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The American Society of Mammalogists (ASM) currently has 13 Restricted Funds intended to make financial resources available to support the mission of the Society by providing grants and awards to students, early-career mammalogists, and members who perform activities relevant to ASM. Restricted Funds are specified to support a Society objective or area of research. When initially established, the originator(s) defined the use of a Restricted Fund. However, descriptions and requirements of each Restricted Fund are not often stored in a readily available location or format making it difficult for potential applicants to determine how to proceed. We collected information on each Fund from journal articles, book chapters, minutes of ASM Board of Directors meetings, and personal communications from ASM members. Then we compiled information relevant to each Restricted Fund to centralize this information and make available the intended purpose of each Restricted Fund. Several of the Funds have reached a level to be self-sustaining at the current award amounts, but others remain in desperate need of funding to be able to support the intentions of the originators. Mammalogists recognize through their establishment of Restricted Funds that allocations from these Funds are instrumental in supporting the development of students and junior colleagues as they hone their science and contribute to the science of mammalogy.

Reforestation and afforestation of agricultural land can lead to increased storage of C and N. Few studies have determined the effect of reforestation on N compared with C accumulation or the impact of forest community structure on soil organic C (SOC) and N stocks. We selected a chronosequence of six forested study sites to investigate whether SOC and N were affected by land-use history or forest community structure. We took soil cores at depths of 15 to 35 cm from eight plots at each study site, measured SOC and N concentrations, SOC/N ratios, the minimum time since partial and full reforestation, and tree composition and structure. The SOC and N concentrations increased with time since partial and full reforestation in shallow soils (top 10 cm; p 0.05; rocky soil limited analyses below 20 cm). The SOC and N concentrations were more closely linked to the onset of reforestation. The SOC/N ratio increased with time since partial and full reforestation in deeper soils (p 0.05). There was no relationship between either SOC or N and forest composition or structure (p > 0.05). Our results demonstrate that the onset of reforestation is a key factor controlling SOC and N concentrations, which increased from partial to full reforestation, particularly in shallow soils. The more pronounced increase in the SOC/N ratio in deeper soils reflected an accumulation of SOC with time in these soils, while N content remained comparatively stable.

Unprecedented population growth and urban expansion are rapidly transforming natural and agricultural settings into highly modified urban and suburban landscapes in developed areas worldwide. A myriad of anthropogenic environmental disturbances invariably accompany such dramatic shifts in land use, and disentangling the effects of these multiple stresses on ecosystem variation pose major challenges as the world’s urban population continues to increase. Here, we quantitatively characterized environmentally-mediated variation in tree-community composition along an Urban-Wildland gradient in southwestern Ohio, using tree censuses conducted in sample plots at six study sites categorized as Urban, Exurban, or Wildland based on analyses of a broad suite of natural and anthropogenic environmental variables. Several direct measures of the tree-census data, including species richness, abundance, diversity metrics, and evenness, exhibited significant increases from Urban to Wildland sites. Non-Metric Multidimensional Scaling (NMDS) showed that tree composition within study plots also varied systematically along the gradient, with significant differences among sites captured primarily on NMDS Axis 1. The dominant tree species at Urban and Exurban sites was Acer saccharum (sugar maple). While this species was also abundant at Wildland sites, two other species, Asimina triloba (paw paw) and Juniperus virginiana (red cedar) tended to be more abundant. Regression-tree analyses demonstrated that tree-community composition was controlled by a complex combination of natural and anthropogenic factors, with primary roles for population density and other indicators of urbanization at broader and intermediate scales; natural factors, such as aspect, soil drainage, elevation, slope, and soil pH were important in differentiating among Urban, Exurban, and Wildland sites already primarily categorized by anthropogenic agents.

Introduced plants threaten biodiversity and ecosystem processes, including carbon (C) and nitrogen (N) cycles, but little is known about the threshold at which such effects occur. We examined the impact of the invasive shrub Amur honeysuckle on soil organic carbon (SOC) and N density at study sites that varied in invasion history. In plots with and without honeysuckle, we measured honeysuckle abundance and size (basal area) and extracted soil cores. SOC and N densities were highest at the site with the longest invasion history and highest invasion intensity (i.e., greatest abundance and basal area of honeysuckle). Basal area of honeysuckle positively affected SOC and N densities likely because of increased litter decomposition and altered microbial communities. Because honeysuckle increases forest net primary productivity (NPP) and SOC, it also may play a role in C sequestration. Our results demonstrate the need to consider the influence of invasion history and intensity when evaluating the potential impact of invasive species.

Invasion by Amur honeysuckle (Lonicera maackii) and browsing by white-tailed deer (Odocoileus virginianus) in eastern deciduous forests negatively affect diversity and abundance of herbaceous vegetation and tree seedlings. We used a 3 x 2 factorial design (L. maackii present/absent/removed and O. virginianus present/excluded) to assess individual and interactive effects of these species on survival of sugar maple (Acer saccharum) seedlings in a deciduous forest in southwestern Ohio. Survival of seedlings was negatively affected by presence of honeysuckle and browsing by deer, but there was no significant deer x honeysuckle interaction. Negative effects on survival and, hence abundance, of sugar maple seedlings could affect the relative dominance of species of canopy trees in these forests. Because there was no honeysuckle x deer interaction, control measures that target Amur honeysuckle and white-tailed deer separately could be employed without producing unintended effects on sugar maple seedlings.

We studied how degree of urbanization affected forest-floor herbs in deciduous forest along an urbanization gradient from west to east of Cincinnati, OH. We measured species diversity, richness, and abundance of herbs in 16 30 × 30 m plots at two Urban, two Exurban, and two Wildland sites. Because the invasive shrub Amur honeysuckle (Lonicera maackii) negatively affects richness and abundance of native herbs, half of these plots contained honeysuckle, except at the Wildland sites where honeysuckle was absent. We used General Linear Models or Generalized Linear Mixed Models to determine the effect of edaphic, geographic, forest composition, human effects, and honeysuckle variables on herbs and used model comparison techniques to identify those variables that significantly affected herbs. Human effects (e.g., proximity to roads) and geography (e.g., aspect, slope) were the most important factors affecting herb richness and abundance, and geography (e.g., elevation) was the most important factor affecting herb diversity. Honeysuckle (measured as diameter of primary stem) had no effect on diversity or richness of herbs, but positively affected herb abundance. Herb diversity did not vary significantly along the urbanization gradient, but higher herb richness and abundance in Exurban and Wildland sites along the urbanization gradient were associated with higher tree diversity, richness, and abundance, shallower slopes, greater distance to roads, and smaller honeysuckle shrubs.

