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In 2005, we assessed the occurrence of leeches on semi-aquatic turtles in nine ponds in the North Carolina Piedmont. Placobdella parasitica (smooth turtle leech) was the only parasitic leech found on turtles and was present on turtles from all ponds. Female Chrysemys picta (Painted Turtles) were more frequently parasitized than males (females 54.7%, males 40.9%; p = 0.039), possibly because they are larger and provide more surface for leech attachment. Chelydra serpentina (Snapping Turtles) had the highest leech load of any species (mean = 32.3/turtle), which we attributed to its large size and bottom-dwelling habits. Most leeches were found attached to the underside of marginal scutes or between the plastron and inguinal region. These sites likely offer protection from the environment when a turtle emerges from the water.
Hyla cinerea (Green Treefrog) is a common wetlands species in the southeastern US. To better understand its population dynamics, we followed a relatively isolated population of Green Treefrogs from June 2004 through October 2004 at a federal office complex in Lafayette, LA. Weekly, Green Treefrogs were caught, measured, marked with VIE tags, and released. The data were used to estimate population size. The time frame was split into two periods: before and after August 17, 2004. Before August 17, 2004, the average estimated population size was 143, and after August 24, 2005, this value jumped to 446, an increase possibly due to tadpoles metamorphosing into adults.
Forest vegetation was studied in relation to hydrogeomorphology on a large fluvial island in the meandering section of the Lower Mississippi River. The island has a relatively wide topographic gradient, including a former channel of the Mississippi River. Vegetation patterns were related to geomorphologic features, elevation, flood duration, and characteristics of surficial sediment. Overstory vegetation was species rich for the island as a whole and dominated by the pioneer taxa Populus deltoides (eastern cottonwood) and Salix nigra (black willow). Both pioneer species dominated the old channel. Vegetation at higher elevations was characterized by tree species from later successional stages such as Celtis laevigata (sugarberry), Acer saccharinum (silver maple), Liquidambar styraciflua (sweetgum) and Ulmus spp. (elm). Seedlings and saplings were dominated by sugarberry and other later successional species, whereas cottonwood was infrequent. Our results suggest that on the Lower Mississippi River, coexistence in the floodplain of pioneer stages and later successional stages will not be perpetuated under the prevailing hydrologic and geomorphologic regimes.
We investigated associations between soricids and coarse woody debris (CWD) in bottomland hardwood forests impacted by Hurricane Hugo. The objectives were to evaluate CWD loadings at three forests disturbed by Hurricane Hugo, monitor soricid captures at these forests, and identify habitat associates of soricids Pitfall traps were used to sample soricids from January 2002–December 2003, and habitat parameters (CWD, vegetation, soils, and microsite) surrounding pitfalls were sampled. We found CWD volume was significantly higher at study sites that experi enced highest hurricane wind speeds. Captures of soricids were highest in forests with high CWD loadings, and regression models associated soricids with log cover and CWD volume. Sorex longirostris (southeastern shrew) was associated with logs in an advanced state of decay and woody litter. Blarina carolinensis (southern short tailed shrew)was associated with log cover and leaf-litter cover. Soricid captures also increased with close proximity of CWD. We found that major disturbances have lasting influence on bottomland hardwood communities, and forests with high load ings of deteriorating CWD provide habitat for S. longirostris and B. carolinensis.
Habitat loss coupled with decline in harvest has raised concern for Sylvilagus aquaticus (swamp rabbit) in Arkansas. We assessed relative abundance and habitat associations of swamp rabbits in eastern Arkansas using presence of latrine sites. We searched for fecal pellets at randomly chosen sites during winters 2002–03 and 2003–04. Swamp rabbits were detected at 85% and 76% of sites searched during years 1 and 2, respectively. Bignonia capreolata (crossvine) stem density was significantly greater at sites inhabited by swamp rabbits (mean = 625, SE = 141) than at uninhabited sites (mean = 0.00, SE = 0.00) in year 1, but no differences were found in year 2. We found no relationship between woodland tract size and pellet-group density. Logistic regression predicted presence of swamp rabbits 88.3% of the time based on crossvine density and percent ground cover of grasses. To understand the potential for conserving swamp rabbit populations in Arkansas, it will be necessary to assess remaining bottomland hardwood stands in relation to the quality of swamp rabbit habitat.
Habitat of Sylvilagus aquaticus (swamp rabbits) in Illinois has been reduced and fragmented due to human land use. Translocation may enable swamp rabbits to colonize isolated habitat patches. We live-trapped and translocated 9 male and 8 female swamp rabbits to unoccupied habitat in southern Illinois in January and February 2004. Eight of 17 translocated rabbits died within 7 days after release. However, mortality rates appeared to drop rapidly over time after release. Predators killed at least 10 of 14 rabbits that died. For conserving swamp rabbits, translocation success is limited by poor live-trapping success and high levels of post-release predation. Intense live-trapping along with predator control in release sites may be necessary to make translocation a viable management strategy.
