Home ranges relate to all aspects of a mammal's biology. The 5 papers in this Special Feature provide statistical, economic, game theoretic, mechanistic, information dependent, and conceptual approaches to understanding home ranges and why animals have them. All the papers emphasize the importance of testing a priori hypotheses, especially hypotheses that elucidate why animals behave as they do. All the papers relate resources and habitat quality to home ranges. Finally, the authors oppose viewing home ranges as the product of measurements and suggest viewing home ranges as the cognitive maps that animals maintain and update.

Statisticians frequently voice concern that their interactions with applied researchers start only after data have been collected. The same can be said for our experience with home-range studies. Too often, conversations about home range begin with questions concerning estimation methods, smoothing parameters, or the nature of autocorrelation. More productive efforts start by asking good (and interesting) research questions; once these questions are defined, it becomes possible to ask how various design and analysis strategies influence one's ability to answer these questions. With this process in mind, we address key sample-design and data-analysis issues related to the topic of home range. The impact of choosing a particular home-range estimator (e.g., minimum convex polygon, kernel density estimator, or local convex hull) will be question dependent, and for some problems other movement or use-based metrics (e.g., mean step lengths or time spent in particular areas) may be worthy of consideration. Thus, we argue the need for more question-driven and focused research and for clearly distinguishing the biological concept of an animal's home range from the statistical quantities one uses to investigate this concept. For comparative studies, it is important to standardize sampling regimes and estimation methods as much as possible, and to pay close attention to missing data issues. More attention should also be given to temporally changing space-use patterns, with biologically meaningful time periods (e.g., life-history stages) used to define sampling periods. Last, we argue the need for closer connections between theoretical and empirical researchers. Advances in ecological theory, and its application to natural resources management, will require carefully designed research studies to test theoretical predictions from more mechanistic modeling approaches.

The coming of age of global positioning system telemetry, in conjunction with recent theoretical innovations for formulating quantitative descriptions of how different ecological forces and behavioral mechanisms shape patterns of animal space use, has led to renewed interest and insight into animal home-range patterns. This renaissance is likely to continue as a result of ongoing synergies between these empirical and theoretical advances. In this article I review key developments that have occurred over the past decade that are furthering our understanding of the ecology of animal home ranges. I then outline what I perceive as important future directions for furthering our ability to understand and predict mammalian home-range patterns. Interesting directions for future research include improved insights into the environmental and social context of animal movement decisions and resulting patterns of space use; quantifying the role of memory in animal movement decisions; and examining the relevance of these advances in our understanding of animal movement behavior and space use to questions concerning the demography and abundance of animal populations.

Economic models predict behavior of animals based on the presumption that natural selection has shaped behaviors important to an animal's fitness to maximize benefits over costs. Economic analyses have shown that territories of animals are structured by trade-offs between benefits gained from resources and costs of defending them. Intuitively, home ranges should be similarly structured, but trade-offs are difficult to assess because there are no costs of defense, thus economic models of home-range behavior are rare. We present economic models that predict how home ranges can be efficient with respect to spatially distributed resources, discounted for travel costs, under 2 strategies of optimization, resource maximization and area minimization. We show how constraints such as competitors can influence structure of homes ranges through resource depression, ultimately structuring density of animals within a population and their distribution on a landscape. We present simulations based on these models to show how they can be generally predictive of home-range behavior and the mechanisms that structure the spatial distribution of animals. We also show how contiguous home ranges estimated statistically from location data can be misleading for animals that optimize home ranges on landscapes with patchily distributed resources. We conclude with a summary of how we applied our models to nonterritorial black bears (Ursus americanus) living in the mountains of North Carolina, where we found their home ranges were best predicted by an area-minimization strategy constrained by intraspecific competition within a social hierarchy. Economic models can provide strong inference about home-range behavior and the resources that structure home ranges by offering falsifiable, a priori hypotheses that can be tested with field observations.

Animals concentrate their activities within areas we call home ranges because information about places increases fitness. Most animals, and certainly all mammals, store information about places in cognitive maps—or neurally encoded representations of the geometric relations among places—and learn to associate objects or events with places on their map. I define the value of information as a time-dependent increment it adds to any appropriate currency of fitness for an informed versus an uninformed forager, and integrate it into simple conceptual models that help explain movements of animals that learn, forget, and use information. Unlike other space-use models, these recognize that movement decisions are based on an individual's imperfect and ever-changing expectancies about the environment—rather than omniscience or ignorance. Using simple, deterministic models, I demonstrate how the use of such dynamic information explains why animals use home ranges, and can help explain diverse movement patterns, including systematic patrolling or “traplining,” shifting activity or focal areas, extra-home-range exploration, and seemingly random (although goal-directed and spatially contagious) movements. These models also provide insights about interindividual spacing patterns, from exclusive home ranges (whether defended as territories or not) to broadly overlapping or shared ranges. Incorporating this dynamic view of animal expectancies and information value into more-complex and realistic movement models, such as random-walk, Bayesian foraging, and multi-individual movement models, should facilitate a more comprehensive and empirical understanding of animal space-use phenomena. The fitness value of cognitive maps and the selective exploitation of spatial information support a general theory of animal space use, which explains why mammals have home ranges and how they use them.