Invasive Amur honeysuckle (Lonicera maackii) has reduced diversity, growth, and reproduction of native herbs in the Midwest USA. These effects may be compounded by browsing from overabundant white-tailed deer (Odocoileus virginianus). We used experimental treatments of honeysuckle (present, absent, removed) and deer (present, excluded) to measure their independent and interactive impacts on diversity, richness, and abundance of herbs in a deciduous forest in southwestern Ohio, USA. Species diversity and richness of herbs were not affected by honeysuckle or deer. Honeysuckle reduced abundance of annuals, graminoids, spring perennials, and summer perennials; deer decreased abundance of annuals and spring perennials, but increased abundance of graminoids. A deer × honeysuckle interaction showed that when honeysuckle was absent or removed, browsing by deer kept abundance of annuals and spring perennials low. Effects of honeysuckle and deer also were assessed for the three most abundant herbs: honeysuckle reduced abundance of Carex rosea and Sanicula odorata, and deer reduced abundance of Viola soraria. Herb abundance varied seasonally and annually. Honeysuckle and deer reduced number of leaves/stem of Maianthemum racemosum and a deer × honeysuckle interaction indicated that the negative effect of honeysuckle was released only when deer were excluded. Herb abundance and M. racemosum rebounded to or near to control levels after removal of honeysuckle. Our findings revealed that impacts of invasive honeysuckle or overabundant deer were not the same across all levels of biological organization (i.e., individual species, growth forms, community measures of species diversity/richness). Measuring impacts of these species at multiple levels of biological organization, considering deer × honeysuckle interactions, and collecting data for several years to account for seasonal and annual fluctuations will help guide management plans. The rapid response by herbs to removal of honeysuckle demonstrated the resilience of this community and is a hopeful sign for restoration of native understory herbs.

Invasive Amur honeysuckle (Lonicera maackii) creates a dense shrub layer in eastern deciduous forests that negatively impacts native herbs and tree seedlings. Given the well-studied influence of habitat structure on spider abundance and guild composition, we examined the effects of this invasive shrub on spiders in forests of southwestern Ohio. Because spiders are sensitive to shrub architecture, we predicted that increased vegetative cover caused by invasion of L. maackii would increase diversity and abundance of spider taxa and guilds. We used paired plots (e.g., honeysuckle present and honeysuckle-absent) in ten deciduous forest locations to sample spiders and measured vertical cover of woody vegetation in the shrub layer. Abundance of spiders overall, spider families (Anyphaenidae, Araneidae, Salticidae, Theridiidae) and spider guilds (foliage runners, orb weavers, space web builders, stalkers), was higher in honeysuckle-present than in honeysuckle-absent plots, but diversity was not affected...

In 1975, wildlife managers reintroduced desert bighorn sheep (Ovis canadensis mexicana) to Tiburon Island, Mexico, where endemic mule deer (Odocoileus hemionus sheldoni) occur. We predicted that these species would use both mountain and plains habitats, but would have different diets, minimizing negative interspecific effects. By censusing pellet groups, we found that both ungulates occurred in both habitats, but bighorn sheep were more abundant in mountains and mule deer were more abundant in plains. Microhistological analyses determined that diets of both species consisted of the same 39 plant species, of which 13 plant species each composed ≥4% of the diet and together composed 70–80% of the total diet. Plants in low abundance represented 26–32% of diets in the mountains and 45–56% of diets in the plains. Overall diet overlap was 68% and overlap did not differ between mountains or plains, but did differ among seasons. Overlap in habitat agreed with predictions, but diet overlap was contrary to our predictions. Our results differ from studies on the mainland, which found overlap in habitat use, but not in diet. Overlap in resource use coupled with the rapid increase in abundance of bighorn sheep since their reintroduction to Tiburon may have an impact on mule deer. Additional research is needed to determine whether abundance of mule deer has changed in response to the reintroduction of bighorn sheep.

Invasive Amur honeysuckle (Lonicera maackii) creates a dense shrub layer in deciduous forests in eastern North America that negatively impacts native herbs and tree seedlings. We predicted that higher vegetative cover caused by this shrub would increase abundance and diversity of insects and alter composition of insect assemblages. We used paired plots, one with and one without honeysuckle, in ten forest locations in southwestern Ohio, USA, to sample insects and measure diversity and vertical cover of vegetation in the shrub layer. Vertical cover of this vegetation was higher on honeysuckle-present plots, but diversity of shrub-layer vegetation did not differ between honeysuckle-present and honeysuckle-absent plots. Species diversity of Hexapoda, Coleoptera, and Psocoptera, richness of Hexapoda, Coleoptera, Diptera, Hymenoptera, and Psocoptera, and abundance of Hexapoda, Diptera, Hymenoptera, and Psocoptera were higher on honeysuckle-present than on honeysuckle-absent plots. Evenness did not differ between honeysuckle treatments. Nonmetric multidimensional scaling distinguished taxonomic composition in honeysuckle-present plots from that in honeysuckle-absent plots. Presence of vertical cover explained higher richness of Hexapoda and Coleoptera, and higher abundance of Hexapoda, Diptera, Hymenoptera, and Psocoptera. Attributes of honeysuckle, independent of its contribution to vertical cover, explained increases in richness of Hexapoda, Coleoptera, and Hymenoptera and abundance of Hexapoda, Hymenopera, and Psocoptera. These attributes of honeysuckle could include a more complex vegetative structure, a greater availability of resources such as food, detritus, or shelter, and/or a more favorable cooler and moister microenvironment. To more fully understand the mechanisms causing increased richness and abundance of insects in honeysuckle-present areas, detailed studies on these attributes of honeysuckle would be necessary.