We used a geographic information system (GIS) and logistic regression to investigate relationships between geomorphology and Castor canadensis (North American beaver) impoundment of lower-order, blackwater streams of a southeastern landscape. Using GIS, we divided streams into 632 500-m reaches and measured a set of geomorphic variables for each reach. Beavers were most likely to impound stream reaches crossed by roads with a gradient of ≈ 0.6 to 1.2% and watershed sizes of ≈ 2500 ha; reaches with watershed sizes < ≈ 500 ha or > 5000 ha were almost completely avoided. Gradient and road crossings contributed little to discrimination among impounded and unimpounded reaches, suggesting these variables had relatively small influences on beaver impoundment when compared to stream size. Our results indicate that GIS and geomorphic variables can be used to model the impoundment of streams over larger areas (e.g., the proportion of third-order watersheds impounded), but are less accurate at predicting the impoundment of individual reaches. However, the temporal dynamics of impoundment creation and abandonment will need to be incorporated into region-specific models before they can be used in ecosystem integrity assessment.
This paper represents the first study of reproductive success for Sturnella magna (Eastern Meadowlark) and Columbina passerina (Common Ground-dove) in Florida dry prairie and, to our knowledge, the first published study of reproductive rates of Chordeiles minor (Common Nighthawk) in North America. We located 34 Eastern Meadowlark, 13 Common Ground-dove, and 14 Common Nighthawk nests during the 1997 and 1998 breeding seasons. We estimated daily nest success (standard error) to be 0.93 (0.01), 0.94 (0.02), and 0.93 (0.02) for Eastern Meadowlarks, Common Ground-doves, and Common Nighthawks, respectively. Subsequently, total nest success was 0.16, 0.22, and 0.28 for Eastern Meadowlarks, Common Ground-doves and Common Nighthawks. Predation was the most common cause for nest failure. Our estimates of nest success for Eastern Meadowlarks and Common Ground-doves are generally lower than reported for other regions, which could be due to the small and fragmented nature of Florida dry prairie.
I used point counts and mist netting at the Lula Lake Land Trust, GA, a reclaimed mining area, to assess its suitability for migrating and breeding long-distance migratory landbirds. The results suggest that the property is suitable for migrants. The proportion of migrants is similar to other areas of the southeastern United States, as well as other reclaimed forestland. In addition, migrant populations were either stable or increased over the three years of monitoring, and 4% of migrants banded returned in subsequent years. Management of the Trust properties should continue to emphasize maintaining large areas of mature forest, and Trust managers should take measures to ensure that increased human recreational activity on the property does not degrade habitat quality.
Fish surveys throughout the Wateree River in 2004–2005 documented the presence of 8 catostomid species—Carpiodes sp. cf. Cyprinus (quillback), Erimyzon oblongus (creek chubsucker), Ictiobus bubalus (smallmouth buffalo), Minytrema melanops (spotted sucker), Moxostoma collapsum (notchlip redhorse), M. macrolepidotum (shorthead redhorse), Scartomyzon rupiscartes (striped jumprock), and Scartomyzon sp. undescribed species (brassy jumprock)—but failed to document C. sp. cf. velifer (highfin carpsucker), Moxostoma sp. cf. Erythrurum (Carolina redhorse), or M. robustum (robust redhorse). Four native (quillback, spotted sucker, notchlip redhorse, and shorthead redhorse) and the nonnative small-mouth buffalo were collected in sufficient numbers to allow observations of unique aggregations. Based on time of year, expression of milt, presence of tubercles, and published thermal preferenda during spawning, we believe these aggregations were associated with spawning, although direct observations of spawning behavior were not made. Spotted suckers used Piedmont and transitional-zone habitats early in the year and also aggregated in larger numbers in the mouths of blackwater Coastal Plain tributaries. Low catches of spotted sucker in riffle habitat in the Wateree River at temperatures exceeding 14 °C appears anomalous and merits further investigation. All other suckers were collected predominantly in areas of gravel, cobble, and bedrock in the Piedmont and transitional zone; aggregations of quillback, shorthead redhorse, and then notchlip redhorse successively followed high spotted sucker catches. The nonnative smallmouth buffalo appeared to use these same habitats during the entire time when quillback, shorthead redhorse, and notchlip redhorse were present, although smallmouth buffalo were collected at low catch rates. The elevated temperatures at which notchlip redhorse aggregated appeared anomalous and merits further investigation.
