Jaguars (Panthera onca) remain virtually unstudied in the desert environments at the northern extent of their range. Historic sightings from the United States indicate a declining population of resident jaguars from the late 1800s into the 1940s, after which only occasional jaguars were reported until the present. After 2 sightings of jaguars in 1996, we established a camera monitoring program in southeastern Arizona. From March 2001 to July 2007, we maintained 9–44 trail cameras and conducted opportunistic track surveys. We documented 2 adult males and a possible 3rd unidentified jaguar with 69 photographs and 28 sets of tracks. One jaguar, originally photographed in 1996, was resighted 64 times during 2004–2007. This ≥13-year-old male used habitats from the Sonoran lowland desert at 877 m above sea level to pine–oak woodlands at 1,577 m, and covered 1,359 km² in 2 mountain complexes. Despite speculation that recent sightings of jaguars in the United States represented dispersing transients on sporadic forays from Mexico, we documented jaguars in Arizona frequently, continuously, and year-round, and videotaped several scent-marking behaviors, indicating the residency of adult jaguars within Arizona. We outline the importance of maintaining cross-border connectivity for long-term survival of the wide-ranging and thinly distributed binational population of jaguars. We recommend further research and we stress the fragmentation consequences of the proposed United States–Mexico border fence to the northernmost jaguar population, and particularly to jaguars in the United States.

Occupancy analysis and its ability to account for differential detection probabilities is important for studies in which detecting echolocation calls is used as a measure of bat occurrence and activity. We examined the feasibility of remotely acquiring bat encounter histories to estimate detection probability and occupancy. We used echolocation detectors coupled to digital recorders operating at a series of proximate sites on consecutive nights in 2 trial surveys for the Hawaiian hoary bat (Lasiurus cinereus semotus). Our results confirmed that the technique is readily amenable for use in occupancy analysis. We also conducted a simulation exercise to assess the effects of sampling effort on parameter estimation. The results indicated that the precision and bias of parameter estimation were often more influenced by the number of sites sampled than number of visits. Acceptable accuracy often was not attained until at least 15 sites or 15 visits were used to estimate detection probability and occupancy. The method has significant potential for use in monitoring trends in bat activity and in comparative studies of habitat use.

Using data collected with thermal imaging technology, we found a major reduction in population estimates of colony size in the Brazilian free-tailed bat (Tadarida brasiliensis) from 54 million, obtained in 1957 without this technology, to 4 million in 6 major cave colonies in the southwestern United States. The 1957 census was based on human visual observations of cave emergence flights that were subject to potentially high errors. The recent census was produced using an accurate, reproducible counting method and based on complete temporal records of colony emergences. Analysis of emergence flights from dusk through darkness also revealed patterns in group behavior that would be difficult to capture without thermal infrared technology. Flow patterns of bats during emergence flights exhibited characteristic single, double, or triple episodes, with the peak flow during the 1st episode. A consistent rhythmic pattern of flow episodes and pauses was revealed across colonies and was independent of emergence tempo.

We examined variability in bat sonar calls related to characteristics of the caller (i.e., individual identity, sex, state of lactation, age category, and colony membership) in 2 situations. If variation in call features reliably reflects characteristics of individuals, then there is potential for information transfer to conspecifics. Thus, sonar calls, in addition to their use in orientation and prey location, may function for communication. We obtained recordings of sonar calls from 66 little brown bats (Myotis lucifugus) captured from buildings at Chautauqua Institution, State University of New York at Fredonia campus, and surrounding areas in 2003–2005. Calls were recorded using a laptop computer, digitizing card, connector box, amplifier, and U30 bat detector while the bat crawled from hand to hand and while in flight. Calls were extracted and analyzed using custom computer programs to generate measurements for variables describing each call, which were then analyzed statistically. Our analysis revealed individual identity, state of lactation, and age category are reliably indicated by call variation of crawling bats, and individual identity information is contained in calls of bats in flight. To our knowledge these results are the 1st report of differences between sonar calls of lactating and nonlactating individuals for any bat species and individual differences in sonar calls for M. lucifugus. Individual identity information is available in calls produced within a situation; however, this information does not transfer well to the calls of the same bats produced in different situations. Our results suggest that the potential for communication of information via sonar calls depends on calling situation.

