A new small-bodied species of spotted cuscus is described from Biak and Supiori, neighboring oceanic islands in Cenderawasih Bay, northwest New Guinea. The nonvolant mammal fauna of Biak-Supiori is almost entirely endemic. The geographic origin of another insular species of the genus (Spilocuscus kraemeri) is also discussed: S. kraemeri is a distinctive species known only from the Admiralty Islands but, due to its putative absence from the fossil record of those islands, it is thought to have been introduced there from an unknown source population in prehistoric times. Based on new evidence, we suggest that kraemeri is either native to the Admiralty Islands, or originally differentiated on the large island of New Britain in the Bismarck Archipelago.

The male genital system was examined in 9 male specimens of Chironectes minimus (2 adult and 7 young) from Brazil. Unlike other didelphids, C. minimus lacks a cloaca and has distinct anal and urogenital openings, and the tunica vaginalis lacks black pigmentation. Similar to other American didelphids, C. minimus has a segmented carrot-shaped prostate gland with 3 anatomical segments that can be distinguished by color, length, and diameter in adults. The 2 pairs of bulbourethral glands of C. minimus are similar to those found in species of Caluromys, Gracilinanus, Monodelphis, Thylamys, and Glironia. The tip of each hemi-glans is rounded and bulbous shaped, whereas the urethral grooves end at the ventral aspect of the tip of each half glans.

The California myotis, Myotis californicus, and western small-footed myotis, Myotis ciliolabrum, are 2 morphologically similar bats which have had a complex taxonomic history due to intraspecific geographic variation across their sympatric distribution in western North America. Despite several published differences, field identification remains problematic in the southwestern United States. Mitochondrial cytochrome-b and control region fragments were amplified from tissue samples (n = 20) from Texas, Oklahoma, New Mexico, Arizona, Utah, and California to examine species boundaries and phylogenetic relationships. DNA sequences (1,184 bp) were used in parsimony and maximum-likelihood analyses. To corroborate species identification, cranial measurements from all specimens included in the molecular analysis along with additional specimens were analyzed statistically using principal components analysis (PCA). Individuals were designated either as M. californicus or M. ciliolabrum. Molecular analysis placed M. leibii within clades containing both M. californicus and M. ciliolabrum. In addition, sequence divergence and phylogenetic results do not recover distinct lineages for each species (M. californicus and M. ciliolabrum) as recognized by morphology. Our results suggest that these species have recently diverged, or alternatively that they are 1 phenotypically variable species. Based on network estimation of cytochrome-b haplotypes, phylogeographic structure is minimally represented between haplotypes with an east-west separation in the southwestern United States.

A review and reappraisal of bats of the genus Eumops (Chiroptera: Molossidae) reveals that considerable geographic variation is present in the bonneted bat, E. glaucinus; it is a complex consisting of >1 species. Bonneted bats in Florida are significantly larger than those in all other populations, and have proportionally shorter and deeper basisphenoid pits, the glenoid fossa is broadly triangular with rounded apices, and bacular shape differs from that in other populations. Additionally, bonneted bats in Florida have a broader palate than bats from populations in South America. Given these differences, the correct name for both Pleistocene and Recent Florida bonneted bats is Eumops floridanus (Allen, 1932). We found no geographic variation in Recent populations of Florida Eumops and little secondary sexual variation. We describe and review the distribution, morphometrics, systematics, ecology, and taxonomic history of the species, which is restricted to southern Florida. E. floridanus has one of the most restricted distributions of any bat in the New World and is one of the most critically endangered mammalian species in North America.

The taxonomic status of Artibeus jamaicensis triomylus was evaluated by mitochondrial cytochrome-b sequences, as well as cranial morphometric comparisons with 4 other subspecies of the A. jamaicensis complex and 5 species of large Artibeus. Phylogenetic analyses showed that 2 monophyletic groups exist within A. jamaicensis complex, separated by a sequence divergence of 3.6%. One clade grouped samples of A. j. triomylus from western Mexico, and the other contained samples of A. j. yucatanicus, A. j. richardsoni, A. j. paulus, and A. j. jamaicensis from the Gulf of Mexico, Central America, and the Caribbean. Additionally, multivariate analyses revealed a significant divergence in quantitative cranial characters between A. j. triomylus and non-triomylus specimens. These results, in conjunction with morphological data previously reported, suggest that A. j. triomylus represents a distinct and monophyletic lineage, consequently deserving recognition at the species rank.

