The genus Abrocoma (family Abrocomidae) is distributed from southern Peru and northern Chile to Bolivia and then southward to the west-central region of Mendoza Province, Argentina. The systematics of the genus is poorly known. Ten taxa were originally described but later synonymized into 2 species. Five taxa were included in Abrocoma cinerea and 5 in A. bennetti. A 3rd species, A. boliviensis, was described in 1990, and a new genus and species, Cuscomys ashaninka, were described in 1999. We reevaluate the systematics of the A. cinerea species complex, with emphasis on Argentine specimens, using cranial, dental, and external morphology. A new species of Abrocoma from Mendoza Province, Argentina, is described. Karyotypic information is presented. Behavior, habitat, and natural history are also discussed.

Phylogenetic relationships among 15 individuals representing 6 subspecies of Neotoma mexicana from the United States and Mexico were examined using DNA sequences from the mitochondrial DNA cytochrome b gene. Parsimony, likelihood, and genetic distance analyses revealed a dichotomy between populations of N. mexicana from the United States and northern Mexico and those from south of the Trans-Volcanic belt in southern Mexico. A 2nd dichotomy existed between wood rats in the Sierra Madre del Sur in southwestern Mexico and those south of the Isthmus of Tehuantepec. Further, populations of N. mexicana from the United States and those from Mexico possessed relatively high levels of sequence divergence indicating substantial genetic differentiation between these 2 groups. These data indicate that the 3 taxa probably represent sibling species and that consideration should be given to the elevation of the southern and southwestern Mexico forms to specific status. Additionally, paleontological material from Pleistocene wood rat middens in New Mexico and Mexico provided evidence for the effects of climatic changes on this group of wood rats and the means for assessing the phylobiogeography of the N. mexicana species group.

We examined genetic variability and spatial heterogeneity of a class-II locus of the major histocompatibility complex (MHC) for 7 populations of white-tailed deer (Odocoileus virginianus) from Iowa, New York, Oklahoma, and Tennessee. Although white-tailed deer east of the Mississippi River have experienced drastic population reduction, all populations exhibited high levels of allelic diversity and all but 2 pairwise comparisons exhibited evidence of significant population divergence. These results suggest that previous bottlenecks have not drastically reduced Mhc-DRB allelic diversity in white-tailed deer.

Whereas it is generally agreed that the Neotropical bat family Mormoopidae is aligned within the superfamily Noctilionoidea, interfamilial relationships within Noctilionoidea and intrafamilial relationships within Mormoopidae have been debated. DNA sequence data have been generated from a few representatives of Mormoopidae to address interfamilial relationships within Chiroptera, but no such study has focused on relationships within Mormoopidae. Our purpose was to test noctilionoid interfamilial and mormoopid intrafamilial relationships by using a combination of DNA sequence (mitochondrial 12S rRNA, tRNA^Val, 16S rRNA) and morphologic data. Parsimony analysis of the DNA sequence data and the combined molecular and morphologic data strongly support: monophyly of Mormoopidae, Mormoops, Pteronotus, and the subgenus Pteronotus; a sister-taxon relationship between Phyllostomidae and Mormoopidae; and Mystacinidae as sister to the Phyllostomidae and Mormoopidae clade. Although resolution and strong support was provided by this study for several noctilionoid and mormoopid clades, relationships within Pteronotus remain somewhat unclear as monophyly of the subgenus Chilonycertis was weakly supported.

We conducted a phylogenetic analysis of DNA sequences from 3 adjacent genes (12S rRNA, tRNA^Val, and 16S rRNA) in the mitochondrial genome from representatives of 14 phyllostomid genera including 7 species of Tonatia. Previous studies of the systematic relationships within Tonatia document that some members of this group are extremely divergent from others. Data on mitochondrial DNA sequence depict a paraphyletic relationship of a clade of T. bidens and T. saurophila with respect to other species of Tonatia and other members of the Phyllostominae. Tonatia schulzi is included as a member of a clade containing all species of Tonatia (with the exception of T. bidens and T. saurophila), congruent with immunologic studies. Results of this study, coupled with those of allozymic, immunologic, and karyotypic data, warrant taxonomic revision of Tonatia. We recommend changing the generic name Tonatia to Lophostoma for all members except T. bidens and T. saurophila.

