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Migrating hawks were observed at Fort Morgan, Alabama during autumn 1995–1998. The three most abundant migrants were Sharp-shinned Hawk (Accipiter striatus), Broad-winged Hawk (Buteo platypterus) and American Kestrel (Falco sparverius). The three species accounted for 84% of all observations. Most individuals (> 80%) were seen heading west. Compared with days with east and south winds, days with north winds were associated with significantly higher passage rates for all species, and passage rates of Broad-winged Hawks were significantly higher on days when both a cold front and north winds occurred than on days with north winds only. Hawks flew higher on east winds than on north and south winds, suggesting that hawks fly lower in winds that may blow them out over the Gulf of Mexico.
We re-evaluate the distribution of the swamp rabbit (Sylvilagus aquaticus) in Southeast Missouri. We developed a list of 276 sites that were identified by the Missouri Department of Conservation as potential swamp rabbit habitat. Most of these sites were surveyed initially in 1992. We visited 245 of these sites in an effort to establish the presence or absence of swamp rabbits. Presence of swamp rabbits was based on scat deposition on down logs or stumps, presence of skulls or carcasses, sightings of live swamp rabbits, reports by trappers, or kills made by hunters. Logistic regression analysis was used to quantify the relationship between site area and likelihood of swamp rabbit presence. A patch size of approximately 48.6 ha was required to ensure a 50% likelihood of swamp rabbits in 1992, whereas in 2001 only 40.5 ha were required. No significant improvement in the distribution of swamp rabbits has occurred in Missouri since 1992.
Depressional wetlands provide habitat for birds, mammals, reptiles, amphibians, invertebrates, and rare plant species. In order to protect, restore, and manage depressional wetlands, it is important to know more about the vegetative composition and productivity of these systems. The species composition and aboveground productivity of three seasonally flooded depressional forested wetlands were studied on the coastal plain of South Carolina from January 2000 to January 2001. The dominant tree species in the depressions were Taxodium distichum [L.] Rich., Nyssa aquatica L., and Nyssa sylvatica var. biflora [Walt.] Sarg. Annual diameter at breast height (dbh) growth was measured for all trees >10 cm dbh in five 20 × 25 m plots within each depression, and changes in dbh were used to estimate annual biomass and stem production. Aboveground net primary productivity (ANPP) was calculated for each wetland by summing stem and leaf litter production. There were no significant differences in ANPP among sites, ranging from 564–774 grams/m2/yr. These ANPP values are similar to values reported for slowly flowing forested wetland systems of the southern United States.
Field studies in the Gus Engeling Wildlife Management Area, which consists of approximately 4465.5 ha (11,034.1 acres) of the Post Oak Savannah of Anderson County, have resulted in an annotated checklist of the vascular flora corroborating its remarkable species richness. A total of 930 taxa (excluding family names), belonging to 485 genera and 145 families are recorded. Asteraceae (124 species), Poaceae (114 species), Fabaceae (67 species), and Cyperaceae (61 species) represented the largest families. Six Texas endemic taxa occur on the site: Brazoria truncata var. pulcherrima (B. pulcherrima), Hymenopappus carrizoanus, Palafoxia reverchonii, Rhododon ciliatus, Tradescantia humilis, and T. subacaulis. Within Texas, Zigadenus densus is known only from the study area. The area also has a large number of species that are endemic to the West Gulf Coastal Plain and Carrizo Sands phytogeographic distribution patterns. Eleven vegetation alliances occur on the property, with the most notable being sand post oak-bluejack oak, white oak-southern red oak-post oak, and beakrush-pitcher plant alliances.
The objective of this study was to assess whether differences in abundance of white-footed mice (Peromyscus leucopus) were related to habitat features within and surrounding 60 sampled bottomland forest patches. Habitat features included patch size, patch shape, and landuse within a 300-m buffer surrounding each patch. During 18,000 trap nights, we captured 1,308 white-footed mice within approximately 3,110 ha of bottomland forest. Type of habitat surrounding a patch was a significant determinant of white-footed mouse abundance. Sample sites where less than 10 individuals were captured were surrounded by a large percentage of upland deciduous forest and a low percentage of urban/other habitats. Sample sites where 30 or more individuals were captured were surrounded by a large percentage of urban/other habitats and a small percentage of upland deciduous forest. Sites where 10–29 individuals were captured were surrounded by intermediate amounts of upland deciduous forest and urban/other habitat. Although deciduous forest is necessary, it may not be the primary determinant of white-footed mouse abundance. Unsuitable habitat may surround and create islands of high density from which successful dispersion is difficult.