Sorex cinereus (masked shrew) and Sorex fumeus (smoky shrew) are syntopic species co-occurring in relict fragments of spruce–fir habitat on southern Appalachian mountaintops. We conducted phylogenetic and population genetic analyses of 20 high-elevation Sorex populations in 8 distinct boreal islands. Partial mitochondrial DNA sequences (cytochrome b and D-loop) were compared with amplified fragment length polymorphism markers obtained by restriction of whole genomic DNA. The 2 species, though similar in morphology and ecological niche, have dissimilar phylogeographic patterns. S. cinereus, despite its more limited present-day southern Appalachian range, exhibits markedly less population structure than S. fumeus. What structure is present among masked shrew populations is randomized geographically, in contrast to a distinct association between genetic partitioning and geographic location among smoky shrew populations. Disparity in post-Pleistocene population densities of these species might be implicated in the discrepant patterns of phylogeographic structuring evident in their genomes as a result of historical vicariance. Although the metapopulations of both species exhibit genetic signatures consistent with continuous historical expansion, we believe that a localized catastrophic event induced a severe genetic bottleneck in Sorex populations at Whitetop Mountain, Virginia. This study contributes to a better understanding of the repercussions of boreal habitat fragmentation on the population dynamics and genetic diversity of associated vertebrate species.

Although the ornate shrew (Sorex ornatus) is widely distributed throughout California and northern Baja California, genetic analyses have shown that it is phylogeographically structured into 3 genetically differentiated regions (southern, central, and northern) within its distribution. These genetic groups might have been separated for more than a million years. In the northern region, ornate shrews cannot be genetically differentiated from their sister taxon, the wandering shrew (S. vagrans). Therefore it has been suggested that northern ornate shrews might have been misclassified. However, by analyzing skull morphology we show that ornate and wandering shrews, as well as the closely related montane shrew (S. monticolus), are well differentiated. Shrews from the northern region have a morphology similar to ornate shrews and not to wandering or montane shrews. Within the ornate shrews, populations across the range differ in morphology. However, morphological differentiation is not concordant with the deep tripartite pattern of genetic differentiation. Our results imply that skull shape differences among populations could be the result of local adaptation, whereas the long history of isolation might have contributed little to morphological differences between species. In addition, these results suggest that wandering shrews might be derived from the postglacial northward expansion of an ancestral population of northern ornate shrews.

We present a systematic study of Scapteromys populations from Argentina, Paraguay, and Uruguay, based on molecular and morphological evidence. First, based on DNA sequences (801 base pairs) from the mitochondrial cytochrome-b gene, we found that Scapteromys populations fall into 2 main clades; 1 formed by Argentinean and Paraguayan populations together with 1 population from western Uruguay, and the other constituted by the remaining Uruguayan populations. Analysis of molecular variance showed that 86.93% of the genetic variation uncovered in Scapteromys is explained by differences between clades. Morphological analyses corroborated the existence of 2 main morphotypes among Scapteromys specimens. The phylogeographic break identified is mostly congruent with patterns of morphological and chromosomic variation. In light of these results, we propose that S. aquaticus be elevated to the rank of species, we redefine the known distributions of S. aquaticus and S. tumidus, and we provide a list of character states that allow an unambiguously diagnosis of both species.

This study examines inter-operational taxonomic unit (OTU) relationships within a morphologically defined species complex of the African water rat Dasymys rufulus that comprises West, North, Central, and East African populations. Based on both traditional skull measurements and skull coordinates, 5 possible cryptic species within the rufulus complex were identified: western West Africa (Senegal to western-southeastern Ivory Coast), eastern West Africa (eastern-southeastern Ivory Coast to Nigeria, Chad), Central Africa (Cameroon, Congo, Democratic Republic of Congo), Central and East Africa (northern Angola, Zambia, southern Malawi, western Mozambique, Sudan) and southern Central and East Africa (southern Tanzania, northern Malawi, Mozambique). Data also confirmed that 2 recently identified species, D. foxi (restricted to Jos Plateau, Nigeria) and D. longipilosus (restricted to Mt Cameroon, Cameroon) are morphologically distinct. Each of the 3 datasets provided similar results, but the ventral skull coordinates were the most useful in separating OTUs with respect to a broad geographic pattern.

