Phylogenetic analyses of sequence data from the nuclear gene encoding the interphotoreceptor retinoid–binding protein (Irbp) provide compelling evidence that the recently described Amazonian marsupial genus Hyladelphys is a didelphid and suggest that it occupies an internal branch separating the traditionally recognized subfamilies Caluromyinae and Didelphinae. Although this phylogenetic position also is supported by morphological character data, analyses of sequence data from the dentin matrix protein 1 gene (Dmp1) place Hyladelphys within the didelphine radiation. A parsimony analysis of the combined morphological and molecular data supports the Irbp-only results, but a partitioned Bayesian analysis of the combined gene data does not provide strong support for either placement. The implications of these results are discussed in terms of long-branch attraction, base-compositional bias, and other possibly confounding factors. Whether Hyladelphys is the sister group of Didelphinae or an independent lineage at some basal level within that subfamily, the absence of any close relationship to other Recent taxa is clearly indicated. We redescribe the genus based on new morphological character data and comment on the probable existence of undescribed taxa in addition to H. kalinowskii, the type species.

Yellow-shouldered bats (genus Sturnira Gray, 1842), found throughout Latin America, are not well understood taxonomically. Four specimens of Sturnira from Bolivia and Venezuela possess dental characteristics differing from those of currently known species, leading us to regard them as representing a new species. We describe external, dental, and cranial characteristics and conduct a multivariate comparison using 29 morphometric characters for 44 male specimens of Sturnira erythromos, S. ludovici, S. hondurensis, and the new species. In a principal components analysis, most of the variation was summarized on component I (78.5% of total character variance), a general size vector. A multiple-comparisons test of component I projections showed all differences among species pairs to be highly significant, except that between S. ludovici and S. hondurensis. For the 29 individual characters, the new species was statistically different from S. erythromos in 21, S. ludovici in 13, and S. hondurensis in 14. The new species has a unique combination of dental characteristics, including bicuspid upper incisors, trilobed lower incisors, and smooth 1st and 2nd lower molars.

The known species of genus Neusticomys occur from the Colombian and Ecuadorian Andes southward to the Amazonian lowlands of Peru and eastward to Venezuela, Guyana, French Guiana, and Amapá, Brazil. In this study we describe a new species, Neusticomys sp. nov., from the Rio Juruena on the Central Brazilian shield, extending the distributional range of the genus and placing it in the center of South America. Neusticomys sp. nov. is defined and diagnosed by a unique combination of character states: ears and feet covered by dark brown hairs; size small; inferior zygomatic root anterior to 1st upper molar; orbicular apophysis absent; M3 present; m3 frequently present; posteroloph absent on M2 and M3; reduction of posterior lobe relative to the anterior lobe on M2; and 2n = 92, FN = 98.

Total population size of the chiru (Pantholops hodgsonii), a species endemic to the Tibetan plateau, has undergone a severe decline in the past several decades. This study investigates the genetic variation, evolutionary history, and current population relationships among the 3 main populations of the chiru. Samples from Xinjiang, Xizang (Tibet), and Qinghai provinces in western China were collected and mitochondrial DNA control region sequences were analyzed. Overall nucleotide diversity (π) was 2.18% and thus indicated a relatively high genetic variation. Neutrality tests suggested a significant historical population expansion (Fu's Fs = −28.152), consistent with a population decline and observed pattern of mismatch distribution. Analysis of molecular variance suggested high degrees of gene flow among all the sampled populations, of which the Xinjiang and Xizang populations were revealed to be the most genetically related. It was inferred that calving ground might play a significant role in the course of gene exchange. These results shed light on the population history and current population status of the chiru, and have strong implications for the continued conservation of the species.

Two isolated and taxonomically unassigned populations of short-tailed shrews (Blarina) exist in Texas, 1 in the Lost Pines region including Bastrop County and 1 at Aransas National Wildlife Refuge on the Gulf Coast. Molecular and morphological methods were used to determine the systematic status of the 2 disjunct Texas populations. Multivariate analyses of size-influenced cranial measurements were unsuccessful in identifying specimens from these populations at the species level. Phylogenetic analyses of the mitochondrial cytochrome-b gene revealed that the samples from disjunct Texas populations form a monophyletic sister clade to B. hylophaga from Kansas and Nebraska; there is little divergence between the 2 Texas populations. Genetic divergence between Texas and Kansas–Nebraska B. hylophaga is comparable to taxonomically recognized east–west divisions within B. brevicauda and B. carolinensis. Therefore, the name Blarina hylophaga plumbea, which originally was applied to the Aransas County population, also should include the Bastrop County population.

