Populations of generalist foragers may in fact be composed of individuals that select different prey. We monitored 9 pumas (Puma concolor) in Chilean Patagonia using Argos–global positioning system (Argos-GPS) technology for a mean of 9.33 months ± 5.66 SD. We investigated 694 areas where puma location data were spatially aggregated, called GPS clusters, at which we identified 433 kill sites and 6 acts of scavenging. Pumas as a population specialized upon guanacos (Lama guanicoe), whereas only 7 of 9 individual pumas specialized upon guanacos. One puma specialized upon domestic sheep (Ovis aries) and 1 upon European hares (Lepus europaeus) in terms of numbers of prey killed. Male and female pumas selected different distributions of prey and pumas exhibited prey selection at both the individual and population level. Three of 9 pumas exhibited selection when we compared individual prey use to prey availability within individual pumas' home ranges. One puma selected endangered huemul (Hippocamelus bisulcus) and 2 selected sheep. When we compared individual prey use to prey use at the population level, 5 of 9 pumas differed from the population norm. Whereas pumas did not select huemul at the population level, 2 individuals did select huemul. Two individuals also selected domestic sheep, and the influence of these 2 pumas was substantial enough to result in a population-level effect. Our research highlights the need to determine whether pumas exhibit individual foraging variation throughout their range, the extrinsic factors associated with (and possibly influencing) such variation, and how pumas that select rare and less abundant species in multiprey systems impact recovering prey populations.

Sound management of large carnivore populations in wildland–urban environments requires accurate information regarding the ecology of these populations and factors contributing to their interactions with people. We quantified cougar (Puma concolor) residential use and interactions with people in western Washington from 2003 to 2008 to characterize the ecology and risks associated with an adaptable large carnivore residing in a wildland–urban environment. We fitted cougars with global positioning system and very-high-frequency radiocollars, quantified residential use, and tested for differences between demographic classes using analysis of variance fixed-effects and multiple-comparison models. We investigated interaction reports to quantify interaction rates and tested for differences among interaction levels for different cougar demographic classes. We captured 32 cougars (16 males and 16 females) and estimated 33 annual utilization distributions (UDs) for 27 individuals. Ninety-three percent of cougars (n = 27; 15 males and 12 females) used residential areas with an average UD overlap of 16.86% (SD = 17.05%, n = 33). There were no differences between male and female (F_1,29 = 0.77, P = 0.49) or resident and transient (F_1,29 = 0.0003, P = 0.99) use of residential areas, but subadult use was significantly higher than that of adults (F_1,29 = 7.20, P = 0.01). Twenty-nine percent of reports were confirmed (n = 73), with livestock depredations accounting for 67% of confirmed reports. The interaction rate for radiocollared cougars was low (1.6 interactions/1,000 radiodays) and all demographic classes were involved in similar numbers of interactions. Use of residential areas in western Washington appears to be a function of the adaptive and mobile nature of the cougar exploiting suitable habitat and resources within the matrix of residential development. Interaction appears to be a function of individual behavior. Management strategies that target problem individuals and maintain older age structures in local populations coupled with proactive landscape planning and public education in residential areas at the wildland–urban interface may provide an effective strategy for decreasing cougar–human interaction.

Genes of the mammalian major histocompatibility complex (MHC) are central to adaptive immunity. High levels of observed polymorphism at MHC loci have been hypothesized to be maintained by natural selection acting to preserve alleles for pathogen resistance. Here we examined patterns of multilocus MHC diversity in natural populations of 2 closely related carnivore species: spotted hyenas (Crocuta crocuta) and striped hyenas (Hyaena hyaena). We also tested hypotheses suggesting specific selection pressures favoring MHC diversity in these hyena species. We found several lines of evidence consistent with positive selection acting at multiple MHC loci in both species. These included high allelic variation, pervasive gene duplication, transspecies segregation of alleles, and codons evolving under positive selection that disproportionately map to known antigen-binding regions. Despite striking behavioral differences between these 2 hyaenids with respect to their mating systems and social behavior, we found no qualitative species differences in MHC loci, nor did we detect differences in the strength of natural selection. Our findings suggest that ancient shared selection pressures, including a common ancestral pattern of carrion feeding, has influenced MHC diversity more strongly in these hyena species than have selection pressures imposed relatively recently by sociality or sexual selection.