“Home range” is a standard concept in animal ecology and behavior but few people try to understand what home ranges mean to the animals that have them and often assume that a home-range estimate, quantified using some method, is the home range. This leads to 2 problems. First, researchers put much energy into discerning and using the “best” methods for estimating home ranges while no one understands, really, what a home range is. Second, maps delineating home-range estimates may have little connection with what home ranges are and what they mean to the animals that have them. To gain insight into these problems, Roger Powell (hereafter, Roger) documented his own use of space for 65 days, obtaining complete data on where he went, what he did, and how much energy and money he expended and gained in each place. Roger's use of space is consistent with how other mammals use space and, therefore, examination of his data provides insight into what a home range is and how ecologists should approach quantifying other animals' home ranges. We present estimates of Roger's home range in 5 different metrics, or currencies, that provide important and different insights. Home-range estimators that combine different types of information to estimate the spatial distribution and qualities of resources that structure animal behavior (i.e., fitness surfaces) will probably provide the most insight into animals' home ranges. To make reasonable estimates of home ranges, researchers must collect data on habitat, resources, and other attributes of the landscape, so that they can understand basic behaviors of animals and understand how animals may view their environment. We propose that the best concept of a home range is that part of an animal's cognitive map of its environment that it chooses to keep updated.

Forest fragmentation demonstrably alters plant species composition, distribution, and diversity, and, in turn, may affect the availability of food resources for primary consumers. We investigated to what extent fragmentation affected the diets of 6 groups of bearded saki monkeys (Chiropotes chiropotes) living in two 10-ha fragments, two 100-ha “fragments” that were no longer fully isolated, and 2 areas of continuous forest in central Amazonia. When changes occurred we tested whether differences in diet were due to plant species availability by comparing the prevalence of consumed items against their relative abundance at the 6 sites. In total, the monkeys consumed fruits, seeds, flowers, and leaves of 244 plant species, of which less than 2% were shared among all 6 groups. Although there was a positive correlation between relative abundance of diet species and consumption frequency, monkeys did not eat all available potential resources, and groups inhabiting the 10-ha fragments consumed items that were ignored in larger forested areas. Our findings suggest that bearded sakis living in small forest fragments are limited in their dietary choices as a consequence of the reduced number of plant species present, and therefore consume species that monkeys inhabiting continuous forests typically can ignore. We conclude that the ability to consume a diverse diet that includes seeds and unripe fruit helps this species survive in forest fragments, but it appears that these conditions are unviable unless connectivity increases among the forest fragments and continuous forest in the landscape.

Comprovadamente a fragmentação florestal altera a composição das espécies de plantas, sua distribuição e diversidade, afetando por sua vez a disponibilidade de recursos para consumidores primários. Neste contexto, investigamos se a fragmentação florestal afetou as dietas de 6 grupos de macaco-cuxiú (Chiropotes chiropotes) presentes em 2 fragmentos florestais de 10 ha isolados, 2 de 100 ha parcialmente isolados, e em 2 áreas de mata contínua na Amazônia Central. Quando mudanças foram detectadas, nós testamos se as diferenças nas dietas foram relacionadas à disponibilidade de recursos, comparando a prevalência de itens consumidos em relação à sua abundância relativa nos 6 sítios amostrados. No total, os macacos consumiram frutos, sementes e flores de 244 espécies vegetais, das quais menos de 2% foram consumidas por todos os 6 grupos. Embora houve uma correlação positiva entre abundância relativa de espécies utilizadas na dieta e frequência de consumo, os macacos não utilizaram todas as espécies de plantas disponíveis no ambiente, e grupos habitantes de fragmentos de 10 ha consumiram recursos que foram ignorados pelos demais em ambientes florestais de maior porte. Nossos resultados sugerem que cuxiús que habitam pequenos fragmentos florestais são limitados em suas escolhas alimentares em consequência do número reduzido de espécies vegetais presentes e, como consequência, consomem espécies de plantas que são ignoradas pelos que habitam floresta contínua. Nós concluímos que a capacidade de utilizar uma dieta diversa, como sementes e frutos imaturos, contribui para que este primata sobreviva em fragmentos florestais. No entanto, esta condição nos parece viável somente se houver maior conectividade entre os fragmentos e florestas contínuas dentro da paisagem.

We studied mountain lions (Puma concolor) and mule deer (Odocoileus hemionus) inhabiting a Great Basin ecosystem in Round Valley, California, to make inferences concerning predator–prey dynamics. Our purpose was to evaluate the relative role of top-down and bottom-up forcing on mule deer in this multiple-predator, multiple-prey system. We identified a period of decline (by 83%) of mule deer (1984–1990), and then a period of slow but steady increase (1991–1998). For mule deer, bitterbrush (Purshia tridentata) in diets, per capita availability of bitterbrush, kidney fat indexes, fetal rates (young per adult female), fetal weights, and survivorship of adults and young indicated that the period of decline was typical of a deer population near or above the carrying capacity (K) of its environment. Numbers of mountain lions also declined, but with a long time lag. The period of increase was typified by deer displaying life-history characteristics of a population below K, yet the finite rate of growth (λ = 1.10) remained below what would be expected for a population rebounding rapidly toward K (λ = 1.15–1.21) in the absence of limiting factors. Life-history characteristics were consistent with the mule deer population being regulated by bottom-up forcing through environmental effects on forage availability relative to population density; however, predation, mostly by mountain lions, was likely additive during the period of increase and thus, top-down forcing slowed but did not prevent population growth of mule deer. These outcomes indicate that resource availability (bottom-up processes) has an ever-present effect on dynamics of herbivore populations, but that the relationship can be altered by top-down effects. Indeed, top-down and bottom-up forces can act on populations simultaneously and, thus, should not be viewed as a stark dichotomy.

