The Eurasian beaver, Castor fiber L., suffered extreme demographic reduction through overhunting until the end of the 19th century. However, active protection measures have led to a powerful recovery in range and population numbers. The vast majority of beavers (83%) now occur in the former Soviet Union. The present study investigates the geographic distribution of genetic variation of C. fiber in this eastern part of the species range (former Soviet Union and Mongolia), with special emphasis on small isolated populations of the Asian subspecies C. fiber pohlei, C. fiber tuvinicus, and C. fiber birulai. The analysis yielded 12 different haplotypes, all of which were population specific. Results indicate that C. fiber displays great population structuration (F_ST = 0.985), coupled with an overall low level of genetic divergence (mean number of pairwise differences 7.262 ± 3.435). In particular, the autochthonous populations in Mongolia or Siberia do not appear significantly different from samples from the European part of Russia, despite the great geographical distance. C. f. birulai appears as the most divergent member, a fact that could result from its longer genetic isolation in an enclosed watershed. Examination of our data suggests a single recent origin of the present beaver population in eastern Europe and Asia.

We use discrete morphological characters in a statistical framework to reassess the taxonomic status of the Palawan pangolin Manis culionensis relative to the Sunda pangolin M. javanica. We recommend that the 15 species-level traits previously proposed in the literature to distinguish the 2 pangolins be replaced by 5 newly defined diagnostic characters related to skull and external scales. Our study supports species-level partition between the Palawan and Sunda pangolins at a frequency of expected polymorphism threshold fixed to 0.10. Isolation through sea level rising (approximately 800,000–500,000 years ago) of proto-Palawan pangolins coming from Borneo through Early Pleistocene land bridges might have promoted the speciation of M. culionensis, a Palawan endemic species to be considered of high conservation concern.

Sequence variation in the mitochondrial DNA (mtDNA) control region was analyzed from 1,568 individuals representing nearly every rookery (n = 50) at which Steller sea lions (Eumetopias jubatus) are known to breed in significant numbers. Rookeries were grouped into regions and regions into stocks to examine structure at different spatial scales. Haplotype diversity (H = 0.9164 ± 0.0035) was high and nucleotide diversity (π = 0.00967 ± 0.00586) was moderate. No evidence was observed for significant genetic bottleneck effects. Previous studies of mtDNA recognized 2 stocks (eastern and western) and suggested the presence of 2 groups within the western stock. In this study, significant (P < 0.05) divergence of eastern stock (southeastern Alaska to California) animals from western stock animals was supported in analyses at all spatial scales. Likewise, rookeries and regions from Asia were found to be significantly different from all other western stock rookeries. This was most clearly demonstrated in regional comparisons. The Commander Islands rookery clearly associates with Alaskan western stock rookeries, not with the Asian rookeries. Within each of the 3 stocks there is significant isolation by distance among rookeries. This relationship does not hold for interstock comparisons, indicating that there are important barriers to gene flow among stocks. We recommend that the western stock be partitioned west of the Commander Islands, yielding a western stock that ranges from Prince William Sound west to the Commander Islands, and an Asian stock including rookeries from the Kamchatka Peninsula, Kuril Islands, and Sea of Okhotsk. The eastern stock remains unchanged and includes rookeries from southeastern Alaska through California.

We examined phylogenetic relationships among species of Liomys, including L. adspersus (Panamanian spiny pocket mouse), L. irroratus (Mexican spiny pocket mouse), L. pictus (painted spiny pocket mouse), L. salvini (Salvin's spiny pocket mouse), and L. spectabilis (Jaliscan spiny pocket mouse), several species of Heteromys, as well as representatives of other genera of heteromyids and 2 geomyids by using 1,140 base pairs of the mitochondrial cytochrome-b gene. Gene sequences analyzed under maximum-parsimony (MP), maximum-likelihood (ML), and Bayesian inference optimality criteria converged on essentially identical gene tree topologies. Liomys is paraphyletic relative to Heteromys and this relationship is well supported, with L. adspersus and L. salvini arranged as basal taxa relative to Heteromys. Our gene trees also recovered L. pictus as paraphyletic relative to L. spectabilis and these 2 taxa formed the sister group to L. irroratus. Constraint trees that held the genera Heteromys and Liomys as monophyletic (MP and ML criteria) were significantly longer or less likely (P < 0.009 and 0.046, respectively) than our optimal trees, whereas trees that arranged L. pictus as monophyletic relative to L. spectabilis were not significantly longer (P < 0.101) under the MP criterion, but were significantly less likely under the ML criterion (P < 0.020).