Karyotypes of 127 individuals, representing 19 species of 10 genera of Brazilian marsupials (Didelphidae) were determined, with karyotypes of Gracilinanus emiliae and G. microtarsus, Marmosops incanus, Thylamys velutinus, and Philander frenata being described for the 1st time. The specimens were collected from 24 localities, in an area between 4°N (Surumú, Roraima) and 31°S (Mostardas, Rio Grande do Sul), in Brazil. Only 3 diploid numbers were found, 2n = 14 in G. emiliae, G. microtarsus, G. agilis, Marmosa murina, Marmosops parvidens, M. incanus, Micoureus demerarae, and T. velutinus; 2n = 18 in Monodelphis dimidiata, M. brevicaudata, M. kunsi, and M. domestica; and 2n = 22 in Chironectes minimus, Lutreolina crassicaudata, Didelphis albiventris, D. aurita, D. marsupialis, Philander opossum, and P. frenata.

Little is known of the neural mechanisms of marsupial olfaction. However, functional magnetic resonance imaging (fMRI) has made it possible to visualize dynamic brain function in mammals without invasion. In this study, central processing of urinary pheromones was investigated in the brown antechinus, Antechinus stuartii, using fMRI. Images were obtained from 18 subjects (11 males, 7 females) in response to conspecific urinary olfactory stimuli. Significant indiscriminate activation occurred in the accessory olfactory bulb, entorhinal, frontal, and parietal cortices in response to both male and female urine. The paraventricular nucleus of hypothalamus, ventrolateral thalamic nucleus, and medial preoptic area were only activated in response to male urine. Results of this MRI study indicate that projections of accessory olfactory system are activated by chemo-sensory cues. Furthermore, it appears that, based on these experiments, urinary pheromones may act on the hypothalamo-pituitary–adrenocortical axis via the paraventricular nucleus of the hypothalamus and may play an important role in the unique life history pattern of A. stuartii. Finally, this study has demonstrated that fMRI may be a powerful tool for investigations of olfactory processes in mammals.

Although conception-to-weaning times in dasyurid marsupials are extremely long and neonates very small, little is known about their growth and thermoenergetics. We studied the growth pattern of Antechinus stuartii from birth to after weaning in relation to thermoregulatory capabilities and energetic cost of lactation in the female. Litter size was 1–8 young. Growth rate was slow for age 0–40 days, increased until weaning at about 100 days of age, and then slowed again. At weaning, males were 18% heavier than females (t-test, P < 0.01). Energy expenditure of females increased significantly by about 30% during late lactation, compared with early or postlactation. Overall, maternal investment increased with increasing litter size. Total energy expenditure from birth to weaning was 2,373 kJ for small litters (1–3 young) and 4,580 kJ for large litters (8 young). However, at weaning, young from small litters were about 30% heavier than young from large litters. Ability of young A. stuartii to thermoregulate improved with age. At 60 days age, young were poikilothermic after cold exposure, but by 79 days, physiological thermoregulation was established.

We measured seasonal variations of gut macrostructure of 36 Mongolian gazelles (Procapra gutturosa) collected in Xiqi, Inner Mongolia. Relative weight of ruminoreticular contents (9–14% of body weight) and relative length of the total intestine (15–18 times body length) were within the range of intermediate feeders. Proportional length of large intestine to total intestine (29–31%) falls within the range of browsers and suggests that distal digestion is important for small intermediate feeders. Total weight of gut with contents was 27–36% greater in winter than in spring because of the increase in contents of ruminoreticulum and large intestine, suggesting that both proximal and distal fermentation are more important in winter than in spring.

