Understanding habitat requirements has implications for numerous aspects of a species' biology, including where individuals live and how they behave. Specialization for mesic, resource-rich habitats known as mallines is thought to have favored group living in the colonial tuco-tuco (Ctenomys sociabilis), a subterranean rodent that is endemic to Neuquén Province in southwestern Argentina. To explore the proposed relationship between mallines and sociality in this species in greater detail, we characterized the habitats occupied by C. sociabilis at 3 locations representing the extremes of this species' geographic range. Specifically, plant composition and vegetative structure were characterized for 57 occupied burrow systems distributed across the 3 sampling localities. Our data indicate that C. sociabilis is not restricted to mallines. Although significant variation in vegetation was detected among the 3 study sites, the majority of active burrow systems surveyed at each site occurred in nonmallín habitats. In addition to providing the first species-wide survey of habitat use by C. sociabilis, our data yield new insights into the role of habitat specialization in promoting sociality in this behaviorally unusual species of ctenomyid rodent.

Comprender los requerimientos de hábitat tiene implicaciones para numerosos aspectos de la biología de las especies, incluyendo donde viven los individuos y como estos se comportan. La especialización en hábitat mésicos, ricos en recursos, conocidos como mallines se cree que ha favorecido la vida en grupo en el tuco-tuco colonial (Ctenomys sociabilis), un roedor subterráneo endémico de la Provincia de Neuquén en el suroeste de Argentina. Para explorar en mayor detalle la relación propuesta entre los mallines y la vida social en esta especie, se caracterizaron los hábitats ocupados por C. sociabilis en 3 localidades que representan los extremos de la distribución geográfica de la especie. Específicamente, se caracterizó la composición y estructura vegetal para 57 sistemas de madrigueras con animales, distribuidos en las 3 localidades de estudio. Los datos indican que C. sociabilis no se restringe a hábitats de mallín. A pesar de que se detectó variación significativa en la vegetación entre los 3 sitios de estudio, la mayoría de los sistemas de madrigueras activos muestreados en cada sitio se encontraron en hábitats no mallínoso. Además de proporcionar el primer muestreo amplio de hábitat para C. sociabilis, nuestros datos podrían ofrecer nuevas perspectivas sobre el papel de la especialización de hábitat en la promoción del comportamiento social inusual de esta especie de roedor ctenomido.

Historical bottlenecks, habitat fragmentation, and small populations resulting in decreased heterozygosity typify conservation concerns of globally threatened carnivore populations. We monitored the endangered Asiatic lion (Panthera leo persica) by radiotelemetry (n = 20), individual profiles (n = 55 adults and 91 cubs from 38 litters), and observed mortalities (n = 88) to estimate survival, mortality causes, interlitter interval, and litter size in the Gir Forest region of Gujarat, western India, between 2000 and 2010. Lions increased from about 177 in 1968 to about 411 by 2010 with r = 0.022 ± 0.001 SE. The male : female ratio was 0.63 ± 0.04 SE, whereas the cub : adult lioness ratio was 0.37 ± 0.02 SE. Mating peaked in winter and birth peaked in late summer. Average litter size was 2.39 ± 0.12 SE. Interbirth interval was 1.37 years ± 0.25 SE (n = 7 lionesses) and was higher (2.25 ± 0.41 years) when cubs of the previous litter survived to independence. Cub survival was 0.57 ± 0.04 SE, whereas survival from cub to recruitment age (3 years) was 51% ± 4% SE, with mortalities due to infanticides being 30% ± 7 %. Juvenile (1–2 years) and subadult (2–3 years) survival rates were 0.87 ± 0.04 SE and 0.90 ± 0.04, respectively. Average annual survival rate of adult lions (>3 years) was 0.9 ± 0.12 SE. Adult lions died primarily due to natural causes (54.5%); however, human-caused mortality was substantial (43.2%) and was likely additive to natural causes. Demographic parameters of genetically less-diverse Asiatic lions did not differ from those of African lions.

