Neotoma Cinerea Research Articles

Seeing the forest for the fuel: Integrating ecological values and fuels management

Management of dry forests often involves trade-offs between ecological values, particularly those associated with closed-canopy forests, and reduction of severe wildlife risk. We review principles and our ecological research that can be used to design stand- and landscape-level fuel treatments in dry coniferous forests of western North America. The focus of ecological values is on the ecological web that includes the northern spotted owl ( Strix occidentalis caurina), its two primary prey species the northern flying squirrel ( Glaucomys sabrinus) and bushy-tailed woodrat ( Neotoma cinerea), and the vegetation (live and dead), mycorrhizal fungi, and arboreal lichens that support those prey species. For the landscape level, we describe an ongoing project to develop the FuelSolve computer tool that optimizes the area and location of a fuel treatment by minimizing potential fire behavior and minimizing loss of spotted owl habitat from treatment and potential fire. Some species will gain and some species will lose habitat when stand structure or composition is changed during fuel reduction treatments. Stand-level prescriptions might be altered to maintain or create patchiness of closed-canopy habitat elements, such as snags, down wood, mistletoe-infected trees, and large old trees, and open-canopy habitats can be tailored to ensure creation of suitable composition and structure for wildlife. Allocation of treatments across the landscape might be managed to minimize cumulative effects and impacts on target species populations. General approaches to landscape-level planning of ecologically sound fuel treatments include coarse- and fine-filter approaches. A coarse-filter approach would use some definition of the historical or natural range of variability to define the composition and pattern that might reasonably be expected to sustain the forest ecosystem. Three general approaches can inform fine-filter analysis and development of fuel reduction treatments at the landscape level. Population viability analysis provides sound principles based on attributes of the species population structure, life history and behavior, and environment (habitat) for guiding fine-filter analysis. Fine-filter analysis can be informed by operational modeling of treatment alternatives. Research publications can guide dry forest landscape management. Our FuelSolve optimization model described in this paper differs from other fuel planning models in this class by equally considering multiple optimization objectives for fuel treatment and ecologically important resources. We describe the results of FuelSolve prototype development, an evaluation of outputs for field use, and future development efforts.

Male reproductive success and female preference in bushy-tailed woodrats (Neotoma cinerea): do females prefer males in good physical condition?

In many mating systems, females may benefit by selecting a male with high genetic quality in the form of good genes or compatible genes. In bushy-tailed woodrats ( Neotoma cinerea Ord, 1815), previous research has shown that male reproductive success correlates with the mass change of males over the breeding season, indicating that physical body condition may directly influence female choice and hence male reproductive success. We examined male physical condition in relation to reproductive success in the field. Male physical condition was measured as body-mass change over the breeding season, body size, body condition (mass versus size), and anaemia (packed cell volume and mean corpuscular volume). We then conducted trials in the laboratory in which captive females were presented with visual and olfactory cues from two males simultaneously. In the field, males with a low mean corpuscular volume had the highest reproductive success. Captive females also showed a preference for males with low levels of anaemia based on mean corpuscular volume. These results suggest that females are employing a condition-dependent preference.

The Late Quaternary biogeographic histories of some Great Basin mammals (western USA)

The Great Basin of arid western North America provides one of the most detailed late Pleistocene and Holocene mammal records available for any part of the world, though the record is by far strongest for small mammals. Of the 35 genera of now-extinct North American Pleistocene mammals, 19 are known to have occurred in the Great Basin, a list that is likely to be complete or nearly so. Of these 19, seven can be shown to have survived beyond 12,000 radiocarbon years ago, a proportion similar to that for North America as a whole. Horses, camels, mammoth, and helmeted musk-oxen appear to have been the most abundant of these genera. Pygmy rabbits ( Brachylagus idahoensis), yellow-bellied marmots ( Marmota flaviventris), and bushy-tailed woodrats ( Neotoma cinerea) declined in abundance at the end of the Pleistocene, at about the same time as populations south of their current arid western distributional boundary were extirpated. Subsequent declines occurred during the hot/dry middle Holocene. Pygmy rabbits also declined as modern pinyon-juniper woodlands developed across the Great Basin. The Snake Range of eastern Nevada has seen the late Pleistocene or Holocene extinction of both northern pocket gophers ( Thomomys talpoides) and pikas ( Ochotona princeps). Coupled with the rarity of yellow-bellied marmots here, these histories make the Snake Range a biogeographic oddity. These and other Great Basin mammal histories provide significant insights into the possible responses of Great Basin small mammals to global warming.