Knowledge of population boundaries and long-distance movements is important for wildlife conservation. We used genetic tools to investigate genetic diversity, population structure, and movements of mountain lions (Puma concolor) in Texas. We amplified 11 microsatellite loci for 245 individuals collected during 1985–2010 from Texas and New Mexico. Bayesian clustering and values of F_ST suggested a partitioning of mountain lions into 3 genetically differentiated groups, New Mexico, western Texas, and southern Texas. New Mexico and western Texas exhibited moderate levels of genetic diversity (expected heterozygosity [H_E] = 0.61 and 0.58, respectively), whereas diversity in southern Texas was lower (H_E = 0.47). Southern Texas displayed elevated genetic structure when compared to western Texas and New Mexico (F_ST = 0.102–0.148), whereas the comparison between New Mexico and western Texas revealed less subdivision (F_ST = 0.056). We documented long-distance movement among regions, and New Mexico and western Texas were sources for putative dispersers we sampled outside known populations. Differences in genetic structure and diversity between southern and western Texas support the designation of separate management units. Southern Texas appears isolated and further investigation is needed to determine the current population status. Mountain lion populations in New Mexico and western Texas may be important for future recolonization into portions of the southern United States.

We studied gray wolf (Canis lupus) homesite attendance rates using global positioning system locations of 17 GPS-radiocollared wolves from 7 packs in Idaho. Nonbreeding wolves attended homesites more once pups were weaned and we hypothesize this is a behavior that benefits subsequent pup-rearing. The breeding status and sex of the wolf was the strongest predictor of homesite attendance in the preweaning period but the dominant predictor postweaning was the number of helpers in the pack. We estimated that each additional helper in a pack decreased an individual's attendance rate by 7.5%. Because helpers can either attend or provision pups, our results suggest that small packs invest in protecting pups at the expense of having additional adults foraging.

In this study 308 milk samples were collected and analyzed from 181 individual female New Zealand sea lions (NZ sea lions; Phocarctos hookeri) breeding on Enderby Island (Auckland Islands). Samples were collected from the 1st part of early lactation (January and February) over a period of 7 years (1997, 1999–2003, and 2005). The effect of year, month, and maternal characteristics (body mass, body condition index [BCI], and age class) on the composition of milk was evaluated using a mixed model for repeated measures. The gross composition (± SD) of the milk was lipid (21.3% ± 8.1%), protein (9.4% ± 2.4%), water (67.9% ± 8.8%), ash (0.48% ± 0.06%), and energy content (10.3 ± 3.2 kJ/g). Overall, the quality of milk of the NZ sea lions in this study was relatively lower in solids and fats than that of other pinnipeds and, in particular, other sea lion species. There were significant effects of year and month on the concentration of lipids in milk, and of year and maternal age class on maternal body mass and BCI. There were significant relationships between various maternal characteristics and milk composition. Thus, the concentration of milk lipids was significantly correlated with maternal BCI, body mass, and pup age. Given that NZ sea lions are a nationally critical species in decline, the relationship between the temporal (yearly and monthly) variations in milk composition, maternal body mass, reproductive success, and changes in food supply in relation to natural perturbations or fisheries resource competition warrants further investigation to disentangle this relationship and implement appropriate management initiatives.

We conducted an 11-year comparative study on temporal variation in rodent density, biomass, and species composition dynamics from adjacent grassland and shrubland environments in the Chihuahuan Desert of North America, in relation to rainfall and plant production. We found that rodent assemblages from those environments were only 14% similar in overall species composition, but consisted of different species in the same genera with similar ecological attributes. Each rodent community was numerically dominated by a different species of granivorous kangaroo rat, and the 2 rodent communities paralleled each other in body sizes and trophic structure. Rodent species compositions changed little over the 11-year period, despite considerable variation in rodent densities and biomass and in rainfall and plant production. Rodent abundance and biomass from both communities increased in relation to temporally variable rainfall and plant production, especially resulting from a series of El Niño and La Niña Southern Oscillation events. However, the grassland rodent community exhibited more rapid within-1-year lag-time responses to plant production, and prolonged high densities for 1 year before declining, whereas the shrubland rodent community exhibited primarily 1-year lag responses and immediate rapid decline in densities. Changes in rodent densities and biomass from both communities were significantly predicted by the production of annual grasses and forbs. Measured rodent reproductive activity was greater and happened sooner after rain and plant production events at the grass site than at the shrub site, and differences in the timing of rodent bottom-up responses between the grassland and shrubland habitats appeared to result from differences in the reproductive potentials of the 2 dominant rodent species. Dipodomys ordii, the dominant grassland rodent species, is known to produce more offspring than Dipodomys merriami, the dominant rodent in the shrubland community. We conclude that differences in the reproductive potentials of these 2 dominant rodent species likely accounted for the quicker and prolonged response of the grassland rodent community to bottom-up influences, rather than differences in the timing of plant production between the sites. Variation in reproductive potentials among rodent communities is likely a key factor affecting the timing of overall rodent community dynamics relative to changes in environmental resources.