Phylogenetic relationships of the Mexican endemic and endangered Perote ground squirrel, Xerospermophilus perotensis (Rodentia: Sciuridae), were examined using 2 mitochondrial (cytochrome-b [Cytb] and 12S ribosomal RNA) and 2 nuclear (growth hormone receptor and interphotoreceptor retinoid-binding protein) genes for a total of 3,403 base pairs. Gene sequences were analyzed using maximum-likelihood and Bayesian models of phylogenetic inference. Independent analyses of the 4 gene sequences converged on essentially identical gene trees, all showing X. perotensis to be sister to X. spilosoma from San Luis Potosí, Mexico, and nested within other geographic samples of X. spilosoma. Given the current absence of diagnostic morphological characters to distinguish X. perotensis from X. spilosoma and the moderate level of Cytb sequence divergence between the 2 forms (3.6%, which is less than divergence values measured between other subspecies of X. spilosoma), X. perotensis is herein reduced to subspecies status as X. spilosoma perotensis. Based on molecular estimates of divergence times, phyletic diversification of the genus Xerospermophilus began near the end of the Pliocene and X. spilosoma perotensis diverged from other Mexican populations of X. spilosoma during Pleistocene times. Climate cycles during the Pleistocene and the final uplift of the Trans-Mexico Volcanic Belt may have played a major role in early diversification in this lineage.

Se examinaron las relaciones filogenéticas de la ardilla terrestre de Perote Xerospermophilus perotensis (Rodentia: Sciuridae), especie mexicana endémica y amenazada, usando 2 genes mitocondriales (Citocromo b [Citb] y 12S ARN ribosomal) y 2 genes nucleares (Receptor de la hormona del crecimiento y la Proteína de unión al retinoide intersticial) para un total de 3,403 pares de bases. Las secuencias genéticas fueron analizadas usando máxima verosimilitud y modelos Bayesianos de inferencia filogenética. Los análisis independientes de las secuencias de los 4 genes convergieron esencialmente en árboles de genes identicos, todos mostrando a X. perotensis como taxa idénticos de X. spilosoma de San Luis Potosí, México y anidados dentro de otras muestras geográficas de X. spilosoma. Dada la ausencia actual de caracteres morfológicos diagnósticos para distinguir X. perotensis de X. spilosoma y el nivel moderado de divergencia de las secuencias de Citb entre las 2 formas (3.6%, que es menor a los valores de divergencia medidos entre otras subespecies de X. spilosoma), X. perotensis aquí se reduce a status subespecífico como X. spilosoma perotensis. Basado en estimaciones moleculares de tiempo de divergencia, la diversificación filetica del género Xerospermophilus comenzó cerca del final de Plioceno y X. spilosoma perotensis divergió de otras poblaciones mexicanas de X. spilosoma durante el Pleistoceno. Los ciclos climáticos durante el Pleistoceno y el alzamiento final del Eje Neovolcánico Trans-Mexicano pudieron jugar un papel importante en la diversificación temprana de este linaje.

Molecular phylogenetic studies suggest that the genus Emballonura, a member of the Old World tribe Emballonurini (Family Emballonuridae), is paraphyletic. This genus has a broad distribution across islands in the Indo-Pacific, southern Asia, and Madagascar. The paraphyly is the result of the genus Coleura, known from sub-Saharan Africa, portions of the Arabian Peninsula, Madagascar, and the Seychelles, being embedded between the Malagasy and Asian/Indo-Pacific clades of Emballonura, and the latter clade has priority for the use of the name. To resolve this situation, we propose a new genus for the Malagasy Emballonura clade. Furthermore, with greater molecular sampling of Coleura across portions of its range in association with morphological and bioacoustical characters, we are able to resolve aspects of the phylogenetic history and species limits of this genus. Coleura contains two well supported clades, including C. afra from mainland Tanzania and the offshore island of Pemba and a sister clade composed of C. cf. afra from Madagascar and C. seychellensis from the Seychelles. The average genetic distance between animals from Madagascar and the Seychelles is 6%, whereas Pemba/Tanzania and Madagascar is 10%. Because of the paraphyletic relationship of populations of C. afra with respect to C. seychellensis, we describe a new species of Coleura from Madagascar.

