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Mottled Ducks (Anas fulvigula) are widely distributed in southeastern coastal marshes, as are American Alligators (Alligator mississippiensis). Although the alligator has been noted to prey upon Mottled Ducks, evidence of Mottled Duck consumption is rare in numerous studies of alligator food habits. This may be due to the season and habitat from which alligators were collected for evaluation (often autumn samples from deep water habitats preferred by adult alligators). We examined stomach contents of alligators in summer (when Mottled Duck broods and molting adults are flightless) from shallow water habitats preferred by Mottled Ducks. Mottled Duck remains were found in 20.9% of 43 alligator stomachs examined, far more than the highest frequency occurrence previously reported (1.27%). Unexpectedly, three relatively small alligators (1.51–1.70 m total length) consumed Mottled Ducks and the sixteen largest alligators did not. This study underscores the importance of season and location of collections when evaluating stomach content data.
The Spotted Turtle (Clemmys guttata) is declining throughout its range in eastern North America as a result of habitat loss and collection for the pet trade. Although the species has been relatively well-studied in the northern part of its range, little is known about southern populations. We conducted a four-year study on a population of Spotted Turtles in South Carolina. A total of 44 turtles were captured: 21 females, 17 males, 5 juveniles, and 1 hatchling. There was no size dimorphism with respect to carapace length. However, females had longer plastrons, greater shell heights, and heavier body masses than males, likely as a result of the concavity of the male plastron. The adult sex ratio did not differ from 1:1. Estimated adult population size varied annually from 31 to 36 turtles, and density was estimated at 0.36 turtles/ha. This information is important for the creation of management plans to conserve populations across the Spotted Turtle's range.
Our study appears to represent the western-most report of autumn breeding within this species' range, the first report of potential environmental cues stimulating the occurrence of fall breeding, and the first examination of egg clutches and spermatogenesis from fall breeding populations. We conducted calling surveys throughout the year over a 4 year period extending from 1999–2002 to determine the frequency of fall breeding in this species. Southern Leopard Frogs bred 20 September 2002 during heavy rains. Although we observed sporadic individual calling males in other years, lack of rain seemed to suppress breeding activities despite the presence of flooded agronomic fields and ditches in the region. We characterized 11 egg masses and the testicular condition of three males during years when fall breeding was observed. The number of eggs per mass in the fall was similar to that observed during the spring, but mass-per-egg was nearly twice that observed in studies of spring breeding frogs. The hatching rate for subsamples from these clutches varied between 91 and 100% hatched. Spermatozoa, spermatids, and spermatogonia were evident in nearly all spermatic cysts. The mean maximum spermatic cyst diameter of the three males was 61.24 µm (s = 0.0125). Spermatic cyst diameter was significantly different among specimens (ANOVA, F = 20.71, df = 92, p = 0.001) suggesting they were not all expressing the same level of reproductive condition. A Tukey's pairwise comaparisons test indicated all three specimens had significantly different spermatic cyst diameters from each other. We suggest that clutch size may vary geographically and may be related to multiple clutching in this species.
Ambystoma mabeei is listed as threatened in Virginia due to its rarity and susceptibility to urbanization and poor forestry practices. The purposes of this study were to determine the composition of the diet of larval A. mabeei and to compare larval diet in different geographic regions to gain insights into the ecology of Virginia populations. Ninety-eight percent (N = 75) of all A. mabeei larvae dissected contained food items. Virginia samples harbored higher loads of gastric parasites (Nematodes) than individuals from other locations. Furthermore, prey species found in the stomachs of Virginia specimens were different than those of conspecifics from more southern locations. Higher loads of gastric parasites in Virginia animals may be related to their diet, which in turn is related to the forest cover over natural ponds. Habitat disturbance and parasite prevalence may have major implications both for larval survival and for the long-term persistence of A. mabeei populations in this portion of their range.
