de La Picada, Chile, during February and March, 1984. The transect consisted of standardized removal trapping (165 traps set in lines at ca. 7-m intervals and operated for 6 consecutive days) at each of seven elevations: 425 m, 505 m, 620 m, 715 m, 820 m, 920 m, and 1,135 m. A total of 514 small mammals representing two species of marsupials and seven species of sigmodontine rodents was collected. Trap success averaged 7.4% across traps, days, and elevations. Number of captures by individual traps during the sample period was indistinguishable from a Poisson distribution, both throughout the transect and at individual levels, suggesting independence of captures among traps. Captures were biased significantly by trap type, with museum specials securing significantly more Dromiciops australis and all forms of Akodon than Sherman live traps; the same biases were suggested by captures of Irenomys tarsalis and Auliscomys micropus. As expected, total number of individuals taken at each elevation declined throughout the sampling period while the cumulative number of species rose. Number of species, number of individuals, and species diversity varied inversely with elevation. Number of species and species diversity taken each day reached a maximum after 2–4 days of sampling. Captures of Rhyncholestes raphanurus, Akodon sanborni, putative hybrids of A. sanborni and Akodon longipilis, and I. tarsalis were correlated inversely with elevation. Conversely, D. australis, A. longipilis, and A. micropus were taken more commonly at higher elevations, whereas captures of Oryzomys longicaudatus, Akodon olivaceus, and Geoxus valdivianus appeared unrelated to elevation. Systematic sampling procedures are viewed as essential for describing fundamental patterns of abundance and distribution that can be compared with other studies. This content is only available as a PDF. Author notes Current address of BKL: Department of Environmental Management, Freshwater Wetlands Section, 83 Park St., Providence, RI 02903 © 1989 The American Society of Mammalogists

Iriarte, J., Agustin;Contreras, Luis, C.;Jaksić, Fabian, M.

doi: 10.2307/1381671pmid: N/A

Abstract We livetrapped small mammals for 18 months with Sherman traps, and for 13 (simultaneous) months with Tomahawk traps, in a central Chilean matorral (chaparral-like shrub-land) locality near Santiago. Eight species (the marsupial Marmosa elegans, the lagomorph Oryctolagus cuniculus, the cricetids Akodon longipilis, Akodon olivaceus, Oryzomys longicaudatus, and Phyllotis darwini, and the caviomorphs Octodon degus and Abrocoma bennetti) were captured, with total mean densities of 57.9 and 12.4 individuals per ha in the Sherman and Tomahawk grids, respectively. Tomahawk traps provided the same estimates of density for the two largest rodents, but did not capture small species or adult rabbits. Weights of adult individuals of four species were 20–30% smaller than those reported previously. Octodon and Oryctolagus used shrub cover as available; Abrocoma avoided dense patches, whereas the remaining five species avoided sparse patches. Six mammal species were associated with the six principal shrub species in proportion to their availability, but A. longipilis and Octodon both associated with Colliguaya odorifera more frequently than expected, while apparently avoiding two other shrubs. Stopwatch-timed captures allowed categorization of one small mammal as diurnal and diurnal-crepuscular, two as nocturnal, four as nocturnal and nocturnal-crepuscular; one species was active all day, except at dawn. Comparisons with similar assemblage studies conducted in neighboring matorral areas demonstrate marked differences in population densities of particular mammal species, apparently related to levels of habitat disturbance and associated reductions of shrub cover. This content is only available as a PDF. Author notes Present address of JAI: Center for Latin American Studies, University of Florida, Gainesville, FL 32611 © 1989 The American Society of Mammalogists

Buskirk, Steven, W.;Lindstedt, Stan, L.

doi: 10.2307/1381672pmid: N/A

Abstract Sex ratios significantly different from 1:1 usually are observed in trap captures of mustelids. Although these ratios could be caused by skewed sex ratios in wild populations, trapped samples consistently are skewed toward males. This apparent sampling bias generally has been attributed to sexual dimorphism of home-range sizes in mustelids, postulated to result in greater exposure of males to traps. The magnitude of differences in rates of capture between sexes appears to be body-size dependent because small mustelids exhibit more strongly skewed sex ratios in trap captures than do large ones. We investigated possible causes of sexual differences in rates of capture of mustelids. Mathematical equations were derived to describe the effect of trap spacing in relation to home-range diameter as a cause of these sex biases. Large trap-spacing values in relation to home-range diameter result in these biases, but this “exclusion effect” (the effect of some smaller home ranges having no traps at all) is only one consequence of sexual dimorphism of home-range size. At low trap-spacing intervals, variations in home-range size result in differential numbers of traps in male and female home ranges (the “trap number effect”), although the density of traps is the same. Computer simulations were used to examine the interaction of known and postulated body-size-dependent factors, including home-range size, rate of travel, sensory acuity, and a body-size-independent factor, dimensionality of trap arrangement, as a possible cause of sexual differences in rates of encounter with traps. Rates of encounter with traps that favor capture of males and that produce greater differences in rates of capture between sexes in small species than in large ones were observed if home ranges were sexually dimorphic, traps were arranged in grids, rate of travel was proportional to the 0.25 power of body mass, and males perceived traps at the same distances as did females. Sex-specific behaviors, either resulting from sexual differences in territory packing, or in the way that animals respond to traps that they perceive, are hypothesized to be contributing causes of differences in rates of capture between sexes. This content is only available as a PDF. © 1989 The American Society of Mammalogists