Insectivorous bats require different resources for diurnal roosting and nocturnal feeding, and sound conservation planning requires knowledge of both. However, ranging behavior and habitat use by foraging bats are poorly known, especially within urban ecosystems. We studied foraging flight behavior and use of an urban landscape by 14 white-striped free-tailed bats (Tadarida australis) in metropolitan Brisbane, Australia. Each evening, the bats emerged from day-roosts in tree-hollows and commuted rapidly to a feeding area (median travel speed 42.9 km/h, based on net distances moved during 10–20 min). Within 30 min from emergence their travel speed was greatly reduced (median 6.7 km/h) to a level that remained similar throughout subsequent hours while they foraged. Day-roosts were widely dispersed across the urban landscape, but foraging bats mostly restricted their movements to a localized area of a few kilometers diameter. This area was closer to a communal roost, visited periodically by all bats, than to their day-roosts (median distance from foraging bats to the communal roost 2.5 km; to their day-roosts 6.2 km). The bats showed a significant preference for foraging above floodplain habitat, and did not prefer to feed above remnant forest. T. australis appears tolerant of deforestation and capable of persisting in urban landscapes, provided that roost trees are protected. However, it remains unknown whether a sustained availability of aerial prey depends on floodplains remaining undeveloped.

Assemblages of neotropical frugivorous bats display a trophic structure composed of groups of species reflecting diet preferences. The structure is hypothesized to be an ancestral trait, suggesting that very similar diets would be observed throughout a species' range. We examined the frequency of occurrence of seeds in feces of a community of frugivorous bats in Lacandon Forest, México. Using metric multidimensional scaling, we found 3 groups of species, similar to those found in other regions and congruent with phylogenetic groupings, lending support to a historical origin of this structure. However, the diets of some species differed from those observed in other regions, in particular Barro Colorado Island (BCI), Panama. Here, we found species of the tribe Ectophyllini to be specialized on plants of the genus Cecropia, rather than Ficus-specialists as on BCI. This discrepancy can be related to differences in plant composition or in disturbance regimes, and we suggest that Ectophyllini (including Artibeus) are facultative specialists of the genera Ficus and Cecropia rather than strict Ficus-specialists.

We tested the suitability of fecal sexual steroid hormone metabolites for use in endocrinological studies of free-ranging, small bats. We monitored estrogen and 20-oxo-pregnane metabolites in fecal samples collected daily from 19 free-ranging female Saccopteryx bilineata during the assumed mating season. Median fecal estrogen metabolite levels equaled 0.09 ng/g for the pre- and postovulatory periods and 4.2 ng/g for the follicular phase of the estrous cycle in female S. bilineata. Median fecal 20-oxo-pregnane metabolite levels were 50.9 ng/g in pre-estrous, 88.8 ng/g in estrous, and 190.2 ng/g in postestrous females. Reliability of fecal steroid metabolite analysis was supported by results of video observations. Two successful copulations for a single male–female pair were recorded; mating coincided with peak fecal estrogen levels (7.0 ng/g) in the copulating female. In contrast, 2 observed mating attempts in a 2nd male–female pair occurred approximately 19 days after the female's physiological estrus and fecal estrogen metabolites in the rejecting female were only 0.2 ng/g. Fecal 20-oxo-pregnane levels were almost 3 times lower in fecal samples collected from the copulating female than those from the rejecting female (157 ng/g versus 410 ng/g). All females that were still present in the colony 6 months later gave birth to a single offspring between late May and early June. Gestation length averaged (mean ± SE) 169 ± 2 days. During the 20 days preceding parturition, fecal 20-oxo-pregnane metabolites were approximately 100 times higher than during the mating period. Fecal 20-oxo-pregnane metabolites of lactating females were comparable to those during the mating season. Noninvasive fecal steroid analysis can be a valuable tool for monitoring reproductive events in colonies of free-ranging small-sized bats.