Sexual dimorphism in body mass, body length, head width, head length, and foreleg guard hair length of polar bears (Ursus maritimus) was examined from live-captured polar bears in Svalbard, Norway. Limited evidence of sexual dimorphism was apparent in cubs shortly after den emergence but was marked after the 1st year of life. Sexual dimorphism in adults resulted from both a higher growth rate and prolonged growth period in males. In mature animals, sexual dimorphism was greatest in mass, followed by foreleg guard hair length, head width, body length, and head length. Foreleg guard hair length was age related and hypothesized to be a form of ornamentation. Geographic variation in sexual dimorphism was evident for mass and body length for seven different populations but there was no evidence of a hyperallometric relationship in sexual dimorphism.

The reasons Lutreolina crassicaudata is always captured in close proximity to water are not clear. We investigated locomotory behavior and performance in swimming, running, climbing, and jumping of L. crassicaudata. One adult male was videotaped in the laboratory while swimming, walking on the ground and on a horizontal tube 1.2 m from the ground, climbing a tree trunk angled 45°, and jumping gaps between supports. The locomotor cycles in these different activities were described by speed, stride length, stroke or stride frequency, time of power and recovery phases or stance and swing phases, and by displacement of points on the animal. L. crassicaudata employed a quadruped paddling gait in swimming. Swimming speed was similar to that of terrestrial didelphids, but stroke frequency and buoyancy ability were more similar to those of the water opossum. Different gaits were used for locomotion in each habitat type and we conclude that L. crassicaudata cannot be considered a specialized species for aquatic locomotion.

Temporal activity patterns of microchiropteran bats were assessed at 4 scales (hourly, nightly, monthly, and yearly) in the Top End of the Northern Territory, Australia, in relation to biotic (insect availability) and abiotic features in the environment. At the hourly scale we found activity declined throughout the night and was most closely associated with temperature. At the nightly scale we found associations between bat activity, moonlight, and temperature as well as a complex association with both moon phase and time of night. At the monthly scale we found bat activity increased dramatically in October and provide evidence that this was triggered by a combination of changing climatic factors that occur at this time of year in the Southern Hemisphere tropics. At the yearly scale, no overall difference was found in bat activity between years (n = 4) and no associations were found with climatic variables. At all temporal scales we found no significant associations or differences in species richness and only weak or no associations with insect availability. There also was a high degree of variation in bat activity across all temporal scales that have significant implications for surveying and monitoring microbats.

The selection of roost cavities by Nyctalus noctula and N. leisleri, 2 widespread species of mainly Eurasian distribution, was examined in Białowieża Primeval Forest in eastern Poland from May to August in 1998–2002. Because N. noctula is one of the most common forest-dwelling bats in Europe, whereas the smaller N. leisleri is relatively rare across its range (except in Ireland) and more limited to ancient forests, we hypothesized that these 2 taxa may differ significantly in their tree-cavity selection. Twenty-five N. noctula and 26 N. leisleri were radiotracked to 52 and 50 roost trees, respectively. For each accessible cavity roost occupied by N. noctula (n = 28) and N. leisleri (n = 39), 16 features were measured and compared with potentially available cavities (n = 72). Both species were selective in roost choice, and preferred cavities located higher (averaging 19 m above the ground), in more open surroundings, with smaller entrances, and with greater safety distance (from martens) than available cavities. Nearly all roosts occupied by bats were dry inside. Both species slightly more frequently settled in cavities with entrances facing NE and SW, but the differences were not statistically significant. Compared to the pool of available cavities, N. noctula was statistically more frequently found in cavities with wider inside cross section and with 1 entrance, unlike N. leisleri, which often used cavities with more than 1 entrance (range 1–6 entrances). One of the most noticeable differences between the 2 species was roost origin. N. leisleri used natural cavities (90%) more often than woodpecker cavities (10%), whereas N. noctula showed the opposite tendency (woodpecker-made cavities accounted for just over half of roosts chosen by this species). The safety distance also was significantly larger in N. leisleri than in N. noctula. A logistic regression model for N. noctula incorporating 4 cavity variables (safety distance from martens, height above ground, cavity origin, and mean distance to nearest vegetation) classified roost and available cavities correctly 85% and 94% of the time, respectively. For N. leisleri, the use of 2 variables only (i.e., height above ground and marten distance) resulted in correct assignment of 85% of roosts and 88% of available cavities. These differences suggest that the 2 species use different antipredator strategies that may have important consequences for their different survival rates in younger forests. In general, roosts in Białowieża Primeval Forest are selected under pressures of predation and climate, and there bats tend to use safe and warm shelters.