Arboreal habitats pose several challenges for locomotion resulting from narrow cylindrical surfaces, steep slopes, and secondary branches that can form obstructions. We used laboratory trials to test whether different diameters, slopes, or complexity of branches affected maximum speeds and perch choice of the semi-arboreal white-footed mouse (Peromyscus leucopus). We tested locomotor performance of mice running horizontally and up and down 45° slopes for cylindrical artificial branches with five diameters ranging from 10 to 116 mm and on a subset of diameters for cylinders that were horizontal and had pegs (e.g., secondary branches) every 10 or 20 cm. Slope, diameter, and presence of pegs on top of cylinders had significant and interactive effects on locomotor performance. On horizontal cylinders the speed of mice increased with increased diameter among the three smallest diameters, but changed little with further increases in diameter, whereas for sloped surfaces the extreme diameters had lower speeds than an intermediate diameter. For a given diameter, the speeds of mice were usually faster when running horizontally rather than running uphill or downhill. The presence of pegs greatly decreased running speed compared to unobstructed surfaces, but the magnitude of this effect decreased as diameter increased. The difficulties of maintaining balance and avoiding toppling may have caused much of the decrease in speed and associated increased amounts of pausing. Only 1 of 11 choice tests detected a significant bias of mice favoring the perch that maximized locomotor performance. J. Exp. Zool. 317A:540–551, 2012. © 2012 Wiley Periodicals, Inc.

Extent of edge habitat is often defined arbitrarily from a boundary between 2 habitats. Instead, we assessed whether space use by white-footed mice (Peromyscus leucopus) responded to habitat changes along an edgeto-interior gradient in eastern deciduous forest. We measured movement distance as mean squared distance from center of activity (MSD), microhabitat variables, and distance to nearest conspecific neighbor. Distance of center of activity from the habitat edge was not affected by animal age (e.g., body mass). Male MSD did not change along the habitat gradient. Female MSD increased with distance from habitat edge, was negatively related to vertical cover, and was positively related to diameter at breast height of trees. Increased MSD in forest interior may reflect lower availability of nesting sites or diet items. Decreased MSD at forest edge may reflect higher vegetative cover that provided more food or behaviors by mice to avoid edge predators/ parasites. Female use of vertical habitat increased with distance from habitat edge, and was related to fewer trees, less woody debris, and smaller distance to nearest conspecific neighbor. Fewer trees and less woody debris could negatively affect availability of nesting sites, travel routes, or diet items, hence greater use of vertical habitat. The nearest-neighbor effect may indicate intraspecific competition from lower availability of resources in forest interiors. Such responses in space use along a habitat gradient indicated that defining edge habitat as an arbitrary distance from a habitat edge may be insufficient to understand ecology and behavior of small mammals.

Litter-dwelling arthropods play crucial roles in litter decomposition and nutrient cycling, and changes in their diversity or abundance can affect these processes. Previous studies have outlined individual effects of invasive plants and overabundant ungulates on litter-dwelling arthropod communities but have paid little attention to whether invasive plants and ungulates interact to affect these arthropod communities. We examined how invasive Amur honeysuckle (Lonicera maackii) and grazing by white-tailed deer (Odocoileus virginianus) affected diversity, abundance, and taxonomic composition of litter-dwelling arthropod communities in a deciduous forest in southwestern Ohio. We also examined whether deer or honeysuckle affected substrate composition and depth of litter. We found no significant effect of honeysuckle, deer, or their interaction on arthropod diversity, but exclusion of deer increased total arthropod abundance and abundance of Araneae, and thereby affected taxonomic composition of the ...

We measured ingestion by Attwater's pocket gopher (Geomys attwateri) in the coastal prairie of Texas by placing feeding chambers in their tunnels. We constructed a nutrient budget from ingestion, species of plants eaten, and nutrient content of these plants, and we compared it to that for the hispid cotton rat (Sigmodon hispidus), also common in this habitat, and the laboratory rat. Concentration of minerals ingested by G. attwateri appeared sufficient for growth and reproduction. Concentration of protein was lower and concentration of fiber was higher in diets of G. attwateri than in diets of S. hispidus or that was required for laboratory rats. High concentration of fiber reduces digestibility and impedes assimilation of protein. We concluded that protein was likely a limiting nutrient and that a low protein:fiber ratio in the diet during summer could be responsible for the observed decline in reproduction in that season.

Many above-ground and fossorial rodents are generalized herbivores, either ingesting various types of monocots and dicots to balance nutrients in their diet or avoiding some plants because they contain secondary plant metabolites. Attwater's pocket gopher (Geomys attwateri) is a common rodent in bunchgrass-annual forb communities in Texas whose diet contains both monocot and dicot plants, with a preference for perennial dicots (as compared to their availability). We reduced availability of dicots with an herbicide and predicted that, because of their importance in the diet, the proportion of dicots in the diet of G. attwateri would not be affected. We found no difference in dicot content in the diet of animals on plots with dicots reduced (DR plots) compared to plots with natural abundance of dicots (DP plots), and that preferences for dicots (compared to their availability) increased on DR plots while preferences for perennial monocots (compared to their availability) decreased. Dicot roots contained more lipid, soluble carbohydrate, Mg, K, and Ca than monocot roots. During the summer non-breeding season, dicot shoots contained more protein, lipid, soluble carbohydrate, Na, Mg, P, and Ca than monocot shoots. During the winter breeding season, content of protein, soluble carbohydrate, Na, Mg, P, K, and Ca was higher in dicot shoots than monocot shoots. Low protein content and high neutral detergent fiber content in diet plants may limit reproduction especially during the summer non-breeding season. We hypothesized that increased use of extant burrow systems, extension of burrow systems on plots with reduced availability of dicots, or extension of tunnels into dicot areas off DR plots may have enabled G. attwateri to maintain the concentration of dicots in the diet. Larger burrow systems would increase intraspecific interactions and could explain lower residency time and decreased density of G. attwateri reported by other studies on plots with low abundance of dicots. We suggest that, in spite of similarity in abundance of dicots in diets of animals on DR and DP plots, ingestion of inadequate amounts of dicots or mixtures of dicot species that did not provide sufficient concentrations of nutrients may have led to a reduction in reproduction on DR plots reported in other studies.