Little is known about the sublethal effects of mesocarnivores on small carnivores, which can have important implications regarding the ecology and behavior of the latter. We investigated the ecology of cape foxes (Vulpes chama) and bat-eared foxes (Otocyon megalotis) in the absence of black-backed jackals (Canis mesomelas), a dominant mesocarnivore and predator of both fox species. Results were compared with a concurrent study that investigated the ecology of both fox species in the presence of jackals, at a site <5 km away. In the absence of jackals, densities of cape foxes increased 64% despite similar food and habitat resources between sites, indicating that jackals suppressed cape fox populations. In contrast, jackals did not suppress populations of bat-eared foxes. For both fox species, the absence of jackals resulted in smaller home-range sizes and nonselective use of habitats for den sites, indicating that jackals had sublethal effects on the ecology and behavior of both fox species. Additionally, in the absence of jackals, cape foxes were marginally more active during daytime, whereas bat-eared foxes exhibited smaller group sizes. The 2 fox species became more segregated in the absence of jackals, indicating that jackals also had sublethal effects on the interspecific relationships of fox species. Our results showed that the effects of a mesocarnivore can extend well beyond population suppression of small carnivores, although sublethal effects varied in intensity and often were species specific. Sublethal effects on small carnivores can occur even if population suppression by a mesocarnivore is not occurring.

The persistence of wildlife in fragmented landscapes is predicted to rely on the presence of critical habitat elements. In urban landscapes, the persistence of hollow-dependent bats arguably depends upon the protection of roosting habitat, yet knowledge of bat roosting requirements within these landscapes is limited. We used radiotelemetry to locate day roosts of a species considered sensitive to urbanization, Gould's long-eared bat (Nyctophilus gouldi), in suburban bushland in Sydney, New South Wales, Australia. We compared roost selection data collected for 9 individuals during the mating season (March–April 2009) and 10 individuals during the maternity season (November–December 2009). We found 41 roosts of N. gouldi under decorticating bark and in tree hollows, which were all located in 1 suburban bushland reserve (∼40 ha), with roosts rarely located elsewhere, despite the abundance of available trees in smaller patches outside of the reserve. N. gouldi displayed a clear preference for trees with a greater amount of understory and canopy cover, and only roosted where the extent of forest cover in the local landscape was greatest. Maternity roosts also were predominately located in gullies, and closer to creek lines than expected. Roost switching differed significantly between seasons, with lactating females switching roosts significantly more often than nonlactating females, where roost switching occurred after 1 day on 71% of occasions. Because competition with other fauna for hollows has been suggested as a potential threat, systematic observations of hollow-using bird species, including rainbow lorikeets (Trichoglossus haematodus), were conducted. We observed birds occupying bat roosts on days following bat occupancy, and bats roosted in trees where there were fewer hollow-using birds than randomly available trees. We recommend that further examination of hollow competition be undertaken because abundant, urban-adapted, hollow-nesting birds may render hollows a limiting resource to hollow-users such as bats in urban landscapes. Protection of a network of potential roost trees in suburban bushland remnants, particularly along creek lines, will assist in maintaining this critical resource for bats.

Giant otters (Pteronura brasiliensis) live in groups that seem to abandon their territories during the flooding season. We studied the spatial ecology of giant otter groups during dry and wet seasons in the Vermelho and Miranda rivers in the Brazilian Pantanal. We monitored visually or by radiotelemetry 10 giant otter groups monthly from June 2009 to June 2011.We estimated home-range size for all groups with the following methods: linear river length, considering the extreme locations of each group, and fixed kernel. For the radiotracked groups, we also used the k-LoCoh method. Spatial fidelity and habitat selection of giant otter groups were analyzed seasonally. On the basis of k-LoCoh (98%) method, home-range sizes during the wet season (3.6–7.9 km²) were 4 to 59 times larger than during the dry season (0.1–2.3 km²). Home-range fidelity between seasons varied among giant otter groups from 0% to 87%, and 2 radiotagged groups shifted to flooded areas during the wet seasons. Giant otter groups were selective in relation to the composition of the landscape available during the dry seasons, when the river was used more intensively than other landscape features. However, they seemed to be less selective in positioning activity ranges during the wet season. During this season, giant otters were frequently observed fishing in the areas adjacent to the river, such as flooded forest, grassland, and swamps.

Ariranhas (Pteronura brasiliensis) vivem em grupos, que parecem abandonar seus territórios durante a estação de inundação. Nós estudamos a ecologia espacial de grupos de ariranhas durante as estações seca e chuvosa nos rios Vermelho e Miranda no Pantanal brasileiro. Nós monitoramos visualmente ou por rádio telemetria 10 grupos de ariranhas mensalmente entre junho de 2009 e junho de 2011. Nós estimamos o tamanho da área de vida de todos os grupos através dos seguintes métodos: 1) comprimento linear do rio, considerando as localizações extremas de cada grupo, e 2) kernel fixo. Para os grupos monitorados com telemetria nós também usamos o método 3) k-LoCoh. Fidelidade espacial e seleção de habitat dos grupos de ariranhas foi analisada sazonalmente. Baseado no método de k-LoCoh (98%), os tamanhos das áreas de vidas durante a estação chuvosa (3.6 −7.9 km²) foram 4 a 59 vezes maiores do que durante as estações secas (0.1–2.3 km²). Fidelidade de área de vida entre estações variou de 0% to 87% entre os grupos de ariranhas e dois grupos monitorados com rádio telemetria dispersaram para áreas inundadas durante as estações chuvosas. Grupos de ariranhas foram seletivos em relação à composição da paisagem durante as estações secas, quando o rio foi mais intensamente utilizado em relação a outras características da paisagem. No entanto, eles pareceram ser menos seletivos no posicionamento de suas atividades durante as estações chuvosas. Durante essa estação, ariranhas foram freqüentemente observadas pescando em áreas adjacentes ao rio, como florestas inundadas, campos e brejos.