Le genre Emballonura appartient à la tribu des Emballonurini (famille Emballonuridae), propre à l'Ancien Monde, et couvre une vaste aire de distribution comprenant des îles de la région Indo-Pacifique, l'Asie du Sud et Madagascar. Les études moléculaires montrent que ce genre est paraphylétique en raison de la position du genre Coleura qui vient s'insérer parmi les espèces d'Emballonura, entre les clades malgache et asiatique/indo-pacifique de ce dernier. Le clade asiatique/indo-pacifique d'Emballonura a la priorité nomenclaturale pour porter ce nom. Pour résoudre cette paraphylie, nous proposons de créer un nouveau genre pour les espèces d'Emballonura de Madagascar. Grâce à un échantillonnage moléculaire accru du genre Coleura, notamment avec l'inclusion de séquences de Tanzanie, des Seychelles et de Madagascar, ainsi que par l'utilisation de caractères morphologiques et bioacoustiques, nous décrivons les relations phylogénétiques et précisons la limite entre les espèces du genre Coleura. Ce dernier se subdivise en deux clades bien soutenus, l'un comprenant C. afra du continent et de l'île de Pemba, et l'autre C. cf. afra de Madagascar et C. seychellensis des Seychelles. La distance génétique ML entre les individus de Madagascar et des Seychelles est de 6%, alors que ceux de Pemba et Tanzanie diffèrent des malgaches de 9.6-10.4%. La Coleura de Madagascar est par conséquent décrite ici en tant qu'espèce nouvelle.

Coarse woody debris (CWD) from forest harvesting and salvage wood from wildfire and insect outbreaks provide habitat for an array of forest-floor small mammal species and some of their mammalian predators. Because forest clear-cutting reduces abundance of many mammal species, strategic management of postharvest debris could help maintain abundance and diversity of forest mammals on harvested sites. We tested hypotheses that abundance and species diversity of forest-floor small mammals would be lower on conventional clear-cuts than in uncut forest; abundance and species diversity of forest-floor small mammals and relative activity and species richness of winter mammals would be higher on clear-cut sites with woody debris arranged in large piles or windrows than a dispersed treatment of debris. Small mammals were intensively livetrapped, and winter mammals snow-tracked, from 2007 to 2009 in replicated (n = 3) woody debris treatments of dispersed, piles, windrows, and uncut mature forest at 3 study areas in south-central British Columbia, Canada. We captured all 9 species of forest-floor small mammals. Compared with uncut forest, clear-cutting had no effect on mean total abundance of the small-mammal community, and species richness and diversity were either similar or higher. With respect to habitat preference, generalist species increased while specialist species declined. Habitat structures of large piles and windrows of woody debris on clear-cuts dramatically ameliorated these responses. On the basis of track counts, relative activity and species richness of winter mammals were enhanced by these structures, but the response was species specific. This is the 1st investigation showing significant increases in abundance and species diversity of forest-floor small mammals associated with constructed piles and windrows of postharvest woody debris on clear-cuts. Large-scale CWD structures as piles or windrows have clear conservation implications for mammals in commercial forest landscapes.

We studied Phyllostomidae bat assemblage structure in patches of secondary forest dominated by the pioneer tree Ochroma pyramidale, largely (>85%) or partially (<35%) surrounded by a matrix of tropical rain forest, to test 3 hypotheses: the highest bat diversity and richness is observed in the matrix rain forest in comparison to secondary forest patches; the proportion of rain forest surrounding secondary forest positively affects bat diversity and richness; and canopy openness is an important structural variable negatively affecting bat abundance. Rain-forest control sites had the highest bat species diversity and richness, and contributed more to total diversity than did secondary forest. Bat diversity was similar between secondary forest patches largely enclosed by rain forest and their controls, but higher diversity, richness, and contribution to total diversity were recorded in largely enclosed patches compared to partially enclosed patches. Partially enclosed patches were dominated by 2 small, frugivorous understory bat species (Carollia sowelli and Carollia perspicillata), whereas largely enclosed patches were dominated by 2 large-bodied, canopy-dwelling, frugivorous bats (Artibeus lituratus and Artibeus jamaicensis), which primarily feed on figs, a tree species that is abundant in rain forest. Bat diversity, richness, and contribution to total diversity were positively correlated with the proportion of area with rain forest, and bat abundance was negatively correlated with canopy openness.