BUSHY-TAILED WOODRAT ABUNDANCE IN DRY FORESTS OF EASTERN WASHINGTON

We studied bushy-tailed woodrats (Neotoma cinerea occidentalis) in the eastern Washington Cascade Range to estimate their density and survival in 3 typical dry forest cover types. We predicted woodrat density to be high, moderate, and low in mature mixed-conifer forests, young mixed-conifer forests, and open ponderosa pine forests, respectively. We livetrapped on 8 � 8 grids (280 m) over an 8-day period each autumn for 4 years to obtain Huggins mark–recapture estimates of woodrat density. We captured woodrats 617 times and marked 193 individual woodrats in 12 sample stands during 42,165 trap nights. The sex ratio of captures was 62% female and 38% male. Adults made up 79% of captures. Woodrat density averaged 0.49 animals/ha among all cover types and years; woodrat density did not differ among types. Regardless of cover type, stands fell into 4 woodratdensity groups, with densities ranging from 0.13 to 0.93 woodrats/ha. Classification tree analysis revealed that woodrat-density groups could be predicted well (proportional reduction in error ¼ 0.73 to 0.89) by the type and amount of cover provided by large snags, mistletoe brooms, and soft downed logs. Over the 4-year period, woodrat density ranged from 0.28 animals/ha to 0.87 animals/ha, increasing each year at a rate of k ¼ 1.8 consistently among cover types. A moderate (r ¼ 0.55) density-dependent response in per capita rate of increase was detected. The apparent annual survival rate was a low 0.14. Management to reduce woody fuels and to restore low-intensity high-frequency fire regimes in ponderosa pine and dry Douglas-fir forest likely will reduce bushy-tailed woodrat populations unless prescriptions can mitigate the loss of snag, mistletoe, and downed log cover.

MAMMAL AND FLEA RELATIONSHIPS IN THE GREAT BASIN DESERT: FROM H. J. EGOSCUE'S COLLECTIONS

Host-parasite association among 58 flea species parasitizing 40 mammal species in the Great Basin Desert of the western United States was investigated. Increased flea species richness was correlated with larger geographic ranges and stable locomotion of hosts. Hosts from habitats of moderately low productivity (sage and grass) and of Peromyscus maniculatus size, 10-33 g, had the highest flea species richness. Larger hosts had fewer flea species, but fleas were more prevalent. Increased host species richness correlated with flea species eye size. Mammals clustered into 3 major and 1 minor ecological groups, and fleas clustered into 2 major groups among rodents, and 6 minor groups, forming 12 host-parasite biocenoses. Factors producing biocenoses were shared burrows of mice and rats; food chains of hares, rabbits, squirrels, and their predators; keystone mammals: Lagurus curtatus, Neotoma lepida, Ochotona princeps, and Spermophilus townsendii; keystone fleas: Megabothris abantis, and Meringis hubbardi; or host isolation, Neotoma cinerea with Oropsylla montana, Sorex vagrans with Corrodopsylla curvata, and Tadarida brasiliensis with Sternopsylla distincta. Although host relatedness accounted for flea prevalence, host sociality explained the presence or absence of mammal-flea relationships.

Anoplocephalid cestodes of wood rats (Neotoma spp.) in the western U.S.A.