A study of chromosomal variation in the Mexican pocket gopher Cratogeomys merriami revealed differences in diploid number that correspond to 3 major genetic and morphological clades within the species. Each of these 3 clades is diagnosable based on multiple characters, including chromosomal diploid number, quantitative and qualitative morphological characters, and mitochondrial DNA. Accordingly, we restrict the name C. merriami (Thomas) to include only pocket gophers of this genus from the states of México, México D.F., northern Morelos, and west-central Puebla. We resurrect the species name C. fulvescens Merriam to represent members of this genus from southern Tlaxcala, east-central Puebla, and parts of west-central Veracruz. Finally, we resurrect the species name C. perotensis Merriam to represent members of this genus from southern Hidalgo, northern Tlaxcala, north-central Puebla, and parts of west-central Veracruz. Based on the observation that differences in diploid number usually signal reproductive isolation between populations of pocket gophers, we hypothesize that C. merriami, C. fulvescens, and C. perotensis are reproductively incompatible. We provide synonymies and descriptions for these 3 species, along with a key to the C. castanops species group to which these species belong.

A new species in the genus Natalus is described on the basis of 71 specimens found in museum collections. The body pelage of the new bat is unique among natalids in having hair bases much darker than hair tips. This new species is also characterized by short tibiae, legs and feet notably hairy, a long braincase, and a shallow rostrum. This species is known from 16 localities in Mexico, from both mountain and lowland areas. At some localities, it has been collected together with the previously known species Natalus stramineus. This constitutes the 1st known case of sympatry among species of the genus Natalus (sensu stricto).

The Natal long-fingered bat (Miniopterus natalensis) and lesser long-fingered bat (M. fraterculus) are morphologically almost indistinguishable and occur sympatrically over much of their southern African range. This raises the possibility that they are sister taxa. We employed a multidisciplinary approach to examine their taxonomic relationship to one another and to other Miniopterus species, whose global phylogeny requires review. We examined echolocation, morphological, and dietary differences between M. natalensis and M. fraterculus, as well as both nuclear and mitochondrial DNA variation between them in the context of a phylogeny incorporating 13 Miniopterus species and subspecies. Despite similarities in their morphology and distribution, M. natalensis and M. fraterculus echolocate at peak frequencies separated by 12 kHz, and both nuclear and mitochondrial DNA markers confirm they are distinct species. Analysis of cytochrome-b (Cytb) sequences further indicates that M. fraterculus and M. natalensis are not sister taxa; M. fraterculus appears to be more closely related to the greater long-fingered bat (M. inflatus). Examination of the global taxonomy of Miniopterus confirms that Schreibers's long-fingered bat (M. schreibersii) forms a paraphyletic species complex. Furthermore, the miniopterine bats are divided into 2 geographically isolated monophyletic groups, one containing African and European species, and the other taxa from Australasia and Asia. Cytb sequence divergence also suggests that M. natalensis is distinct from the European M. schreibersii. These results support the elevation of M. natalensis to full species rank.

The Ozark big-eared bat (Corynorhinus townsendii ingens) is federally listed as endangered and is found in only a small number of caves in eastern Oklahoma and northwestern Arkansas. Previous studies suggested site fidelity of females to maternity caves; however, males are solitary most of the year, and thus specific information on their behavior and roosting patterns is lacking. Population genetic variation often provides the necessary data to make inferences about gene flow or mating behavior within that population. We used 2 types of molecular data: DNA sequences from the mitochondrial D loop and alleles at 5 microsatellite loci. Approximately 5% of the population, 24 males and 39 females (63 individuals), were sampled. No significant differentiation between 5 sites was present in nuclear microsatellite variation, but distribution of variation in maternally inherited markers differed among sites. This suggests limited dispersal of female Ozark big-eared bats and natal philopatry. Areas that experience local extinctions are unlikely to be recolonized by species that show strong site fidelity. These results provide a greater understanding of the population dynamics of Ozark big-eared bats and highlight the importance of cave protection relative to maintaining genetic integrity during recovery activities for this listed species.

