The U.S. Fish and Wildlife Service proposed the restoration of wetlands impacted by a series of drainage ditches and pools located in an extensive undeveloped peatland in the Seney National Wildlife Refuge, Michigan. This study examined the nature and extent of degradation to the Marsh Creek wetlands caused by alteration of natural hydrology by a water-storage pool (C-3 Pool) that intersects the Marsh Creek channel. We tested the hypothesis that a reduction in moderate-intensity disturbance associated with natural water-level fluctuations below the C-3 dike contributed to lower species richness, reduced floristic quality and a larger tree and shrub component than vegetation upstream from the pool. Wetland plant communities were sampled quantitatively and analyzed for species richness, floristic quality and physiognomy. Aerial photographs, GIS databases and GPS data contributed to the characterization and analysis of the Marsh Creek wetlands. Results showed that there was lower species richness in vegetated areas downstream from the pool, but not the anticipated growth in shrubs. Wetland vegetation upstream and downstream from the pool had similar floristic quality, except for a greater number of weedy taxa above the pool. Seepage through the pool dike and localized ground-water discharge created conditions very similar to those observed around beaver dams in Marsh Creek. In essence, the dike containing the C-3 Pool affected hydrology and wetland plant communities in a manner similar to an enormous beaver dam, except that it did not allow seasonal flooding episodes to occur. Management actions to release water from the pool into the original Marsh Creek channel at certain times and in certain amounts that mimic the natural flow regime would be expected to promote greater plant species richness and minimize the negative impacts of the dike.

Clumps of the cactus Opuntia fragilis growing in association with mats of the lichens Cladina mitis, Cladina rangiferina and a spikemoss, Selaginella rupestris, were discovered in an agricultural field in Pepin County, Wisconsin, that had been abandoned for over 50 y. The association appeared to be beneficial to the cactus, which flowered almost exclusively in the presence of lichens. Of 294 cactus clumps examined in 2001, 127 grew in the presence of lichen mats and, of these, 24 flowered, producing 91 flowers, while none of the cacti growing in the absence of lichens flowered. In 2002, 19 out of 265 cactus clumps flowered, all but one in the presence of lichens. All sizes of cacti in the presence of lichens flowered and the probability of flowering increased with cactus size. In addition, the cacti that flowered had cladodes that were on average 19% heavier than those of cacti that did not flower. The presence of lichens lowered summer soil temperatures 2–4 C compared to soil temperatures in the absence of lichens. Cooler soil temperatures conserve soil moisture better, which may enhance flowering in these cacti.

Alliaria petiolata, an invasive biennial plant, actively grows and achieves high maximum rates of photosynthesis in early spring during its second growing season, when many indigenous ground layer species are still dormant and high levels of irradiance reach the forest floor. Alliaria petiolata also extends its growing season into the summer through stem elongation and production of new leaves that are adapted to ambient irradiance levels, unlike native deciduous forest spring ephemeral species or summer forbs. Photosynthetic rates for two populations of A. petiolata in a forest ground layer were measured in summer and fall of the plant's first growing season (1998) and in spring of the second growing season (1999). During the second growing season, estimates of native ground layer cover were made at 3–4 wk intervals from early April to late May. Maximum photosynthetic rates (A_Max) were positively correlated (r² = 0.791, df = 3, P = 0.0436) with mid-day irradiance reaching the forest ground layer and were negatively correlated (r² = 0.911, df = 3, P = 0.0116) with percent ground layer cover. The highest A_Max (mean ± SE) occurred on 6 April (17.8 ± 0.6 μmol CO₂ m⁻² s⁻¹) and then declined during May, being 8.8 ± 0.3 μmol CO₂ m⁻² s⁻¹ and 4.7 ± 0.4 μmol CO₂ m⁻² s⁻¹ on 2 and 24 May, respectively. Alliaria petiolata's pre-adaptation to achieve maximum rates of photosynthesis before the active growth of many native ground layer species when irradiance reaching the ground layer is high, and temperature and moisture conditions are favorable for the species, contributes to its successful spread and eventual domination of forest ground layers.