Numerous model systems have informed classical ideas of the deterministic structure of natural communities. Although a number of important insights have been gained from desert rodents, little is known regarding the relative role of local environmental and spatial processes that embody the emerging metacommunity paradigm in structuring these model systems. We compared patterns of community composition based on environmental characteristics and estimates of spatial isolation by distance to test predictions characterizing contemporary models of metacommunity structure. Analyses were based on rodent community structure at 31 sites within the Mojave Desert. Consistent with previous studies of rodent communities, local environmental characteristics accounted for a significant amount of variation in community structure. Nonetheless, spatial isolation by distance contributed significantly to structure as well, even after accounting for the shared effect between environmental and spatial descriptors. Indeed, regional collections of rodent communities represent metacommunities and a metacommunity perspective promises to complement much that has been learned from primarily local perspectives. Examination of data suggested that the mass effects model of metacommunity structure may best describe regional patterns of species composition, at least for this data set. Moreover, 2 further important insights emerge from analyses. First, important life-history differences among taxa translate into different spatial effects that are likely due to dispersal abilities. Second, despite the spatially uncorrelated nature of environmental variation across our sampling array much of the structure of this metacommunity could be attributed to the shared effects of spatial and environmental characteristics. Typically, empirical analyses of metacommunity structure have attributed this variation to spatial structure generated by environmental spatial autocorrelation, but our analyses suggested that this component of variation may to some degree represent a unique yet underappreciated spatial effect. Moreover, this substantive component of variation suggests that prior analyses of empirical metacommunity structure provide conservative estimates of regional spatial effects and that the role of dispersal in determining metacommunity structure may be greater than is commonly considered.

Golden mice (Ochrotomys nuttalli) occur throughout the southeastern United States, and are on the periphery of their geographic range in southern Illinois, where they are a state-listed threatened species. We assessed relative abundance and distribution of populations of golden mice in southern Illinois by mark–recapture and occupancy models, and throughout the core geographic distribution to determine if they should be removed from threatened status (delisted). We also tested the “abundant-center” hypothesis that states that occurrence and abundance of a species is greater in the core of the range than at the periphery. We captured golden mice in 21 of 24 sites in southern Illinois, but only 13 of 24 sites in the core of the range. The total number of individual golden mice captured in southern Illinois (n = 99) was 3.3 times greater (χ²₁ = 36.91, P < 0.001) than in the core (n = 30). Habitat factors at sites (mean number of climbing vines, woody stems, and herbaceous stems) affected occupancy of golden mice; no model variables affected occupancy of sympatric Peromyscus. Based on occupancy models, the probability of capturing golden mice was not affected by occurrence of the potential interspecific competitors white-footed mice (Peromyscus leucopus) or cotton mice (P. gossypinus). Our results for occurrence and abundance of golden mice at the periphery of their range in Illinois do not support the abundant-center hypothesis.

When isolated, pups of muroid rodents emit ultrasonic vocalizations, an indication that they are stressed by being alone and exposed to cooling temperatures. Rate of vocalizations is greatest at the end of their 1st week and beginning of the 2nd week, declines in the 2nd week as eyes open and thermoregulation becomes fully established, and ceases in the 3rd week. Young of 1 vole species, the prairie vole (Microtus ochrogaster), vocalize significantly more than those of other species, which has been attributed to the social structure of the species, because they have monogamous mating behavior and high level of biparental care. To determine whether this vocalizing behavior is typical of vole species with monogamous social systems, I examined calling behavior in another monogamous species with biparental care, the pine (or woodland) vole (M. pinetorum), and I compared it to that of a polygynous species that has only maternal care, the meadow vole (M. pennsylvanicus). Pups were isolated for 20 min at 22°C ± 2°C and the number of ultrasonic calls they emitted was monitored. Pine vole pups vocalized at high rates, similar to prairie voles, emitting a mean of 47 calls/min at the ages when calling was greatest (8–16 days). In contrast, meadow vole pups vocalized significantly less, emitting a mean of 9 calls/min at the age of greatest calling (5–9 days). Pine voles continued vocalizing to 23 days, like prairie voles but different from other vole species, including meadow voles, which cease calling earlier. I conclude that young voles of monogamous species, which are highly affiliative and have paternal as well as maternal care, respond to the stress of isolation more strongly than do other vole species and emit more ultrasonic vocalizations than species that are less social and have less parental care.

The Perote ground squirrel (Xerospermophilus perotensis) is endemic to Mexico and is currently at risk of extinction. Its original range comprised 5,250 km² in an area known as the Oriental Basin, between the states of Puebla and Veracruz. By the end of the 20th century, however, extensive agricultural practices, overgrazing, and urbanization had already restricted suitable habitat for this species to only 16 localities. Temporal changes in genetic diversity and structure in this species were assessed from 34 museum specimens from 5 historical populations (1990–1992) and 44 individuals from 3 current populations (2007) using the mitochondrial (mtDNA) control region and 5 nuclear microsatellites. We observed a general trend (significant in some cases and nonsignificant in others) suggesting a decrease in genetic diversity within populations and an increase in genetic structure between them in recent years for both sets of markers. A Bayesian skyline reconstruction for the mtDNA sequences was congruent with a recent demographic decline scenario. If genetic drift is the predominant evolutionary force in Perote ground squirrels, then the loss of genetic diversity could intensify in a few generations even if the effective population sizes remain constant. Urgent measures to increase the effective population sizes and maintain the genetic cohesion among populations are critical to the conservation of this species. Because no protected areas are planned in the Oriental Basin, we suggest translocating individuals between populations to avoid further loss of genetic diversity in the short run. In the long run, however, it will be necessary to devise a strategy to introduce individuals into suitable patches of habitat and to spatially link these populations so that genetic exchange can take place without the need for management assistance.