Entomofauna in monospecific stands of the introduced Chinese tallow tree (Sapium sebiferum) and native mixed woodlands was sampled in 1982 along the Texas coast and compared to samples of arthropods from an earlier study of native coastal prairie and from a study of arthropods in S. sebiferum in 2004. Species diversity, richness, and abundance were highest in prairie, and were higher in mixed woodland than in S. sebiferum. Nonmetric multidimensional scaling distinguished orders and families of arthropods, and families of herbivores in S. sebiferum from mixed woodland and coastal prairie. Taxonomic similarity between S. sebiferum and mixed woodland was 51%. Fauna from S. sebiferum in 2001 was more similar to mixed woodland than to samples from S. sebiferum collected in 1982. These results indicate that the entomofauna in S. sebiferum originated from mixed prairie and that, with time, these faunas became more similar. Species richness and abundance of herbivores was lower in S. sebiferum, but propo...

Peromyscus leucopus (White-footed Mouse) use the 3-dimensional space of their habitat. We studied whether Cuterebra fontinella (Bot Fly) larvae affected rate of capture in traps set above ground compared to traps set on the ground in deciduous forests in Ohio and Georgia. Rates of infestation were nearly three-fold greater in Ohio than in Georgia. Infested animals were captured equally in traps on the ground and in traps 1.5 m above ground in Ohio, but were captured less frequently in traps on the ground than in traps 1.5 m above ground in Georgia. Sex of animals did not affect these results. Infested animals were not captured in traps 4.5 m above the ground in Georgia, suggesting a possible limit to use of vertical habitat space by infested mice.

Factors that affect movement of small mammals include vegetation structure, resource distribution, interspecific interactions and parasitism. The objective of this study was to assess the effect of bot fly (Cuterebra fontinella) parasitism on movement distance [estimated by mean squared distance (MSD)] of white-footed deermice (Peromyscus leucopus), using a repeated measures approach. Although there was no significant effect of infestation on MSD, there was a nonsignificant trend towards increased movement during infestation for females. In addition, there was no difference in MSD between individuals with single infestations and those harboring several larvae. These results are unexpected given the large size of the parasite relative to the host. Studies of fine-scale temporal movements within a single night could shed further light on the effects of infestation on movement.

We compared small mammals in Gulf cordgrass (Spartina spartinae) to coastal-prairie and low-marsh, Spartina alterniflora communities, and we considered the effect of standing-crop biomass and nutrient concentration in plants in the Gulf cordgrass community on dynamics of populations of small mammals. We predicted lower species richness and density of small mammals and shorter residence time in Gulf cordgrass because of little vertical habitat structure, sparse ground cover, and low abundance of dicots, plants that contain nutrients necessary for reproduction by hispid cotton rats (Sigmodon hispidus). Richness in Gulf cordgrass (seven species of rodents) was similar to coastal prairie (six species plus three non-native rodents) with S. hispidus and fulvous harvest mice (Reithrodontomys fulvescens) numerically dominant in both communities. Density of S. hispidus was higher in Gulf cordgrass likely reflecting high standing-crop biomass; however, lack of ground cover contributed to low residence time...

Stress placed on individuals in a population from natural and anthropogenic disturbances can elevate developmental instability. We studied the result of a natural disaster when one-third of a forested nature preserve was destroyed by an F3 tornado. Populations of two abundant species of small mammals, Peromyscus maniculatus and P. leucopus, were monitored in both disturbed and undisturbed habitats. We used an X-ray technique to measure developmental instability as indicated by fluctuating asymmetry (FA) in cranial and skeletal features of live animals. FA in femur length was higher in disturbed habitat for P. leucopus but was higher in undisturbed habitat for P. maniculatus. This difference in developmental instability mirrors differences in habitat preference between these species: P. leucopus prefers forest habitat and P. maniculatus prefers open, herbaceous habitat. These results were not explained by either food availability or body condition, both of which were higher in the disturbed habitat suggesting higher quality for this habitat. Thus, the FA response may be related to other indicators of habitat quality, e.g., vertical stratification, coarse-woody debris, or population density, which may differ between undisturbed and disturbed habitats.

Animals subject to environmental stress often exhibit higher levels of developmental instability, frequently measured as Fluctuating Asymmetry (FA), small, random deviations from perfect left-right symmetry in bilaterally symmetrical animals. We used FA measurement as a means of determining the impact of a catastrophic ecosystem disturbance (a major Class F3 tornado) on populations of Schizocosa ocreata, a common forest-dwelling wolf spider. As FA in sexually selected ornamental traits in males has been shown in some (but not all) species studied to be a sensitive indicator of environmental stress, we measured FA of foreleg tufts in male S. ocreata. Spiders from the first post-disturbance generation were collected by pitfall trapping in the spring of 2000, and preserved specimens were photographed and measured using digital imaging. Spiders from disturbed and undisturbed areas within the forest did not differ significantly in body size parameters, although body condition varied significantly bet...

Most landscapes are heterogeneous in vegetation composition and thus, in the distribution of nutrients required by herbivores for growth and reproduction. Hispid cotton rats (Sigmodon hispdus) inhabit Texas coastal prairies which are characterized by habitat patches dominated by dicots, monocots or both [mixed] plant types. Hispid cotton rats must obtain nutrients necessary for reproduction by ingesting both dicots and monocots, and reproductive females concentrate their activity in mixed patches. Mixed patches may be selected because they have high nutrient contents or because presence of both monocot and dicot food plants lowers cost of foraging movements. Because hispid cotton rats select a nutritionally complete diet and may detect protein by odor and taste cues, we hypothesized that nutrient concentrations may cue position of foraging paths. We used nutrient maps to measure amount of protein, P and Ca encountered during foraging from radiotracked individuals. We compared these values to thos...

The Texas coastal prairie is composed of habitat patches characterized by monocots, dicots, or a mixture of both plant types. Radiotelemetry revealed that reproductive female hispid cotton rats (Sigmodon hispidus) preferred mixed habitats and avoided dicot habitats, whereas males did not show a preference. Such habitat selection can be attained by shorter distances moved or increased turning (i.e., area-restricted search). Reproductive females, but not males, moved shorter distances in mixed habitats. However, turns relative to straight-ahead movements for females, but not males, were fewer in mixed habitats than in monocot or dicot habitats suggesting directed foraging rather than area-restricted search. To obtain necessary amounts of nutrients, especially carbohydrates, protein, phosphorus, and calcium, reproductive females ingest both monocots and dicots. Directed movement may facilitate foraging for dicots because these food items occur in clumps in mixed habitats. Because their nutritional needs are less than those of females, males do not exhibit the same patterns of habitat selection. Differential patch occupancy was not explained by overhead plant cover, but more bare ground in dicot habitats may explain avoidance of these habitat types because of increased predation risk.