In northern regions, ruffed grouse (Bonasa umbellus) conserve considerable energy during winter by burrowing under snow cover to roost. When conditions are unsuitable for snow burrowing grouse almost invariably roost in conifers. We studied selection of winter night roosts by ruffed grouse in western Virginia, a region where snow accumulations are rare and transient. Grouse almost always used ground roosts when snow was present even though snow was never deep enough for snow burrowing. When snow was absent grouse did not show any clear preference in roost microsite type, and were found roosting in and under deciduous and evergreen trees and shrubs, in brush piles, and in leaf litter. We hypothesize that this ambivalence to conifers was due in part to persistent accumulations of fallen oak leaves, which likely afford grouse good thermal cover and concealment. Grouse were frequently found at low elevations during daytime, but rarely roosted in bottoms. This suggests daily elevational movements, possibly to avoid cold air settling in low-lying areas during night.
We studied the federally threatened eastern indigo snake (Drymarchon couperi) from 1992 to 2002 in southeastern Georgia, including a 4-year markrecapture study conducted on the Fort Stewart Military Reservation. Indigo snakes in this region are sexually dimorphic in size, with males attaining greater maximum lengths. Subadult and small adult snakes grow more rapidly than larger adults. Georgia specimens prey on a variety of vertebrates, including juvenile gopher tortoises (Gopherus polyphemus). The return of adult indigo snakes to the same sandhills in multiple years has conservation and management significance. Long-term population monitoring of indigo snakes is feasible and may yield valuable information.
A new species of diatom, Meridion alansmithii sp. nov. is formally described from a soft-water montane wetland in western North Carolina, U.S.A. Meridion alansmithii is characterized by its shape in valve view, its range of length, diminished costae near the foot pole, and the location of the rimoportula. This species occurs in isolated habitats in the ancient landscape of the Southern Appalachians, an area well-known for high biodiversity and endemism in other groups of organisms.
I report an observation of singing by a Canada Warbler (Wilsonia canadensis) in basic or female plumage. The individual was observed three times over a period of 5 days. The timing of the observation in the annual cycle of this species suggests this to be the first reported example of singing by a female Canada Warbler. Previous reports of female song in the congeneric Wilson's Warbler (Wilsonia pusilla) and Hooded Warbler (Wilsonia citrina) support this inference.
Predators of caterpillars (Lepidoptera larvae) can indirectly enhance economic gains from plant resources by reducing herbivore damage to plants. For this study, we directly observed predation of caterpillars on understory trees in the Ozarks. Our objectives were to determine the relative importance of diurnal guilds of caterpillar predators, the time of day most diurnal predation events occur, and whether predators spend more time feeding in open or closed canopy areas. Once per month, June–September, we tethered caterpillars to understory saplings and recorded all predation events. Only invertebrate predators were observed feeding on caterpillars, and most predation events were attributed to ants and vespids (wasps, hornets and yellow jackets). Predation by vertebrate predators such as birds, small mammals, reptiles and amphibians was not observed. Most predation events took place at mid-day between 1200 and 1600 hrs. Predation pressure differed significantly over the four observation dates with peak ant predation in July and peak vespid predation in September. Canopy environment appeared to influence predation events as there was a trend towards higher vespid predation of caterpillars on open canopy as opposed to closed canopy saplings. Ants and vespids accounted for 90% of observed predation events; therefore they appear to be important predators of caterpillars during the summer months. Future studies at earlier sampling dates would be valuable in determining whether the relative importance of other diurnal guilds of caterpillar predators might be greater in the spring.
The Greater Chassahowitzka Ecosystem (GCE) in west central Florida supports one of the smallest black bear (Ursus americanus floridanus) populations (< 20 adults) in North America. Females were markedly older (8.9 years) than those in other bear populations and recruitment appears infrequent. Mean annual home ranges (male: X̄ = 105 km2; female: X̄ = 31 km2) tended to be smaller than those observed in other Florida populations. Habitat was used in proportion to what was available in the GCE with a tendency to select bottomland hardwood forest. Habitat beyond the inhabited core area was dominated by anthropogenic land uses, less forest, and was not used by GCE bears. Land management must focus on maintaining the quality of existing habitat and facilitating connectivity with other black bear populations.
We developed an Index of Biotic Integrity (IBI) for wadeable Ozark Highland streams in Arkansas by using fish-assemblage data from 96 stream sites. All sites were classified as reference or non-reference based on both subjective and objective information, and we used uni- and bivariate statistics to examine 39 potential IBI metrics. Seven metrics were chosen for the IBI. They were percent (of individuals) as algivorous/herbivorous, invertivorous, and piscivorous; percent with black spot or an anomaly; percent green sunfish Lepomis cyanellus, bluegill L. macrochirus, yellow bullhead Ameiurus natalis, and channel catfish Ictalurus punctatus; percent invertivorous; percent top carnivores; number of darter Etheostoma and Percina, sculpin Cottus, and madtom Noturus species; and number of lithophilic spawning species. Trophic metrics contributed most to IBI scores, and metrics were most often correlated with chloride, nutrient, land use, road density, and sedimentation levels, which suggests that our IBI should be able to successfully differentiate stream conditions in wadeable Ozark Highland streams of Arkansas.
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