Isotopic analysis of serially sampled vibrissae (whiskers) is a powerful method to investigate changes in an individual's resource and habitat use over time, which is difficult or impossible to accomplish using traditional dietary proxies such as observation or scat analysis. A vibrissae-based isotopic approach is limited by knowledge of vibrissae growth rates, which are required to determine the time period represented by each subsampled segment. Likewise, determining the magnitude of, and variation in, isotopic differences between a consumer and its diet, commonly referred to as trophic discrimination factors (TDFs), is a crucial step in quantifying diet composition using stable isotopes. TDF estimates are available only for a few mammalian taxa. We measured vibrissae growth rates and δ¹³C and δ¹⁵N TDFs in captive southern sea otters (Enhydra lutris nereis). Sea otters were administered ¹⁵N-enriched glycine intravenously and vibrissae were collected periodically and serially sampled for carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope analysis. Growth of adult sea otter vibrissae was linear with a mean (±SD) rate of 7.7 (± 1.2) cm/year. Mean (±SD) whole diet–vibrissae TDFs were 2.8‰ (±0.2‰) for δ¹³C and 5.5‰ (±0.2‰) for δ¹⁵N. Mean (±SD) lipid-extracted diet–vibrissae TDFs were 2.4‰ (±0.2‰) for δ¹³C and 4.9‰ (±0.3‰) for δ¹⁵N. δ¹³C TDFs were similar to previously reported values for mammalian carnivores, but δ¹⁵N TDFs were higher than expected. These results will increase the accuracy of isotopic diet analyses of mustelids and other carnivores for which there are few estimates of TDFs and no estimates of vibrissae growth rates.

The Patagonian weasel (Lyncodon patagonicus) is one of the least known carnivores from South America, and excluding some contributions, knowledge of it seems anecdotal. It is supposed to inhabit herbaceous and arid environments of Argentina and Chile. Here we assess the potential distribution of the Patagonian weasel both during the present and the Last Glacial Maximum (LGM). We also integrate some of this information, providing a historical and geographic analysis (both through ecological niche modeling and biogeographic schemes) of the distribution of L. patagonicus. We found 2 major core areas of distribution, 1 in northwestern Argentina and another in southern Argentina (i.e., Patagonia). Patagonian weasel distribution seems to be primarily related to cold areas with marked temperature seasonality and elevations below 2,000 m above sea level. From LGM to the present, we observed a major retraction in potential distribution areas that might indicate the existence of a vicariance process affecting Patagonian weasel distribution.

El Huroncito Patagónico (Lyncodon patagonicus) es uno de los carnívoros menos conocidos de Sudamérica, y excluyendo algunas contribuciones, su conocimiento parece anecdótico. Se supone que habita ambientes áridos con vegetación herbácea de Argentina y Chile. En el presente estudio evaluamos la distribución potencial del Huroncito Patagónico durante el presente y el Último Máximo Glacial (UMG). Para ello integramos información proveniente de análisis históricos y geográficos (Modelado de Nicho Ecológico y esquemas biogeográficos) de la distribución de L. patagonicus. De esta manera obtuvimos dos grandes áreas núcleo de distribución para la especie, una en el noroeste de Argentina y otra hacia el sur de Argentina (i.e., Patagonia). La distribución del Huroncito Patagónico parece estar relacionada en primer lugar con áreas frías de marcada estacionalidad térmica y altitudes por debajo de los 2000 m.s.n.m. El modelo generado indica que desde el UMG hasta el presente, hubo una mayor retracción en las áreas de distribución potencial, lo cual podría indicar la existencia de un proceso de vicarianza que afectó la distribución del Huroncito Patagónico.

We documented the fluctuation of daily time budgets in Japanese black bears (Ursus thibetanus japonicus) throughout the year using continuous day-to-day data from activity sensors integrated into global positioning system collars, during 2003–2009. We evaluated the influence of availability of food resources on daily active time of bears in conjunction with differences in sex and reproductive status of females (with or without offspring). The daily active time of bears fluctuated nonlinearly throughout the year. There were 3 turning points at which the activity level clearly changed from increasing to decreasing, or vice versa. Level of activity gradually increased in spring and reached a peak in July, then decreased and reached a trough in late August, and increased and reached a peak again in October. Males and females exhibited similar patterns of seasonal fluctuation in daily active time, although there were differences of activity levels between sexes during some periods. Dates of the 3 turning points did not differ between sexes, or among years. Seasonal variation in food availability may explain the timings of the turning points, at least in part. In addition, yearly variation in food resources, especially hard mast, may have affected the increasing and decreasing pattern of daily active time during autumn. Our results suggest that evaluating activity level based on pooled data without examining differences within a season (or month), and differences in year, sex, and reproductive status may result in misinterpretation.