Parasites can often impose a cost on their hosts by interfering with traits affected by sexual selection. We studied the effects of the bot fly, a common parasite of the white-footed mouse, Peromyscus leucopus, on host social behaviour using field-based experiments. Assuming parasite-induced costs on host behaviour, we expected that males uninfested with bot fly larvae would be more aggressive than infested males, and that reproductively active females would show a preference for uninfested males over infested males. Uninfested males were not more aggressive than infested males, based on two measures of aggression (principal component scores and number of aggressive behaviours). Contrary to our expectations, our results suggested that infested males may be more aggressive than uninfested males, but this result was based on the analysis of both aggressive and submissive behaviours. In addition, females spent more time with infested males. Thus, infestation may increase body size which could alter the outcome of female choice. Additional experimentation is necessary to tease apart the effects of increased body size and infestation on female choice.

Bot flies are common parasites of Peromyscus leucopus, although determination of a cost to the host has been elusive. The goal of this study was to further explore the potential costs of bot fly parasites for a population of P. leucopus. We investigated the effects of parasitism on host condition (mass after controlling for parasite mass and host body length) and survivorship (the number of days animals persisted on trapping grids). Parasitism was quantified by prevalence (proportion of the population infected), intensity (the number of parasites per infected host), and dispersion of parasites within hosts (clumped, regular, or random). In addition, we searched for spatial and temporal patterns in infection. Finally, we analyzed the relationship between population demography and parasitism. Contrary to expectations, we found that infected mice persisted longer on trapping grids and were in better condition than uninfected mice. Also, we discovered that when considering overall infection levels, parasites were clumped within hosts, but when considering the number of simultaneous infections, parasites were randomly distributed among hosts. Although most animals had single infections, there was a high incidence of reinfections, leading to bimodal patterns of parasitism. Prevalence was not correlated with host density, sex ratio, or proportion reproductive, but there were significant relationships between intensity and density and sex ratio in 1 year. In addition, prevalence and proportion of reproductively active animals were asynchronous. These results suggest that bot flies do not impose an obvious cost to their hosts, and hosts may express some degree of tolerance for bot fly parasitism.

Hispid cotton rats (Sigmodon hispidus) occur primarily in grass-dominated habitats. These habitats abut tidal wetlands along the Gulf and Atlantic coasts of the United States occupied by the marsh rice rat (Oryzomys palustris). Few data document whether cotton rats also occupy wetlands and whether interspecific interactions exist with rice rats. We used livetraps to sample 4 grids that each encompassed wetland and upland habitats near Galveston, Texas. Cotton rats occurred in both upland and wetland habitats. Density of cotton rats was lower in wetlands; their residence time was less in wetlands, which perhaps indicated poorer survival or movement to uplands. Sex ratio, proportion reproductive, and age structure, however, did not differ between upland and wetland habitats. Density of cotton rats and rice rats was negatively correlated. Such density compensation coupled with differences in diel activity and diet minimizes potential for interspecific competition.

Home-range size and shape are influenced by cost–benefit relationships associated with acquiring resources. Subterranean animals may be particularly affected by food availability and soil conditions because of the close coupling of their activity to soil and the high energetic expense of digging. We examined foraging tunnel length, area, and geometry (e.g., number of branches and turning angles) of 3 species of pocket gophers (Geomys attwateri, Geomys bursarius, and Thomomys bottae) in their natural habitats, which differed in food abundance and soil characteristics. Burrow features (except length and area) were similar among species, sexes, ages, and habitats. However, burrows of adults were longer and occupied larger areas than those of juveniles, and burrow system length and area decreased with increasing vegetation biomass and with increasing soil clay content of soil (i.e., increasing expense of digging). Our findings reveal common patterns of burrow geometry, which suggest that there may be an underlying strategy defining geometric features of burrows within this family of subterranean rodents.

We tested whether differences in composition and nutrients of diet explained higher density of Peromyscus aztecus in mature cloud forest and higher density of Reithrodontomys fulvescens in disturbed cloud forest. P. aztecus ate dicot leaves, stems, fruit, and seeds in mature cloud forest and dicot leaves, stems, and seeds, and monocot seeds and insects during the dry-hot season in disturbed cloud forest. R. fulvescens ate dicot leaves, stems, fruit, and seeds in mature cloud forest but monocots and insects during the hot season; dicot leaves, stems, and seeds were eaten in disturbed cloud forest. The diet of P. aztecus contained more protein and soluble carbohydrates in disturbed cloud forest where rodent density was lower; the diet of R. fulvescens contained more protein, lipid, soluble carbohydrate, Na, Mg, and P in mature cloud forest where density was lower. Nutrient differences resulted from R. fulvescens eating more monocots and dicot fruit, P. aztecus eating more monocot seeds and less dicot fruit, and both species eating more insects. Differences in composition or nutrient content of diet did not explain between-habitat differences in demography because nutrients in diet were higher in habitat of lower rodent abundance, suggesting other factors must be considered.

The choice of scale (both grain and extent) of a research project can directly affect the results of the project itself, and the comparability of those results to similar research. This paper reviews 149 self-described landscape studies published between 1987 and 2001. From each paper, data for several variables were gathered that we proposed may influence the choice of scale. These variables included the taxa the research considered, the characteristics of the landscape of interest, the species response variables measured, the type of methodology employed by the study, the habitat type(s) surveyed, and the technique(s) used to create habitat maps. Our results demonstrated that only 61% of the papers identified both the grain and extent at which the research was conducted. Taxonomic group, landscape characteristics, and study type all appeared to influence both the choice of grain and extent for the study. Wide variation (standard deviation) in grain and extent among studies suggests that researchers either used some factor not considered here to select scale, or made decisions of the scale on pragmatic grounds, rather than on the appropriateness of the scale to the variables. Finally, 24 of the 149 studies reviewed researched the same combination of categories of the six variables that we considered, yet only for one combination was the grain and extent used within the same order of magnitude. This review highlights the need for more structured choice of scale in landscape studies, and in particular the need for more standardized size of grain and extent for greater comparability among studies.