Changes in landscape cover in the Great Plains are resulting from the range expansion and invasion of eastern red cedar (Juniperus virginiana). By altering the landscape and local vegetation, red cedar is changing the structure and function of habitat for small mammals. We examined effects of invasion by eastern red cedar on small mammals in 3 plant communities (tallgrass prairie, old field, and cross-timbers forest) in the cross-timbers ecoregion in Oklahoma. We sampled small mammals seasonally from May 2001 to August 2002 by using Sherman live traps and mark–recapture techniques on 3.24-ha, 450-trap grids in each plant community. We sampled vegetation in two hundred twenty-five 12 × 12-m cells within each grid. The structure of the small-mammal community differed among the 3 habitat types, with higher species diversity and richness in the tallgrass-prairie and old-field sites. Overall, the small-mammal community shifted along a gradient of increasing eastern red cedar. In the old-field and tallgrass-prairie plots, occurrence of grassland mammals decreased with increasing red cedar, whereas only 1 woodland mammal species increased. In the cross-timbers forest site, percent woody cover (<1 m in height), rather than cover of red cedar, was the most important factor affecting woodland mammal species. Examination of our data suggests that an increase in overstory cover from 0% to 30% red cedar can change a species-rich prairie community to a depauperate community dominated by 1 species, Peromyscus leucopus. Losses in species diversity and changes in mammal distribution paralleled those seen in avian communities invaded by eastern red cedar. Our results highlight ecological effects of invasion by eastern red cedar on diversity and function at multiple trophic levels.

We assessed annual home-range area for 23 adult, resident American martens (Martes americana atrata) in a low-density population in eastern Newfoundland, Canada (1996–2003), and evaluated seasonal habitat requirements during a peak in abundance of snowshoe hares (Lepus americanus). Home-range estimates were 29.54 km² and 15.19 km² for males and females, respectively, and reflect significantly larger territories than those maintained by martens across most of their geographic range. We suggest that these exceptionally large territories reflect the low diversity and abundance of small mammals available to martens as prey. Seasonal requirements were examined by using an index to home-range area. The relationship between the index and snowshoe hare abundance indicated that movement rates of individuals decreased during winters when snowshoe hares were abundant, but that this relationship was not apparent during summer. Analyses of stand-scale habitat use indicated that mature coniferous forest was the dominant cover type in most home ranges (49.6% of area) and was the only forest type used proportionately more than its availability by resident martens. Other forest types used in proportion to their availability included coniferous scrub and insect-defoliated stands. Open areas and sites recently disturbed by fire were avoided at this scale.

Identifying factors that are limiting to populations is fundamental to understanding population dynamics of wildlife, and such knowledge is important for conservation and management. I compared survival and cause-specific mortality patterns between urban and rural populations of striped skunks (Mephitis mephitis) in northeastern Illinois. Rabies, an important mortality factor for skunks, was absent from the study populations. Body weights of skunks declined during winter in both areas, but there was a slightly greater decline for rural skunks. Estimates of annual survival were similar (P > 0.1) between areas, as were seasonal patterns of survival. Disease or poor physical condition was the greatest cause of mortality at the urban site throughout the year, whereas it was the most common mortality factor at the rural site only during winter and spring; vehicle collision was the most common cause of death at the rural site during summer and autumn. I found little evidence that body weight or condition before winter denning, sex, or age were related to survival during winter; however, relationships between these covariates and survival may have been obfuscated by parasites. Results from this study suggest that the winter season is a critical period for survival for skunks from rural and urban areas at temperate climates, anthropogenic factors associated with urban landscapes have minimal effects on skunk survival distributions, and disease is a major cause of mortality even in the absence of rabies.

