How population density scales with habitat area is an important consideration for spatial population dynamics and community patterns. I examined the relationship between local population density and habitat area for an herbivorous beetle Tetraopes tetraophthalmus (Forster) inhabiting patches of its host plant Asclepias syriaca L. Field observations over 4 y (1992, 1995–97) at the same site revealed that the relationship was variable during the adult fight season. Highest densities occurred on large patches early in the season, but as the season progressed, densities tended to equilibrate among patches of various sizes. Among years the relationship also showed considerable variability, but similar within generation patterns. Considering entire generations, increasing, decreasing and constant density with patch size were observed over the four years of observation. The results of this study indicate that there is considerable within and between generation variability in the density-area relationship. How population density varies with habitat area affects conservation reserve design and underlies spatial population and community theory. Variability in density-area relationships will introduce greater uncertainty for predictions of metapopulation persistence as well as estimates of community structure. Given the degree of variability seen in this system, any single estimate of a density-area relationship would be misleading. Multiple estimates, taken both within and between generations, should be performed before applying density-area relationships in studies of spatial population dynamics, community patterns and reserve design.

Eastern deciduous forests of North America have productive ground layers, but information regarding the role of ground layer vegetation in carbon cycling is limited. The ground layer, here defined as all vascular plants ≤1 m in height, contributes most of its biomass and nutrient content annually to the above-ground litter pool. This study assessed the species composition and biomass and nutrient contributions of summer ground layer vegetation to the above-ground litter pool at the AmeriFlux Site in the Morgan-Monroe State Forest, Indiana. Two hundred fifteen 1-m² subplots were sampled for ground layer species and cover (%). Forty-three of those subplots were harvested for above-ground biomass and tissue nutrient analysis. A 10-cm soil sample was obtained from each harvested subplot and analyzed for pH, organic matter and nutrient content. Boehmeria cylindrica (false nettle), Lindera benzoin (spicebush), Viola spp. (violets), Parthenocissus quinquefolia (Virginia creeper), Polystichum acrostichoides (Christmas fern) and Asplenium spp. (spleenworts) were the most important and abundant ground layer species. Ground layer species were distributed along gradients of weathering and soil organic matter. Mean ground layer cover was 36.7 ± 17.4 % and mean calculated ground layer biomass was 24.7 ± 15.4 g/m² in the mid- to late-growing season. Ground layer biomass was positively correlated with available soil P. Woody plants accounted for approximately 51% of ground layer biomass followed by non-graminoid herbs (35%) and graminoids (14%). Ground layer litter, comprised of graminoids, non-graminoid herb foliage and stems and woody plant foliage, contributed 26.5 g/m² and 11.1 g C/m², or ≤5% of the biomass and C, to the above-ground litter pool in 1999. While the ground layer contributed relatively small quantities of biomass and C to the above-ground litter pool, it provided nutrient-rich tissues with C:N ratios lower than tree leaf litter. With the exception of K, tree leaf litter contributed more nutrients by mass to above-ground litter than did ground layer litter because tree leaf litter comprised 88% of the biomass of above-ground litter.

The timing of herbivory may have important consequences to components of plant fitness as well as the growth rate and persistence of plant populations. Specifically, this study examines whether the timing of herbivory by white-tailed deer (Odocoileus virginianus) affects the population dynamics of the long-lived herb, Trillium grandiflorum. This study combines results from a clipping experiment with demographic matrix modeling in four different T. grandiflorum populations to determine how both the frequency and timing of herbivory alter the population growth rate. Herbivory early, but not late in the season, increased the probability that reproductive plants fail to reproduce in the next year. Both early and late season herbivory resulted in a complete loss of reproductive success in the current year. Because the growth rates of these populations were sensitive to changes in the fate of reproductive plants, but insensitive to changes in annual fecundity, early season herbivory was more detrimental to population growth rates than late season herbivory. Plant persistence may depend as much on the timing of herbivory as it does its frequency.

Small isolated wetlands in the southern Appalachian mountain region contain a disproportionate amount of the region's rare and uncommon herbaceous species. Many of these herbaceous communities may be threatened by invading trees and shrubs. We investigated changes in vegetative communities between 1994 and 2001 and the impact of woody encroachment upon herbaceous wetland communities in a southern Appalachian wetland complex in western North Carolina. We conducted a quantitative investigation of herbaceous, shrub and tree vegetation in forested and unforested fen and floodplain wetland sites. Additionally, soil chemistry, water level and precipitation data were collected. We found that woody encroachment was the strongest predictor of diminished herbaceous wetland communities, while water levels had the strongest positive relationship with herbaceous coverage.