Avian communities are often used by ecologists as indicators of environmental decline over large spatial areas, because of the ease with which birds can be monitored by nonprofessionals and the availability of continent-wide breeding bird data. The influence of scale on the relationship between bird diversity and the characteristics of the landscape, which can serve as proxies for decline, is receiving greater attention but is still not well understood. We combined data from the Breeding Bird Survey with landscape characteristics derived from the National Land Classification Data for Ohio, USA, to determine the effects of landscape extent on relationships between birds and landscape characteristics. These relationships were determined through previous work to be correlated with avian richness and diversity. We created areas of varying sizes using buffers around each of 58 routes, and calculated diversity for several groups of birds: all birds, five habitat guilds, and three migration guilds. The landscape extent over which landscape characteristics were considered affected the relationship between these characteristics and bird richness and diversity overall, as well as richness and diversity for several of the habitat and migratory guilds. Diversity of woodland birds, Neotropical migrants, and richness of short-distance migrants were best explained by the landscape characteristics examined here, possibly due to a less homogeneous collection of species in the other guild groups. These results suggest that more attention is required in selecting the appropriate scale when using landscape characteristics to predict or manage avian communities, as some characteristics may be more useful for management activities over small areas versus efforts over larger areas.

We examined the energy, nutrient, time, and habitat consequences of diet choice by a generalist herbivore, the hispid cotton rat (Sigmodon hispidus) on the Texas coastal prairie. Benefit-cost and linear programming models were developed and used to test several specific hypotheses about diet choice, foraging strategy, and habitat use by cotton rats. Within cotton rat habitat, there were significant differences among both seasons and habitat patches in the abundance and biomass of foods available. Monocot patches typically were higher in standing crops of energy and nutrients than were either dicot or mixed patches. Relative to available biomass and nutrients in dicot foods, this cotton rat habitat was both spatially and temporally heterogeneous and dynamic. Although the abun- dance of dicot foods in a habitat patch did influence costs of foraging time, time costs of cotton rats foraging for suitable foods did not decrease when standing crops of energy and nutrients in these habitats increased. Higher requirements for energy and nutrients needed for lactation by reproductive cotton rats resulted in higher foraging costs than for non- reproductive female rats. A mixed diet incorporating both monocot and dicot foods was nutritionally superior to either a monocot-only diet or a dicot-only diet. A diet of only monocots would meet minimum daily energy requirements and would not exceed either maximum daily digestive capacity or maximum daily foraging time, but it would not meet minimum daily requirements for protein and phosphorus during reproduction. Conversely, a diet of only dicots would meet nutrient requirements for reproduction but would exceed maximum daily foraging time. Mixing of monocot and dicot plant parts in the diet met both net energy and nutritional requirements, and increased foraging time, as compared to a diet of only monocots. Diets of cotton rats foraging to maximize net energy intake each season differed from the observed diets. Likewise, diets of cotton rats foraging to minimize total daily foraging time differed from the observed diets. Thus, we conclude that repro- ductive females of this generalist herbivore neither maximized their energy nor minimized their time, but rather, consumed a mixed diet to balance intake of requisite nutrients. Accordingly, a diet choice that included a mixture of monocot and dicot foods was most efficient when foraging occurred in a habitat having a mixture of monocot and dicot plants. Mixed patches provided higher energy and nutrient benefits to foraging cotton rats than did either monocot or dicot patches. Finally, we observed that reproductive female cotton rats concentrated their activities in mixed-patch habitats.

High productivity and accessibility have made coastal wetlands attractive sites for human settlements. This study analyzed the patterns of wetland landscapes in Galveston Bay, Texas, USA. The first objective of the study was to describe the relationships between the fractal dimension of wetland boundaries and those factors which affect the wetland landscapes (e.g., land use, type of vegetation, size, location, and level of human disturbance). The second objective was to construct a historical database to contrast wetland areas which had experienced different levels of disturbance between 1956 and 1989. The fractal dimension, a measure of how much of the geographical space is filled by boundaries, was measured by the perimeter-area method. The fractal dimension of wetlands was significantly affected by land use, type of vegetation, size, and level of anthropogenic disturbance. In addition, increasing the size of buffers around roads did not significantly affect the fractal dimension of wetlands. Landscape indices, such as fractal dimension, dominance, and diversity, were used to characterize spatial heterogeneity in the historical database. Lake Stephenson, an area of low anthropogenic disturbance, experienced no changes in wetland composition and abundance over time. Anahuac, an area of medium disturbance, experienced changes in both wetland composition and abundance. Texas City, an area of high disturbance, experienced a change in wetland composition. These differences can be associated with the type and level of disturbance present; however, more evidence is needed to determine whether certain landscape patterns have stable, intrinsic properties which allow persistence in the face of disturbance. These results will be informative to resource managers determining how wetlands can be managed as natural resources and nature reserves.

Herbivory and soil movement by subterranean mammals influences structure and species composition of plant communities they inhabit. Tunnels constructed by pocket gophers (Geomys bursarius) in Kansas produced an edge effect wherein biomass of the dominant plant species, big bluestem (Andropogon gerardii), increased adjacent to tunnels, then decreased, before increasing again. This wave-like phenomenon was attributed to reduction of biomass of big bluestem above tunnels releasing plants adjacent to tunnels from intraspecific competition. We tested for edge effects on vegetation over tunnels of Attwater's pocket gopher (Geomys attwateri) in a floristically diverse (>10 species of monocots, >30 species of dicots) prairie in coastal Texas. No community-level edge effect was detected; neither biomass, species richness, nor diversity of all plants, monocots alone, or dicots alone over tunnels differed significantly from that in quadrats 0 to 10, 10 to 20, 20 to 30, or 30 to 40 cm away from tunnels. Biomass of 4 individual species of plants prominent in the diet of G. attwateri did not show an edge effect. We conclude that tunnels of pocket gophers have a minor impact on plant biomass or community structure in the floristically diverse coastal prairie of Texas. This result contrasts to the negative effect of deposition of mounds above ground on plant biomass in prairies elsewhere in Texas and Kansas.