We surveyed 39 tributaries of the Tallapoosa River drainage in Alabama in an effort to increase the available knowledge of its crayfish fauna. The survey yielded six crayfish species: Cambarus (Depressicambarus) englishi, C. (Depressicambarus) halli, C. (Depressicambarus) latimanus, Orconectes (Tubericambarus) holti, Procambarus (Pennides) spiculifer, and P. (Pennides) versutus. Cambarus englishi and C. halli are endemic to the Piedmont Plateau province of the Tallapoosa drainage, where they were syntopic with each other and with C. latimanus and P. spiculifer. The genus Orconectes has not previously been reported from anywhere within this drainage. Orconectes holti and P. versutus were found only in the Coastal Plain, where O. holti was syntopic with P. spiculifer, but not with P. versutus. The two Procambarus species occupied mutually exclusive sites. Crayfishes were present at sites with lower pH, lower conductivity, shallower riffles, lower stream order, and lower link magnitude than occurred at sites where no crayfish were found. The presence of one or more individual species was significantly correlated with specific environmental factors.
Samples of the Notropis rubellus complex were collected from 33 localities in Kentucky and Tennessee during the late spring and early summer of 1998–2001. Based on nuptial coloration, scale and fin-ray counts, and body shape, two taxa were diagnosed and recognized as species in the study area. Notropis rubellus (Agassiz) occupies upland streams of the Ohio River basin upstream of the mouth of the Green River and in the Cumberland River drainage above Cumberland Falls. Notropis micropteryx (Cope) occurs in upland streams of the Cumberland River drainage downstream of Cumberland Falls and the Tennessee River and Green River drainages. This species differs from N. rubellus in having modally fewer circumferential scales (23–24 vs. 25–26), modally fewer scales below the lateral line (three vs. four), and less red on the dorsum of the head of nuptial males. Green River populations exhibit more mean scales below the lateral line and slightly more intense red than other N. micropteryx populations. Support for recognition of these taxa as evolutionary species includes zoogeographic evidence in addition to the array of morphological characters.
Hoplosternum littorale is a South American catfish (Family Callichthyidae) first discovered in the United States in 1995 in Florida. The presence of H. littorale was documented from early 2002 to late 2003 in Lake Tohopekaliga (Kissimmee River Basin) in central Florida. In this paper, 22 H. littorale nests and nest sites are described. The characteristic bubble nests were present from late May to early September, with number of nests peaking in August when water stage and temperature were both high. Nest habitats (shallow, open marshes) and timing of nest construction (rainy season) were similar to what has been reported for H. littorale in its native range. Most nests (n = 14) were in areas dominated by Hydrilla verticillata and constructed largely from parts of this Asian aquatic plant, representing a unique association between two non-native species. Nevertheless, during August, as water levels increased, nesting shifted from H. verticillata-dominated communities to use of inshore grass zones dominated by Luziola fluitans. Knowledge of H. littorale nesting seasonality and habitat preferences may be useful for any efforts to control or manage this invasive fish.
Woodpeckers in North America are not widely recognized as nest predators. In this paper, we describe several eyewitness accounts of songbird nest predation by Red-bellied Woodpeckers (Melanerpes carolinus), document evidence that songbirds recognize woodpeckers as nest predators, and show that our observations are consistent with previously published notes. We believe that this species, commonly overlooked, may be an important predator of songbird nests in many eastern North American forests.
We assessed breeding-pair density and habitat associations of Barred Owls (Strix varia) at the edge of their range in north-central Oklahoma in 1995–1996. We played taped calls of Barred Owls to solicit and record responses (visual and auditory) and thereby determine density in our 1155-ha study area. Numbers of owls ranged from 7 pairs in 1995 to 11 pairs in 1996, or 1 Barred Owl pair/105–165 ha in a relatively contiguous bottomland forest. To assess habitat associations, we overlaid core areas of owl activity, as inferred from the locations of Barred Owl responses, on aerial photographs and quantified habitats in a 0.65-km2 cell surrounding owl core areas. Barred owl pairs were associated with closed-canopy forest (62.8%), fallow agricultural fields (10.6%), water (8.1%), and treeless (open) areas (6.2%), which differed from single owls (presumed nonbreeders) that showed a greater affinity for open-canopy forest and agricultural fields.