Estudiamos el ensamble de murciélagos de la familia Phyllostomidae en parches de vegetación secundaria dominada por árboles pioneros de Ochroma pyramidale (Malvaceae) en dos condiciones de vegetación circundante, aquellos mayormente rodeados por una matriz de bosque tropical (>85%), y los rodeados parcialmente (<35%). Se testearon 3 hipótesis: la matriz de bosque tropical que rodea parches de vegetación secundaria presenta una mayor diversidad y riqueza de murciélagos en comparación con la vegetación secundaria; la proporción de bosque tropical que rodea a la vegetación secundaria favorece la diversidad, riqueza y abundancia de murciélagos sensibles al disturbio; y el incremento en la apertura del dosel disminuye la abundancia de murciélagos. Los sitios de control de bosque tropical, presentaron la mayor diversidad y riqueza de murciélagos y contribuyeron mayormente a la diversidad total. En los parches de vegetación secundaria mayormente rodeados de bosque tropical se encontró que la diversidad de murciélagos fue similar a las áreas de control de bosque tropical. Sin embargo, los parches de vegetación secundaria mayormente rodeados por bosque tropical presentaron mayor diversidad y riqueza de murciélagos y contribuyeron a la diversidad total en comparación con parches de vegetación secundaria parcialmente rodeados por bosque tropical. Los parches de vegetación secundaria parcialmente rodeados por bosque tropical, estuvieron dominados por 2 especies murciélagos frugívoros pequeños característicos de la vegetación secundaria (Carollia sowelli y Carollia perspicillata) mientras que los parches mayormente rodeados por bosque estuvieron dominados por 2 especies de murciélagos frugívoros grandes (Artibeus lituratus y Artibeus jamaicensis), típicos de vegetación madura que se alimentan principalmente de higos (Ficus spp.), un árbol abundante del bosque tropical. La diversidad, riqueza y la contribución total a la diversidad estuv

Wolves (Canis lupus) belong to 3 genetically distinct subpopulations despite the absence of topographic barriers limiting dispersal. Based on data on wolf diets from 13 localities and wolf kill remains from a national-scale census, we investigated regional variation in wolf diet in relation to species structure of ungulate communities and spatial genetic differentiation of wolf populations. We also tested if various sources of data on wolf prey (scats and kills) and availability of ungulates (game inventory and harvest) yielded comparable results on prey selection. The main prey of wolves was red deer (Cervus elaphus), roe deer (Capreolus capreolus), and wild boar (Sus scrofa). The proportion of main prey in wolf diets increased with prey availability in the community, yet wolves selected red deer, preyed on roe deer proportionally to their relative abundance, and avoided wild boar. Large prey was recorded among kills more often than small prey. Despite similar species structure of ungulate communities throughout Poland, there were significant regional differences in wolf diet, which corresponded to the genetic structure of populations. In northeastern Poland, wolves frequently hunted red deer, roe deer, wild boar, beavers (Castor fiber), and moose (Alces alces). In eastern Poland, roe deer dominated kills. In southeastern Poland, wolves were strongly specialized on red deer. We propose that prey and habitat specialization of wolves, rather than geographic distance or topographic barriers to dispersal, are responsible for the observed ecological divergence of wolf populations, as reflected in their diet composition.