The evolution of the neocortex in primates has been associated with social complexity, but the relationship between neocortex evolution and components of social complexity such as sexual selection and mating systems is not well studied. I examined the evolutionary relationship between relative neocortex size and the intensity of male–male competition for mates among various primate mating systems using bootstrapped estimates of least-squares regression parameters. A significant negative evolutionary relationship was found between relative neocortex size and the level of male–male competition for mates associated with various mating systems. The largest relative neocortex sizes among primate species were associated with monogamy This negative evolutionary relationship suggests that monogamy may require greater social acuity and abilities for deception and manipulation, and promote selection for larger brains.

We describe the diet of fossas (Cryptoprocta ferox) in a dry deciduous forest of western Madagascar from 376 scats collected between June 1994 and September 1996, from which 554 prey items were identified. More than 90% of these were vertebrates, and more than 50% were lemurs. No other nonprimate mammal includes such a high proportion of primate items in its diet. The principal prey comprised approximately 6 lemur species and 2 or 3 spiny tenrec species, along with snakes and small mammals. Significant differences were apparent in the composition of the scats in wet and dry seasons, with a higher proportion of Tenrec in the former, and fewer lemurs. Within the confines of a diet of vertebrates, fossas appeared to be opportunistic predators. For those prey types for which data were available, a significant relationship was found between the estimated relative number of individuals taken of any one type of prey and its abundance. Fossas were estimated to remove up to 19% of their prey populations per year. This high impact suggests that they were living close to the maximum population density possible on the available prey. Species of a wide range of body masses were included in the diet. Verreaux's sifaka (Propithecus verreauxi), weighing more than one-half of the body mass of the fossa, constituted approximately 11% of the prey biomass.

The island spotted skunk (Spilogale gracilis amphiala), an insular endemic carnivore, recently increased unexpectedly from rarity to abundance on Santa Cruz Island, California. Two explanations have been proposed for this striking increase: competitive release due to decline of the island fox (Urocyon littoralis santacruzae) and vegetative recovery due to removal of feral livestock. To examine the causes and consequences of the increase, we assessed abundance, body mass, home-range size, spatial resource use (den sites and habitat use), temporal resource use, and diet of island spotted skunks during abundance in 2003–2004 and compared it with similar measures during rarity in 1992. Capture success of skunks increased exponentially from 1992 to 2004 (r = 0.38), leading to extraordinarily high densities (9–19 individuals/km²). Both body mass and home-range size remained unchanged, suggesting that per capita resource abundance was not higher in 2003–2004 compared to 1992. We found modest shifts in habitat use, diet, and possibly diurnal activity, providing some support for release from exploitative competition as an explanation for the increase. However, there was a marked shift in den selection, toward unprotected dens and away from multiple use, that is not likely attributable to either release from exploitative competition or to island recovery. Thus, our results suggest that, although both of these processes have likely played a role, release from interference competition also may be a factor behind the dramatic increase in number of skunks. Skunks on Santa Cruz Island may be nearing or even exceeding carrying capacity, and the future of the population and its effects on the endangered island fox remain unclear.