Much research on wild mammals requires trapping, especially livetrapping, yet few methods used to capture wild mammals have been tested against an accepted standard for animal welfare and few data exist regarding physiological responses to capture. My coworkers and I livetrapped 208 American black bears (Ursus americanus) 356 times between May 1981 and August 2001 in the Pisgah National Forest in the Southern Appalachian Mountains by using Aldrich-type foot snares modified for bear safety with automobile hood springs and swivels spliced into cables. We outfitted most bears with transmitter collars and followed 18 bears to their winter dens. We outfitted 8 bears with transponder collars mounted with remotely dischargable darts loaded with anesthesia. We recorded the physical injuries of all bears handled and obtained 186 standard blood chemistry profiles from 112 bears. I compared the blood chemistry profiles of snared bears to profiles of bears in dens, to profiles for healthy, captive bears, and to profiles for wild bears that were collar-darted. Aldrich-type foot snares modified for bear safety, as we used them, and den handling met the accepted standard for trap injuries. Blood chemistry profiles indicated that bears captured in snares experienced high levels of physical exertion and were dehydrated. Blood chemistry parameters responsive to exertion increased with increasing injury scores.

Predators influence the distribution of prey directly if predation reduces local population density, or indirectly if the presence of predators induces behavioral or physiological responses to predation risk. We analyzed whether the foraging behavior of wood mice (Apodemus sylvaticus) was affected by the presence and activity of small-spotted genets (Genetta genetta) at “risky” baiting stations monitored with automatic cameras. Sampling stations in 6 × 6 grids spaced at 250 m were arranged in 3 habitat types (shrubland, pine woodland, and holm oak woodland). Grids were sampled systematically by means of groups of 2–9 cameras monitoring sampling stations during a week. We obtained 377 independent contacts of wood mice and 35 independent contacts of at least 8 different genets. Patterns of habitat use by genets and wood mice were spatially discordant, because only 2 cameras detected both. Wood mice visited baits more often and during longer periods in groups of sampling stations where genets were not detected than in groups where genets were detected within the same week. Mean time spent foraging by genets negatively influenced both the number of foraging bouts per night and the mean duration of such bouts by mice using nearby baits. Finally, temporal patterns of activity of mice along the night were different depending on whether genets were foraging nearby. Temporal patterns of mice when and where genets were absent were positively correlated with patterns of genet activity, whereas mice patterns were negatively correlated with genet patterns when and where genets were present. Sampling dates, habitat types, and moonlight levels did not seem to have influenced these results. Wood mice showed spatial and temporal changes in foraging behavior in response to the presence of genets, and decisions about how often and how long to forage were affected by foraging activity of genets. Results obtained provided direct evidence of a foraging game of stealth and fear between mice and their predator that could help to explain mice distribution in Mediterranean postfire habitats.

Some granivorous rodents scatter hoard; they bury seeds in shallow pits throughout their territory. These buried caches can represent food stores for the hoarders, food for competitors, or a means of seed dispersal and propagation for plants. Large numbers of seeds may be buried in many caches throughout an area; thus, fate of caches has important consequences for granivores, other animals, and plants. This study examined the ability of Ord's kangaroo rat (Dipodomys ordii) to exploit artificial caches of different sizes, at 2 depths, and in substrates of differing moisture content. Kangaroo rats harvested significantly more caches in moist substrates and at shallower depths; however, small caches containing ≤5 seeds were removed infrequently by individuals regardless of substrate moisture and depth. As cache size was increased in moist sand, a threshold existed at each depth where caches were greatly exploited by kangaroo rats. Results suggest that pilferage of caches under natural conditions is not linear with respect to cache size in moist substrates. As cache size was increased in dry sand, no threshold of increased exploitation was observed for cache sizes used in this experiment. Results also suggest that pilferage of caches under natural conditions is not strongly influenced by size in dry substrates for relatively small caches. Overall, size and depth of caches greatly influence their fate. Perturbations, such as rainfall, also alter detection of caches. To reduce detection of caches by competitors, scatter hoarders should distribute relatively small caches, especially during wet conditions.