The diets of large, scarce mammals are difficult to study. We compared the food habits of Asiatic black bears (Ursus thibetanus) in the Tanzawa area, Japan, from before (1989–1993) and after (2001–2010) 2000 using both fecal contents and carbon and nitrogen stable isotope ratios in bear hairs. Bears ate the same foods before and after 2000, but some food categories differed in their frequencies of occurrence in autumn. Fruits of Prunus grayama, vine fruits, colonial insects, and Sasa vegetation declined and fruits of Swida controversa and sika deer (Cervus nippon) increased significantly as parts of the fall diet after 2000. Hair samples from 18 bears collected between 1973 and 2009 indicated that bears had higher summertime δ¹⁵N rates after 2000 than before, indicating more meat in the diet. Thus, the Tanzawa bear population's diet changed over 2 decades. Habitat conditions may have changed, causing bears to adjust their food habits. We discuss some factors, such as vegetation changes caused by overabundant deer or bears eating deer carcasses, that may be partly responsible. We argue that long-term diet studies are valuable for detecting habitat changes at scales that may not be apparent solely with habitat monitoring.

Although black bears (Ursus americanus) were believed to be extirpated from the Interior Highlands of North America by the early 1900s, populations have recently recovered, aided in part by reintroductions in Arkansas. Today black bears can be found in the Ozark and Ouachita National Forests of northern and western Arkansas, the White River National Wildlife Refuge in eastern Arkansas, and the Ozark region of southern Missouri. Previous genetic studies have investigated the effects of translocating black bears from Minnesota and Manitoba, Canada, into the Ozark and Ouachita National Forests between 1958 and 1968, with differing results. We used nuclear microsatellite loci to infer the genetic structure of black bears across the Interior Highlands and to investigate the sources of bears found today in southern Missouri. Our results suggest that the Ozark population was strongly influenced by the reintroductions, whereas the Ouachita population was influenced to a lesser degree. Although the majority of bears in the Ozark region of Arkansas and Missouri represent a single genetic unit, bears in Webster County, Missouri, may represent a remnant of the historical population of the region. Our results confirm that the bear population in the White River National Wildlife Refuge is strongly differentiated genetically from other Arkansas populations and support previous reports that the Ouachita bear population may have resulted from an admixture of a remnant population and reintroduced bears.

Understanding the relationship between foraging ecology and the presence of human-dominated landscapes is important, particularly for American black bears (Ursus americanus), which sometimes move between wildlands and urban areas to forage. The food-related factors influencing this movement have not been explored, but can be important for understanding the benefits and costs to black bear foraging behavior and the fundamental origins of bear conflicts. We tested whether the scarcity of wildland foods or the availability of urban foods can explain when black bears forage near houses, examined the extent to which male bears use urban areas in comparison to females, and identified the most important food items influencing bear movement into urban areas. We monitored 16 collared black bears in and around Missoula, Montana, during 2009 and 2010, while quantifying the rate of change in green vegetation and the availability of 5 native berry-producing species outside the urban area, the rate of change in green vegetation, and the availability of apples and garbage inside the urban area. We used parametric time-to-event models in which an event was a bear location collected within 100 m of a house. We also visited feeding sites located near houses and quantified food items bears had eaten. The probability of a bear being located near a house was 1.6 times higher for males, and increased during apple season and the urban green-up. Fruit trees accounted for most of the forage items at urban feeding sites (49%), whereas wildland foods composed <10%. Black bears foraged on human foods near houses even when wildland foods were available, suggesting that the absence of wildland foods may not influence the probability of bears foraging near houses. Additionally, other attractants, in this case fruit trees, appear to be more important than the availability of garbage in influencing when bears forage near houses.