Climate change during the late Quaternary has been implicated as the cause of both massive range shifts and extinction events. We combined molecular marker data and previously published fossil data to reconstruct the late Quaternary history of a grassland-dependent species, the black-footed ferret (Mustela nigripes), and to determine whether populations from Pleistocene refugia in the Columbia Basin, eastern Beringia, and Great Plains persisted into the Holocene and Recent eras. Using DNA extracted from 97 museum specimens of extirpated populations, we amplified 309 bp of the mtDNA control region, and 8 microsatellite markers from the nuclear genome. Overall haplotype diversity from 309 base pairs (bp) of mitochondrial DNA (mtDNA) control region was low (5 haplotypes, nucleotide diversity = 0.001 ± 0.001 SD) and was contained within a single phylogenetic clade. The star phylogeny and unimodal mismatch distribution indicated that a rapid range expansion from a single Pleistocene refugium occurred. Microsatellite data corroborated this genetic pattern: populations from the mixed grasslands of the Great Plains had significantly higher expected heterozygosity and allelic richness than populations to the west (H_E = 0.66 versus 0.41, AR = 4.3 versus 2.7, respectively), and 𝜰, a measure of relative population size, was substantially greater in the east than west (2.4 versus 0.7). We infer from these data that black-footed ferrets rapidly colonized western ecoregions in a stepwise fashion from the Great Plains to the intermountain regions of the Rocky Mountains and the Colorado Plateau after the last ice age. It appears that glacial retreat and global warming caused both range expansion and localized extinction in this North American mustelid species.

Animals should use habitats that increase their chances of survival and reproductive output; thus, information on habitat use can be useful both from an ecological and a conservation perspective. Using global positioning system tracking collars, we studied habitat use by a pair of Chrysocyon brachyurus (maned wolves) living in a cerrado–Atlantic forest transition zone in Brazil. During our study, the female had a litter of pups, and we were able to evaluate how reproduction affected habitat use. To investigate habitat use, we mapped our telemetry fixes onto vegetational and geographical data obtained from satellite images of our study site. We investigated habitat use by maned wolves in relation to vegetation and land cover, proximity to buildings, proximity to roads, elevation, and distance to water sources. Maned wolves showed a strong preference for rocky fields, which are a subhabitat of cerrado, and a strong avoidance of Atlantic rain forest. Maned wolves also were associated significantly and positively with buildings and roads at night, likely because of supplemental feeding and ease of locomotion. Elevation was confounded with habitat type and the location of supplemental feeding; therefore, no firm conclusions could be drawn about this factor. The female remained ≤250 m from water when she was lactating. Although maned wolves can be behaviorally flexible in terms of habitat use, they show a strong preference for open habitats such as cerrado that is especially pronounced during a reproductive phase.

It remains unclear if patterns of habitat use are driven by animals moving to and increasing residency time in selected areas, or by animals simply returning frequently to selected areas. We studied a population of North American elk (Cervus elaphus) in the Chequamegon National Forest, Wisconsin, to examine how spatial and temporal factors influence residency time in localized areas. We used global positioning system telemetry data from 7 elk and addressed 2 questions. First, does residency time vary as a function of spatial and temporal factors and if so does that relationship vary with measurement scale? Second, can residency time in the summer be predicted by a resource-selection map previously constructed for this population? Cross validation demonstrated that the statistical models had very poor predictive strength of independent data, which indicates that the explanatory variables have very little influence on elk residency time. Resources are patchily distributed on this landscape, and results demonstrate that elk preferentially use areas with high resource-selection function values. Unexpectedly, residency time was unrelated to values of resource-selection functions, which indicates that elk do not slow down in preferred areas. We conclude that patterns of elk habitat use are not driven by residency time but by elk returning frequently to favorable areas on the landscape. Random residency times may be a behavioral mechanism to lower predictability on the landscape and reduce predation risk.