We analyzed the patterns of habitat use by insectivorous bats in Mexico City, one of the largest and most populated cities of the world. We tested the hypotheses that richer patches of food, expected in more vegetated areas, have higher bat activity levels, and that fast-flying species benefit most from urbanization. We compared activity of insectivorous species and relative abundance of insects in 5 habitats (large parks, small parks, illuminated open areas, residential areas, and natural forest). Sampling of bat activity and insects was conducted every 2 weeks in 12 sites per habitat during summer 2002. Measures of bat activity were based on 3,600 one-minute sequences of sound that were recorded and analyzed. The average number of taxa per site was significantly higher in the natural forest than in urban habitats, but overall bat activity was significantly higher in large parks and illuminated open areas than in small parks, residential areas and natural forest. Vespertilionid bats (Eptesicus fuscus, Myotis, and an unidentified species), along with Eumops perotis, occurred almost exclusively in extensive green areas (large parks or natural forest). The molossid Nyctinomops macrotis made the broadest use of the urban–natural mosaic, whereas Tadarida brasiliensis used urban sites (illuminated areas and large parks) more intensively. Insect abundance was higher in large parks and natural forest, and it was significantly correlated with overall bat activity and with the number of taxa recorded per site. The observed patterns of habitat use and foraging can be explained by considering the flight and echolocation performance of species. Although some species successfully exploited highly urbanized sites, large areas with vegetation are needed to maintain the most diverse insectivorous bat fauna in Mexico City.

When minerals are deficient in the diet, animals often seek out concentrated sources of essential nutrients to relieve deficiencies. In this study, we documented fruit bat (Pteropus tonganus) preference or avoidance of calcium-rich fruits and use of commercial calcium blocks to obtain additional calcium. Individual captive wild-caught bats were videotaped nightly to document food choice, and results were compared to the nutritional content of the given fruits. Low-calcium, high-sugar fruits were the most preferred by bats of both sexes. Overall, sugar appears to be the primary basis for fruit selection, but sex differences in calcium block use suggest that females also may forage to relieve calcium deficiencies incurred by pregnancy and lactation.

This study presents data from 2 years of extensive sampling from July to October at 7 caves and mines used by bats in the Appalachian Mountains region of western Maryland and southwestern Pennsylvania. In total, 2,860 individuals from 7 species were captured. We examined species composition at roosts and compared our data to a survey conducted at 5 of the same caves and mines 2 decades ago; roosts were used by up to 6 species, and species composition has remained stable. In addition, we examined roost fidelity via mark and recapture (at 1 cave); population structure; and nightly, seasonal, and yearly patterns of use. Bats exhibited a very low rate of recapture (2.8%). Few bats were captured exiting the roosts before or during the 1st hour after sunset; peaks in nightly captures at roosts generally occurred 3–5 h after sunset, with few differences between sex and age classes. These patterns were indicative of frequent use of these caves and mines as night roosts by large numbers of individuals. For the 4 most abundant species (Myotis lucifugus, M. septentrionalis, Pipistrellus subflavus, and Eptesicus fuscus), roosts were used by adults and juveniles of both sexes. Adult sex ratios were skewed toward males, whereas juvenile sex ratios approached 1:1 in 1 of 2 years for each species. Nightly ambient temperatures explained little of the variation in capture times (2%) or capture success (10%). For each species, seasonal patterns of activity were similar between years, but there were differences among species. Overall, bat activity was highest in late August in both years.

Abert's squirrels (Sciurus aberti) are reported to depend on ponderosa pine (Pinus ponderosa) for food and nest sites. Introduced Abert's squirrels in the Pinaleño Mountains of Arizona, however, occupy mixed-conifer forests that contain almost no ponderosa pine (about 2%). We examined selection of drey sites in this introduced population. Dreys (i.e., spherical nests) were built adjacent to the trunk at 75% of the tree height. Dreys were found in 5 different conifer species and <2% were in ponderosa pine. Drey trees were larger and had more access routes than did random trees. Drey sites were steeper, had more large trees, Douglas-fir (Pseudotsuga menziesii), and southwestern white pine (Pinus strobiformis), and less corkbark fir (Abies lasiocarpa var. arizonica) than random sites. The structural characteristics of drey trees in the Pinaleños population also were very similar to drey trees used by natural populations of Abert's squirrels in ponderosa pine forests. Our results suggest that the dependence of Abert's squirrels on ponderosa pine is not as strong as previously reported. Structural features such as tree size and access routes appear to be more important to selection of drey sites than tree species.