Characteristics of estrus, mating, and pregnancy were studied in captive fennec foxes. The monestrous cycles had mean intervals of 9.9 (±1.2) months, whether or not pups survived to weaning. Proestrus, judged by vulval swelling, began 6.5 (±0.7) days before estrus and was not accompanied by sanguineous discharge. Percentage cornified epithelial cells in vaginal smears increased at the time of estrus. In 8 of 10 estrous periods, a single mating followed by an extremely long copulatory lock (mean 1 h 58 min) was observed during continuous video monitoring. In the other two cycles, copulation occurred 2 and 3 times. Patterns of both fecal and serum estradiol and progesterone concentrations during estrous cycles were similar to those reported for other canids.

Recent field surveys searching for the rare Andean mountain cat, Oreailurus jacobita, have had difficulty in identifying this species from sightings and skins. This is caused by the paucity of museum specimens (only 3 skulls available to date) and the lack of criteria to differentiate this species from other small sympatric felines (e.g., Lynchailurus pajeros). In a study to solve these problems, 3 new skulls of O. jacobita were identified and a total of 5 skulls and 41 skins examined. Skulls of O. jacobita average 12–14% larger than skulls of L. pajeros, showing a large anterior chamber in the bulla. Andean mountain cats have vertical series of yellowish-brown blotches on the sides, and a long, bushy tail with wide dark rings. Two keys to differentiate these felines, based on these and other characters, are offered.

A study of cranial shape in dolphins of genus Sotalia was done using 104 specimens (92 from localities along the Brazilian coast and 12 from the Amazon River basin). Twenty-two cranial landmarks, assumed to be homologous, were selected for analysis. The first 2 principal components of aligned coordinates explained 40.6% of the total variation in cranial shape. Although no sexual dimorphism was detected (P = 0.811), shape differences among populations of Sotalia were highly significant (P < 0.000001). The 1st and 2nd principal components of shape showed that the Sotalia population from the Amazon basin differed in cranial shape from marine populations. Based on differences in geometric shape, a discriminant analysis of 3 linear measurements between landmarks provided an equation that classified skulls as belonging to Amazonian or marine populations. Based on these results and evidence from several other divergent character systems and life history attributes, we suggest the use of Sotalia guianensis for marine dolphins and S. fluviatilis for Amazonian dolphins.

A recent taxonomic review of the Otariidae, based on morphometric techniques applied to skulls, revealed a number of specimens with cranial morphology divergent from typical otariid species. The specimen considered in this paper was a large adult male otariid with cranial morphology most similar to the California sea lion, Zalophus californianus, but differing from it in significantly greater condylobasal length and rostral and palatal structure. Discriminant function analyses were applied to compare the cranial morphology of the anomalous specimen with those of 7 otariid taxa: the Steller sea lion, Eumetopias jubatus; the southern sea lion, Otaria byronia; the California sea lion, Z. californianus californianus; the Galapagos sea lion, Z. c. wollebaeki; and the presumed-extinct Japanese sea lion, Z. c. japonicus. Results suggest that the aberrant skull was that of a hybrid between Z. californianus and O. byronia.

We studied morphological and functional variations in jaws of coastal and mountain populations of subterranean Spalacopus cyanus inhabiting soils with contrasting hardness. We found almost no morphological differentiation between populations in the variables we measured. However, there were clear differences in incisor resistance between them. Apparently, soil hardness did not represent a selective pressure on cururos' digging apparatus. An Andean origin of this genus could explain our results.

Daily patterns of activity were studied under laboratory conditions in 12 coruros, Spalacopus cyanus, subterranean social rodents originally from Chile. When able to burrow, coruros spent 90% of the total time underground, and surface activity occurred during the 1st hours of darkness. When prevented from burrowing, locomotory activity of coruro groups peaked near the onset of darkness but also occurred during episodes of light. Individually housed coruros displayed a clear nocturnal activity pattern. Coruros exhibited endogenous circadian rhythms entrained by a light–dark cycle.

