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Despite global concern for the status of animal pollinators, studies on pollination systems in the southeastern United States are disproportionately low compared to the diversity of this region. For example, sphingophilous, or hawkmoth-attracting plants, occur in the southeastern US, but confirmation is lacking for the large, long-tongued hawkmoths predicted to visit these flowers by previous researchers. Hymenocallis coronaria (Shoals Spider Lily, or Cahaba Lily), H. occidentalis (Woodland Spider Lily), Oenothera biennis (Common Evening Primrose), and O. grandiflora (Large-flowered Evening Primrose) were studied to confirm this prediction. Manduca rustica (Rustic Sphinx) was confirmed as a frequent visitor to all four plant species studied. M. sexta (Carolina Sphinx) was confirmed for three of the four plants. To determine the range of animal visitors to these plants, three of the plant species were observed during day- and night-observation periods, and total visitation was compared between these times. For H. coronaria, flower-visitation rates did not differ between day and night periods. H. occidentalis and O. biennis were visited significantly more during night hours than during the day. Although hawkmoths are frequent visitors to H. occidentalis and O. biennis, and are probably their most efficient pollinators, Archilochus colubris (Ruby-throated Hummingbird) may also play a role in the pollination of H. coronaria.
Phototactic behavior toward ultraviolet light varies among nocturnal flying insects. By recording sex ratios of 28 southeastern US moth species, we tested the commonly held belief that UV light-trap collections of moths are significantly skewed toward males. Twelve species demonstrated a statistically significant male preponderance, but a wide range of sex ratios was found. Two of the 28 species demonstrated both significant male and female bias during different observation periods, illustrating the need to collect over the entire flight period. Since the sex ratio of collected organisms varies by species and by time, this must be taken into consideration when using light-trap collection to make population estimates and to gather information for conservation or control of any particular species.
Spruce-fir forests of the southern Appalachians are threatened by the widespread death of Abies fraseri (Fraser Fir) caused by the exotic Adelges piceae (Balsam Woolly Adelgid). Subsequent canopy opening, due to decimation of the fir population, has likely affected ground-layer dynamics and diversity. We sampled bryophytes on 60 randomly selected plots within the spruce-fir zone of Great Smoky Mountains National Park (GSMNP) using the line-intercept method (total sampling distance of 1800 m). Our sampling revealed 97 bryophyte species (64 mosses and 33 liverworts) comprising 32 families and 60 genera on ground-layer substrates in spruce-fir forests. Our results suggest that upwards of 20% of the bryoflora of GSMNP can be found on ground-level substrates in the spruce-fir zone.
Grazing lands and rangelands are increasingly recognized as an important alternative to other developed land uses for sustaining ecological communities in Florida, the rest of the southeastern United States, and other regions. It is important to understand factors that influence ecological communities on private grazing lands, especially in areas with abundant wetlands, which are often sensitive habitats. This study examined the effects of different vegetation types and simulated grazing (clipping) on the abundance, diversity, and composition of the invertebrate community in seasonally flooded, isolated wetlands on a cattle ranch in south-central Florida. We compared invertebrate communities in wetland areas dominated by two different types of vegetation: emergent macrophytes (Pontederia cordata [Pickerelweed]) and grasses (primarily Luziola fluitans [Southern Watergrass]). There was a trend toward greater abundance and diversity of invertebrates in grass-dominated communities. Experimental removal of vegetation to simulate heavy grazing significantly decreased the abundance and diversity of invertebrates. It also shifted the community composition of invertebrates to favor members of Diptera and Ostracoda. Management practices in grazed wetlands that use light or intermediate levels of grazing, or that foster a greater diversity of vegetative cover, may support more diverse and populous wetland invertebrate communities.