The capture and handling of free-ranging animals is an important tool for wildlife research, conservation, and management. However, live capture may expose individual animals to risk of injury, impairment, or mortality. The polar bear (Ursus maritimus) is a species of conservation concern throughout its range and physical mark–recapture techniques have formed the basis of polar bear research and harvest management for decades. We examined movement patterns of polar bears postcapture to measure their recovery from chemical immobilization and determine whether captured bears experienced prolonged effects that would affect individual fitness. Adult female (n = 61) and juvenile (n = 13) polar bears in 3 Canadian subpopulations were captured during the course of other studies using a combination of tiletamine hydrochloride and zolazepam hydrochloride delivered via remote injection from a helicopter. Bears were fitted with satellite-linked global positioning system collars and we used 3 individual-based metrics to assess their recovery from immobilization: time to move 50 m; time to move 100 m; and time to reach a baseline movement rate threshold (km/day) derived from each individual's movements in a fully recovered state (i.e., 30–60 days postcapture). There were no differences in recovery rate metrics across years, age classes, or between females with cubs of different ages. When compared across subpopulations, only the time to move 50 m differed, being shortest in the southern Beaufort Sea. Bears captured on land during the ice-free period in western Hudson Bay and Foxe Basin were more variable in their response to capture than were those handled on the sea ice of the Beaufort Sea, but in all 3 areas, bears showed gradual increases in movement rates. Movement rates indicative of recovery were often reached 48 h after capture and 51 (69%) of 74 bears appeared to be fully recovered in ≤3 days. Consistent with preliminary work on chemical immobilization of polar bears, there was no relationship between drug dose and rate of recovery. Our results indicated that polar bears captured in different locations, seasons, and life-history stages recovered predictably from chemical immobilization in a time frame that is unlikely to affect individual fitness.

Variation in space-use patterns among free-ranging mammal populations has been an important area of study in behavioral ecology. We investigated the influence of landscape characteristics associated with landscape fragmentation and diversity on the home-range size of white-tailed deer (Odocoileus virginianus). We evaluated the relative contribution of 3 main land-cover types (forest, agriculture, and rangeland) to the composition of each home range and constructed sex- and season-specific linear regression models using landscape metrics relevant to habitat fragmentation and diversity. Both core and home-range areas were dominated by forest, agriculture, and rangeland. We found that landscape configuration metrics aimed at quantifying landscape fragmentation were good predictors of space use by white-tailed deer and that deer occupied smaller home ranges in highly fragmented areas. Our results indicate that once important cover types are present and patches are sized to meet the resource needs of the individual, configuration of those resource patches influences overall space use. These findings support the assertion that space use by white-tailed deer varies along a gradient of fragmentation.

We used 15 years (1992–2006) of capture–mark–recapture (CMR) data obtained from a population of nine-banded armadillos (Dasypus novemcinctus) located at the Tall Timbers Research Station near Tallahassee, Florida and multistate CMR models to estimate and model capture probabilities, annual apparent survival, and transition probabilities between reproductive and nonreproductive states (for adult females only). Using an information theoretic approach, we then examined various influences on these parameters. Across all years, capture probability, p, was higher for adults than for yearlings, and higher for males than for females. There was also substantial yearly variation. Conditional on survival, the annual transition probability, ψ, for reproductive adult females to remain reproductive was 0.853 ± 0.044; the estimate for nonreproductive adult females to become reproductive was 0.388 ± 0.060. Annual apparent survival, S, was lowest for juveniles (S = 0.541 ± 0.118) and highest for reproductive adult females (S = 0.753 ± 0.034). Contrary to expectation, these data provided no evidence for a cost of reproduction among adult females. Finally, annual apparent survival was lower for all animals during an extensive hardwood removal that occurred from 1998 to 2000 than in either preceding or subsequent years.

Oak-dominated forest has declined in the eastern United States as shade-tolerant mesophytic species (e.g., maple [Acer spp.]) replace oaks (Quercus spp.), sparking concern among ecologists regarding species that consume acorns. Our goal was to describe how increasing mesophication of oak forests may affect consumers in higher trophic levels. We investigated relationships among forest composition, mast production, small-mammal density, and carnivore occurrence in 8 stands representing a gradient of oak–hickory dominance in central hardwood forest in southern Illinois. We livetrapped small mammals for >24,000 trap-nights in June–August 2009–2011 with trapping webs to estimate population density of mice (Peromyscus spp.). We collected mast seeds during October–November 2009–2010 and calculated average dry biomass (g/m²) for each species and stand. During winters 2009–2011, we photographed carnivores using baited camera traps. We regressed mast biomass on measures of forest composition and regressed Peromyscus density and carnivore occurrence on estimates of mast biomass. Peromyscus summer density was not related to percent hard-mast basal area or hard-mast biomass from the previous autumn. Logistic regressions of carnivore occurrence on Peromyscus density were not significant. Many other studies have demonstrated links of several species to oak forest and mast production, but the lack of associations that we observed was consistent with recent meta-analyses across latitude. The landscape matrix of oak–hickory forest and alternative soft-mast foods also may act to homogenize Peromyscus density across our study sites. Maintenance of stand heterogeneity in the forest landscape will support a wider diversity of species.