The majority of the literature describing howling monkeys (Cebidae) has focused on only 2 of 6 species in the genus. These studies have revealed differences in behavior between species and differences within species at different locations. One study has been published describing the vocal patterns of the black howler monkey (Alouatta pigra). This species appears to differ markedly from previously described Alouatta. In an effort to further distinguish A. pigra from its congeners, we observed the vocal patterns of an additional population of black howler monkeys. This population exhibited a bimodal calling pattern similar to that previously described for A. pigra, but absent in all but one (A. fusca) of the other species in the genus. The bimodal pattern was evident in both the rainy and dry seasons, with peaks in the morning and afternoon. Midday and afternoon calling were significantly reduced in the dry season. We also made a detailed comparison between both populations to examine the function of the afternoon peak. Contrary to the results of the previous study, we conclude that there is insufficient evidence to describe either of these populations as territorial.

Radiotracking studies of Townsend's big-eared bat (Corynorhinus townsendii) were conducted in grazed grassland and coastal forest (California bay, Douglas-fir, and redwood) at Point Reyes National Seashore in coastal central California. Radiotagged bats were used to determine the foraging patterns of both female and male bats and to locate alternate roost sites. The animals showed considerable loyalty to their primary roost sites even though the study was conducted after the nursery period had ended, when the bats would normally be dispersing for the season. Foraging patterns differed between male and female bats, with females traveling greater distances than males. Males consistently stayed close to the maternity colony both during day and night. Both sexes flew in the immediate vicinity of vegetation, both when foraging and when traveling from the roost to foraging areas. Foraging activity was concentrated primarily along the edges of riparian vegetation.

Abundance, distribution, and ranging patterns of bottlenose dolphins (Tursiops truncatus) in the western Atlantic Ocean are not well understood. As part of an initial attempt to understand their ecology and social system, I examined the ranging patterns of coastal resident dolphins in South Carolina. From October 1994 through December 1998, I conducted 209 surveys in Calibogue Sound and adjoining coastal waters. Individual dolphins were identified by distinctive fin characteristics and categorized as resident or transient inhabitants based on resighting patterns. Home range boundaries and core use areas were defined for 20 resident dolphins. Resident dolphins occurred in inshore waters, were moderately mobile, exhibited strong site-fidelity, and showed distinct patterns of core use within their home ranges. Ranging patterns exhibited geographic partitioning along environmental and social parameters within the resident population.

Between May 1995 and June 1999, we studied denning ecology of 81 barren-ground grizzly bears (Ursus arctos) equipped with satellite radio-collars within a study area of 235,000 km², centered 400 km northeast of Yellowknife, Northwest Territories, Canada. All dens were located on well-drained slopes (X̄ = 25.3°, SE = 1.20, n = 55). Choice of den aspect was nonrandom (χ² = 12.4, d.f. = 3, P < 0.01, n = 56); the majority of dens faced south (25), followed by west (13), east (10), and north (8). Most dens were constructed under cover of tall (>0.5 m) shrubs (Betula glandulosa and Salix), the root structures of which supported ceilings of dens. Selection of denning habitat by bears was significantly different from random (G = 127.67, d.f. = 6, P < 0.0001). Bonferroni confidence intervals indicated that esker habitat was selected more than expected by chance (P < 0.10). Den entrance occurred primarily in last 2 weeks of October. The majority of bears emerged from dens in the 1st week of May.

We estimated annual survival rates of swift foxes (Vulpes velox) and documented number of young per pair in a transition zone between shortgrass prairie and sagebrush steppe plant communities in southeastern Wyoming during 1996–2000. Annual adult survival ranged from 40% to 69%, with predation by coyotes (Canis latrans) the primary cause of deaths. Two foxes died of canine distemper virus. Annual survival rates did not differ among years (P > 0.12). Nineteen of 24 (79%) swift fox pairs were observed with young over 3 years. Mean minimum litter size was 4.6 based on these 19 litters and 6 others not associated with our radiocollared foxes. Adult survival was similar and litter size slightly larger than observed elsewhere in the species range, suggesting that viable swift fox populations can be supported by sagebrush steppe and shortgrass prairie transition habitat.