Global warming has the potential to reduce arctic sea ice and thereby increase the length of summer–fall fasting when polar bears (Ursus maritimus) lose access to most marine mammals. To evaluate the consequences of such changes, we compared the cost of fasting by polar bears with hibernation by brown bears (U. arctos), American black bears (U. americanus), and polar bears and made projections about tissue reserves polar bears will need to survive and reproduce as fasts become longer. Hibernating polar bears expend energy at the same rate per unit mass as do brown bears and black bears. However, daily mass losses, energy expenditures, and the losses of lean mass are much higher in fasting, active polar bears than in hibernating bears. The average pregnant polar bear living around Hudson Bay during the 1980s and 1990s could fast for 10.0 ± 2.3 months (X̄ ± SD), and the average lactating female with cubs born during the preceding winter could fast for 4.2 ± 1.9 months. Thus, some pregnant or lactating females with lower levels of body fat content were already approaching or beyond the constraint of being able to produce cubs and survive the required 8 months of fasting if producing new offspring or 4 months if accompanied by older offspring. Pregnant or lactating females and their dependent offspring have the most tenuous future as global warming occurs. Thus, we predict a significant reduction in productivity with even modest increases in global warming for polar bears living in the very southern part of their range and are concerned about more northern populations depending on their ability to accumulate increasing amounts of fat.

Species of management concern that have been affected by human activities typically are characterized by low genetic diversity, which can adversely affect their ability to adapt to environmental changes. We used 18 microsatellite markers to genotype 362 Florida manatees (Trichechus manatus latirostris), and investigated genetic diversity, population structure, and estimated genetically effective population size (N_e). The observed and expected heterozygosity and average number of alleles were 0.455 ± 0.04, 0.479 ± 0.04, and 4.77 ± 0.51, respectively. All measures of Florida manatee genetic diversity were less than averages reported for placental mammals, including fragmented or nonideal populations. Overall estimates of differentiation were low, though significantly greater than zero, and analysis of molecular variance revealed that over 95% of the total variance was among individuals within predefined management units or among individuals along the coastal subpopulations, with only minor portions of variance explained by between group variance. Although genetic issues, as inferred by neutral genetic markers, appear not to be critical at present, the Florida manatee continues to face demographic challenges due to anthropogenic activities and stochastic factors such as red tides, oil spills, and disease outbreaks; these can further reduce genetic diversity of the manatee population.

Pacific walruses (Odobenus rosmarus divergens) occupying shelf waters of Pacific Arctic seas migrate during spring and summer from 3 breeding areas in the Bering Sea to form sexually segregated nonbreeding aggregations. We assessed genetic relationships among 2 putative breeding populations and 6 nonbreeding aggregations. Analyses of mitochondrial DNA (mtDNA) control region sequence data suggest that males are distinct among breeding populations (Φ_ST = 0.051), and between the eastern Chukchi and other nonbreeding aggregations (Φ_ST = 0.336–0.449). Nonbreeding female aggregations were genetically distinct across marker types (microsatellite F_ST = 0.019; mtDNA Φ_ST = 0.313), as was eastern Chukchi and all other nonbreeding aggregations (microsatellite F_ST = 0.019–0.035; mtDNA Φ_ST = 0.386–0.389). Gene flow estimates are asymmetrical from St. Lawrence Island into the southeastern Bering breeding population for both sexes. Partitioning of haplotype frequencies among breeding populations suggests that individuals exhibit some degree of philopatry, although weak. High levels of genetic differentiation among eastern Chukchi and all other nonbreeding aggregations, but considerably lower genetic differentiation between breeding populations, suggest that at least 1 genetically distinct breeding population remained unsampled. Limited genetic structure at microsatellite loci between assayed breeding areas can emerge from several processes, including male-mediated gene flow, or population admixture following a decrease in census size (i.e., due to commercial harvest during 1880–1950s) and subsequent recovery. Nevertheless, high levels of genetic diversity in the Pacific walrus, which withstood prolonged decreases in census numbers with little impact on neutral genetic diversity, may reflect resiliency in the face of past environmental challenges.

The foraging behavior of the western pygmy-possum (Cercartetus concinnus) was investigated at Innes National Park (INP), South Australia, in the context of understanding survival strategies in a variable environment. Individual C. concinnus were radiotracked continuously for periods of up to 9 days over a 1-year period. Movements, timing of activity, and use of food trees were recorded, as well as information on availability of floral resources. Nectar feeding was the most common feeding behavior when the nectar of Eucalyptus spp. was available. Eucalyptus rugosa was the preferred food source; other myrtaceous species were used when flowers of E. rugosa were unavailable and possums switched to sap and lerp when nectar was scarce. Movement patterns of C. concinnus varied seasonally and among individual animals. C. concinnus was capable of traveling long distances of up to 4.7 km in a single night in search of resources. Areas of use tended to be larger when E. rugosa was flowering (up to 300 ha), but possums also undertook long-distance travel to reach resources when nectar was rare. These long-distance movements suggest that the home ranges of C. concinnus can be several hundred hectares in size. C. concinnus at INP rely on long-distance movements, diet-switching, floristically and structurally diverse habitats, and torpor to cope with temporal and spatial fluctuations in resource availability.