Based on 1,362 radiotelemetry positions, mean home range for 10 adult black-bellied fruit bats, Melonycteris melanops (Pteropodidae), in lowland rainforest at Mount Garbuna, West New Britain Province, Papua New Guinea, was 2.3 ha ± 1.2 SD. Mean core-use area of adults was 0.5 ha ± 0.4 SD, and mean long axis of home range was 370 m ± 90 SD. Core-use areas were associated with day-roost shelters or flowering bananas. Means of home range, core-use area, and long axis across home range were significantly larger in subadults than in adults. During the day, M. melanops roosted singly under banana leaves or in subcanopy foliage, often showing extended fidelity to day-roost sites. Adults excluded other same-sex adults from feeding territories around bananas, but mixed-sex pairs overlapped strongly. During the first 2 h of the night, individual bats made 69–99 flights of 2- to 139-s duration. Cumulative flight represented 24–36% of the 2-h sampling periods.

The present work investigates how a fallow deer (Dama dama) population in central Italy might have been affected from 1984 to 2003 by the increase of human access to the study site, where humans were the main deer predators. By using deer census data, possible correlations were analyzed between the increase in human presence and the response of each age and sex class. The numbers of different age and sex classes of deer recorded inside and outside the sector affected by human presence throughout the 20-year period of study were compared. A differential response was recorded among classes. Adult females and juveniles left this area (reducing their presence from 37% of all deer observed to 11% for adult females and from 19% to 3% for juveniles) when human pressure became higher, whereas the opposite result was true for males older than 24 months (adult males) that remained inside the disturbed sector (from 27% to 50% of deer observed). Intermediate values were recorded for yearling males, because they can be associated with both groups of females and groups of males. Results of this long-term study are best explained with the reproductive strategy hypothesis, because the increase of predation risk evoked a marked spatial sexual segregation in the fallow deer population. Females and juveniles used relatively predator-safe habitats, whereas males used habitats with higher predation risk but better food quality. Furthermore, as females increased their presence outside the disturbed sector, males gradually abandoned the undisturbed area, increased use of the disturbed sector, and maximized foraging opportunities by going to areas where indirect competition with females was probably reduced.

Resources that limit reproductive success differ between the sexes in many vertebrates. We used focal animal observations to determine sex-specific activity periods, time budgets, and movements of endemic Mexican fox squirrels (Sciurus nayaritensis chiricahuae) in montane forests of southeastern Arizona during June, August, and December 1994 and January 1995. Activity periods during summer were bimodal with peaks in morning and afternoon separated by a midday lull in activity; winter activity was unimodal. No sex differences were detected in activity periods, although males retired later than females in winter. Resting, feeding, and locomotion were the most common behaviors and accounted for >75% of activities of each sex. Activity by females did not differ between seasons. Males spent more time in locomotion in summer and more time feeding in winter than in other seasons. Differences in time budgets of the sexes suggest that males and females apportion daily activity to maximize access to resources that limit fitness of each sex.

We examined breeding behavior responses of male root voles (Microtus oeconomus) to temporal risk of predation by using acute and chronic exposure to predator odor. The 2 series of exposure experiments provided 2 types of temporal patterns of risk: continuous safety with a brief period of risk and sustained risk with a brief period of safety. Male root voles that were acutely exposed to predator odor for 1 h suppressed their breeding behavior, but bred immediately after exposure to control odor for 1 h. Those chronically exposed to predator odor for 20 days maintained behavioral suppression during the 1-h period of exposure to control odor. Acutely exposed males did not change their physiological patterns of breeding, but those chronically exposed to predator odor had reduced testosterone concentration and epididymis index. Our results indicate that breeding behavior in a given situation depends on the overall patterns of risk experienced by male root voles, and the acute and chronic stress responses that affect reproduction are responsible for different behavioral responses to the 2 types of temporal patterns of risk. We also discuss the reasons for conflicting results about breeding suppression of voles between previous studies in the laboratory and the field.