Niche partitioning among sympatric populations of white-lipped peccary (Tayassu pecari), collared peccary (Pecari tajacu), and feral hog (Sus scrofa) is evaluated using an ecomorphological approach. Masticatory apparatus and head-elevation lever system of the 3 species are compared by skull measures related to moment arms of associated muscles. Force-rates based on the equation of static equilibrium are proposed as a basis of comparison between species-specific cranial designs related to mastication and digging ability. Morphofunctional data suggest that feral hogs have a powerful bite and are able to feed on seeds of different degrees of resistance. With an optimized lever system of head elevation, feral hogs are more efficient than peccaries at rooting. These facts, along with the capacity of feral hogs to explore a wide range of habitats, support the view that the species acts as a potential competitor of native peccaries.

We used logistic regression to develop habitat models from observation of mountain goats (Oreamnos americanus) in alpine habitats near Mt. Evans, Colorado. Mountain goats used areas near escape terrain, on moderate slopes, at midelevations, and on southerly exposures more than expected. Habitat models for summer, winter, or all-seasons correctly classified 81–83% of observations and incorrectly classified 12–13% of locations not used by mountain goats. A model based only on distance to escape terrain correctly classified 87% of observations and classified 38% of the study area as suitable habitat. Our models provide a way to use readily available data and simple techniques to quickly identify suitable habitat over large geographical areas.

Rocky Mountain elk (Cervus elaphus nelsoni), Rocky Mountain mule deer (Odocoileus hemionus hemionus), and cattle frequently co-occur on landscapes in the northwestern United States. We hypothesized that niche overlap would be greatest between introduced cattle with either of the 2 native herbivores because coevolution between native elk and mule deer should have resulted in strong patterns of resource partitioning. We observed strong differences among species in use of space, especially elevation, steepness of slope, and use of logged forests. We used 2 temporal windows to examine both immediate (6 h) and long-term (7 days) effects of competition. We noted strong avoidance over a 6-h period among the 3 ungulates. That effect was weaker for the previous 7 days. Cattle were generalists with respect to habitat selection; the 2 native herbivores avoided areas used by cattle. Mule deer and elk avoided one another during the short temporal window (6 h), although spatial differences in habitat use often were not maintained over 7 days. Elk used lower elevations when cattle were absent and moved to higher elevations when cattle were present, indicating shifts in niche breadth and competitive displacement of elk by cattle. We demonstrated strong partitioning of resources among these 3 species, and presented evidence that competition likely has resulted in spatial displacement.

Horn growth in the Caprinae is affected by several factors including age and nutrition, and analysis of annual horn increments can be used to interpret past events. We documented patterns of horn growth in male alpine ibexes (Capra ibex ibex) in the central European Alps and analyzed relationships between annual horn increments, weather, and plant phenology in 2 different climatic regions during 1981–1990. Age accounted for 50% of total variance in horn growth in male alpine ibexes 1–6 years of age. Horn growth differed among climatic regions and calendar years. In years with early onset of vegetation growth, horn growth was enhanced uniformly over all age classes in both climatic regions. Horn growth was a function of ambient temperature during March–May and of plant phenology in spring, implicating onset of growth of vegetation and availability of food resources. Duration of growth of vegetation was assumed to be directly related to date of vegetation onset, but further studies are necessary to test this hypothesis.

Dispersal and philopatric tendencies were examined in Alabama beach mice (Peromyscus polionotus ammobates) during a 26-month study. Data on microgeographic dispersal (126,410 trap nights) were used to test hypotheses relating to dispersal, persistence time, and home-range size. We predicted that dispersal between zones would be nonrandom and that dispersal patterns would fit a simple competition-based model. In addition, we predicted that philopatry would be beneficial in terms of persistence times and home-range size. Counter to our prediction, dispersal distance (average 160.2 m) was equal both within and between habitat zones. Home-range size (average 3,586.2 m²) was significantly smaller for philopatric mice (1,933.7 m²) but persistence times were longer for dispersers ( 37.5 days). We hypothesize that predation risk may counteract normal advantages of philopatry for this population.