Leaf herbivores potentially reduce plant fitness by increasing fruit abortion. The impact of leaf herbivory on fruit abortion, however, may vary with branch height in trees because of differential investment in reproduction among branches, differences among branches in exposure to solar radiation and the mobility of resource movement among branches following defoliation. Here we describe spatial patterns in abundance of lepidopteran herbivores and resultant damage in the canopy of mature white oak trees, Quercus alba. The effect of foliar damage on fruit abortion for upper and lower canopy branches was also examined. A significant positive correlation occurred between foliar damage and spring herbivore abundance. Damage measured at the end of the season was unevenly distributed throughout the canopy, varying from 10–20% leaf area loss. A significant positive correlation between percent herbivore damage and percent fruit abortion also existed. Moreover, upper canopy branches had a higher percentage of fruit abortion for a given damage level than lower canopy branches, even though herbivore damage did not differ significantly with canopy height. These results suggest that early season leaf-chewing herbivores negatively affected fruit production, but the impact on fruit abortion depended upon the location of the damaged branch. Resources apparently did not move from lesser-damaged branches to more heavily damaged branches to reduce reproductive losses.

Invertebrate prey have been shown to select suboptimal resource patches in the face of predation (the food-predation risk trade-off). The foraging strategy used by a predator and the environmental context under which an interaction occurs potentially mediates prey responses to predators. Here, I determined whether season, predator presence or alternative prey availability affected prey patch use when faced with a sit-and-wait predator from streams in southern Maine. In addition, instantaneous mortality rates and predator movement behavior were assessed as possible mechanisms explaining patch use by prey in different seasons. In the absence of predators, prey did not show any preference for substrate patches based on particle size. But, depending on prey type and season, substrate position in streams had a significant effect on prey survival. Mayflies survived most in summer when pebble substrates were located upstream whereas caddisfly survival was highest when pebble substrates were located downstream in winter. Season and taxa significantly affected instantaneous mortality rates, suggesting this predator responded differently to available prey in each season. Predators changed ambush positions in the streams significantly more during winter than during summer, both with and without prey present. The presence of caddisflies in mixed-prey trials reduced consumption of mayflies in summer, but increased their mortality in winter. Increased movement behavior of predators in winter may have led to greater encounters with prey, thus increasing winter mortality. Collectively, these data reveal season can influence the outcome of predator-prey interactions. Environmental context, as well as predation mode, is critical to predicting predation effects in macroinvertebrate communities. Further studies of the seasonal changes in organism-specific behavior are needed to evaluate the importance of biotic interactions in structuring stream communities.

We studied clutch size and ovum mass in the rock darter, Etheostoma(Etheostoma) rupestre, from one site (population) in Big Flat Creek, Alabama, using two collections made in consecutive years. Clutch sizes of 98 females 28–50 mm standard length (SL) ranged from 18–94 (x̄ = 44) eggs. Mean dry ovum mass from 29 females ranged from 391–595 (x̄ = 491) μg. Both clutch size and ovum mass were correlated significantly with SL, and both SL-adjusted clutch size and SL-adjusted mean ovum mass showed significant differences between samples. Our general comparisons with the results of life history studies on several other members of the subgenus Etheostoma suggest that the reproductive life-history traits of E. rupestre are similar to those of other species to which it is most closely related.

Black ratsnakes (Elaphe obsoleta obsoleta) prey extensively on both birds (eggs and nestlings) and mammals. There is conflicting evidence, however, regarding whether the snakes specialize on birds during the birds' nesting season or whether predation on birds is opportunistic. We tested these alternatives by determining seasonal dietary patterns from 81 fecal samples collected from black ratsnakes in eastern Ontario over 4 y. We also used these data to determine how diet varies with snake size. Birds occurred in the snakes' diet from May through August, but the occurrence of birds never exceeded that of mammals in any month. This pattern was the same as that previously reported for black ratsnakes in Kansas and supports the hypothesis that black ratsnakes prey on birds opportunistically. Relative to smaller individuals, larger ratsnakes preyed on larger species of mammals and reduced their consumption of smaller species of mammals. The reduction in the consumption of small prey by large snakes was due to diet diversification rather than specialization. However, because larger snakes continued to include small prey in their diet, predation patterns on birds and mammals suggest that ratsnakes are opportunistic predators.