La ardilla terrestre del Perote (Xerospermophilus perotensis) es endémica de México y actualmente se encuentra en peligro de extinción. Su distribución original comprendía 5,250 km² en un área conocida como el Valle del Oriental, entre los estados de Puebla y Veracruz. No obstante, a finales del siglo XX actividades como la agricultura extensiva, el sobrepastoreo y la urbanización ya habían restringido el hábitat tipo de esta especie a sólo 16 localidades. Cambios temporales en la diversidad y estructura genética en esta especie fueron evaluados en 34 ejemplares de museo de 5 poblaciones históricas (1990–1992) y 44 individuos de 3 poblaciones actuales (2007) utilizando la región control mitocondrial (ADNmt) y 5 microsatélites nucleares. Observamos una tendencia general (significativa en algunos casos y no significativa en otros) indicando una reducción en diversidad genética dentro de las poblaciones y un aumento en estructura genética entre ellas en años recientes para ambos juegos de marcadores. Una reconstrucción Bayesiana de horizonte para las secuencias de ADNmt fue congruente con un escenario de reducción demográfica reciente. Si la deriva génica es la fuerza predominante en las ardillas terrestres del Perote, entonces la pérdida de diversidad genética podría intensificarse en algunas generaciones aún si los tamaños efectivos poblacionales se mantienen constantes. Medidas urgentes para incrementar los tamaños efectivos poblacionales y mantener la cohesión genética entre las poblaciones son críticas para la conservación de esta especie. Debido a que no existen planes para crear áreas protegidas en el Valle del Oriental sugerimos translocar individuos entre poblaciones para evitar una mayor pérdida de diversidad genética en el corto plazo. En el largo plazo, sin embargo, se requiere estructurar una estrategia para introducir individuos en parches de hábitat tipo y vincular espacialmente estas poblaciones para que el intercambio genético se lleve a cabo sin asistencia de manejo.

Gunnison's prairie dogs (Cynomys gunnisoni) are rare, diurnal, colonial, burrowing, ground-dwelling squirrels. Studies of marked individuals living under natural conditions in the 1970s, 1980s, and 1990s showed that males are heavier than females throughout the year; that adult females living in the same territory are consistently close kin; and that females usually mate with the sexually mature male(s) living in the home territory. Research from 2007 through 2010 challenges all 3 of these findings. Here we discuss how different methods might have led to the discrepancies.

Establishing status and trend for an endangered species is critical to recovery, especially when it is faced with a nascent extinction agent. We calculated, with hierarchical log-linear change-point models, hibernaculum-level population trends between 1983 and 2009 for the endangered Indiana bat (Myotis sodalis) now subjected to the fast-spreading fungal disease white-nose syndrome. We combined trends from 222 wintering populations before and after onset of the disease to determine trend for clusters of interacting wintering populations, recovery units, and the species. Before onset of the disease, a west-to-east gradient in trends existed, with westernmost populations declining and easternmost populations increasing in abundance. The species as a whole, however, was stationary between 1983 and 2005 (−0.5% mean annual change; 95% confidence interval [CI] = −2.8, 1.8%). Estimated mean population size in 2009 was 377,124 bats (195,398–957,348), with large variance apparently caused by white-nose syndrome. With the onset of white-nose syndrome (2006–2009), the species exhibited a 10.3% annual decline (95% CI = −21.1, 2.0%). White-nose syndrome is having an appreciable influence on the status and trends of Indiana bat populations, stalling and in some cases reversing population gains made in recent years.

Geophagy is a widespread behavior among plant-eating animals. In the Neotropics, mineral licks are activity hot spots for frugivorous bats (Stenodermatinae). Bats drink mineral-rich water accumulated in soil depressions made by geophagous mammals. Two mechanistic hypotheses have been proposed to explain this behavior: licks are reliable sources of limiting nutrients, especially sodium; and licks provide substances that render dietary toxins less harmful. We assessed the former by examining bats' diets in conjunction with lick chemistry in the Peruvian Amazon. We found that most bats that visit licks belong to the subfamily Stenodermatinae and are specialists on Ficus fruits—a keystone resource. In addition, although Ficus fruits are good sources of some minerals, their sodium content is limited in relation to the physiological requirement of a small mammal. In contrast, bats of the subfamily Carolliinae supplement their fruit diets with insects, potential sources of sodium. Complementary results among diets, Ficus chemistry, and lick-water chemistry strongly support the sodium-limitation hypothesis for bat lick use and suggest a mechanistic link between bats and ecosystem engineers that make soil-borne resources available. Because sodium is an essential nutrient for vertebrates and Ficus is a keystone resource for many animal species, our results may have implications for the community of frugivorous vertebrates in areas where sodium is limited. Licks may play a critical role as sodium sources and thus they should be considered as important conservation targets.

La geofagia es un comportamiento común entre animales que se alimentan de plantas. En los Neotrópicos, los saladeros, llamados también collpas, son centros de actividad de los murciélagos frugívoros (Stenodermatinae). Estos murciélagos toman agua con alto contenido de minerales que se acumulan en las depresiones hechas por mamíferos geófagos terrestres. Dos hipótesis mecanísticas han sido propuestas para explicar este comportamiento: los saladeros son fuentes confiables para suplementar nutrientes limitados, especialmente sodio; y los saladeros proveen sustancias que hacen las toxinas de la dieta menos dañinas. Nosotros evaluamos la primera hipótesis a través de un análisis de la dieta de los murciélagos en conjunto con la química de los saladeros en la Amazonía peruana. Encontramos que la mayoría de los murciélagos que visitan los saladeros pertenecen a la subfamilia Stenodermatinae y que son especialistas en Ficus – un recurso clave. Además, encontramos que a pesar de que los frutos de Ficus en el sureste peruano son buenas fuentes de algunos minerales, sus contenidos de sodio son limitados en relación a los requerimientos fisiológicos de un mamífero pequeño. Por otro lado, murciélagos de la subfamilia Carolliinae complementan sus dietas de frutas con insectos, una fuente potencial de sodio. Los resultados complementarios entre la dieta de los murciélagos, la química de Ficus, y la química del agua de los saladeros apoyan fuertemente la hipótesis de la limitación de sodio para explicar el uso de saladeros por murciélagos y además sugieren una relación estrecha entre estos murciélagos y los ingenieros de ecosistemas terrestres que mantienen los saladeros disponibles. Debido a que el sodio es un nutriente esencial para los vertebrados y el Ficus es un recurso clave para muchas especies animales, nuestros resultados pueden tener implicancias para la comunidad de vertebrados frugívoros donde el sodio es limitado. Los saladeros podrían jugar un papel crítico como fuentes de sodio y por lo tanto deberían ser consideradas como recursos estratégicos de conservación.