We investigated differences between sizes of home ranges using trapping and radiotelemetry data for syntopic Peromyscus boylii and P. truei. Sizes of home ranges were calculated from the minimum convex polygon of trap locations and radiotelemetry locations and compared between individuals. The 2 estimates of home-range size were significantly correlated, although on an average trapping home ranges were significantly smaller than sizes of radiotelemetry home ranges. Home-range sizes from radiotelemetry were inversely correlated with conspecific density, but home-range sizes from trapping were not. Thus, at low density, radiotelemetry home ranges were significantly larger than trapping home ranges, but at high density there was no difference between radiotelemetry and trapping home ranges. These results indicate that radiotelemetry results in larger estimates of home-range size, particularly at lower densities of conspecifics. The largest size estimates of home ranges were from a combination of radiotelemetry and trapping data.

Studies of food supplementation in small mammals often result in significant increases in population density. These numerical responses to increased food availability may interact with other variables, such as predation, territoriality, and emigration, to limit population size. In this study, the demography of Peromyscus leucopus was compared between an oak wood undergoing a high mast year and a reference wood. At a smaller spatial scale, replicated plots were supplemented with rodent chow in an attempt to reproduce patterns occurring at the larger woodlot scale. Some of the food supplemented plots also had predators excluded to test for interactions between top–down and bottom–up effects. Very low-densities of P. leucopus responded numerically to increased food availability. Results for a relatively large “natural” experiment and a more controlled manipulative experiment were similar. In both cases, the increase in numbers was primarily the result of immigration, not reproduction. Increased food availability in the spring resulted in earlier reproduction but a decline in numbers—probably because of territorial defense. The food supplementation led to increased predator activity and decreased survivorship of the prey. This resulted in a rapid turnover of individuals and a significant predator × food interaction.

Elliot's short-tailed shrews (Blarina hylophaga) were studied in tallgrass prairie at Konza Prairie Biological Station, Kansas. Based on sampling of 14 permanent traplines from autumn 1981 to spring 1999, relative abundance was high in autumn (X̄ = 2.5 ± 0.4 SE shrews/trapline) but very low in spring (<0.1 shrews/trapline). Interannual variability in abundance in autumn was large with a range 0.1–7.0 shrews/trapline. Relative abundance of shrews in autumn was correlated positively with precipitation, soil moisture, and depth of plant litter and correlated negatively with proportion of area burned and maximum temperature. Two variables, precipitation, and amount of litter, accounted for 87% of variation in abundance of shrews in autumn. Ambient moisture and a well-developed litter layer that ameliorates microclimatic extremes appear to be the most important factors influencing abundance of shrews in tallgrass prairie.

Twelve Afromontane grassland fragments and 12 control sites were created in a pine-afforested region at Groenvaly in South Africa. Three live-trapping surveys of small mammals were performed, 1 survey a year before planting, 1 immediately after planting, and one 4 years later, yielding 768 small mammals representing 8 species. In 1998, small-mammal assemblages inside the plantations were also monitored. Between 1994 and 1998, similar changes in assemblage structure occurred in control sites and experimental fragments. In small fragments, Crocidura was comparatively abundant, apparently attributable to edge effects. Despite extensive habitat disturbance through afforestation by 1998, assemblage structure and movement distances within the plantation were similar to those recorded in undisturbed grassland assemblages. We conclude that, 4 years after afforestation, small mammals do not yet experience afforestation as a major habitat fragmenting force, and that gradual fragmentation at Groenvaly yields trends in small-mammal assemblages that are quite different from those of experiments employing abrupt habitat fragmentation.