Gundis (Ctenodactylus gundi) are gregarious, rock-dwelling rodents found in northern Africa. Very little is known about the behavioral ecology of C. gundi, or any other ctenodactylid rodent. The current study uses mark and recapture data of social groups of C. gundi in Tunisia to ascertain information on group composition and to obtain preliminary evidence on group formation. The majority of groups were found to be multimale and multifemale. Group size averaged 5.6 individuals ± 2.0 SD with 2.6 ± 0.9 adult males and 3.0 ± 1.7 adult females per social unit. Examination of recapture data suggests that groups of C. gundi result from both male and female natal philopatry in conjunction with male-biased dispersal. This study provides evidence that C. gundi may be a cooperatively breeding rodent, although results may be confounded by the effect of a drought.

Climbing ability can be a major component of the capability of terrestrial mammals to use vertical habitats. Previous studies suggest that small mammals from central Chile have low climbing capabilities. However, those studies have not disentangled the influence of tree diameter in natural habitats from true climbing ability of different species. We carried out a laboratory experiment by studying the climbing ability of 4 central Chilean small mammals, 2 octodontid rodents (Octodon bridgesi and O. degus), 1 murid rodent (Phyllotis darwini), and 1 marsupial (Thylamys elegans), in situations with different stem diameters. Species showed distinctive climbing abilities. The marsupial T. elegans showed efficient climbing ability independent of stem diameter. P. darwini and O. bridgesi were both influenced by stem diameter, but the former species used smaller-diameter stems less frequently. O. degus showed the lowest climbing ability.

It has been suggested that pikas are less active during inclement weather. We hypothesized that this decrease in activity is a predator-avoidance response to wind conditions that decrease the effectiveness of the alarm calls of pikas. We examined this hypothesis by broadcasting and rerecording the prominent frequencies (900–5,500 Hz) of pikas' calls and by observing behavior of focal pikas during varying weather conditions. Both attenuation of pure tones and the amount of wind noise increased significantly as wind speed increased. Additionally, wind direction created asymmetrical patterns of attenuation of pure tones, potentially distorting and degrading the call. Further, pikas spent significantly more time inactive at higher wind speeds, with nonvigilant active behaviors decreasing at a higher rate than vigilant active behaviors. Examination of these data supports the hypothesis and suggests that wind influences the behavior of animals that rely on alarm calls.

Despite its biological richness, the rodent and marsupial fauna of many parts of the Amazon Basin remains poorly known and the efficacy of different methods in assessing its diversity are poorly understood. We present results of small mammal trapping at a previously unsurveyed site in the Xingú Basin of the southeastern Amazon, Pará, Brazil; provide details on a new method for arboreal trapping; and compare species richness among traps at different heights and between different trap types. Mammals were livetrapped at 3 trap heights: ground, understory (1–3 m above ground), and canopy (mean height = 11.5 m ± 3.2 SD, range = 4.8–16.8 m, n = 76 trap stations). We recorded 1,769 captures of 1,178 individuals of 8 marsupial and 17 rodent species in 38,090 trap-nights (or 19,320 station-nights, where a station-night consisted of 1 Sherman and 1 Tomahawk live trap at 1 height for 1 night). Overall trap success was 6.1 individuals per 100 station-nights; success by trap position was 9.0% for ground (7,850 station-nights), 4.7% for understory (7,850 station-nights), and 2.9% for canopy (3,490 station-nights). Success by trap type was 4.7% for Shermans and 5.9% for Tomahawks, with Tomahawk traps showing a more rapid accumulation of species. Rarefied species accumulation curves showed little improvement with the inclusion of canopy trapping, which we attribute to high variability in the development of vertical structure at the site. We suggest that in areas with low and often-broken canopies, only ground and understory traps need be employed for long-term studies; however, some form of canopy trapping should be used during initial surveys so that the utility of arboreal trapping can be evaluated.