The aquatic food web found within the leaves of the purple pitcher plant (Sarracenia purpurea) is useful for studying top-down and bottom-up effects. The food web has an omnivorous top-predator and is fueled by invertebrates drowned in the pitfall trap of the pitcher plant. Modeled on a previous experiment for the purpose of comparison, I conducted a 3 × 3 factorial press experiment over 4 wk, using 45 pitcher leaves in a bog in Michigan. Treatments included 3 levels (none, low and high) of both resource input and top-predator density. Both top-down and bottom-up treatments had significant effects on populations within the inquiline food web. Rotifer, mite, protozoan and bacterial density and protozoa richness increased when resources were added. Top-predator density negatively affected rotifer, protozoa and bacteria density. These findings suggest that in this food web bottom-up forces predominate, but top-down forces are also important. A similar study conducted in Florida is used to make a latitudinal comparison of food web regulation and temperature is hypothesized to be responsible for observed differences between the inquiline food webs.

Introduced species have become one of the most important anthropogenic impacts in aquatic ecosystems and are implicated in the declines of many native amphibian populations. Despite the effects of introduced fish species on amphibian communities, there is little information concerning the responses of amphibians following the removal of introduced predatory fish. We present results of a 4-y field experiment designed to determine the amphibian community- and population-level responses to the removal of introduced predatory fish from two experimental ponds. We observed an increase in amphibian species diversity in experimental ponds following the removal of fish. We also observed temporal changes in smallmouth salamander (Ambystoma texanum) population dynamics. Although A. texanum size at metamorphosis was unaffected by introduced fish in experimental ponds, fish removal resulted in prolonged A. texanum larval period and improved reproductive success. We attribute these responses to increases in A. texanum larval densities, as we caught considerably more metamorphosed A. texanum juveniles from experimental ponds following the removal of fish. Collectively, these observations support previous studies indicating that introductions of predatory fish have adverse effects on amphibians at both the community and population levels. Furthermore, our results suggest that amphibian communities are capable of recovering from environmental perturbations.

The ellipse, Venustaconcha ellipsiformis (Bivalvia: Unionidae), was first recorded in Minnesota from the Straight River in 1987, but we knew little of its distribution in the state, brooding behavior, glochidial host fish relationships or status. To examine these questions, we followed standard procedures to conduct an extensive, qualitative statewide mussel survey, described mantle flapping behavior from field and laboratory observations and identified suitable glochidia hosts in the laboratory and from naturally infested fishes. We found extant populations in five Mississippi River tributaries in southeastern Minnesota: the Cannon, Cedar, Root, Upper Iowa and Zumbro rivers. This appears to be the extent of its historic range in Minnesota as no valid records were found elsewhere. Among these, the largest population occurred in the headwaters of the Root River drainage, which was also the only drainage where we observed recent recruitment. Brooding V. ellipsiformis quickly flap a small mantle extension, often in response to passing shadows or jarring of the substrate, or their mantle extensions may be slowly undulated. We identified 11 fish species as suitable hosts for V. ellipsiformis glochidia in the laboratory: brook stickleback (Culaea inconstans), mottled sculpin (Cottus bairdii), slimy sculpin (C. cognatus), logperch (Percina caprodes), mud darter (Etheostoma asprigene), rainbow darter (E. caeruleum), Iowa darter (E. exile), fantail darter (E. flabbelare), Johnny darter (E. nigrum), banded darter (E. zonale) and blackside darter (P. maculata). Rainbow darter, fantail darter and blackside darter were also found naturally infested with V. ellipsiformis glochidia. Venustaconcha ellipsiformis should remain classified as a “Threatened” species in Minnesota and management should include conserving populations within drainages due to its restricted range and likely low dispersal ability.

Fire is an important tool for limiting woody plant invasions into prairies, but using fire management to maintain grassland plant communities may inadvertently reduce arthropod diversity. To test this, we established twenty-four 100 m² plots in a tallgrass prairie in Galveston County, Texas, in spring 2000. Plots were assigned a fire (no burn, one time burn [2000], two time burn [2000, 2001]) and fertilization treatment (none, NPK addition) in a full factorial design. Fertilization treatments allowed us to examine the effects of fire at a different level of productivity. We measured plant cover by species and sampled arthropods with sweep nets during the 2001 growing season. Path analysis indicated that fertilization reduced while annual fires increased arthropod diversity via increases and decreases in woody plant abundance, respectively. There was no direct effect of fire on arthropod diversity or abundance. Diptera and Homoptera exhibited particularly strong positive responses to fires. Lepidoptera had a negative response to nutrient enrichment. Overall, the negative effects of fire on the arthropod community were minor in contrast to the strong positive indirect effects of small-scale burning on arthropod diversity if conservation of particular taxa is not a priority. The same fire regime that minimized woody plant invasion also maximized arthropod diversity.