The Texas State Bison Herd is directly descended from the herd assembled from 5 wild-caught bison by Charles Goodnight in the 1880s. In 1997, 36 bison were used to establish a herd at Caprock Canyons State Park. To aid in the development of a long-term genetic conservation plan for this population, we examined and analyzed allelic variation at 54 microsatellite loci representing each of the nuclear chromosomes in the bison genome. The current Texas State Bison Herd population exhibits low genetic diversity and heterozygosity levels compared with bison at Yellowstone National Park and Theodore Roosevelt National Park. Parentage analysis indicates that relatively few adults have contributed offspring in the last 5 years, leading to low effective population size estimations and a rapid increase in the average age of animals in the herd. The very limited number of original founders, multiple population bottlenecks over the last 120 years, and chronically small population size, coupled with genetic drift and inbreeding, have resulted in dangerously low levels of genetic diversity. This, in turn, has likely triggered demographic problems such as low recruitment and high calf mortality rates. Population viability analysis based on current population demography reveals that there is a 99% chance of extinction of the herd within the next 41 years. Based on these findings, the continued existence of this historically important bison population appears doubtful without the introduction of new genetic variation from another plains bison herd.

Populations often are sampled with a coarse scale of measurement. As scale becomes increasingly coarse, the variance estimate can become biased; Sheppard's method has been used to correct that bias. Sheppard's correction, however, also becomes inadequate when the scale of measurement is too coarse. We develop a rule to decide how coarse a scale should be for a particular population variance. In addition, we propose a generalization of Sheppard's correction that allows for divisions of the scale to be unequal. Divisions of a measurement scale (intervals or bins) should be no larger than twice the population SD (σ). When the population variance (σ²) is small, a large amount of variation in interval size can produce inaccurate results. As σ² becomes large, more variation in interval size can be allowed without producing large inaccuracies. This new methodology has wide application for estimating timing of life-history events for mammals where dates must be pooled into intervals. We demonstrate this method with computer simulations and with an example for estimating mean and variance of birth date in Dall's sheep (Ovis dalli).

We examined the effects of maternal age and parity on litter size in 2 populations of white-footed mice (Peromyscus leucopus) in southwestern Ontario, Canada, to determine whether these factors cause seasonal variation in litter size. Litter size increased from 1st to subsequent litters among females that bred for the 1st time in their natal year, but not among females that 1st bred as overwintered adults. Thus, prior reproductive experience was not an important determinant of litter size. Maternal age accounted for approximately 70% of the variance in litter size; mean litter size was greatest among females between 150 and 250 days of age at parturition. Date of birth explained 79% of the variation in mean litter size, with litters born in summer significantly smaller than those born in spring or autumn. This effect was attributed to the fact that most summer litters were produced by primiparous young-of-the-year females. Although litter size declined among old, multiparous females, few individuals survived to the age at which reproductive senescence was apparent. Thus, reproductive senescence plays a minor role in population-wide variation in litter size.

We assessed the influence of 19 microhabitat factors on the distribution and abundance of small mammals at 60 plots across Fort Sill Military Reservation in Comanche County, Oklahoma. Trapping took place each spring from 1989 to 1992. We collected 15 small mammal species and used 10 of these (Chaetodipus hispidus, Cryptotis parva, Microtus ochrogaster, Neotoma floridana, Peromyscus attwateri, P. leucopus, P. maniculatus, Reithrodontomys fulvescens, R. montanus, and Sigmodon hispidus) in our analyses. Microhabitat variables for each mammal species were evaluated as unweighted measures based on the presence or absence of each species at a plot and as weighted measures based on the abundance of each species at each plot. Both weighted and unweighted data were subjected to cluster analysis, principal components analysis, and discriminant-function analysis. General trends of the microhabitat affinities of species in each cluster were summarized on principal components. Four species (C. hispidus, N. floridana, P. attwateri, and P. leucopus) occupied barren or rocky areas with a tall herbaceous or woody canopy, and 6 species (C. parva, M. ochrogaster, P. maniculatus, R. fulvescens, R. montanus, and S. hispidus) preferred open grassy areas. Weighted discriminant analysis produced better predictive accuracy (75% correctly classified) than the unweighted data (63% correctly classified). Total number of broadleaf trees and rocky ground cover were the most important factors in discriminating among groups.