AbstractThis study reviews the taxonomy of anoplocephaline cestodes of wood rats, Neotoma cinerea, N. fuscipes and N. mexicana (Sigmodontinae) in the western and south-western U.S.A. The anoplocephaline fauna included five species, only one of which, Andrya neotomae Voge, 1946, was relatively common and occurred in all three host species. Other species were Paranoplocephala freemani Haukisalmi, Henttonen et Hardman, 2006, P. primordialis (Douthitt, 1915), both host-generalist species of North American rodents, and two apparently undescribed species of Paranoplocephala s. str. Aprostatandrya octodonensis Babero et Cattan, 1975 from the indigenous South American rodent Octodon degus is regarded as a junior synonym of A. neotomae. A redescription is provided for A. neotomae.

PACKRAT MIDDENS AND LATE HOLOCENE ENVIRONMENTAL CHANGE IN SOUTHWESTERN COLORADO

Seventeen middens of the bushy-tailed packrat (Neotoma cinerea), ranging in age from 3450 ± 40 to 160 ± 50 radiocarbon years before present (B.P.), were collected in 1996 from the Upper Gunnison Basin, Colorado. Eight of these subfossil middens contained plant remains from species that no longer occur near the locations of the middens. Radiocarbon dates on conifer remains indicated shifts in forest communities in the late Holocene at 3320, 560, and 240 B.P. Past climates were cooler than today at 3320 B.P., when mixed lodgepole (Pinus contorta) and ponderosa pine (P. ponderosa) forest expanded to lower elevations in the basin. Conditions became warmer between 1500 to 950 B.P., with additional cooling from 660 to 170 B.P., corresponding with cooling periods in the 1300s and during the Little Ice Age (500–150 B.P. or 1500–1850 CE). These data indicated that the late Holocene of Colorado was marked by episodes of climate change that previously have not been identified in the paleoclimatic record.

Within-taxon morphological diversity in late-Quaternary Neotoma as a paleoenvironmental indicator, Bonneville Basin, Northwestern Utah, USA

Ecological data indicate that as the amount of precipitation in an arid areas increases, so too does mammalian taxonomic richness. This correspondence has been found in two late-Quaternary mammalian faunas from Utah, one from Homestead Cave in the Bonneville Basin. We use the remains of two species of woodrat ( Neotoma cinerea and Neotoma lepida) from Homestead Cave to test the hypothesis that as the amount of precipitation in an arid area increases, so too does morphological diversity within individual mammalian taxa. Morphological diversity is measured as corrected coefficients of variation and as richness of size classes of mandibular alveolar lengths. Coefficients of variation for N. cinerea are few and coincide with moisture history if temporally successive small samples are lumped together. More abundant coefficients of variation for N. lepida coincide only loosely with moisture history, likely because such coefficients measure dispersion but not necessarily other aspects of variation. Richness of size classes of N. lepida is high during the early and late Holocene when moisture was high, and lowest during the middle Holocene when climate was most arid.

Validating the use of woodrat (Neotoma) middens for documenting natural invasions

AbstractAim Plant macrofossils in fossil woodrat (Neotoma) middens are the primary source of information on late Quaternary biogeographical history of plants in arid and semi‐arid regions of North America. Macrofossil records from middens are playing particularly important roles in documenting spatial and temporal patterns of plant migrations and invasions since the last glacial maximum 21,000 years ago. However, relatively few actualistic studies comparing contents of modern middens with surrounding flora and vegetation have been carried out. The primary aim of this study is to assess the reliability of midden assemblages in detecting the presence of tree, shrub and several other plant species growing on the surrounding landscape. The secondary aims are to determine whether probability of occurrence of species in middens is related to abundance in vegetation, and whether representation of individual species in middens is contingent on presence/absence or abundance of other species.Location Our five study sites were bedrock escarpments or canyons in the central Rocky Mountains (north‐eastern Utah, central Wyoming and south‐central Montana). All sites were in conifer woodland or forest/woodland variously dominated by Juniperus osteosperma, J. scopulorum, Pinus edulis, P. flexilis and Pseudotsuga menziesii. Neotoma cinerea is the only woodrat species in the region.Methods Macrofossil assemblages from 59 modern middens (all showing clear signs of recent or ongoing woodrat activity) were compared with floristic composition of vegetation within 50 m of the middens, and with percent cover of vegetation within 30 m of the middens.Results Coniferous trees and shrubs were well‐represented in middens, occurring consistently even when abundance in the local vegetation was very low. Juniperus osteosperma and J. scopulorum were particularly well‐represented, occurring in middens regardless of local abundance. Other conifers (P. edulis, P. flexilis, P. ponderosa, Pseudotsuga menziesii) were occasionally absent from middens when abundance in vegetation was low (< 20% canopy cover). Occurrence of dicot shrubs and graminoids was less consistent.Main conclusions Middens constructed by N. cinerea are highly reliable sensors of presence/absence of J. osteosperma and J. scopulorum, and hence can be used to infer invasions and past biogeographical distributions of these species. The middens are also reliable in registering populations of other conifers, although presence in middens may be contingent on local abundance. Additional comparative studies are needed to develop a sound empirical basis for using middens of N. cinerea and other species to infer past presence/absence of plant species on the landscape, and to explore the vegetation‐sensing properties of midden assemblages.