Forest buffalo (Syncerus caffer nanus) occur throughout the Congo Basin forest region of central Africa. Unlike for the well-studied Cape (or savanna) buffalo (Syncerus caffer caffer), few data exist for forest buffalo. I tracked 7 radiocollared adult female forest buffalo at Lopé National Park, Gabon, over a 2-year period (2002–2004) to examine home ranges, habitat selection, and diurnal activity patterns. Home ranges of female forest buffalo averaged 4.55 km² in area (mean number of locations per animal = 205); the percent of home-range overlap between individual radiocollared buffalo was small. Home ranges remained the same size and in the same locations over both study years. Distance analysis of habitat use from radiotracking data was used to assess forest buffalo habitat selection at 2 spatial scales. At the landscape scale, buffalo selected savanna and marsh habitat over forest habitat within a 72-km² study area. Thus, forest buffalo home ranges were savanna-dominated despite the greater amount of forest habitat available in the overall landscape. At the scale of the home range (2.30–7.64 km²), habitat selection within home ranges varied with season. Adult female forest buffalo preferred forest habitat between March and August but preferred marsh to forest between September and February. Forest buffalo dwell in forest habitat, feed in savannas, and wallow in marshes, utilizing all habitat types in the landscape. Although the subspecies is forest-dwelling, forest buffalo depend on open habitat adjacent to continuous forest.

The Texas coastal prairie is composed of habitat patches characterized by monocots, dicots, or a mixture of both plant types. Radiotelemetry revealed that reproductive female hispid cotton rats (Sigmodon hispidus) preferred mixed habitats and avoided dicot habitats, whereas males did not show a preference. Such habitat selection can be attained by shorter distances moved or increased turning (i.e., area-restricted search). Reproductive females, but not males, moved shorter distances in mixed habitats. However, turns relative to straight-ahead movements for females, but not males, were fewer in mixed habitats than in monocot or dicot habitats suggesting directed foraging rather than area-restricted search. To obtain necessary amounts of nutrients, especially carbohydrates, protein, phosphorus, and calcium, reproductive females ingest both monocots and dicots. Directed movement may facilitate foraging for dicots because these food items occur in clumps in mixed habitats. Because their nutritional needs are less than those of females, males do not exhibit the same patterns of habitat selection. Differential patch occupancy was not explained by overhead plant cover, but more bare ground in dicot habitats may explain avoidance of these habitat types because of increased predation risk.

Using a comparative approach, we examined the gut morphology of 6 ecologically similar rodent species coexisting in an African savanna. Although all species are primarily granivores, we aimed to establish whether modifications of the gut morphology exist that would promote the potential for exploiting different food types, particularly foliage. The species examined exhibited a gradation in gut structure, with some showing modifications more toward granivory and others toward folivory. These findings are supported by studies of food preferences in captivity. Modifications of the gut, enabling the potential for exploitation of a greater folivorous diet in some species compared to others, may be 1 way in which dietary partitioning as a method of coexistence may be promoted. Nonetheless, other mechanisms, such as spatial and temporal segregation, social tolerance, and behavioral differences, also may determine coexistence in this community.

Regular, multiannual cycles observed in the population abundance of small mammals in many arctic and subarctic ecosystems have stimulated substantial research, particularly among population ecologists. Hypotheses of mechanisms generating regular cycles include predator–prey interactions, limitation of food resources, and migration or dispersal, as well as abiotic factors such as cyclic climatic variation and environmental stochasticity. In 2004 and 2005, we used indirect methods to estimate trends in population size of Richardson's collared lemmings (Dicrostonyx richardsoni) retrospectively, and evaluated the extent of synchrony between lemming populations at 2 coastal tundra study areas separated by approximately 60 km near Cape Churchill, Manitoba, Canada. We collected scars on willow plants (Salix) resulting from lemming feeding. Ages of scars ranged from 0 to 13 years at both study areas. Scar-age frequency appeared cyclic and we used nonlinear Poisson regression to model the observed scar-age frequency. Lemming populations cycled with 2.8-year periodicity and the phase of the cycle was synchronous between the 2 study areas. We suggest that our approach could be applied in multiple settings and may provide the most efficient way to gather data on small mammals across both space and time in a diversity of landscapes.