The aquatic macrophyte Podostemum ceratophyllum (Hornleaf Riverweed) commonly provides habitat for invertebrates and fishes in flowing-water portions of Piedmont and Appalachian streams in the eastern US. We quantified variation in percent cover by P. ceratophyllum in a 39-km reach of the Conasauga River, TN and GA, to test the hypothesis that cover decreased with increasing non-forest land use. We estimated percent P. ceratophyllum cover in quadrats (0.09 m2) placed at random coordinates within 20 randomly selected shoals. We then used hierarchical logistic regression, in an information-theoretic framework, to evaluate relative support for models incorporating alternative combinations of microhabitat and shoal-level variables to predict the occurrence of high (≥50%)P. ceratophyllum cover. As expected, bed sediment size and measures of light availability (location in the center of the channel, canopy cover) were included in best-supported models and had similar estimated-effect sizes across models. Podostemum ceratophyllum cover declined with increasing watershed size (included in 8 of 13 models in the confidence set of models); however, this decrease in cover was not well predicted by variation in land use. Focused monitoring of temporal and spatial trends in status of P. ceratophyllum are important due to its biotic importance in fast-flowing waters and its potential sensitivity to landscape-level changes, such as declines in forested land cover and homogenization of benthic habitats.
The Barataria Preserve unit of Jean Lafitte National Historical Park and Preserve is located in wetlands of the upper Barataria-Terrebonne estuary near New Orleans, LA and subject to perturbations that affect aquatic resources. A study of submersed aquatic vegetation (SAV) was conducted to determine community composition, distribution, and abundance. Seven native species—Cabomba caroliniana, Ceratophyllum demersum, Heteranthera dubia, Najas guadalupensis, Potamogeton pusillus, Vallisneria americana, and Zannichellia palustris—and three exotic species—Egeria densa, Hydrilla verticillata, and Myriophyllum spicatum—were present. The highly invasive, exotic, floating fern Salvinia molesta was also present. The Preserve is affected by a coastal restoration project designed to return Mississippi River flow to the upper Barataria Estuary. Preserve SAV did not conform to the general estuarine management paradigm of decline and loss with nutrient introductions. Instead, freshwater dominated the Preserve, and sufficient light was present to support robust SAV growth in ponds, canals, and Lake Cataouatche. Native and exotic species formed large surface mats that clogged waterways. Vallisneria americana may be decreasing due to the increase in nuisance SAV and floating plants.
This study is the first of its kind for any wetland habitat in the states of the Northern Gulf Coast and therefore will be an important baseline to future studies both generally and specifically for the Preserve as Louisiana's coastal wetland waterways experience change brought on by the general coastal wetland loss from sea level rise and efforts to restore the wetlands.
Alligator holes are a key feature of Everglades marshes that provide refugia and foraging sites for a wide range of species. We investigated the spatial pattern of alligator holes in Water Conservation Area 3, a part of the central Everglades, and examined associations among alligator holes, canals, and hydrology. There were fewer alligator holes within 1000 m of canals than expected, supporting the hypothesis that Alligator mississippiensis (American Alligator) are using canals as aquatic refugia rather than creating or maintaining alligator holes in the marsh. In addition, density of holes was associated with hydrology; specifically, areas that were drier had more than twice as many alligator holes than areas that were wetter. Analyses from this study provide a baseline for evaluating changes in location and density of alligator holes in response to canal removal and hydrologic changes that will occur as part of Everglades restoration.
Samples from Walnut Creek, upstream of the Troy Wastewater Treatment Plant (TWWTP), and the influents to and effluents from the TWWTP were assayed for mutagenicity using the Salmonella typhimurium fluctuation test. Samples were prepared with metabolic activation (channel catfish S9 and rat S9 enzymes) and without using TA100 and TA98 strains of Salmonella. Results indicated that catfish S9 enzymes (FS9) were more capable of activating base-pair substitution mutagens in upstream samples than rat S9 enzymes (RS9). For influent samples, RS9 activated higher levels of base-pair and frameshift mutagens than FS9. The comparison of changes from influent to effluent samples showed a significant reduction in base-pair and no change in frameshift mutagens with FS9; conversely, no change in base-pair and a significant reduction in frameshift mutagens with RS9 were found. For direct-acting compounds (without enzymatic activation), a significant increase in frameshift mutations was found in effluent compared to influent, while no significant change was seen in base-pair substitutions. These results indicate that Walnut Creek contains both mutagenic and promutagenic compounds, and influents to TWWTF exhibit mutagenicity that may be refractory to or created by treatment processes. The generally higher mutagenicity ratios following RS9 activation vs. FS9, suggest that current toxicity studies in fish species and water quality requirements may be inadequate to assess the hazards of water resources that receive municipal wastewater treatment discharges and that may be habitat to both fish and mammalian wildlife and may eventually become sources for human exposures.