Bushy-tailed woodrats and other small mammals in bird pellets from Grasslands National Park, Saskatchewan

Bushy-tailed woodrats and other small mammals in bird pellets from Grasslands National Park, Saskatchewan

Intraspecific variation in testis size of small mammals: implications for muscle mass

Intraspecific variation in testis size is usually interpreted in the context of sperm competition, yet an unconsidered consequence of increased testis size may be an increase in the production of testosterone, which can affect the growth of muscle mass. After muscle mass is corrected for body size, male small mammals have more muscle mass than females, which suggests that it may be a sexually selected trait. An enhanced musculature may have fitness consequences with respect to male mate-searching activities and male–male competition for access to females. We tested the prediction that males with large testes have more muscle mass (measured as lean dry mass) by examining testis size and body composition in three species of small mammals (bushy-tailed wood rat (Neotoma cinerea), deer mouse (Peromyscus maniculatus), and red-backed vole (Clethrionomys gapperi)) from the Kananaskis Valley, Alberta. In all three species, males with relatively large testes had relatively more lean dry mass than males with relatively small testes. This suggests that a secondary consequence of relatively large testes may be a relative increase in muscle mass. Further research should investigate alternative effects of intraspecific variation in testis size on individual fitness within wild populations to gain further insight into sexual selection.

The effect of Holocene temperature fluctuations on the evolution and ecology of Neotoma (woodrats) in Idaho and northwestern Utah

Animals respond to climatic change by adapting or by altering distributional patterns. How an animal responds is influenced by where it is positioned within its geographic range; the probability of extirpation is increased near range boundaries. Here, we examine the impact of Holocene climatic fluctuations on a small mammalian herbivore, the bushy-tailed woodrat ( Neotoma cinerea), at five locations within south central Idaho and northwestern Utah. Previous work demonstrated that woodrats adapt to temperature shifts by altering body size. We focus here on the relationship between body mass, temperature, and location within the geographic range. Body mass is estimated by measuring fossil fecal pellets, a technique validated in earlier work. Overall, we find the predicted phenotypic response to climate change: animals were larger during cold periods, and smaller during warmer episodes. However, we also identify several time periods when changes in environmental temperature exceeded the adaptive flexibility of N. cinerea. A smaller-bodied species, the desert woodrat ( N. lepida) apparently invaded lower elevation sites during the mid-Holocene, despite being behaviorally and physically subordinate to N. cinerea. Analysis of contemporary patterns of body size and thermal tolerances for both woodrat species suggests this was because of the greater heat tolerance of N. lepida. The robust spatial relationship between contemporary body size and ambient temperature is used as a proxy to reconstruct local climate during the Holocene.