Reproductive success of females in iteroparous species usually increases early in life, then remains constant or declines. The restraint hypothesis suggests that primiparous females limit their 1st reproduction in order to avoid future costs to survival, reproduction, or both, whereas constraint indicates that primiparous females are limited in their 1st reproductive attempt either because they lack sufficient resources (measured by body mass) or lack experience at weaning a litter. To evaluate these alternatives, we examined age- and experience-related patterns of reproduction in female Columbian ground squirrels (Spermophilus columbianus) with data from a long-term study and by experimentally altering age at 1st reproduction. In the results of the long-term study, experienced females had significantly higher reproductive investment and reproductive success (number of offspring surviving to yearling age) compared to inexperienced females. Annual survival of females was not affected by their level of previous weaning experience or current reproductive investment. Additionally, subsequent reproductive success was not impaired by earlier reproduction. In the experimental results, experienced females had significantly higher reproductive investments compared to inexperienced females. Constraint in terms of previous weaning experience best explained the differences in reproductive investment and reproductive success between primiparous and multiparous females.

Data on the reproductive patterns of the Brazilian slender opossum (Marmosops paulensis) were collected in an area of Montane Atlantic forest, southeastern Brazil, from August 2002 to July 2004. Reproduction occurred from September to March in both years, a period of high food supply, probably as a way to maximize survival of juveniles. There was nearly zero postmating survival, thus, no individual took part in more than 1 breeding event. This pattern characterizes a semelparous life history, which has been described in other small didelphids and dasyurids. Females were reproductively active during months with longer day lengths and abundant fruit supply. Breeding seems to be initiated by a 12L:12D photoperiod and a rapid rate of change in day length, as demonstrated in semelparous dasyurids. Hence, the effect of photoperiodic cues on the onset of reproduction also may stand for other semelparous didelphids. We suggest that fruit availability controlled the length of breeding activity in M. paulensis, and it could play a role in the occurrence of semelparity in this species. However, semelparity may occur only due to phylogenetic constraints, whereas food supply works as a selective force maintaining this trait.

Density and biomass may reveal different aspects of the dynamics of populations, but most studies have focused on density or relative abundance. Density and biomass also may behave differently in parts of the population composed of males and females because of differences in vagility and parental care between sexes. Herein, we explore seasonal and multiannual variation in density and biomass in a population of black-eared opossums (Didelphis aurita). Females and males were analyzed separately for associations with precipitation and litterfall, indicators of resource availability. Litterfall, density, and biomass were estimated from 1997 to 2003 on three 0.64-ha trapping grids in an area of Atlantic Forest in Rio de Janeiro, Brazil. Density of females exhibited a significant increase during the study. Density and biomass of males were more variable, without any significant positive trend or correlation with precipitation or litterfall. Seasonal and biannual patterns of precipitation were detected, followed by the density and biomass of females with time lags varying from 0 to 1, and from 9 to 12 months. The relative stability of biomass of females, and its association with precipitation and litterfall, suggests that resource availability combined with density-dependent responses regulated the local population of females. The local population of males may be more influenced by the stochasticity resulting from the higher vagility of males.

We report on aspects of the ecology and natural history of 2 species of armadillos commonly found in a cerrado remnant in southeastern Brazil—the naked-tailed armadillo (Cabassous unicinctus) and the 6-banded armadillo (Euphractus sexcinctus). Armadillos were captured in pitfall traps or by hand, double-marked, and the habitat (campo sujo, campo cerrado, and gallery forests), season, and time of capture were recorded. We also recorded the sex and age of all armadillos, and reproductive condition of females. Population densities were estimated as 0.27 and 0.14 individuals/ha for C. unicinctus and E. sexcinctus, respectively. E. sexcinctus did not preferentially use any of the habitats included in the study area, whereas C. unicinctus preferentially used habitats with a more complex vegetation structure, such as gallery forests. C. unicinctus was diurnal and E. sexcinctus was mainly nocturnal. Neither species changed its activity pattern with season, but C. unicinctus was more active in months with decreased abundance of arthropods—the main food resource consumed by this species. Both species of armadillos appeared to reproduce year-round. Differences in habitat use and daily activity between C. unicinctus and E. sexcinctus suggest spatial and temporal displacement between these species.