Our studies of the association between the lesser earless lizard (Holbrookia maculata) and Gunnison's prairie dogs (Cynomys gunnisoni) revealed: (1) the lesser earless lizard was more abundant on prairie dog colonies than off; (2) lesser earless lizard abundance was positively correlated with prairie dog burrow abundance; (3) lesser earless lizards responded positively to artificial burrows created on noncolonized areas; and (4) lesser earless lizards used prairie dog burrows as refuges from predators; however, the relative use of burrows was greatest at high and low temperature extremes. Although prairie dogs alter habitat in many ways, our study suggests that burrows are an important mechanism involved in the association between the lesser earless lizard and Gunnison's prairie dogs.

The Conservation Reserve Program (CRP) was designed to reduce soil erosion and curb agricultural overproduction by converting highly erodible agricultural land to various forms of perennial habitat. It has had an incidental benefit of providing habitat for wildlife and has been beneficial in reversing population declines of several grassland bird species. However, the mechanisms behind these reversals remain unknown. One such mechanism may be differences in food availability on CRP vs. non-CRP land or between different types of CRP. The influence of CRP habitat type on the abundance of arthropod prey used by grassland birds has not been previously explored. We compared the abundance and diversity of arthropods among four CRP habitat types in Texas [replicated plots of exotic lovegrass (Eragrostis curvula), Old World bluestem (Bothriochloa ischaemum), mixed native grasses with buffalograss (Buchloë dactyloides) and mixed native grasses without buffalograss] and native shortgrass prairie. Attention was focused on adult and juvenile spiders (Order Araneae), beetles (Coleoptera), orthopterans (Orthroptera: grasshoppers and crickets) and lepidopterans (Lepidoptera: butterflies and moths), as these taxa are the primary prey items of grassland birds during the breeding season. Arthropod diversity and abundance were higher on indigenous prairie compared to CRP, reflecting differences in vegetative diversity and structure, but there were no differences in arthropod richness or abundance among CRP types. These results indicate that, although CRP is not equivalent to native prairie in terms of vegetation or arthropod diversity, CRP lands do support arthropod prey for grassland birds. More direct assays of the survivorship and fitness of birds on CRP compared to native shortgrass prairie are clearly warranted.

Mallards (Anas platyrhynchos) typically hatch no more than one nest per year. Herein, we document two cases of re-nesting by radio-marked mallards after hatching a nest earlier in the breeding season in northern Ohio during 2001. One radio-marked female hatched 13 eggs during her first nesting attempt and, subsequently, lost her brood. She then initiated a second nest that was later depredated during incubation. A second radio-marked female hatched 11 eggs during her first nesting attempt and, after losing her brood, initiated a second nest, hatched 5 eggs and reared her second brood to fledging. Double brooding may be associated with age of the female (AFY), early nest initiation date, loss of initial brood and breeding season length.

Catching two animals in the same trap, a double capture, can provide information on social organization. House mice (Mus musculus) have not been previously studied in terms of double captures. We examined rates of double captures and effects of age, sex and density on double captures. We used DNA-based parental assignment to examine the hypothesis that double captures would differentially involve related mice more than unrelated mice. House mice were involved in double capture events less frequently than several other rodent species. Double captures accounted for only about 0.2% of all house mouse captures and only 12.6% of eligible mice were involved in double captures. Season and density influenced the rates of double captures. Pairs of juvenile males were captured together significantly more than expected, possibly because these young mice have a greater tendency to be together more while foraging or entering traps, but, without direct observation, this can only be inferred. Adult female-adult male pairs also occurred more frequently than expected, as has been reported for Peromyscus and Microtus. Unlike other rodent species in which double captures have been examined, pairs of adult males occurred with significantly lower frequency than expected, as males in the house mouse social system apparently avoided one another. Related individuals were captured together significantly more often than unrelated individuals. Adult females were caught frequently with their progeny of both sexes. Adult males were never caught with male or female progeny. These data shed light on the social and spatial systems of house mice.