Conservation efforts are frequently hampered by uncertainty regarding species' distributions. Range maps as representations of species distributions are known to overestimate the area occupied by the species, with significant implications for the prioritization of conservation efforts among species. We investigate the disparity between extent of occurrence (i.e., “range”) and area of occupancy of a population or species and discuss its implications. Using as a test group a community of subalpine butterflies (Lepidoptera: Papilionoidea), we estimated range occupancy based on three levels of analysis: two field guides with differing mapped resolution of range and microdistribution data collected in the vicinity of the Rocky Mountain Biological Laboratory, near Crested Butte, Gunnison County, Colorado. We conclude butterfly range occupancy across species is low and variable, ranging from 1% to 37% among species present in our sample. A large proportion of species identified as present by range maps in both field guides (70%) were absent from our sample and we present species-specific expert opinion regarding their absence. We demonstrate potential practical and conceptual challenges inherent in the use of range maps to assess endangerment and conservation priority.

Although spores from most macrofungi are wind- or water-dispersed, dispersal may also occur via biotic vectors. The Eastern box turtle (Terrapene carolina carolina) is a facultative mycovore that may play an important role in fungal spore dispersal although, to date, no information exists on fungi occurring in fecal samples of box turtles or on the ecological significance of box turtles as spore dispersal vectors. Consequently, a study of the potential for Eastern box turtles to act as vectors for spore dispersal was initiated by capturing wild turtles and collecting fecal samples. Serial dilutions from fecal samples were made to enumerate spores, quantify the number of spores per gram of fecal material and to isolate and identify fungi. Fungal spores were found to be extremely abundant throughout all samples. Fecal samples from 36 turtles yielded a total of 23 different fungal taxa in the Zygomycota, Ascomycota and Basidiomycota. Two yeasts that were isolated, Cryptococcus albidus and Rhodotorula mucilaginosa, are reported to naturally occur on Trifolium seeds found in fecal samples. A mold previously unreported from fecal material, Aspergillus wentii, was also found in fecal samples. Data collected suggests Eastern box turtles influence fungal spore dispersal by browsing on plant materials and defecating large numbers of fungal spores within their home ranges.

Fertilised eggs, stage one and stage two juveniles of the smooth marron, Cherax cainii, are attached to the pleopods of the gravid female via specialised structures. The eggs are fixed to the maternal pleopods by egg stalks, whereas stage one and stage two juveniles remain attached by recurved spines on the dactyls of their fourth and fifth pereopods. Crayfish of the third juvenile stage are independent of the mother and receive no maternal care; their dactyl spines are straight and cannot grasp the mother's pleopods; the female displays agonistic behaviour toward her young commencing with stage III instars. We suggest that eggs and the first two juvenile stages attached to the mother would experience reduced levels of predation and be secured against strong river flow. We conclude by reviewing, briefly, the potential fitness costs and benefits of maternal care, to the mother and young of freshwater crayfish, from a life-history perspective.

In many areas, soil calcium is an important limiting factor for land snail distributions. Some tree species are able to extract calcium from lower soil depths, concentrate it in their leaves and deliver it to the surface upon leaf fall. Flowering dogwood (Cornus florida) is an example of a “calcium-pumping” species and has been suggested to promote land snail diversity in woodland ecosystems. In this study, leaf tissue calcium, O- and B-horizon soil calcium and land snail diversity were compared for three common understory tree species: flowering dogwood, American beech (Fagus grandifolia) and blackgum (Nyssa sylvatica). Using a litter sieving technique, land snails were sampled underneath these three focal tree species. Land snail density, species richness and diversity were estimated for a total of 19 trees. As expected, B-horizon soil calcium was similar across all tree species, while leaf tissue calcium and O-horizon soil calcium were significantly higher for flowering dogwood. Land snail density, species richness and diversity (Shannon-Wiener Index) were also significantly higher for flowering dogwood. Calcium-pumping tree species are important ecosystem components in that they increase soil fertility and promote invertebrate diversity. Land snails are an important food and calcium source for a variety of woodland species including passerine birds, woodland salamanders, cychrine beetles, and wild turkeys. Flowering dogwood is currently seriously threatened in the southeastern United States by the parasitic dogwood anthracnose fungus (Discula destructiva). In light of the findings of this study, the implications of dogwood anthracnose may reach beyond the target species and impact multiple taxa.