Minimum number alive (MNA) is commonly used to assess population size with capture-mark-recapture data. However, MNA uses information from prior and subsequent capture sessions to assess the population at each point in a longitudinal study. Therefore, it is subject to negative bias that is greatest at the beginning and end of the study and least in the middle. Stochastic simulations performed with constant population size and capture rate showed that MNA peaked at the middle of the study. The tapering bias was greatest when survival rate between capture sessions was high. If indices (rather than statistical estimators) are used to assess population size, then the number of individuals captured should be chosen in preference to MNA.

We used photo-identification records to estimate annual survival of adult humpback whales (Megaptera novaeangliae) for the central North Pacific stock using models within the software application Program MARK. The analysis is based on 10,567 photographs of 2,400 individual whales taken from 1979 to 1996. The central North Pacific stock winters in Hawai'i and migrates to discrete feeding areas in Alaska for the summer and autumn. The Cormack–Jolly–Seber (CJS) estimate of annual survival based on annual sightings in Hawai'i was 0.963 (95% confidence interval [CI]: 0.944–0.978) and the Pradel estimate was 0.963 (95% CI: 0.944–0.976), with a population rate of increase of 1.10 (95% CI: 1.03–1.16). The best survival estimate for southeastern Alaska whales, based on Barker's model, was 0.957 (95% CI: 0.943–0.967). The best survival estimate for Prince William Sound whales, also based on Barker's model, was 0.984 (95% CI: 0.954–0.995). Whales from the central North Pacific stock mix in Hawai'i; therefore, the best apparent survival estimate for the entire stock is from the pooled Hawai'i data. However, this analysis also demonstrated that we could reduce heterogeneity with Barker's model and obtain more plausible estimates of survival for the whales in discrete feeding areas using semiannual sightings in Hawai'i as opportunistic resightings.

The coyote (Canis latrans) has recently expanded its geographic range into Florida, and the impacts of this range expansion on Florida ecosystems are likely to be complex. An area of particular concern is the effect on native carnivores. From May 2001 to May 2002, we investigated the ecological relationships between the coyote and bobcat (Lynx rufus) in south-central Florida to determine how they partition space, habitat, time, and food. Ecological separation was facilitated by dietary differences. Coyotes preyed primarily upon large ungulates and consumed substantial quantities of fruit, whereas bobcats primarily consumed rodents and lagomorphs. Coyotes and bobcats displayed similar habitat selection and activity patterns, and their high interspecific overlap in home ranges indicated a lack of large-scale spatial segregation. However, at the finer scale of core areas, patterns of spatial segregation were present. The lack of evidence for negative interactions at our study site suggests that non-overlapping core areas reduces agonistic encounters between the 2 species.

Bobcat (Lynx rufus) social organization has been studied extensively, and a land tenure system based on prior residence appears to influence home range selection and maintenance. However, few studies have presented information about home range vacancies and the pattern of replacement by other bobcats. We documented 10 cases in which home ranges of deceased male and female resident bobcats were filled by transient or neighboring bobcats, and quantified the extent to which home ranges of new bobcats were similar to those of prior residents. For males (n = 5) and females (n = 5), respectively, an average of 85% and 79% of each replacement's home range and 89% and 74% of their point locations overlapped with the former resident's home range. This extensive overlap suggests that a land tenure system exists for bobcats and that home range vacancies are filled by transients or neighboring residents of the same sex. Although our results generally support the land tenure concept, we suggest that bobcat social organization may be more complex than previously reported.

Use of abandoned mines by Corynorhinus mexicanus and C. townsendii is documented for a sample of 25 mines in Guanaceví, Durango, Mexico, during 1 year. Presence–absence of bats was recorded, and significance of associations between bat presence and environmental and structural characteristics of mines was tested. Bats occupied 15 of 25 mines examined. Males and females were observed in low numbers, and scattered throughout mine workings. Mines were used as hibernation roosts in winter, and as day roosts and temporary night roosts during the rest of the year. A maternity colony of endemic C. mexicanus was observed in 1 mine. Temperature and adit length were significantly associated with bat occupancy. Bats were more commonly found in mines that were at least 50 m long, had temperatures <10°C in winter, and temperatures >16°C the rest of the year. Mines might be providing an alternative refuge for these species in heavily deforested habitats.