We investigated nest site use of the federally endangered northern flying squirrel (Glaucomys sabrinus coloratus) in southwest Virginia at Mount Rogers National Recreation Area. In second-growth and old forests, number of nests used by both sexes combined was x̄ = 3.3 ± 0.8 (females n = 3, x̄ = 2.7 ± 0.9, males n = 8, x̄ = 3.7 ± 1.2, overall range = 1–6). Nest site characteristics varied and flying squirrels used a variety of nest types including subterranean structures. We found northern flying squirrels chose larger taller nest trees regardless of nest tree type [red spruce (Picea rubens), n = 3, P = 0.04, deciduous, n = 8, P = 0.02, snags, n = 3, P = 0.01] compared to the available trees of the same type within a 200 m² area of the nest tree. Nest sites in old forest stands (i.e., ≥125 y old) were characterized by greater downed wood (% cover/ha) that can be associated with the increased density of fungal colonies, lower snag density (n-snags/ha) that means a more open midstory for clearer glide paths, lower live-tree density (n-trees/ha) relating to clearer glide paths and lower shrub cover (% cover/ha) indicating a more open understory compared to nest sites in second-growth stands.

In 1994 a major wind power development project was initiated in southwest Minnesota that may eventually produce 425 megawatts (MW) of electricity. The wind plant currently consists of 3 phases that total 354 turbines capable of generating 236 MW. During a study conducted from 1996–1999 to assess effects of wind power development on wildlife, 184 bat collision fatalities were documented within the wind plant. Hoary bats (Lasiurus cinereus) and eastern red bats (L. borealis) comprised most of the fatalities. After correcting bat fatality estimates for searcher efficiency and scavenger removal rates, we estimated that the number of bat fatalities per turbine ranged from 0.07 per y at the Phase 1 wind plant to 2.04 per y at the Phase 3 wind plant. The timing of mortalities, and other factors, suggest that most mortality involves migrant rather than resident breeding bats.

Etheostoma spectabile pulchellum (Orangethroat darter) and E. radiosum paludosum (Orangebelly darter) inhabit, but do not co-occur, in the Washita River, Oklahoma. Behavioral isolation between these two allopatric taxa has evolved to an intermediate degree that is consistent with their genetic distance. Behavioral isolation is asymmetric. Mating was commonly observed between E. r. paludosum females and E. s. pulchellum males, but only rarely between E. r. paludosum males and E. s. pulchellum females.

The effect of arboreal activity on species richness and abundance estimates of rodents was investigated in a chaparral habitat in southern California. During 2 y, 60% (2000) and 48% (2001) of the rodent captures were recorded in arboreal traps. There was no significant difference in numbers of rodents caught in arboreal vs. ground-level traps. Excluding juvenile Peromyscus, arboreal trap-success was significantly higher than ground-level trap-success. Arboreal trapping success did not differ significantly between other age groups or sexes in any of the species studied.

We examined home range size and habitat use of nine female northern myotis (Myotis septentrionalis) within an intensively managed forest in the central Appalachians of West Virginia. Using the 95% adaptive kernel method, we calculated a mean home range of 65 ha. Northern myotis used recent diameter-limit harvests and road corridors more than expected based on availability of these habitats. Intact forest stands and more open deferment harvested stands were used less than expected based on the availability of these habitats, although intact forest stands still constituted the overall majority of habitat used. Partial timber harvests that leave a relatively closed canopy appear to promote or improve northern myotis foraging habitat in heavily forested landscapes. However, the long-term ecological impacts on bats and other biota from this silviculturally unacceptable practice are unclear.