Phylogenetic relationships within marsupials were investigated based on a 20.1-kilobase molecular supermatrix comprising 7 nuclear and 15 mitochondrial genes analyzed using both maximum likelihood and Bayesian approaches and 3 different partitioning strategies. The study revealed that base composition bias in the 3rd codon positions of mitochondrial genes misled even the partitioned maximum-likelihood analyses, whereas Bayesian analyses were less affected. After correcting for base composition bias, monophyly of the currently recognized marsupial orders, of Australidelphia, and of a clade comprising Dasyuromorphia, Notoryctes, and Peramelemorphia, were supported strongly by both Bayesian posterior probabilities and maximum-likelihood bootstrap values. Monophyly of the Australasian marsupials, of Notoryctes Dasyuromorphia, and of Caenolestes Australidelphia were less well supported. Within Diprotodontia, Burramyidae Phalangeridae received relatively strong support. Divergence dates calculated using a Bayesian relaxed molecular clock and multiple age constraints suggested at least 3 independent dispersals of marsupials from North to South America during the Late Cretaceous or early Paleocene. Within the Australasian clade, the macropodine radiation, the divergence of phascogaline and dasyurine dasyurids, and the divergence of perameline and peroryctine peramelemorphians all coincided with periods of significant environmental change during the Miocene. An analysis of “unrepresented basal branch lengths” suggests that the fossil record is particularly poor for didelphids and most groups within the Australasian radiation.

The Southern Coahuila Filter-Barrier (SCFB) effectively subdivides the mammalian fauna of the Mesa del Norte, the northern and most extensive section of the Mexican Altiplano. Pocket gophers of the genus Cratogeomys north and south of this filter-barrier have been informally recognized as 2 distinct species, C. castanops and C. goldmani, respectively. Support for species recognition derives from early morphological comparisons and recent chromosomal and ectoparasite studies. Contradictory conclusions based on the only comprehensive morphometric study have prevented formal recognition of C. goldmani. A morphometric reevaluation based on ratio-transformed data reveals that the previous analysis was unduly biased by size, an ecophenotypically plastic character. When this factor is removed, morphometric variation is fully concordant with chromosomal diploid number and sequence data of mitochondrial and nuclear DNA. We provide synonymies and descriptions for C. goldmani apart from C. castanops, and revise the number of subspecies from a total of 26 to 2 subspecies in each species. The SCFB is most effective in its central portion (Desierto Mayrán), and least effective in its western portion (Río Nazas), which should be geographically broadened to include the neighboring Río Aguanaval.

The chiropteran family Myzopodidae is endemic to Madagascar and is characterized by several unique morphologies, such as sessile adhesive discs on the thumb and sole. A new species, Myzopoda schliemanni, was recently described from western Madagascar that is morphologically distinct and geographically disjunct from the eastern species, M. aurita, the only other member of this family. Geographic variation within Myzopoda has only recently been studied at the morphological level and has never been addressed at the genetic level. We used a combination of phylogenetic, coalescent, and population genetic analyses to characterize the speciation history of Myzopoda and to clarify current and former patterns of gene flow within and between Myzopoda. Mitochondrial DNA sequences were used to determine whether genetic data support the morphologically distinct species M. schliemanni, to infer the distribution of the common ancestor of extant Myzopoda, to estimate effective population sizes (N_e) and levels of migration between species, and to determine patterns of population structure within species. Phylogenetic and network analyses revealed the existence of 4 well-supported clades in Myzopoda, but could not resolve relationships among those clades. Divergent haplotypes within species may result from either recent gene flow between the 2 species or more likely from incomplete lineage sorting. Multiple coalescent-based methodologies produced concordant estimates of N_e for Myzopoda, but conflicting signals for migration between the species, probably reflecting differences in the underlying models used by the methods. We found significant genetic structure within M. aurita, but no correlation with geography. This pattern may result from recent gene flow facilitated by expansion of Ravenala stands, an important day-roost tree for Myzopoda, associated with anthropogenic deforestation and the opening up of new habitat for members of this genus.