This study reports results of a 14-month live-trap study of small-rodent communities in 2 habitats, cloud forest and disturbed areas, at Las Joyas Scientific Station of the Sierra de Manantlan Biosphere Reserve, western Mexico. Seven taxa of 2 families (Muridae, Heteromyidae) of small rodents were captured (Hodomys alleni, Liomys pictus, Oryzomys couesi, Peromyscus aztecus, Reithrodontomys fulvescens, R. sumichrasti, and Sigmodon alleni). Information about age structure, population dynamics, biomass, and reproduction were obtained with mark–recapture techniques for the most abundant species (P. aztecus and R. fulvescens) in both habitats. These species comprised 80.3% of the 707 captures in the cloud forest (P. aztecus, 51.2%; R. fulvescens, 29.1%), whereas, in the disturbed areas, R. fulvescens represented 81.7% of the 916 captures. Species varied in population density, relative abundance, and timing of reproduction, which was seasonal. Reproductive activity for P. aztecus peaked in the middle o...

Nutrient balancing is a foraging strategy whereby herbivores ingest a mixture of dietary items to ensure an adequate intake of nutrients to maintain individual health and reproduction. Recent findings indicate that terrestrial herbivorous rodents select dietary items from both dicotyledonous (dicots) and monocotyledonous (monocots) plants to obtain requisite nutrients, which may, in turn, influence demographic processes within the population. We investigated how availability of a major food source, dicots, affected population dynamics of Geomys attwateri , a fossorial herbivore. We removed dicots from the habitat in four plots and compared body mass, density, reproduction, recruitment, age-class, sex ratio, length of residency, and spatial distribution of pocket gophers in these areas to pocket gophers in areas with dicots. Removal of dicots reduced the proportion of reproductive females and average length of time in residency within a plot for both sexes. These effects, in turn, resulted in reduced density of pocket gophers in areas having lowered dicot availability. Spatial arrangement of pocket gophers within plots was not affected by removal of dicots but differed by season. Our experiment demonstrates the mechanism for reduction in density of pocket gophers and shows a link between foraging strategy, intake of dietary items, and demographic processes.

Determining mating strategies and social behavior of natural populations of mammals is equivocal when individuals can not be observed directly. DNA fingerprinting holds promise to elucidate relationships among individuals indirectly; however, few empirical data assess accuracy of DNA fingerprints in portraying relatedness in natural populations of mammals. Using the hispid cotton rat ( Sigmodon hispidas ) as a model, we determined accuracy of DNA fingerprinting for separating wild-caught individuals into categories according to their relatedness and ascertained repeatability of the pattern of DNA fingerprints. We used individuals from known breedings to compute similarity (S) in DNA fingerprints from pair-wise matchings. Because relatedness of these individuals was known, we obtained the actual distribution of band-sharing scores and computed the known mean S for each relatedness category. We detected significant differences in S between primary, secondary, and unrelated categories but could not distinguish statistically among related groups within these categories. High within-gel repeatability in the DNA banding pattern indicated a robust technique, but variation in scoring among readers confirmed that a single individual should score gels. Our results demonstrated that DNA fingerprints can be used to determine relatedness categories and uncover behavioral-social interactions for species that can not be observed directly. Routine demographic information (e.g., body mass, spatial proximity) collected during field studies and used in conjunction with DNA fingerprinting can provide a finer level of distinction among related groups.

General circulation models provide predictions for global climate under scenarios of increased at- mospheric CO2. Climate change is expected to lead directly to changes in distributions of vegetation associa- tions. Distribution of animals will also change to the extent that animals rely on vegetation for food or shel- ter. Bat species in Texas appear to be restricted, in part, by the availability of roosts. We used geographic information systems and the Holdridge vegetation-climate association scheme to model the effect of climate change on bat distributions and species richness in Texas. Habitat characteristics for each species were identi- fied from the literature and included vegetation, topography, and availability of caves. We assumed caves and topography to be fixed relative to climate. Vegetation changes were predicted from the Holdridge vegeta- tion-climate association scheme. The redistribution of bats following climate change was predicted based on the new locations of suitable habitat characteristics. Under conditions of global warming tropicalforests were predicted to expand into Texas; tree-roosting bats were sensitive to this change in vegetation. Cavity-roosting bats were less affected by changes in vegetation, but, where response was predicted, ranges decline.

Hispid cotton rats ( Sigmodon hispidus ) ingest both monocotyledon (monocot) and dicotyledon (dicot) plants, ostensibly to balance intake of nutrients. On the Texas coastal prairie, monocots are more abundant, require less handling time, and have more fiber and soluble carbohydrates than dicots, which contain more protein, lipid, water, energy, and minerals. Because availability of protein may be limiting here, cotton rats were raised on artificial diets that mimicked protein content of either monocots (4%) or dicots (11%). Body mass, growth rate, and length of hind foot were lower and liver mass was higher in individuals fed a monocot-protein diet. Tissue protein, but not lipid, content was higher in individuals fed a dicot-protein diet. First estrus occurred at the same body mass on both diets, but slower growth on a monocot-protein diet resulted in females being 50% older at first estrus. Cotton rats must ingest dicots to obtain sufficient protein for growth and reproduction because monocots are not a complete food source.

Hispid cotton rats ( Sigmodon hispidus ) occupy habitat patches nonrandomly on the Texas coastal prairie. We addressed the hypothesis that this pattern of habitat occupancy was influenced by nutrient content of habitat patches. Because availability of protein varied among habitat patches and amount of protein available in monocot patches was insufficient for reproduction, a specific objective was to determine whether animals would shift their habitat affinity toward monocot patches when protein was experimentally increased. We also tested whether overhead cover affected selection of habitat. Experiments were conducted in enclosures open to field weather conditions. Quadrants in these enclosures contained vegetation from monocot (i.e., low protein content, 4%) or mixed (i.e., high protein content, 11%) habitat types. In addition, quadrants received treatments of high or low cover and artificial diets containing either 0 or 15% protein. Hispid cotton rats selected quadrants containing high cover and supplemental food with 15% protein. The greatest increase in occupancy was in monocot habitats supplemented with 15% protein and where cover was low. Thus, nutritional content of habitat patches affects habitat occupancy by this herbivore, and cotton rats balanced risk against reward.