We studied foraging behavior and habitat selection of barbastelle bats (Barbastella barbastellus) at two breeding colonies in southern England. In total, 28 adult female bats were radiotracked to determine home range use, habitat preferences, and patterns of nocturnal activity. Individual home ranges varied considerably, with bats traveling between 1 and 20 km to reach foraging areas (X̄ = 6.8 km ± 4.8 SD). Nonreproductive females foraged at greater distances than reproductive females, providing evidence of state-dependent foraging behavior. Commutes were typically rapid and direct and bats moved freely across large open areas. Individual bats foraged independently from one another and were highly faithful to their respective core foraging areas, which formed just a small fraction of home ranges. Riparian zones and broad-leaved woodland were habitats most strongly selected for foraging. Unimproved grassland and field margins were also important components of the foraging environment. Bats night-roosted only occasionally and for short periods. Conservation efforts for B. barbastellus should target the protection and enhancement of preferred foraging habitats within 7 km of roost sites. Linear landscape elements such as tree lines and hedgerows should be managed to improve their value to foraging bats and to enhance connectivity with roost sites.

Identifying and characterizing trophic linkages is fundamental to understanding how prey availability affects predator behavior, distribution, and density, and to elucidating the extent to which predators regulate prey populations. Vertebrate insectivores, such as bats, are a pervasive top-down force on insect populations in forest ecosystems. Bats are predators sensitive to habitat perturbations, whose prey selection behavior warrants further study. We identified trophic connections between a forest bat (Myotis septentrionalis) and its prey by isolating and sequencing cytochrome c oxidase subunit I gene (COI) fragments of insect prey obtained from bat fecal samples. Prey identities were inferred using GenBank and the Barcode of Life Data System (BOLD). We also identified prey remains morphologically from the same fecal samples, allowing comparisons across novel (GenBank and BOLD) and traditional (morphological) techniques. Lepidopterans were the most frequently detected prey in all approaches. Detection of common insect orders varied across procedures (P < 0.001), suggesting methodological bias at coarse taxonomic resolutions. Of the DNA-based approaches, GenBank provided the more diverse assessment of prey. We reveal trophic linkages for northern bats by identifying 20 prey genera and species using BOLD, more than one-half of which were smaller lepidopterans. The disproportionate number of smaller lepidopteran prey (mean [±SE] wingspan 24.2 ± 2.05 mm) exceeded expectations based on field-based assessments. M. septentrionalis is known to use both aerial-hawking and gleaning behaviors. Lepidopteran prey consumed by M. septentrionalis were smaller than reported for conspecfic genera, suggesting this species differentiates itself from sympatric insectivorous bats with the prey it selects.

Understanding mechanisms that influence the grouping tendencies of large herbivores is necessary to predict the influence of environmental and human factors on threatened populations. Locations of 53 adult female pronghorn (Antilocapra americana) in Yellowstone National Park during June 1999–April 2005 indicated that mean and typical group sizes and the variation in group size decreased during fawning when females secluded themselves, but became larger and more dynamic during fawn rearing and the rut and winter. Mixed-effects models indicated a strong effect of time of year on mean group sizes, with some evidence that predators negatively affected group sizes during winter. Within-animal variability (0.64) was substantially higher than between-animal variability (0.02). Pronghorn density, snow water equivalent, and predation apparently influenced variations in group size. Multiple regressions indicated effects of pronghorn density and snow water equivalent on typical group size, the size of the group in which the average animal finds itself. Overall, there was fluidity in group cohesion, with female associations changing within and among days. The behavioral plasticity of pronghorn with respect to grouping and social cohesion might confer resilience to changes in environmental conditions, but often makes it difficult to predict the consequences of conservation actions to control disease, protect or restore key habitat, regulate harvests, and limit adverse effects of development and recreation.

Most studies on the relationship between home-range size and composition focus on natural factors, whereas effects of anthropogenic factors are poorly understood. I evaluated effects of multiple natural and anthropogenic habitat factors, population density, and sex on the annual home-range size of red deer (Cervus elaphus) in well-preserved forest areas in the Dinaric Mountains of Slovenia, Europe, based on >11,000 telemetry locations from 17 males and 25 females. Home ranges were 90–2,107 ha and averaged 460 ha. Using a mixed linear model, I estimated that home-range size decreased with increasing 1) red deer density, 2) supplemental feeding intensity, and 3) average annual temperature; 4) home-range size increased as the distance of main roads from the edge of the home range increased; and 5) males had a larger home range than females (580 ha versus 400 ha). These results were explained by effects of food availability (1, 2, and 3), energy expenditure of an individual (4 and 5), intraspecific interactions (1 and 5), and size of unfragmented habitat patches (4) on home-range size. To my knowledge, this is the 1st large mammal study to explicitly show that the density and spatial distribution of roads and supplemental feeding affect home-range size of red deer and that humans can have a greater impact on home-range size and shape than natural habitat factors. Ungulates are often supplementally fed to increase their value to hunters and to reduce forest damage, particularly in Europe; however, this practice can greatly reduce the home-range size, potentially leading to increased disease transmission and competition associated with the higher deer densities around feeding sites, which can result in just the opposite of what was intended.