The blue-spotted salamander (Ambystoma laterale) has the northern-most distribution of any North American salamander and primarily occurs in areas that were once covered by the southern Laurentide Ice Sheet during the last glacial maximum. We examine the phylogeography of this primary post-glacial invader of northern North America. Mitochondrial DNA sequence data indicate a clade comprised of populations from the western portion of the species' range. Data from six nuclear DNA microsatellite loci support this finding. Taken together, the genetic data suggest rejection of the existing hypothesis of a single, western glacial refugium for this species in favor of two alternative hypotheses.

We quantified home range size and philopatry in ornate box turtles, Terrapene ornata ornata, with minimum convex polygons (MCP) and 95% Kernel areas (K) calculated from radio telemetry data in Iowa during 1999–2001. We also analyzed philopatry by mark-recapture data during 1994–2000. Ten adult turtles were followed every other day from May to Sep. 2000 and seven of the turtles were followed in 2001. Mean monthly MCP and K home ranges of males and females did not significantly differ. Mean annual MCP and K home ranges for males were significantly larger than those of females. For an individual, monthly MCP home ranges overlapped on average 19.3% between years and K home ranges overlapped an average of 6.0%. There were no significant differences in annual or monthly home range overlap between sexes for K home ranges, but MCP monthly home range overlap was significantly larger for males. Annual MCP home ranges overlapped on average 40.9% between years and K annual home range overlap averaged 6.8%. Seven years of mark-recapture data were analyzed to determine movements between habitat zones. Turtles were found in sand prairie or shrubby border to sand prairies 69% of the time. Regardless of sex, turtles were twice as likely to be recaptured in the same sub-habitat from where they initially were found compared to the adjacent sub-habitat. Turtles were 2–3 times more likely to be in the adjacent sub-habitat than two sub-habitats away. Given the degree of philopatry exhibited by ornate box turtles in this area, turtle populations faced with habitat fragmentation or destruction will most likely decline.

Although much is known about raccoon (Procyon lotor) denning ecology, little information is available regarding habitat correlates to raccoon daytime resting site (DRS) selection at multiple spatial scales. We studied the influence of habitat factors on DRS selection of raccoons in the Mississippi River bottomlands of southern Illinois. During 2003–2005, 54 adult females were equipped with radiocollars and were tracked to 313 DRS. Using field measurements and remotely sensed data, 156 microhabitat (e.g., den height) and macrohabitat (e.g., forest patch size) variables were measured at: (1) breeding season DRS (1 Dec.–1 Mar.), (2) cub-rearing season DRS (15 Mar.–30 Jun.) and (3) control locations. Tree cavities represented 73% of DRS; the remaining 27% were more exposed DRS. A 5-variable multinomial logistic regression model incorporating tree circumference at breast height, den height, distance to nearest road, distance to nearest water and number of nearby dens was significant (P < 0.001) and correctly classified 71% of DRS and control locations. Thus, microhabitat variables, but not macrohabitat variables, were influential in the selection of DRS for raccoons on our study area. Our study elucidates the importance of microhabitat in the selection of raccoon DRS and provides additional insight into how raccoons use the landscape.

Little is known about sex differences in parental behavior of biparental mammals and if mates in such species coordinate care of young. We studied parental care displayed by prairie voles (Microtus ochrogaster) under seminatural laboratory conditions during the first 3 d of life of their offspring. Through direct observations and videotaping, we monitored members of male-female pairs to determine if sex differences in early parental behavior exist and if mothers and fathers coordinate visits to the nest. To assess the impact of fathers on survival of pups and behavior of mothers, we also examined parental care displayed by single females toward their young. Male and female members of breeding pairs differed dramatically in degree of parental care. Females spent more time in the nest with young and licked them more frequently than did males. Additionally, females maintained the nest more frequently than did males, whereas they maintained runways less frequently. Although coordination of visits to the nest was not perfect between members of pairs, pups of pairs were left alone for less time than were pups of single females. Parental behavior displayed by paired and single females did not differ, nor did survival of their young to day 3 or 15. We suggest that provision of ample space and cover to vole parents rearing young in captivity promotes expression of sex differences in parental behavior, but that even seminatural conditions are not sufficient to yield benefits of father presence to survival of young. Under more challenging conditions, such as cold temperatures or presence of predators, benefits of father presence might emerge.