We compared 7 populations of woodmice, Hylomyscus stella (Thomas, 1911), from west-central, east-central, and east Africa using traditional morphometric data of the cranium. Our results are congruent with previous molecular and cytogenetic data, and demonstrate that specimens previously identified as H. stella represent 2 cryptic species: H. stella from east-central and east Africa, and Hylomyscus sp. nov. from west-central Africa. According to current knowledge, the new species of Hylomuscus is a forest-dwelling species inhabiting the region between the Sanaga River and the Oubangui and Congo rivers in Cameroon, Central African Republic, Gabon, and Republic of the Congo. It is sympatric, and even syntopic, with the morphologically closely related species H. alleni. These 2 cryptic species can be distinguished by traditional morphometric analysis of the cranium and by examination of molecular data.

A variety of estimators have been used by paleontologists for reconstructing body mass of fossil mammals. For rodents, the most commonly used proxy is m1 area, although that value is known to overestimate masses in muroid rodents and is generally problematic in rodent taxa in which the m1 is either enlarged (as in muroids) or reduced (as in extinct mylagaulids). This paper explores the potential utility of 2 alternative proxies, toothrow length and toothrow area; these measures are shown here to be very tightly correlated with body mass among rodents. Regression within certain clades of the Rodentia provides an even tighter fit. Applying these proxy measures to several fossil rodents provides an estimate of their masses. Comparison to published body masses of extinct rodents estimated from postcrania reveals that body masses for Castoroides and Palaeocastor estimated from femur length are consistent with those from dental proxies but that toothrow-based estimates for Phoberomys, the largest known fossil rodent, are discordant with the mass estimated from limb bone diameter. This difference may be explained by both allometric scaling of limbs and locomotor differences between Phoberomys and the caviomorph rodents on which the limb bone diameter regression was based.

The sequence of molar eruption, along with the timing of replacement of the 3rd deciduous premolar by a permanent premolar, has been documented in several species in the family Didelphidae, and routinely used to establish age classes. We documented the dental eruption and replacement patterns in the 3 species of the neotropical marsupial genus Caluromys, which constitute one of the most basal groups within the Didelphidae. We examined 258 specimens of Caluromys derbianus, 54 specimens of C. lanatus, and 386 specimens of C. philander. These species have a dental eruption pattern that is similar to that of Marmosops, with replacement of the 3rd deciduous premolar after eruption of the 4th molar. However, we sometimes found incompletely erupted P3 and M4 occurring simultaneously as part of a M4–P3 eruption sequence. We suggest that the occurrence of this intermediate pattern in other taxa should be verified by examination of large series of specimens. Because teeth erupting in sequence can be erroneously considered as fitting an intermediate pattern, eruption sequence and time of completion of development should be used separately when using dental eruption in phylogenetic analyses. Because of the high degree of intraspecific variation observed in several taxa in Didelphidae, a system of age classes based solely on eruption of upper molars may be more useful than those that combine information on molar eruption sequence and timing of premolar replacement.

Reanalysis of a recently published data set on the responses of 2 species of kangaroo rats to the 1997–1998 El Niño Southern Oscillation (ENSO) event revealed an error during data manipulation, and underscored the perils associated with electronic data storage, manipulation, and analyses. Renewed analyses revealed that Dipodomys simulans was not catastrophically impacted by the ENSO event. Both species were negatively impacted by 2 separate rainy periods, and both species appeared to recover rapidly. The rate of demographic recovery may be a function of habitat preferences. Dipodomys stephensi occurs in valley bottoms and recovered numerically only after cessation of rains, whereas D. simulans, which occurs on better-drained habitat in adjacent hill slopes, appeared to initiate demographic recovery half way through the rainy period associated with the 1998 ENSO. In contrast, however, D. simulans was not observed to recover for about 5 months after the rainy period in 2000.