Antler traits are both genetically determined and environmentally influenced. However, the degree to which environmental factors affect antler expression has rarely been quantified. We captured 30 to 150 male white-tailed deer (Odocoileus virginianus) annually at 7 South Texas sites during 1985 to 2009 to determine repeatability of antler traits from a semiarid environment with variable rainfall. Repeatability is defined as the intraclass correlation between repeated measures of the same trait over time. Repeatability was moderate to high (0.42–0.82) for all antler traits. Overall, number of antler points had the lowest repeatability, whereas inside spread of main beams and length of main beams had the highest repeatability. Repeatability of total antler score and number of antler points from sites with variable rainfall was 16% and 24% lower than sites with consistent rainfall, respectively. Sites with variable rainfall had 13–18% higher repeatability when enhanced nutrition was available. Studies of cervids reveal a tendency for lower repeatability of antler traits as the environmental conditions become more variable. The association between repeatability and variable environmental conditions illustrates the magnitude of environmental effects and supports the role of antlers as an honest advertisement of individual condition or quality. Our results help to understand potential of microevolution in antlers and have implications for sexual selection and harvest management.

The white-tailed deer (Odocoileus virginianus) occurs over a broad latitudinal range from South America to Canada. Thirty-eight subspecies are recognized, 14 of which occur in Mexico. Genetic studies in Latin America are lacking and the diversity and structure of white-tailed deer in Mexico are unknown. We sampled white-tailed deer from 13 sites in the range of 5 subspecies occurring in Mexico, O. v. texanus, O. v. carminis, O. v. veraecrucis, O. v. sinaloae, and O. v. yucatanensis. We estimated genetic diversity and structure based on 12 microsatellite DNA loci. Observed heterozygosity (H_O) was comparable to that of white-tailed deer in the United States (H_O = 0.53–0.64), with the exception of O. v. yucatanensis (H_O = 0.41). We observed statistically significant genetic structure among all 13 sites (F_ST = 0.15). Analysis of molecular variance revealed that grouping sites by subspecies (F_SC = 0.09) or geographic region (F_SC = 0.13–0.14) explained a moderate portion of genetic variation. However, no higher-level group minimized differentiation among populations within the subspecies or regional groups (F_ST = 0.16–0.20). Pairwise genetic distances among sites were correlated with geographic distance (r² = 0.38), but some geographically proximate sites were genetically differentiated (F_ST > 0.20), especially in the Yucatan. Deer in the Yucatan were genetically differentiated from other subspecies and had comparatively lower genetic diversity, consistent with the biogeographic history of the region. Populations of white-tailed deer in Mexico are subject to a range of management challenges. Additional research is needed to understand the effect of management on the diversity and genetic structure of white-tailed deer.

El venado de cola blanca (Odocoileus virginianus) se distribuye en un amplio rango latitudinal desde el sur de América hasta Canadá. De las 38 subespecies reconocidas, 14 habitan en México. Debido al número limitado de estudios genéticos en Latinoamérica, la diversidad y estructura poblacional del venado de cola blanca en México es desconocida. En este estudio, muestreamos venado de cola blanca de 13 sitios ubicados dentro del rango de distribución de 5 subespecies de México, O. v. texanus, O. v. carminis, O. v. veraecrucis, O. v. sinaloae, and O. v. yucatanensis. La diversidad y estructura genética fue estimada con 12 marcadores microsatélites. La heterocigosidad observada fue comparable a lo observado en el venado de cola blanca de Norteamérica (H_O = 0.53–0.64), con excepción de O. v. yucatanensis (H_O = 0.41). Se observó una estructura genética significativa entre los 13 sitios de muestreo (F_ST = 0.15). El análisis de varianza molecular reveló que los sitios de muestreo agrupados por subespecie (F_SC = 0.09) o región geográfica (F_SC = 0.13–0.14) explicaron una porción moderada de la variación genética. Sin embargo, la diferenciación entre las poblaciones no fue minimizada a un nivel de agrupamiento mayor, es decir dentro de subespecies o grupos regionales (F_ST = 0.16–0.20). La distancia genética entre sitios de muestreo estuvo correlacionada con la distancia geográfica (r² = 0.38), pero algunos sitios geográficamente próximos estuvieron genéticamente diferenciados (F_ST > 0.20), especialmente en Yucatán. El venado de cola blanca de Yucatán fue diferenciado genéticamente de las otras subespecies y fue comparativamente el de menor diversidad genética, lo cual es consistente con la historia biogeográfica de la región. Las poblaciones de ve

Paenemarmota Hibbard and Schultz, 1948 includes 3 species of giant ground squirrels within Marmotini (Rodentia, Sciuridae) from the Late Miocene and Pliocene of central and western North America. We developed skeletal and dental models for estimating body mass across modern species of Marmotini and apply these models to Paenemarmota. The most reliable models for estimating body mass of modern species (on the basis of length and width of femur, lengths of p4 and P4) generally yielded lower estimates of body mass for Paenemarmota than less reliable models (on the basis of lengths of m1, m2, M1, and M2). Models that were most reliable across modern species yielded 2 nonoverlapping estimates for P. barbouri Hibbard and Schultz, 1948: 9.5–9.8 kg on the basis of femur dimensions, and 14.4–16.2 kg on the basis of lengths of premolars. On the basis of lengths of premolars, P. mexicana (Wilson 1949) closely resembled P. barbouri in estimated mass (14.4–15.7 kg), but P. sawrockensis (Hibbard 1964) was smaller (10.0–12.4 kg). These large ground squirrels probably differed in mass-dependent biological attributes from all modern marmotines.