Prescribed burning and mechanical thinning are used to manage fuels within many western North American forest ecosystems, but few studies have examined the relative impacts of these treatments on forest wildlife. We sampled northern flying squirrels (Glaucomys sabrinus) and microhabitat variables in burned, thinned and control stands of mixed-conifer forest of the southern Sierra Nevada at the Teakettle Experimental Forest. We used this information to determine the effects of burning and thinning on the microhabitat associations of flying squirrels. Across pretreatment stands, the probability of flying squirrel capture increased with decreasing distance to a perennial creek and increasing litter depth. The probability of flying squirrel capture also was greater with increased canopy cover in thinned stands and increased litter depth in burned stands. Greater canopy cover may provide protection from predators, thicker litter layers may harbor a greater abundance of truffles, a primary food of northern flying squirrels, and creeks may provide squirrels with food sources, drinking water and nest trees. Results from this study underscore the need for more information on the effects of forest management on northern flying squirrels near the southern extent of the species' geographic range.

Dispersal behavior was examined for 119 male and 102 female white-tailed deer (Odocoileus virginianus) fawns marked in central and northern Illinois. Fawn movement behavior was recorded for 35 single, 78 pair and 10 triplet litters that survived intact beyond family breakup in late spring. Males (65%) dispersed at a higher rate than females (39%). Females dispersed Apr.–Jul., while males dispersed Apr.–Jul. and Sep.–Nov. The dam's and siblings movements most affected fawn movement behavior with most fawns of dispersing/migrating females and siblings leaving their natal range. As yearling-adult densities and forest cover increased on our study areas, female fawn dispersals decreased. Habitat scarcity in spring coupled with high fawn survival into the spring months promoted higher than expected female dispersal behavior. Distance traveled to a new range did not differ among study areas, years or month of dispersal for either sex. Single fawns were as likely to disperse as fawns from pairs or triplets. Control of high density deer populations will be more difficult where female dispersal is prevalent, as in the agriculturally dominated Midwest landscape.

Results of recent studies have indicated that the amount of edge habitat in an area may be an important factor in determining home range size of pumas. We tested this hypothesis with data on home ranges of pumas in southern Idaho/northwestern Utah. The study area is highly fragmented into forest patches and sagebrush open areas. We tested three predictions: (1) the percent of edge would be negatively related to home range size, (2) the amount of edge habitat in the home ranges of pumas would be similar, regardless of the size of the home range and (3) there would be more edge habitat within home range boundaries than in general areas of similar size. Home range size (90%) varied from 29.8 to 118.7 km². The percent of edge within home ranges was negatively correlated with home range size (F  =  22.3, P < 0.001, R²  =  0.53), but amount of edge habitat within the home ranges was not. The mean percent of edge within home range boundaries (16.0 ± 1.4 (se) %) was significantly greater (t  =  2.88, P  =  0.006) than general areas of similar size (11.3 ± 1.2%). We concluded that the amount of edge within an area was influencing the size of home ranges. We proposed that pumas needed a certain minimum amount of edge (hunting habitat) to successfully hunt their prey and that the amount of “catchable” prey was more important than just general prey abundance.

We observed diel patterns in CPUE, size and age-structure for freshwater drum (Aplodinotus grunniens) from Alabama waters during May–July 2003 . Drum were significantly more susceptible to capture along shoreline habitat at night. CPUE of freshwater drum was often zero during the day and increased up to 84.5 fish * h⁻¹ at night suggesting that many drum shift location to nearshore habitat after dark. Drum captured at night were also significantly smaller and younger that drum captured during the day. Age-0 drum were the most abundant age-class in nighttime samples whereas age-8 drum were the most abundant age-class in daytime samples. The dynamic interplay between food availability and predation on juvenile fish likely drives diel habitat shifts of freshwater drum.

We took advantage of unique aspects of the red-sided garter snake's breeding biology at northern latitudes to investigate whether mating was correlated with a reduced risk of predation. We scored the number of mated vs. unmated and predated vs. surviving female snakes at four dens in Manitoba, Canada. Predation intensity did not significantly vary through time during the course of the study, nor did it vary among dens. Female mating significantly decreased the odds that a female would be the victim of predation. This is likely a result of reduced courtship of females after mating, which reduces female conspicuousness and facilitates the ability to escape. These results provide support for the hypothesis that the copulatory pheromone, which communicates female mating status to males and thus reduces male courtship, benefits females by indirectly reducing their risk of predation after mating.