An Extralimital Prairie Population of Bushy-Tailed Woodrats, Neotoma Cinerea, along the South Saskatchewan River, Alberta, Canada

BUCHANAN JB, LUNDQUIST RW, AUBRY KB. 1990. Winter populations of Douglas' squirrel in different-aged Douglas-fir forests. Journal of Wildlife Management 54:577-581. CAREY AB. 1991. The biology of arboreal rodents in Douglas-fir forests. Portland, OR: USDA Forest Service, General Technical Report PNW-GTR-276. 46 p. FRANKLIN JF. 1972. Wind River Research Natural Area. In: Franklin JF, Hall FC, Dyrness CT, Maser C, editors. Federal Research Natural Areas in Oregon and Washington: A Guidebook for Scientists and Educators. Portland, OR: USDA Forest Service, Pacific Northwest Forest and Range Experiment Station. Irregular pagination. FRANKLIN JF, DEBELL DS. 1988. Thirty-six years of tree population change in an old-growth Pseudotsuga-Tsuga forest. Canadian Journal of Forest Research 18:633-639. HALL ER. 1981. The mammals of North America.

Evaluating body condition in small mammals

Body condition (energy reserves) can have important fitness consequences. Measuring condition of live animals is typically done by regressing body mass on measures of body size and using the residuals as an index of condition. The validity of this condition index was evaluated by determining whether it reflected measured fat content of five species of small mammals (yellow-pine chipmunks (Tamias amoenus Allen), bushy-tailed wood rats (Neotoma cinerea Ord), deer mice (Peromyscus maniculatus Ord), red-backed voles (Clethrionomys gapperi Vigors), and meadow voles (Microtus pennsylvanicus Ord)). We also determined whether body water could predict fat content, enabling the use of hydrogen-isotope dilution for estimating condition. For all five species, condition estimates weakly predicted fat content and more accurately predicted variation in lean dry mass and water content. The relationship between body water and fat content was inconsistent among the five species, discouraging against the general use of isotope dilution in these animals. Although ecologically important, these indices are best interpreted as explaining variation in all constituents of body composition.

Sexual dimorphism in body composition of small mammals

Differences in reproductive roles between the sexes may lead to sexual dimorphism in body composition. Body size and composition of three species of small mammals (bushy-tailed wood rats (Neotoma cinerea Ord), deer mice (Peromyscus maniculatus Wagner), and red-backed voles (Clethrionomys gapperi Vigors)) were analyzed to test the predictions that (i) males will have more muscle mass than females and (ii) females will have more fat than males. Results supported the first prediction but not the second. For all three species, males had more lean dry mass relative to body size than females, but females did not have relatively more fat than males. Muscle mass of males may aid in mate-searching and mate-guarding activities, but fat content may not differ between the sexes because female small mammals depend on increased ingestion rates, rather than fat stores, to support reproduction.

A New Afrocamilla from Colorado, the Third Species of Camillidae (Diptera: Schizophora) from the United States

Diptera, which are known mainly from the Palaearctic Region and Africa (Papp 1982, Barraclough 1997a, b, 1998a, b). Although it has long been known that the European species Camilla glabra (Fallen, 1823) had been accidentally introduced to Canada and the New World (McAlpine 1960, Barraclough & Wheeler 1995), the discovery of endemic, New World camillid species has been relatively recent (Barraclough & Wheeler 1995). Only three New World camillid species are known, all described by Barraclough & Wheeler (1995): Afrocamilla arizona (Huachuca Mountains, southern Arizona); A. bispinosa (San Dimas Canyon, southern California); Camilla arnaudi (San Bartoleme, Mexico). The discovery of a long series of a new species of Afrocamilla Barraclough, 1992, associated with the litter of the bushy-tailed wood rat Neotoma cinerea (Ord, 1815), near Fort Collins, Colorado, convinces us that many more North American species of Camillidae await discovery. As with the now relatively substantial African fauna, the factor limiting discovery of further material is the association of Camillidae with the nests, burrows and latrines of small mammals (and sometimes with bat caves), where the immature stages develop in the faeces of the mammal concerned. It is invariably very difficult to collect adult flies from such micro-habitats.