Spatial heterogeneity in risk is a critical component of predator-prey interactions. However, at small spatial scales, it is difficult to quantify predation risk without altering it. We used track plates to measure local predation risk created by white-footed mouse (Peromyscus leucopus) foraging activity on oak-forest plots in Millbrook, New York. Live gypsy moth pupae (Lymantria dispar) were placed at 2 heights on trees and monitored for predation. Pupae deployed on trees visited by mice were more likely to be eaten than those on trees not visited. Logistic regression indicated that predation rates on gypsy moth pupae were positively correlated with track activity, indicating that areas of concentrated mouse activity were areas of heightened risk for gypsy moths. Survival of individual oat grains placed on and 50 cm from track plates were not statistically different, indicating that mice exhibited no detectable behavioral reaction toward track plates. We conclude that track plates offer an economical and reliable means of quantifying local risk of attack by terrestrial mammals without substantially altering the spatial distribution of risk.

A capture–mark–release program was run for 3 years in a rice-growing area of the inner delta of the Niger River in central Mali to monitor population dynamics of a major pest species, the multimammate rat Mastomys huberti. The abundance pattern showed a phase of low-to-medium abundances (June 2000–March 2002) leading to a peak (October 2002) followed by a dramatic crash ending in total population disappearance induced by general flooding of the area in October 2003. Reproduction started well after the end of the rainy season, contrary to observations for this genus elsewhere. Survival was very low between the end of the rainy season and the middle of the dry season, then high during the rest of the dry season. The annual flood of the Niger River was found to have a major influence on population and spatial dynamics of M. huberti in this area by eliminating available ground surface in high-flood years, thus causing local extinction, and by delaying the onset of reproduction to the beginning of the dry season. Overall, the dynamics of multimammate rats in the inner delta of the Niger River appeared to be linked to rainfall and flooding patterns in a complex way. Maximum demographic growth appeared to be associated with intermediate levels of flood height, consistent with the intermediate disturbance hypothesis.

The centrifugal community organization model describes the habitat-use pattern of competing species that share a primary habitat preference but differ in their secondary habitat preferences. Our goal was to study the gradients underlying centrifugal organization in a community of 2 gerbil species, Gerbillus pyramidum (the greater Egyptian sand gerbil) and G. andersoni allenbyi (Allenby's gerbil), in the southern coastal plain of Israel. Theory suggests that the ideal combination of food and safety should occur in the semistabilized-sand habitat. However, our measurements showed that this combination actually occurs at the stabilized-sand habitat. Yet, both species prefer the semistabilized-sand habitat. By using artificial seed patches, we show that foraging at the stabilized-sand substrate is at least twice as costly as foraging at the nonstabilized substrate. This, together with potential differences in resource renewal rates and predation risk may underlie the shared-preference for the semistabilized-sand habitat and thus affect the community organization.

A decline in the dominance of oaks (Quercus) in eastern deciduous forests generally has been attributed to herbivory by white-tailed deer (Odocoileus virginianus) or fire suppression, but few studies have considered a role for mammalian consumers of acorns. We used acorns placed on the soil surface and acorns buried approximately 2 cm underground in 4 types of exclosures to evaluate the effects of white-tailed deer, tree squirrels (Sciurus carolinensis and S. niger), and white-footed mice (Peromyscus leucopus) on survival and germination of red oak (Q. rubra) acorns. Buried acorns were intended to mimic caches of squirrels. When deer were excluded from a plot, squirrels and mice consumed or removed all surface acorns. When both deer and squirrels were excluded from a plot, mice consumed >90% of the acorns on the surface. Thus, acorn consumption by deer is unlikely to be a causal factor in the widespread decline of many oak species. Survival of buried acorns did not differ between open plots and plots where only squirrels and mice had access, but when squirrels were excluded from a plot, the survival of buried acorns increased. In addition, buried acorns germinated at a much higher rate than acorns on the surface. As suggested for many oak species, unrecovered caches of acorns are likely a critical source of red oak seedlings.