Infant abuse by males has been observed in many pinniped species, but its adaptive significance and defense mechanism remain uncertain. We studied harassment and abduction of pups by nonterritorial male northern fur seals (Callorhinus ursinus) on St. Paul Island, Alaska, from 1993 to 1998. Juvenile, subadult, and adult males entered the breeding area and sniffed, bit, grabbed, or mounted pups. They also abducted pups to other places on land or to sea. Three pup mortalities caused by drowning, skull damage, or separation from the mother leading to emaciation were observed during the study period. Nonterritorial males did not exhibit a preference for the sexes of pups they attacked, and never consumed dead pups. Intrusions of juvenile and subadult males into breeding areas increased in the late breeding season, when harassment and abduction of pups occurred frequently. Frequency of intrusion and harassment of pups by adult nonterritorial males was lower than that by juvenile and subadult males, and did not increase in the late breeding season. On average, each pup was harassed or abducted 3.8 times in a breeding season. Pups changed their behavior to avoid nonterritorial males as pups moved out of the central breeding area in the late breeding season. Territorial males protected pups indirectly through territory defense, but their vigilance against juvenile and subadult males diminished in the late breeding season. Adult females protected their pups against juvenile and subadult males only while they were attending pups within the breeding territories. However, formation of breeding aggregation in rocky habitats may contribute to reducing the risk of harassment of pups by nonterritorial males because it provides pups with protection by territorial males as well as shelters created by irregular terrain.

Progesterone concentrations after implantation and the observation of live births were used to investigate the reproductive performance and timing of reproductive failure in New Zealand fur seals (Arctocephalus forsteri). Progesterone concentrations in females that gave birth were relatively low during early active gestation (8.6 ± 0.9 ng/ml) and increased significantly toward the end of the 1st trimester (14.9 ± 0.9 ng/ml). In contrast, progesterone concentrations in females that did not give birth remained low. Estimated pregnancy rates and live births varied significantly between years. In 2000, the overall reproductive success of mature females was low (25.7%) and 42.3% of reproductive failure occurred at or before implantation. In 2001 and 2002, reproductive rates were higher (56.5% and 63.5%, respectively) and reproductive failure was greatest (70% and 89.5%, respectively) in mid- to late active gestation. Reproductive failure during active gestation appears to be the most significant stage in determining reproductive success; however, in years of low reproductive success, failure before or at implantation also contributed significantly to reduced reproductive rates. The finding that significant fetal mortality occurs in late gestation reinforces the caution that the use of pregnancy rates, without consideration for the stage of gestation at which measurements were taken, can positively bias estimates of reproductive rates.

Gonadal development in immature, pubertal, young mature, and sexually mature male common dolphins (Delphinus delphis) was assessed for 212 dolphins collected between 1991 and 2003. The sample consisted of animals stranded along the Irish and French coasts, and also bycatch samples from Irish and French observer programs. Through histological analysis of the testes, individuals were categorized into reproductive stages by using characteristics of their gonadal morphology. These stages were immature, pubescent, young mature, and sexually mature. Male common dolphins were 102–233 cm in length and 0–28 years of age. Sexually mature individuals were 195–233 cm in length and 8–28 years of age, and the average age at attainment of sexual maturity was 11.86 years. Combined testes weight for mature male dolphins ranged from 0.45 to 5 kg, which is relatively large considering the overall size of the dolphin. Reproductive seasonality was found to occur, as evidenced by marked seasonal changes in both testes weights and cellular activity in testes outside the mating period; the mating period was estimated to take place during May–September. Moderate sexual dimorphism and large testes suggest sperm competition and a promiscuous mating system, with female common dolphins mating with multiple mates.