Neotropical ungulates are poorly understood with regard to age-specific mortality and how it relates to different mortality causes. During January 2008–April 2011, we investigated mortality patterns of calf (<1 year old) and adult vicuñas (Vicugna vicugna) in west-central Argentina. Specifically, we analyzed whether birth mass, birth date, and sex of radiomarked vicuña calves affected 1st-year survival; quantified cause of death for marked calves and unmarked adults; and explored how primary productivity and quality of forage and diet related to body condition of adult vicuña carcasses. Birth mass was a strong predictor of 1st-year survival: a 1-kg (∼18%) increase in birth mass resulted in a 54% decline in the risk of death. Further, low survival rate in 1 calendar year was associated with low mean birth mass during that year, but not with population density and forage quality in the previous year. Puma (Puma concolor) predation accounted for ≥49% (n = 93) and 91% (n = 89) of the mortality in calves and adults, respectively. Body condition of adult vicuñas killed by pumas varied seasonally and correlated with seasonal changes in primary productivity and forage and diet quality. Our results highlighted the importance of puma predation and low birth mass as proximate causes of vicuña mortality. How environmental factors (e.g., early summer precipitation) influence forage and ultimately mortality has yet to be determined.

En ungulados Neotropicales, la relación entre la mortalidad especifica por edades y sus causas ha sido poco estudiada. Entre enero de 2008–abril 2011, investigamos los patrones de mortalidad de crías (<1 año de edad) y adultos de vicuñas (Vicugna vicugna) en el Parque Nacional San Guillermo, ubicado en los Andes centrales de Argentina. En este trabajo analizamos la relación entre el peso al nacer, la fecha de nacimiento y el sexo de las crías con la probabilidad de supervivencia durante el primer año de vida; cuantificamos las causas de muerte en crías y adultos; y exploramos la relación entre la productividad primaria, calidad del forraje y calidad de la dieta y el estado nutricional de las carcasas de vicuñas adultas. El peso al nacer fue un buen indicador de la supervivencia durante el primer año de vida: un incremento de 1-kg (∼18%) en el peso al nacer resultó en una declinación del 54% en el riesgo de muerte. Adicionalmente, un bajo promedio del peso al nacer en un año estuvo asociado con una baja tasa de supervivencia durante ese año, pero no con la densidad poblacional ni calidad del forraje en el año previo. La depredación por puma (Puma concolor) explicó ≥49% (n = 93) y 91% (n = 89) de la mortalidad en crías y adultos, respectivamente. La condición corporal de las vicuñas adultas cazadas por pumas varió estacionalmente. Este patrón estuvo asociado con cambios estacionales en la productividad primaria, la calidad del forraje y la calidad de la dieta en vicuñas. La influencia de factores ambientales (e.g., precipitación al inicio del verano) sobre el forraje y, en ultima instancia, la mortalidad todavía debe ser determinada.