We investigated the role of changing abundance of spring foods on female American black bear (Ursus americanus) diet, milk composition, and cub survival in western Massachusetts. We hypothesized that diets would change, percentage milk fat would be higher, and cub survival would be higher in a year when overwintered hard mast was more abundant. We obtained paired samples of milk from 7 adult female bears across consecutive reproductive cycles during which spring diets differed; 1 year followed a bumper acorn (Quercus rubra) crop and estimated spring diets were >25% acorns; the other year followed an extremely poor acorn crop and spring diets were estimated to be 99% skunk cabbage (Symplocarpus foetidus). Postdenning milk was higher in fat (26.7% versus 18.2%; P = 0.0557) during the spring when acorns were abundant, but we did not identify any carryover affect to cub survival. We suggest that adult female black bears compensate for changes in food availability by eating greater volumes of alternative foods, and perhaps allocate resources primarily to milk production; the bears appear to be able to produce milk of adequate quality to sustain cubs, regardless of spring diet.

We estimated survival, fertility, and realized and asymptotic population growth rates from 1981 to 2002 for a protected population of black bears (Ursus americanus) in the southern Appalachian Mountains. We used Akaike's information criterion to assess the time interval for averaging observations that was best for estimating vital rates for our study, given our yearly sample sizes. The temporal symmetry approach allowed us to directly assess population growth and to address all losses and gains to the population by using only capture data, offering an alternative to the logistically intensive collection of reproductive data. Models that averaged survival and fertility across 5- and 7-year time intervals were best supported by our data. Studies of black bear populations with annual sample sizes similar to ours should be of at least 5 years in duration to estimate vital rates reliably, and at least 10 years in duration to evaluate changes in population growth rate (λ). We also hypothesized that survival would not track changes in λ because λ is influenced by both survival and fertility. The 5-year model supported our hypothesis, but the 7-year model did not. Where long-term dynamics of large, relatively stable bear populations are of interest, monitoring survival is likely to be sufficient for evaluating trends in λ. For rapidly changing, small populations, however, failure to incorporate fertility into assessments of λ could be misleading.

Population dynamics and life-history evolution depend heavily on fecundity, which, in the coyote (Canis latrans), can vary substantially according to environmental conditions. Although well studied in the central part of its range, little is known about coyote reproduction in the Mediterranean climates associated with Pacific-coastal North America. I used postmortem examinations of 441 coyotes collected throughout central California to investigate reproduction, including age-specific fecundity, breeding synchrony and seasonality, and relationship to nutritional condition. Reproductive parameters did not vary significantly among sampling locations. Overall, numbers of corpora lutea averaged 6.9 (range = 4–11) and litter size (based on fetuses or placental scars) averaged 6.6 (range = 1–12) among postpartum females. The number of corpora lutea increased with maternal age, and litter size also increased with age to 6 years but decreased in older females. Most (77%) adult females became pregnant and 13% of 1st-year females became pregnant. During January–March, 96% of adult males and 68% of 1st-year males had reproductive testes. Reproductive signs in both sexes occurred 3–4 weeks later in 1st-year coyotes than in adults. Parturition dates, which decreased with increasing maternal age, ranged from 9 March to 7 May, indicating that estrus occurred from early January to late March. Of 1st-year coyotes, reproductive individuals were larger during the breeding season and had higher marrow fat indexes than nonreproductive ones (both sexes). After the breeding season, 1st-year females that did not breed (become pregnant) had similar body mass to 1st-year and adult coyotes that did breed, and adult females that did not breed were larger than the others but similar to the weight of breeders during the breeding season. Thus, whether yearlings attained breeding condition apparently depended on their nutritional condition. Adult fecundity estimates were among the highest reported for coyotes.

In an investigation of the postnatal growth of the vertebral column of the Norway rat (Rattus norvegicus), we recorded hind-foot length as a standard metric, along with skull, tail, femur, and tibia lengths, against which to compare the growth of axial components. We confirmed a nonlinear relationship of head–body length against hind-foot length, tail length, and tibia length across the time course from neonate to adult and also discovered a nonlinear relationship between both skull and femur length to head–body length. Differences in growth rate are directly related to preweaning and postweaning periods. The pattern of differential growth was distinctly least pronounced for femoral length. We therefore advocate the latter as the most appropriate to use as an easily measured proxy for growth across the entire neonate to adult growth period. This study reveals implications for the choice of optimal variables used as size proxies and also suggests functional implications of shifts in form–function relationships from unweaned to weaned individuals. However, variation in body form across mammals and altricial versus precocial modes of natal expression will continue to complicate the search for appropriate comparative metrics in the study of the development and evolution of body form.