Understanding the impact of small mammals on the development of grasslands requires information on their food preferences. We conducted feeding trials with 4 species of common small mammals, prairie voles (Microtus ochrogaster), meadow voles (M. pennsylvanicus), white-footed mice (Peromyscus leucopus), and eastern cottontails (Sylvilagus floridanus), to determine the relative palatability of plant shoots and seeds in introduced grasslands of east-central Illinois. Because we needed to conduct many feeding trials we developed a rapid method for comparison of palatability of plants to multiple species of small mammals in the field. We evaluated the method by comparison with previous data on food preference and palatability for voles at nearby study sites. Shoots of herbaceous legumes (Medicago sativa and Trifolium pratense) and dandelions (Taraxacum officianale) were among the most palatable foods for voles, and bluegrass (Poa pratensis) was among the least palatable. Meadow voles found palatable more species of graminoids than did prairie voles, and meadow voles, but not prairie voles, found palatable a greater percentage of graminoids than of forbs. A greater percentage of introduced plants than of native plants were palatable to prairie voles, but this likely reflected a high proportion of introduced graminoids among tested plants. White-footed mice found palatable a few forbs and a greater percentage of annual plants compared with perennial plants, whereas cottontails found palatable many forbs and woody plants and a greater percentage of perennial plants. White-footed mice tended to eat larger amounts and more kinds of seeds than voles, and only white-footed mice tended to eat more of large-seeded species. Plant type did not appear to significantly affect palatability of seeds for any mammal. We used these results to predict the likely impact of small mammals on the development of nonnative grasslands.

It is well established that massive consumption of plants by the abundant and diverse assemblage of savanna ungulates in East Africa competitively suppresses the native guild of herbivorous to omnivorous small mammals. An important role of woody plant suppression in the Acacia-dominated savannas for this guild of rodents, when released from ungulate competition, has been demonstrated only recently, but without direct evidence of which species are involved. In an effort to establish which of the common species in this guild are most likely to impact growth of trees and forbs, as opposed to grasses or insects, or both, I present data on atomic and isotopic ratios of fecal carbon and nitrogen from 8 commonly occurring muroid rodents from savanna and bush habitats on the Laikipia Plateau of central Kenya: Acomys percivali, Acomys wilsoni, Aethomys hindei, Arvicanthis niloticus, Mastomys natalensis, Mus spp. (thought to be mostly M. minutoides), Saccostomus mearnsi, and Gerbilliscus robustus. In this region where all grasses are C₄ and all trees and other nongrasses are C₃, different ratios of ¹³C:¹²C (δ¹³C) in plant tissues give pure grazers, pure browsers, and mixed-feeding herbivores distinctive carbon isotope signatures. Degree of omnivory is revealed by C:N and, arguably, by δ¹⁵N, but the latter is influenced by dietary protein quality and varies widely by plant species and soil type. Joint consideration of stable-isotope data, total C:N, and microhistological analysis of feces allowed better resolution of dietary niche of each species than any of these data sets could, alone. Grass was either coequal to browse (dicots) or dominated the plant portion of each species' diet, which was somewhat unexpected given rodents' hypothesized role in limiting Acacia recruitment. All species consumed some arthropods. A. niloticus, the only diurnal species, was the most herbivorous, being largely a grazer. S. mearnsi, A. hindei, and M. natalensis were mixed-feeding (grass–browse) herbivores. Mus spp. and Acomys spp. were omnivores whose plant components were largely grass. G. robustus was primarily an insectivore–omnivore whose smaller plant component was grass. Both S. mearnsi and A. niloticus displayed a significant increase in proportion of C₄ grasses in the diet in periods following significant rains, a pattern previously documented from δ¹³C diet studies in large mammalian herbivores. Fecal δ¹⁵N was significantly higher for rodents that consumed more grass and for rodents released from competition with ungulates, suggesting a partial mechanism for that competitive release. S. mearnsi, followed by A. hindei and M. natalensis, were most likely to feed on woody dicots including Acacia.

Plasticity of circadian rhythm was investigated for the model species desert hamster (Phodopus roborovskii) under natural conditions in the Alashan Desert using the radiofrequency identification (RFID) technique, that is, animals were caught in the field and marked with passive transponders, and burrows were equipped with integrated microchip readers and photosensors for detection of movements into or out of the burrow. Additionally, video observations with infrared cameras were conducted at feeding sites to verify RFID data and analyze interspecific behavior. Composition of the rodent community changed during observation periods from a midday gerbil (Meriones meridianus)-dominated community to a desert hamster (P. roborovskii)-dominated community in 2009 and from a northern three-toed jerboa (Dipus sagitta)-dominated community to a hamster-dominated community in 2010. Activity pattern of hamsters was clearly affected by species composition. In the hamster-dominated community, activity started 1.7 h ± 1.0 SD after sundown and ended 7.2 ± 1.4 h after sundown. A similar activity pattern was found for the jerboa-dominated community. In contrast, hamsters shortened their activity tremendously in the gerbil-dominated community, to 2.2 ± 1.3 h (activity began at 0.8 ± 0.3 h after sundown and ended at 3.0 ± 1.5 h after sundown). An analysis of interspecific behavior at feeding sites showed clearly that gerbil behavior was characterized by aggressive attacks (60.4% attacks versus 6.1% being attacked), whereas jerboa behavior was dominated by avoidance of direct contact (67.5% avoidance versus 22.9% attack). Hamster intraspecific behavior included all 4 elements in a similar ratio (27.3% attacks, 21.8% being attacked, 22.7% fleeing without direct contact, and 22.7% causing fleeing without direct contact).