Previous studies of the relationship between acorn production and Peromyscus populations have been conducted in regions with severe winter climate where winter breeding is rare. I trapped white-footed mice, Peromyscus leucopus, in a southern Piedmont oak-hickory forest during autumn and winter for four consecutive years to determine how acorn availability influences winter reproduction in P. leucopus. Acorn production in years 1 and 4 of the study was over 10 times higher than in years 2 and 3. Peromyscus leucopus density was highest in winters following large mast crops, but also increased following a low mast crop in year 3. Body weight was significantly lower during one of the poor mast years, but not the other. More than 50% of female mice were reproductively active during all four winters of the study. Thus, P. leucopus responded positively to high mast availability, but mice remained reproductively active even in poor mast years.
A survey of the vascular flora of Dale County, AL, was conducted from August 1999 through December 2000. Dale County consists of 145,039 ha in the southeastern section of Alabama and occurs entirely within the Coastal Plain Province. Plants were collected from all major habitats within the county, including xeric and mesic woods, fields, floodplains, and swamps. Additionally, a search of the pertineant literature was conducted, and the herbaria at Troy University (TROY), Auburn University (AUA), and The University of Alabama (UNA) were searched for taxa not collected during this study. A total of 921 species, representing 458 genera and 142 families, were found within the county. The largest families were Asteraceae (121 species), Poaceae (94 species), and Fabaceae (75 species). Twenty-one of the taxa documented for this study are globally or state ranked for rarity of occurrence.
Species composition, extent of coverage, biomass and factors influencing the distribution of submerged aquatic vegetation were determined within 428 10-m2 plots located along the 213-km Piedmont section of the 6th order James River, VA. The six species of submerged plants dominant in the river were ranked in abundance as follows: Heteranthera dubia > Elodea spp. > Potamogeton pectinatus > Vallisneria americana > P. illinoensis > Najas guadalupensis. The combined air-dry biomass of all species of submerged plants in the river increased rapidly from a minimum in May of 3 g/m2 to 55 to 75 g/m2 from July through October. Thirty-six percent of the riverbed along the 213 km of river was covered by submerged plants, with coverage peaking at nearly 60% of the riverbed in the middle section of the river. Stepwise regression analysis showed a weak relationship (R2 ≤ 0.12) between the distribution of plants and type of substratum, water depth, and water velocity. Digitial multispectral videography (DMSV) of submerged aquatic vegetation revealed the estimated coverage by plants of specific areas of the river bottom differed by a mean of 11% when comparing the DMSV data with that estimated visually from a boat, showing that this form of remote sensing can be used for broad scale detection and monitoring of submerged riverine macrophytes.
In the active delta of the Mississippi River, Phragmites australis occurs in large contiguous stands of predominantly two clonal genotypes. We determined morphological variability among and within clones in this environment. Eight morphological variables were measured on culms from eight clonal populations within three subdeltas. Six populations were from the two dominant genotypes, whereas two populations were of two recombinant genotypes. All eight populations were genetically assessed from previous isozymic analysis. Culm, leaf and panicle morphology varied significantly between the two predominant genotypes, whereas the morphology of the two recombinant genotypes generally fell intermediate to that of both dominant genotypes. Morphological differences found within genotypes among the three subdeltas demonstrated phenotypic plasticity within P. australis. Morphological variability across subdeltas is likely the result of one or several environmental factors related to water depth or substrate quality.
We conducted a landscape-level survey of Microstegium vimineum (Trin.) A. Camus (Japanese grass, Nepal grass) at the Oak Ridge National Environmental Research Park to: (1) document the distribution of this species, (2) measure several important characteristics of the populations and invaded habitats, (3) identify biotic and abiotic environmental factors that may limit its distribution, and (4) quantify its response to environmental gradients. We found that M. vimineum exhibits the broad environmental tolerance of many “weedy” species, and it appears that no single variable explains presence or performance. Presence of M. vimineum was correlated only with soil pH, whereas M. vimineum performance was positively correlated with canopy openness and biomass of other species. Explanatory variables differed among sites, which suggests that other factors (such as disturbance or dispersal) may be locally important, or that different factors may interact to control the distribution and performance of this species at any given site. The nearly ubiquitous presence of M. vimineum along roads and trails in the study area, and the frequent incursion of roadside populations into adjacent forested habitat, highlights the importance of early control of source populations at forest edges.
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