Although hoary bats (Lasiurus cinereus) are presumed to be migratory and capable of long-distance dispersal, traditional marking techniques have failed to provide direct evidence of migratory movements by individuals. We measured the stable hydrogen isotope ratios of bat hair (δD_h) and determined how these values relate to stable hydrogen isotope ratios of precipitation (δD_p). Our results indicate that the major assumptions of stable isotope migration studies hold true for hoary bats and that the methodology provides a viable means of determining their migratory movements. We present evidence that a single annual molt occurs in L. cinereus prior to migration and that there is a strong relationship between δD_h and δD_p during the molt period. This presumably reflects the incorporation of local δD_p into newly grown hair. Furthermore, we present evidence that individual hoary bats are capable of traveling distances in excess of 2,000 km and that hair is grown at a wide range of latitudes and elevations. Stable hydrogen isotope analysis offers a promising new tool for the study of bat migration.

We examined intraspecific space use of free-ranging kangaroo rats (Dipodomys heermanni) during the breeding season using behavioral observations and radiotelemetry. Home ranges of males were significantly larger than those of females. Female D. heermanni maintained exclusive territories with essentially nonoverlapping home ranges, whereas home ranges of males overlapped with both same- and opposite-sex conspecifics, reflecting the different strategies of the different sexes. This follows a general pattern found in mammals in which spacing reflects limiting resources. There was, however, high individual variation in home range size for males, which may suggest a role for social interactions in determining spatial behavior in this species. D. heermanni, a medium-size species, appears intermediate in space use compared with the larger D. spectabilis and the smaller D. merriami.

Philopatry can arise from lack of a suitable territory (ecological constraints hypothesis) or a potential mate (limited mate hypothesis) outside the natal area. We tested predictions from these hypotheses by creating territorial vacancies with and without potential mates for female prairie voles (Microtus ochrogaster). Standard mark-recapture techniques were used to determine group composition and residency before and after removals. Either all adults, all adult females, or no animals were removed from 1 group within each enclosure. Territorial vacancies stimulated rapid immigration of adult female prairie voles. The presence of adult male(s) on the territory resulted in an intermediate amount of immigration compared to vacant and control territories. Immigrants arrived from neighboring groups more often than expected, suggesting that proximity to territorial vacancies affected replacement. The patterns of immigration observed in this study were more consistent with the ecological constraint hypothesis than with the mate limitation hypothesis.

Effects of fragmentation on distribution of ectoparasites of mammals are not well understood. A previous study reported higher nymphal tick (Ixodes scapularis) densities in smaller than in larger fragments. We tested whether there was a higher prevalence of ticks on white-footed mice (Peromyscus leucopus) in small forest fragments in an agricultural landscape. We observed a lower prevalence of ticks on mice in smaller than in larger fragments. Differences in infection rates between fragments, use of fragments by white-tailed deer, and agricultural history of landscapes could contribute to the apparent differences in tick abundance between this study and that reported previously. Resolution of the apparently contradictory data will require that the abundance of host-seeking ticks and prevalence on mice be measured in both landscapes.

Techniques used by North American badgers (Taxidea taxus) when hunting Richardson's ground squirrels (Spermophilus richardsonii) were assessed over a 15-year period in southern Alberta to determine the relationship between activity of prey and methods used to capture prey. Badgers frequently hunted hibernating squirrels in autumn, sometimes hunted infants in spring, and rarely hunted active squirrels in summer. Badgers always captured hibernating squirrels and infants underground, usually captured active squirrels underground, and sometimes intercepted fleeing squirrels aboveground. Regardless of season or year, the most common hunting technique used by badgers was excavation of burrow systems, but plugging of openings into ground-squirrel tunnels accounted for 5–23% of hunting actions in 4 consecutive years. Plugging occurred predominantly in mid-June to late July before most ground squirrels hibernated and in late August to late October when juvenile males were active but other squirrels were in hibernation. Badgers usually used soil from around the tunnel opening or soil dragged 30–270 cm from a nearby mound (72% and 22% of 391 plugged tunnels, respectively) to plug tunnels. The least common (6%), but most novel, form of plugging used by 1 badger involved movement of 37 objects from distances of 20–105 cm to plug openings into 23 ground-squirrel tunnels on 14 nights. Aimed movement of objects to plug openings into burrow systems occupied by ground squirrels qualified this badger as a tool user.