We examined the phylogeography of the South American subterranean rodent Ctenomys talarum (Talas tuco-tuco) using mitochondrial DNA control region (D-loop) sequences. This species is an herbivorous rodent endemic to the province of Buenos Aires, Argentina, that lives in natural grasslands in coastal sand dune habitats and in some fragmented inland populations. In this study we assessed the genetic relationship among populations of C. talarum across its entire distributional range and analyzed how the geological history of the habitat has affected the genetic structure and demographic history of these populations. A complex network of haplotypes in conjunction with analysis of molecular variance results showed high genetic subdivision and a strong phylogeographic pattern among populations of C. talarum. Pairwise F_ST-values showed significant differentiation among all populations studied. The overall pattern was similar to that expected under the isolation-by-distance model, suggesting equilibrium between gene flow and local genetic drift. Major geographical barriers (e.g., rivers and unsuitable habitat) in the area, in conjunction with population isolation, appeared to be associated with strong genetic differentiation among the different geographical groups. Local mismatch distributions and tests of neutrality suggest contrasting histories for different groups of populations; although some populations appeared to be characterized by demographic stability and no significant departures from neutrality, others showed departures from strict neutrality consistent with a recent demographic expansion. Finally, a close association seems to exist between the major climatic changes that occurred during the late Pleistocene and Holocene in the central region of Argentina and the main historical demographic changes inferred from C. talarum. Current populations of C. talarum appear to be relicts of a more extended historical distribution along the Argentinean Pampas. These historical extinctions, however, have not erased the signature of long-term stability and geographical structure in this species along the coastal and inland distribution ranges.

A partir del uso de secuencias de ADN mitocondrial de la región control (D-loop), analizamos la filogeografía del roedor sudamericano Ctenomys talarum (tuco-tuco de los talares). Esta especie es un roedor herbívoro y endémico de la Provincia de Buenos Aires, Argentina, que habita pastizales naturales en dunas costeras y en algunas poblaciones continentales fragmentadas. En este estudio evaluamos las relaciones genéticas entre las poblaciones de C. talarum a través de su rango de distribución total y analizamos cómo la historia geológica de su hábitat ha afectado la estructura genética y la demografía histórica de estas poblaciones. Tanto la red de haplotipos como los análisis de la varianza molecular mostraron alta subdivisión genética y un patrón filogeográfico profundo entre las poblaciones de C. talarum. Los valores de F_ST pareados mostraron una diferenciación significativa entre todas las poblaciones estudiadas. El patrón general fue similar al esperado bajo un modelo de aislamiento por distancia, evidenciando un equilibrio entre flujo génico y deriva genética local. Las barreras más importantes en el área (e.g. ríos y hábitat poco apto para la ocupación) y el propio aislamiento poblacional se asociarían con una fuerte diferenciación genética entre los diferentes grupos geográficos. Las diferencias pareadas entre sitios nucleotídicos y los tests de neutralidad sugieren historias con

The reproductive benefits of maintaining a high body temperature (T_b) are well understood, but costs may be prohibitively high. Many small mammals raise offspring in insulated nests, burrows, or roosts, and may form communal maternity colonies, all of which are behaviors that reduce the costs of maintaining T_b. However, some temperate-zone bats are solitary and raise young in exposed roosts. Little is known about how these species maintain energy balance in the face of high thermoregulatory costs, and whether they stay warm invariably for reproductive benefits, or use a more adaptive thermoregulatory strategy. We studied T_b patterns in response to foraging conditions, weather, and pup age in free-ranging adult and juvenile hoary bats (Lasiurus cinereus). Lactating females regularly entered torpor, although its use was most extensive following poor foraging conditions, during inclement weather, and when pups were young. Juvenile L. cinereus appeared capable of staying warm from 3 days of age, but used torpor throughout development, gradually decreasing its use as they grew. Our results indicate that for this species, torpor is important throughout lactation, and torpor use changes in response to individually specific trade-offs between energetic cost and developmental benefit. We suggest that the costs of active thermoregulation during early development of L. cinereus pups outweigh the benefits of staying warm, and an extended growing season (as a result of their migratory nature) is more conducive to using torpor. Finally, we suggest that torpor use during lactation is dynamic and adaptive. Fine-scale changes within reproductive stages need to be considered, rather than broadly assessing thermoregulatory behavior among stages.