The long-tailed weasel (Mustela frenata) has the largest distribution of any mustelid in the Western Hemisphere, yet little is known of its genetic history. As a result of its broad distribution, the species provides an excellent model for identifying potential barriers influencing general phylogeographic patterns shared across multiple taxa. Here we used mitochondrial DNA with phylogenetic, phylogeographic, and molecular dating techniques to investigate molecular and geographical structure, as well as demographic history of M. frenata. Samples encompass 38 of the 42 recognized subspecies ranging from southern Canada to Bolivia. Our results suggest that long-tailed weasels are divided into distinct genetic clades, with eastern and western groups present in North America, 2 distinct lineages in Mexico and Central America separated by the trans-Mexican volcanic belt, and 1 clade in South America. Unlike other Mustela in North America, long-tailed weasels appear to have originated in the tropical areas of Mexico and Central America prior to dispersing 1st to the south before also expanding north in the Pleistocene.

La comadreja de cola larga (Mustela frenata) tiene la distribución más amplia entre todos los mustélidos del hemisferio occidental. Sin embargo, poco se conoce acerca de su historial genético. Dada su amplia distribución geográfica, la especie es un excelente modelo para identificar posibles barreras que influyen en patrones filogeográficos compartidos entre varios taxones. Usamos ADN mitocondrial con técnicas moleculares de datación, filogenia, y filogeografía para investigar la estructura molecular y geográfica así como la historia demográfica de M. frenata. Las muestras incluyen 38 de las 42 subespecies reconocidas desde el sur de Canadá hasta Bolivia. Nuestros resultados sugieren que comadrejas de cola larga se dividen en distintos clados, con grupos orientales y occidentales presentes en América del Norte y dos linajes distintos en México y Centroamérica, separados por el eje transvolcánico mexicano, y finalmente, un clado en América del Sur. A diferencia de otros mustélidos de América del Norte, las comadrejas de cola larga parecen haberse originado en las áreas tropicales de México y América Central previa a dispersión hacia el sur y luego hacia el norte durante el Pleistoceno.

The hispid pocket mouse (Chaetodipus hispidus) is one of the most genetically and morphologically divergent species within the heteromyid genus Chaetodipus. Four subspecies of C. hispidus currently are recognized, C. h. hispidus, C. h. paradoxus, C. h. spilotus, and C. h. zacatecae, ranging from North Dakota south through the Great Plains and Texas to central Mexico. We investigated the phylogeographic structure within C. hispidus by examining mitochondrial DNA from both freshly collected and museum specimens from localities distributed throughout the range of the species. We also examined 11 cranial characters in 303 specimens to assess morphological variation within the species. Although morphometric analyses were unable to differentiate the subspecies, phylogenetic analyses of molecular data indicated that the 4 currently recognized subspecies of C. hispidus are not genetically distinct. Instead, our results indicate that there are 4 distinct mitochondrial clades of C. hispidus that do not correspond to the currently recognized subspecies, but whose geographic limits instead coincide with major geographical features in the southern United States and northern Mexico. The Southern Coahuila filter-barrier (Durango and Coahuila), the Deming Plains (New Mexico), and the Balcones Escarpment (Texas) likely have acted as intermittent physical barriers to gene flow among the distinct mitochondrial clades, which we recognize as subspecies within C. hispidus.

El ratón Chaetodipus hispidus es uno de los miembros más divergentes genéticamente y morfológicamente dentro de los heterómidos del género Chaetodipus. Existen 4 subespecies de C. hispidus reconocidos, C. h. hispidus, C. h. paradoxus, C. h. spilotus, y C. h. zacatecae, cuya distribución se extiende desde Dakota del Norte hacia el sur por las Grandes Llanuras y Texas hasta el centro de México. En este estudio, se investigó la estructura filogeográfica de C. hispidus através del examen de datos de ADN mitocondrial en muestras recientes y antiguas a lo largo de las zonas de la distribución de las especies. También se examinaron 11 caracteres craneales en 303 muestras para determinar la variación morfológica en las especies. Aunque los análisis no pudieron diferenciar entre las subespecies, los análisis filogenéticos indican que 4 subespecies actualmente reconocidas de C. hispidus no son genéticamente distintos. En cambio, nuestros resultados indican que hay 4 nuevos clados mitocondriales distintos de C. hispidus que no corresponden con las subespecies actualmente reconocidas, pero cuyos límites geográficos coinciden con grandes rasgos geográficos delsur de los Estados Unidos y el norte de México. La barrera-filtro de Coahuila Meridional (Durango y Coahuila), las llanuras de Deming (Nuevo México), y el escarpado de Balcones (Texas) han actuado probablemente como barreras físicas intermitentes al flujo genético entre los distintos clados mitocondriales, los cuales reconocemos como subespecies dentro de C. hispidus.