Noturus munitus (Frecklebelly Madtom) is a diminutive catfish with a disjunct distribution across the southeastern United States in large rivers and tributaries of the Mobile Basin and Pearl River drainage. Its distribution has contracted since extensive river modification began throughout its range in the 1960s, and it is likely extirpated from the Alabama River. We collected 242 specimens of N. munitus from a gravel island in the Cahaba River on the Coastal Plain in Alabama from May 2005 to March 2007 to examine life-history characteristics. Adults were associated with fast flow over large gravel at depths of 0.5–1.0 m. Young (<23 mm) were found at water depths of 0.4–0.5 m. Gonad development indicated a reproductive season from May to August, with collection of young-of-the-year in June and July supporting a mid- to late-summer spawn. Stomach content analysis revealed a diet similar to other Noturus species and dominated in volume by Baetidae nymphs (31.2%), Hydropsychidae larvae (20.3%), and Simuliidae larvae (19.7%). Some seasonal and sex differences in diet were apparent. Relative fecundity data indicate that N. munitus is one of the most fecund madtoms of the subgenus Rabida (mean of 30.6 mature oocytes) studied thus far. Few males were found in riffles during summer, and no young were found in riffles outside summer, indicating potential sex and size differences in seasonal habitat use. This knowledge is important for conservation of the species.
We present new state records for 3 crayfish species in the Tennessee River basin in Mississippi, and the first drainage-specific distributional information in the state for a fourth. The species—Cambarus girardianus, Cambarus rusticiformis, Orconectes spinosus, and Orconectes wright,—are all known from the Tennessee River basin in Tennessee, while all but O. wrighti are also known from Alabama. We also expand the distribution of Procambarus viaeviridis in the state to include the Tennessee River drainage in Alcorn and Tishomingo counties, MS. We briefly discuss taxonomic issues involving C. girardianus and O. spinosus. Based on their distributions in neighboring states, we suspect that several other species may occur in the Mississippi portion of the basin.
The emergence of Southern Tick-Associated Rash Illness (STARI) questions the validity of reported Lyme disease (LD) cases throughout the southern United States. Acute symptoms are identical, and an efficient method of diagnosis is currently unavailable, with the cause(s) in question. The etiologic agent of LD, Borrelia burgdorferi, is transmitted by Ixodes scapularis (Black-legged Tick), while Amblyomma americanum (Lone Star Tick) is known to carry B. lonestari, the bacterium associated with cases of STARI. Peromyscus leucopus (White-footed Mouse) is a very efficient reservoir for these bacteria and tolerant of their vectors. We sampled small (<3 ha) and large (>3 ha) forest patches in Virginia for tick densities, burdens, and infestation rates by collecting ticks by drag sampling and from mice. We also tested ticks for infection by Borrelia. Although mouse density was greater in small patches, tick densities, burdens, and infestation rates did not differ with patch size. B. burgdorferi was not detected in any tick species, but 3.4% of nymphal and 5.9% of adult Lone Star Ticks removed from vegetation were infected with B. lonestari.