To better understand resource allocation in the herbivore Sigmodon hispidus , nutritional requirements for reproduction were determined. Adult female cotton rats were fed Purina® #5001 Laboratory Chow ad lib in the laboratory. They and their progeny were sacrificed at either 10, 20, 24, or 26 days after breeding, at birth (27 days), or at weaning (39 days). Protein, lipid, and element concentrations in body tissues of pregnant females were constant. From birth to weaning, protein concentration in lactating females increased and lipid concentration decreased, whereas no concentration of elements changed significantly. In progeny, concentration of protein, K, Na, Fe, Zn, and Cu declined significantly, while concentration of lipids, Ca, P, Mg, Mn, and energy increased significantly from birth to weaning. An energy and mass-balance analysis indicated that laboratory chow easily met nutritional requirements for reproduction. This analysis was used to estimate minimum nutritional requirements for reproduction in S. hispidus . A second energy and mass-balance analysis using a natural diet indicated that protein and phosphorus ingestion by adult females was lower during autumn and winter than required for production of a litter. Thus, protein and phosphorus are critical dietary components that may limit reproduction in S. hispidus under field conditions.

Invasion of deciduous forests by woody shrubs such as Lonicera maackii is known to negatively impact the abundance and richness of native herbs, but effects on recruitment of seedlings and saplings of native trees, such as Acer saccharum, are less well known. Ultimately, these impacts could alter the species composition of forest trees. Our study was designed to evaluate the impact of L. maackii and environmental factors on recruitment of A. saccharum seedlings and on the transition of seedlings to saplings and saplings to mature trees. We selected four study sites in southwestern Ohio where we censused L. maackii and A. saccharum seedlings, saplings, and trees in 16 plots (eight with and eight without L. maackii) at each site. We measured L. maackii abundance and maximum diameter of the primary stem (an indication of shrub size), edaphic factors (soil density, pH, soil percentage of nitrogen [%N], soil percentage of carbon [%C]), topographic factors (elevation, slope, aspect), biotic factors (overall tree abundance), and human influences (proximity to roadways). Using a generalized linear mixed model with model comparison techniques, we found that in plots with larger L. maackii, seedling recruitment was lower, the transition from seedlings to saplings was greater, and the transition from saplings to trees was unaffected. Seedling recruitment increased with increasing soil %C, but decreased with increasing soil %N. Slope was positively associated with a greater transition from seedlings to saplings, and soil density and soil %C negatively affected the transition to trees. The transition to trees was higher with greater tree abundance, and the transition to saplings and trees was greater away from roadways. Overall, these results indicate that environmental factors have positive and negative impacts on recruitment of A. saccharum, and large L. maackii have both a negative and positive relationship to recruitment. Further studies will be necessary to uncover the mechanisms involved in the negative and positive relationships of L. maackii to recruitment of A. saccharum.

Arboreal habitats pose several challenges for locomotion resulting from narrow cylindrical surfaces, steep slopes, and secondary branches that can form obstructions. We used laboratory trials to test whether different diameters, slopes, or complexity of branches affected maximum speeds and perch choice of the semi-arboreal white-footed mouse (Peromyscus leucopus). We tested locomotor performance of mice running horizontally and up and down 45° slopes for cylindrical artificial branches with five diameters ranging from 10 to 116 mm and on a subset of diameters for cylinders that were horizontal and had pegs (e.g., secondary branches) every 10 or 20 cm. Slope, diameter, and presence of pegs on top of cylinders had significant and interactive effects on locomotor performance. On horizontal cylinders the speed of mice increased with increased diameter among the three smallest diameters, but changed little with further increases in diameter, whereas for sloped surfaces the extreme diameters had lower speeds than an intermediate diameter. For a given diameter, the speeds of mice were usually faster when running horizontally rather than running uphill or downhill. The presence of pegs greatly decreased running speed compared to unobstructed surfaces, but the magnitude of this effect decreased as diameter increased. The difficulties of maintaining balance and avoiding toppling may have caused much of the decrease in speed and associated increased amounts of pausing. Only 1 of 11 choice tests detected a significant bias of mice favoring the perch that maximized locomotor performance.

The purpose of this study was to demonstrate the use of Geographic Information Systems to evaluate the effect of global climate change on mammals. Two general circulation models were used to predict climate change in Texas as a result of increased atmospheric CO2 and the Holdridge model of climate‐vegetation association was used to predict distributions of plant communities under current and increased levels of CO2 .Habitat specificities of the four species of Insectivora and the four species of Lagomorpha in Texas were used to predict impact of global climate change on their geographic distribution and, hence, on species richness within these two orders. The warmer climate in Texas predicted from climate models resulted in tropical vegetation moving into the state from the south. GIS models predicted that geographic ranges of these mammals would shrink, although none would be extirpated, and that mammalian richness would decrease (i.e., area of the state containing a high number of species would...

Cladocerans (Daphnia obtusa) in seasonal ponds in southeast Texas are infected with a trematode parasite (n. sp.). Infestation rate varies considerably among ponds and years, and among ponds within years. The parasite is rare in individuals < 1.00 mm long but is common in individuals 1.25-1.75 mm long. The parasite has no effect on whether females become gravid. Although there is a significant correlation between length and egg production for unparasitized females, this is not the case for parasitized individuals. An infection of l-2 parasites does not aflect fecundity; however, greater infections are correlated with reduced egg production. Another cost to Daphnia of harboring the parasite is reduced survivorship, particularly among larger individuals. As lthese individuals have the capacity to produce l more eggs than smaller individuals, it is likely that the parasite also causes a reduction in lifetime reproduction in addition to that in any one reproductive episode.

Dietary choice as well as the nutritional and perceptible characteristics of known dietary items were determined for cotton rats (Sigmodon hispidus) on the Texas coastal prairie. The nutritional landscape of the coastal prairie is dynamic : monocots are abundant, dispersed in clumps, and exhibit relatively little seasonal variability ; by contrast, dicots are highly variable both spatially and temporally. The lower green stems of four species of grasses constitute the bulk of the cotton rat diet ; however, some plant parts of dicots are always ingested. Parts of plants with high soluble-carbohydrate content and short-handling times were selected by cotton rats ; however, these same parts of plants typically were low in protein and phosphorus content