The early life-history requirements of Polyodon spathula (paddlefish) are not well understood, in part due to the difficulty of sampling early life stages. Passive sampling with benthic, mat-style devices effectively collected paddlefish eggs in the Tombigbee watershed (Mobile River basin) during spring 2005, facilitating identification and characterization of egg-incubation microhabitats. Eggs were collected over gravel, sand-impacted gravel, and bedrock substrates at corrected depths ranging from 1.2 to 7.7 m. Sampling occurred continuously (489 sampler-days) in the lotic bendway of the Tennessee-Tombigbee Waterway from late February through April, when water temperatures ranged from 11.5 to 20.8 °C. Of 106 paddlefish eggs collected from this unique macrohabitat, 95% were taken on either April 6 or April 16. Nine paddlefish eggs were collected in a tributary (Noxubee River) on April 13 after four sampler-days of effort. Water temperatures associated with peak spawning activity ranged from 16.9 to 19.4 °C, slightly higher than temperatures recorded for Mississippi River basin populations. A substantial (> 2.74-m) rise in water level triggered spawning activity, similar to that observed in other systems. Benthic mats proved useful for delineating paddlefish egg-incubation habitat in areas not subject to shifting substrate, and could be used in the future to address hypotheses regarding micro- and macrohabitat suitability.
I examined sexual dimorphism in the long-lived Aplodinotus grunniens (freshwater drum) from five lakes and four rivers in Alabama. Using the Von Bertalanffy growth function combined with nonparametric statistics, I found males and females had similar annual growth rates from years 0–4 years of age, but then showed significantly different growth rates across subsequent ages. Female drum grew significantly faster through adulthood, and ultimately attained significantly larger sizes (L∞ = 510.8 mm, TL) compared to males (L∞ = 385.3 mm, TL). This study highlights the difference gender can have in evaluation and interpretation of population characteristics, especially for long-lived and highly fecund fishes such as freshwater drum.
We sampled fish communities in 19 isolated cypress pond and herbaceous marsh wetlands at locations in southwest, south-central, and southeast Florida. Breder fish traps were more effective at sampling fish communities at these sites than either seine or dip nets. We collected 23 total species, but species richness varied from 1–16 among sites. The availability of deepwater refugia and the extent to which periodic flooding connected these wetland habitats to other aquatic environments appeared to be principal factors influencing composition of fish assemblages. Models of fish distribution in response to hydrological changes in the Everglades have proposed size-structured, fish functional groups of ≤ or > 7 cm, but our data suggested size and ecology of fish functional groups in isolated wetlands may be better described as small, omnivorous species (≤15 cm) and larger predatory species (> 15 cm). We suggest incorporating fish functional groups in programs to monitor ecological health of isolated wetlands in south Florida may be more productive than attempts to identify specific indicator species or relying solely upon measurements of physical, chemical, or plant-community parameters.
Observations on tidal flats in North Inlet, SC suggested facultative suspension- and deposit-feeding in the chaetopterid polychaete, Mesochaetopterus taylori. Fecal coils consisted of two disparate sections, the first composed of small, brown fecal pellets wrapped together by mucus into long strands, which abruptly transitioned into a second gray, ropy section. We also made direct observations of exposed palps and probing of the sediment surface intermittently following tidal emersion. Granulometric analyses of gray and brown fecal material, surficial sediments, subsurface sediments, and materials in suspenson above the worm at high tide, corroborate our field observations that M. taylori is a facultative feeder, switching from suspension- to deposit-feeding with tidal emersion. Typically, this shift in feeding mode is not thought to effect a fundamental change in diet, i.e., the same materials are ingested, suspended or deposited depending on hydrodynamic regime. In contrast, M. taylori ingests finer particulates during tidal immersion, with concomitant differences in granulometric characteristics. The distinct provenance and composition of the dietary components of M. taylori likely supplies a relatively broad range of essential nutrients. The geophysical effects of M. taylori feeding are likely profound, in that it both translocates subsurface sediment to the surface during deposit feeding and deposits fine, suspended materials following filter-feeding.
Uniola paniculata (sea oats) is a perennial, clone-forming dune grass of coastal beaches in the southeastern United States. We used random amplified polymorphic DNA (RAPD) markers to compare clonal diversity in younger and older patches of U. paniculata. Older patches were found to contain a significantly higher level of clonal diversity, suggesting that, in some cases, U. paniculata populations may increase in clonal diversity over time. The high level of clonal diversity found in the older patches provides further evidence for the important role of sexual reproduction in maintaining diversity in U. paniculata.
We estimated summer abundance of juvenile Loggerhead Turtles at our study site in Core Sound, NC with a Horvitz-Thompson type estimator, which uses count data and recapture probability to estimate abundance. Abundance ranged from 192 (95% CI = 88–1047) to 633 (95% CI = 219–1047) turtles over the six years of this study. These results provide preliminary estimates of juvenile Loggerhead Turtle abundance during the summer in Core Sound.
Previous studies have documented that cavities < 10 liters are consistently rejected as nest sites by Apis mellifera (European honey bees). During a study of Glaucomys volans (southern flying squirrel) ecology in Alabama, however, honey bees occupied a total of 10 nest boxes with volumes of 5–6.7 liters. These observations are significant because they represent the smallest documented cavity volume accepted by honey bees, and also because they lend support to the theory that minimum acceptable cavity volume varies geographically. Small volume cavities may be accepted in the southeastern United States due to milder climates, a paucity of natural cavities, genetic differences in honey bees among regions, or some combination of these factors. Consequently, there may be increased potential for competition between honey bees and other cavity-nesting species in the Southeast.