Sylvilagus aquaticus (Swamp Rabbit) is of conservation concern throughout portions of its range, primarily due to habitat loss and alteration. Understanding habitat selection is requisite for natural resource managers providing suitable habitat to support populations of Swamp Rabbits. Swamp Rabbits are thought to be territorial and, as such, emphasis should be placed on males when studying habitat selection. Seasonal (dormant, growth, and senescent) habitat selection by male Swamp Rabbits was assessed at landscape, home-range, and plot scales. In each season, young (<20 yr) bottomland hardwood forests were selected in greater proportion, open field was selected intermediately, and old (>35 yr) bottomland hardwood forests were selected least relative to availability at the landscape scale. Male Swamp Rabbits selected home ranges from the landscape to include access to higher-elevation habitats, perhaps important during flood events. At the home-range scale, young bottomland hardwood forests and open fields were selected most during the dormant and senescent seasons, respectively, and old bottomland hardwood forests were selected least during the senescent season; the remaining cover types in each season were selected in proportion to their availability. At the home-range scale, locations with suitable cover were selected suggesting predation-risk was important at this scale. At the plot scale, predictor variables indicated Swamp Rabbits selected sites conducive to daytime resting, nighttime foraging, or latrine use. We present the first work that examines habitat selection of male Swamp Rabbits at multiple scales. Our results emphasize the importance of interspersion of cover types and stand age selected by male Swamp Rabbits.
Although summer roosting by Lasionycteris noctivagans (Silverhaired Bats) has been studied in various ecological regions of North America, no quantitative studies have examined winter roost selection. We radiotracked 11 bats to 31 day-roosts during winter in forests of the Ouachita Mountains, AR. We quantified roost structures and examined the association between roosts and forest stands. We also examined effects of temperature on roost use. Ninety percent of roosts were in trees (5 species): 55% of all roosts were under loose bark on the bole of live overstory Pinus echinata (Shortleaf Pine), 3% of roosts were in a rock outcrop, and 6% were at ground level (under a tree root or in a cavity at the base of a live pine). Bats selected pine or pine-hardwoods stands >50 years old, and used forest stands 15–50 years of age less than their availability. Roost locations were influenced by temperature and solar radiation; most (90%) roosts were on southern topographic aspects, and bats roosted in the rock outcrop or on the ground on colder days (<5 °C). Retaining open pine and hardwood stands >50 years old on south slopes would likely maintain roosting habitat for wintering Silver-haired Bats in the Ouachita Mountains.
The coastal plain of the southeastern United States has experienced rapid and intense urbanization that has substantially changed the area's landscape. Much of this landscape change has been associated with the development of golf courses and associated communities, and cumulatively, these landscape units occupy thousands of hectares in the region. The opportunity for these golf courses to support native wildlife requires examination as these habitats are becoming more common and often represent some of the largest tracts of remaining open space within an area. Although declining throughout the southeastern US, Sciurus niger (Fox Squirrel) populations are still found on golf courses in this region. We investigated the relationship between Fox Squirrel presence and landscape characteristics on 98 golf courses in coastal South Carolina. Visual and telephone surveys indicated Fox Squirrels were present on 68 of the courses surveyed. The best predictor of Fox Squirrel presence on a course was the presence of a Fox Squirrel population on the nearest neighboring course. The probability of Fox Squirrels being present on a course if they were also present on the nearest neighboring course was 87.3%. Course age was the best predictor of Fox Squirrel presence on golf courses without a Fox Squirrel population on their nearest neighboring course. Our results suggest that regional Fox Squirrel populations may be stabilized by multi-patch population dynamics.
Skulls of wild Canis collected 2003–2004 in north-central Texas are morphometrically similar to a series taken there and in nearby areas in 1964–1971, which was considered to represent a population of Coyotes (C. latrans) modified through introgression from Red Wolves (C. rufus). A few of the new specimens closely resemble small examples of Red Wolves. Such affinity is supported by authoritative examination of living and videotaped animals. The persistence of influence of Red Wolves, long after presumed extirpation through hybridization and human persecution, may be relevant to wolf conservation.