BIOGEOGRAPHIC IMPLICATIONS OF RECENT LOW-ELEVATION RECOLONIZATION BYNEOTOMA CINEREAIN THE GREAT BASIN

Homestead Cave, a paleontological site located in a low-elevation arid setting in the northern Bonneville Basin of northcentral Utah, documents the local extinction of Neotoma cinerea during the Middle Holocene. N. cinerea is present there today, and the Homestead Cave record suggests that recolonization likely occurred sometime prior to 1,000 years ago. This history supports the view (forwarded by T. E. Lawlor) that cross-valley dispersal by mammals that generally are most abundant in cooler and moister (and therefore higher elevation) parts of the Great Basin is still occurring, showing that Brown's model of Great Basin montane mammalian biogeography is incorrect. These dispersal patterns suggest that conservation efforts directed toward montane mammals in the Great Basin must include low-elevation access corridors to mountain masses.

The effects of moonlight on nocturnal activity in bushy-tailed wood rats (Neotoma cinerea)

The nocturnal activity of bushy-tailed wood rats (Neotoma cinerea) was monitored for two breeding seasons (1993 and 1994) in the Canadian Rockies. Radiotelemetry was used under three levels of moonlight to assess two measures of nocturnal activity: (i) the proportion of animals crossing rocky outcrops and entering the surrounding forest to forage, search for mates, or both, and (ii) the distance moved from the den site while in the forest. Males and females exhibited significant differences among moonlight levels, with greater activity on nights of intermediate-level moonlight and less activity on nights with bright or dark moonlight. There was no difference in the proportions of males and females active at any moonlight level. The distances moved from the den did not differ among moonlight levels for either males or females. Having traversed the rocks and entered the forest, individuals moved similar distances regardless of light level. These results suggest that wood rats respond to moonlight only when making the decision to cross rocks and enter the forest. This behaviour presumably serves to counteract the increased risk of predation on bright nights.

Fidelity of terrestrial vertebrate fossils to a modern ecosystem

An exceptionally rich paleontological site, well-dated with 18 radiocarbon samples and containing 10,597 identified mammalian fossils, shows a high affinity to the local habitat with little evidence of long-distance transport of faunal elements. The organic deposits in Lamar Cave, Wyoming, are composed almost entirely of the decomposed collections of wood rats ( Neotoma cinerea) and carnivores, mainly wolves ( Canis lupus) and coyotes ( Canis latrans). The fossil sample, whether analyzed by level or as the total site accumulation, more closely approximates the local living fauna than a modern raptor-pellet and carnivore-scat collection does. The combination of taxa from all but 2 out of 16 levels unambiguously describes the mammalian community of the local sagebrush grassland. Absence of certain extralocal species clearly reflects lack of long-distance (>5 km) transport of non-sagebrush grassland species. If the aim of a paleontological study is specifically to reconstruct the local mammalian community, these data demonstrate that only a minimum of sampling effort may be required for similar localities. However, the data from Lamar Cave do demonstrate that if the goal of a paleontological, or in fact modern, study is to tally the total number of species, an intensive sampling effort is required in order to include the rare taxa. Though time-averaged records indeed may obscure some analyses, particularly those of discerning disharmonious faunas such as those found at the Pleistocene–Holocene transition, this study shows that some time-averaging will benefit the interpretation of faunal diversity of both present and past ecosystems by inclusion of less common taxa.

Mating success of male bushy-tailed woodrats: when bigger is not always better

To determine the factors that regulate mating opportunities of male bushy-tailed woodrats (Neotoma cinerea), we used stepwise multiple regression on measurable morphological and behavioral traits. DNA fingerprinting was used to determine the paternity of juveniles, allowing mating success (the number of females mated with), and reproductive success (the number of offspring fathered) to be quantified. Both measures of male success were significantly related to the growth rate of males while reproductively active. The most successful males were those that had higher growth rates, indicating that there is relatively little cost (weight loss) associated with successful mating in male woodrats. Our findings demonstrate that although this species is highly sexually dimorphic, large body size does not influence mating success. In addition, it appears that male mating success cannot be predicted from morphological measures and may instead be determined by behavioral or olfactory cues.