Information on animal reproduction is critical for the application of wildlife conservation plans. The lesser long-nosed bat (Leptonycteris yerbabuenae) is classified as threatened in Mexico; however, many aspects of its reproductive biology are still unstudied. The formation of a dorsal patch in males of Leptonycteris spp. during the mating period has been described and evidence suggests this patch is involved in reproductive behavior. We determined the male reproductive cycle of L. yerbabuenae over time based on the seminiferous cycle. We then related these internal indicators with 3 external indicators—testis size, dorsal patch size, and female/male ratio in the population. Finally, we evaluated whether the epididymis functions in long-term sperm storage. Bats were captured monthly and external indicators were registered. Three adult males were euthanized each month for the evaluation of internal indicators. We determined only 1 period of spermatogenesis per year beginning in September and completing in January. The seminiferous epithelium cycle showed 11 stages and 14 steps. Internal reproductive indicators were correlated with external indicators. External testis size and female/male ratio were positively correlated with dorsal patch size. A testis size of approximately 48.2 mm² corresponded with the beginning of sperm production. The epididymis was not involved in long-term sperm storage. This study provides the 1st description in L. yerbabuenae of the annual timing of the male reproductive cycle based on histological characteristics, and also reports a relationship between the size of the dorsal patch and male reproductive function.

La información sobre biología reproductiva es crítica para la ejecución de planes de conservación de la vida silvestre. El murciélago magueyero (Leptonycteris yerbabuenae) está clasificado como Amenazado en México; sin embargo, muchos aspectos de su biología reproductiva no han sido aún estudiados. La formación de un parche dorsal en machos de Leptonycteris spp. durante el período de apareamiento ha sido descrita y la evidencia sugiere que este parche está vinculado al comportamiento reproductivo. Nosotros describimos la dinámica del ciclo reproductivo de los machos de L. yerbabuenae en base al ciclo seminífero. Posteriormente, relacionamos estos indicadores internos con 3 indicadores externos—tamaño de testículos, tamaño del parche dorsal, y proporción de sexos en la población. Finalmente, evaluamos si el epidídimo funciona almacenando esperma por tiempo prolongado. Los murciélagos fueron capturados mensualmente y se registraron los indicadores externos. Tres machos adultos fueron sacrificados cada mes para la evaluación de los indicadores internos. Detectamos solo un período de espermatogénesis al año comenzando en septiembre y finalizando en enero. El ciclo del epitelio seminífero presentó 11 estadíos y 14 pasos. Los indicadores reproductivos internos mostraron correlación con los indicadores externos. El tamaño externo de los testículos y la relación hembras/machos presentaron correlación positiva con el tamaño del parche dorsal. Un tamaño de testículos de aproximadamente 48.2 mm² se corresponde con el inicio de la producción de esperma. El epidídimo no está involucrado en el almacenamiento de esperma por tiempo prolongado. Este estudio provee la primera descripción cronológica del ciclo reproductivo masculino en L. yerbabuenae basada en características histológicas, y además evidencia la relación entre el tamaño del parche dorsal y la función reproductiva

Biological rhythms exist in many diverse forms of life. Individuals must remain entrained to environmental changes to survive. Some hibernating mammals maintain biological rhythms even during deep torpor; however, cues used for entrainment are poorly understood. We studied activity in an assemblage of hibernating Myotis bats (mainly M. nattereri) inhabiting a temperate maritime climate over 3 consecutive winters using ultrasound detectors and a series of active infrared motion detectors. Here we demonstrate that the timing of peak activity changed as day length changed over winter, but nevertheless remained entrained to a time close to dusk that would be most advantageous for winter foraging. Diurnal activity was infrequent throughout winter. There was an increase in activity at higher hibernaculum temperatures, particularly as temperatures rose above the lower threshold for insect flight (6–10°C). Finally we show that ultrasound detectors and infrared motion detectors produce broadly comparable measures of bat activity within a hibernation site.

Quantifying distributions, home ranges, and individual movements for wildlife species is crucial for understanding their ecology and is important for conservation. This has become especially urgent for bat species affected by white-nose syndrome, a new disease of hibernating bats associated with the fungus Geomyces destructans. We studied within- and between-season movements of individual little brown bats (Myotis lucifugus) throughout a 337,540-km² study area in Manitoba and northwestern Ontario, Canada. Our objectives were to quantify proportions of male and female bats that relocated from hibernacula and/or summer roosts between years, proportions of males and females captured at swarms that hibernated at those sites versus other hibernacula, and distances traveled by males and females during relocation events. We predicted that bats would exhibit male-biased dispersal, with males significantly more likely to relocate and more likely to travel long distances during relocation events. Between 1989 and 2010, we recaptured 1,459 of 10,432 banded individuals. Seasonal movements from hibernacula and/or swarms to summer colonies ranged widely from 10 to 647 km. Consistent with previous studies we found high fidelity to summer colonies and hibernacula across years. However, some individuals switched sites between years and the median relocation distance was 315 km, with over 20% of individual movements exceeding 500 km. Surprisingly, we found that females were significantly more likely to relocate than males. Our data could help explain apparent jumps in the distribution of G. destructans, but more data on transmission of the fungus in the wild are needed.