Although investigators have compared radio-transmitter attachment devices and their likelihood of failure before the end of a study, few have directly evaluated the harness materials and fastening methods that are to be shed by a bird after the research period is over. We compared the likelihood of effective detachment after transmitter life of four harness materials (7-mm- and 9-mm-wide polyester ribbon tape and polyester-coated rubber elastic) and three fastening methods (polyester thread, cotton thread, and Gorilla Super Glue™) using dummy transmitters exposed to the elements for >1.5 years. Both polyester ribbon and polyester-coated rubber elastic materials resulted in similar physical wear and remained intact for longer than a typical field seasonal, but fastening harnesses using Gorilla Super Glue™ resulted in the earliest and most consistent harness failure. Polyester ribbon material and glue fastening resulted in the earliest failure; mean failure time for 7-mm- and 9-mm-wide polyester ribbon tape with glue fastening was 408 days ± 30 SE, and 249 days ± 29 SE, respectively. Failure times for both 7-mm- and 9-mm-wide polyester-coated rubber elastic and Gorilla Super Glue™ fastening treatments were in excess of one year (438 days ± 14 SE and 438 days ± 13 SE, respectively). All harnesses with sewn thread fastening treatments lasted a minimum mean of 456 days, and in the case of both 7-mm-wide polyester ribbon and polyester-coated rubber elastic, neither treatment ever failed over the period of study. Results suggest that using Gorilla Super Glue™ as a fastener maximized the likelihood of eventual harness failure, whereas transmitters fastened via sewing showed minimal signs of wear and were unlikely to be shed by a bird during a period of time less than two years. Additional experimental studies are warranted to examine alternative harness material types, fastening methods, and harness styles to maximize the potential of successful radio transmitter shedding.
Eastern Bluebirds inhabiting a grass-dominated agricultural environment within a northwestern Georgia land tract were examined over the course of three breeding seasons (2004 through 2006) to assess the presence of ectosymbionts. More than 90% of bluebirds examined harbored plumicolous feather mites of four species: Pterodectes sialiarum (Proctophyllodidae), Mesalgoides sp. (Psoroptoididae), Analges sp. (Analgidae), and a previously undescribed Trouessartia sp. The recovery of P. sialiarum represented the second report of this species, which had previously been recorded from Eastern Bluebirds in Guatemala. New host records for Mesalgoides sp. and Analges sp., and a description of Trouessartia sialiae sp. nov. also resulted from the study. Mite abundance did not vary among groups of birds categorized by subjective quantification, with the exception of a group of a few individuals harboring a vast number of mites. Abundance was not correlated with mean host body mass or body condition and was also independent of host sex. Feather mites were most commonly found on primary remiges, occasionally on secondary remiges, and rarely on rectrices; each mite species was located on a specific type of feather. Lice were also occasionally recovered, but were reported separately.
We report the kleptoparasitism of a Picoides borealis (Red-cockaded Woodpecker) cavity by a Melanerpes carolinus (Red-bellied Woodpecker). We believe this is the first video documenting kleptoparasitism of a Red-cockaded Woodpecker nest by a male Red-bellied Woodpecker in which both a nestling and an attending adult Red-cockaded Woodpecker adult were forcibly ejected. The Red-bellied Woodpecker was resolute in its attempt to usurp the nest, reaching into the cavity over 2000 times in an attempt to evict the cavity occupants. The male Red-bellied Woodpecker and his mate took over the cavity soon after. Adult Red-cockaded Woodpeckers continued to visit their nest cavity during diurnal hours for 2 days post-kleptoparasitism. It is important that resource managers incorporate proactive management techniques to lessen the impact of interspecific competition for cavities, especially in smaller or fragmented Red-cockaded Woodpecker populations.
Although flehmen behavior is reported in felids, this display has been rarely documented in wild pumas. On 11 Nov. 2008, we recorded a female Puma concolor coryi (Florida Panther) exhibiting the flehmen response and scent marking in reaction to a baited trail camera site in Everglades National Park. The addition of scent lures to our camera sites increased the number of exposures per panther visit, enhancing the possibility of gender identification, an essential component of our annual survey.