Understanding social relationships and organization in colonial bat species can provide valuable insight into species ecology and potentially aid in conservation efforts of rare bat species. We applied social network analysis to describe social relationships and organization in 3 colonies of Rafinesque's big-eared bats (Corynorhinus rafinesquii) roosting in bottomland hardwood forests in Kentucky. We radiotracked 48 adult big-eared bats to 64 day-roosts over 549 bat-days during the summers of 2009–2011. We measured homophily, network centralization, density, transitivity, and core–periphery structure of networks of bats sharing common roosts, and we measured degree centrality of nodes (bats or roosts) within networks. Patterns of ties within each colony were homophilous by sex (E-I index = −0.87). Males were consistently the least central nodes in bat networks. Bat network centralization ranged from 1.2% to 40% among colonies, and roost network centralization ranged from 17% to 40%. The colony exhibiting the least centralized and most dense bat network also occupied habitat with low roost availability. This roost network was highly centralized, with bats frequently aggregating at a single roost. The colony with the most centralized and least dense bat network occupied habitat with a greater availability of roosts, resulting in diffuse networks of bats and roosts. Transitivity decreased after young became volant in the colony with highest roost availability. Our findings suggest that social structure in colonies of Rafinesque's big-eared bats is affected by the sex of individuals in colonies, reproductive season, and the preponderance of available day-roosting habitat.

We examined population density of Oligoryzomys longicaudatus (colilargo) and prevalence of Andes virus (ANDV) antibody at regional and landscape spatial scales in northwestern Chubut Province (Argentina) and contrasted it with climatic variables recorded by meteorologic stations near the study area. Mice were trapped in late summer–early fall (March–April) for 3 years (2007–2009). The composition of the rodent assemblage and species representation in the community varied among years, regions (forest, ecotone, and steppe), and landscape units (Nothofagus and Austrocedrus forests, sweet briar shrublands, and without sweet briar shrublands). Colilargos occurred in all regions and landscape units within the study area, from dense forest to open habitats such as steppe. The species dominated the rodent assemblages of ecotone and forest at a regional scale and the assemblages in sweet briar shrublands and Austrocedrus forests at a landscape scale. Abundance of colilargos also varied among periods, regions, and landscape units. Antibodies to ANDV were found in all regions but not in every landscape unit. Thus there is a potential for human hantavirus pulmonary syndrome (HPS) cases to occur not only in forests and shrublands, but also in steppe. At a landscape scale, Nothofagus forests appeared to pose a higher risk than Austrocedrus in wet years, because colilargo abundance and ANDV antibody prevalence were significantly greater. Within ecotone, sweet briar shrublands posed greater risk than habitats without sweet briar. Sweet briar shrublands were the landscape unit with the highest colilargo abundances during the driest periods. Sweet briar shrublands may play an important role in HPS dynamics, and should be considered when designing prevention policies.

Nuestro objetivo fue examinar la densidad poblacional de Oligoryzomys longicaudatus (colilargo) y la prevalencia de virus Andes (ANDV) a escala regional y de paisaje en el noroeste de la provincia de Chubut, Argentina. Los muestreos se llevaron a cabo durante el verano tardío–otoño temprano (Marzo–Abril) por un período de 3 años (2007 a 2009). La composición de la comunidad de roedores y la representación de cada especie en la misma varió entre años, regiones (bosque, ecotono y estepa) y unidades de paisaje (bosques de Nothofagus y de Austrocedrus, matorrales de rosa mosqueta y matorrales sin rosa mosqueta). O. longicaudatus fue encontrado en todas las regiones y unidades de paisaje del área de estudio. Esta especie dominó los ensambles de roedores de bosques y ecotono a escala regional y los ensambles de los matorrales de rosa mosqueta y bosques de Austrocedrus a escala de paisaje. La abundancia de colilargos varió entre períodos, regiones y unidades de paisaje. Se detectaron anticuerpos contra ANDV en todas las regiones, pero no en todas las unidades de paisaje. Por lo tanto, el riesgo de enfermedad en humanos existe no sólo en bosque y ecotono, sino también en estepa. Además, a escala de paisaje, los bosques de Nothofagus parecieron implicar un mayor riesgo que los de Austrocedrus en años húmedos, ya que las abundancias de colilargos y la prevalencia de ANDV fueron significativamente mayores en los primeros. Dentro del ecotono, los matorrales de rosa mosqueta significaron un mayor riesgo que los matorrales sin rosa mosqueta. Los primeros constituyeron la unidad de paisaje con las mayores abundancias de colilargos durante los períodos secos. Estos matorrales podrían tener un papel importante en la dinámica del Síndrome Pulmonar por Hantavirus y debieran ser considerados a la hora de diseñar medidas de prevención.