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Two of 36 forest restoration sites in the Mississippi Alluvial Valley surveyed from 2000–2002 harbored Quiscalus quiscula (Common Grackle). Occupied sites were in less-forested landscapes and had sparser understory vegetation due to flooding. Probability of daily nest survival (0.9077) of 169 Common Grackle nests was influenced by nest-placement, temporal, and landscape effects. Age of nest markedly affected nest survival, which increased from <0.89 during egg laying (age < 6 days) to >0.92 when nestlings were present (age > 18 days). Extrapolating daily nest survival to a 31 -day nest period resulted in 5% nest success, far less then previously estimated for this species in more northern latitudes and likely less than required to sustain populations on these sites.
Picoides borealis (Red-cockaded Woodpecker) is an endangered species inhabiting pine savannas of the southeastern United States. Because the intensity of hurricanes striking the southeastern United States is likely to increase as global temperatures rise, it is important to identify factors contributing to hurricane damage to Red-cockaded Woodpecker cavity-trees. Our objectives were to examine the effects of landscape-level factors on wind damage to cavity-trees and assess the relative risk of wind damage for different tree species and trees with different types of cavities. We evaluated wind damage to cavity-trees from Hurricane Rita on the Angelina, Sabine, and Davy Crockett national forests in eastern Texas. Basal area and number of cavity-trees in a cluster were identified as factors influencing the likelihood of damage to a cavity-tree. The likelihood of damage increased with decreasing basal area and an increasing number of cavity trees in a cluster. The increase in damage associated with an increase in the number of cavity-trees in a cluster likely reflects an increase in cluster area with more cavity-trees and the maintenance of lower basal areas in clusters to meet the habitat requirements of Red-cockaded Woodpeckers. Therefore, increasing basal area is not a reasonable management option because clusters will become unsuitable for Red-cockaded Woodpeckers. A higher proportion of trees with natural cavities were damaged than trees with artificial cavities in all three forests. A higher proportion of Pinus echinata (Shortleaf Pine) cavity-trees were damaged than Pinus palustris (Longleaf Pine) or Pinus taeda (Loblolly Pine) cavity-trees. Longleaf Pine cavity-trees were more likely to snap at the cavity, compared to a higher likelihood of wind throw for Shortleaf and Loblolly Pine cavity-trees. Restoring Longleaf Pine habitat and allowing stands to develop under lower tree densities could decrease the likelihood of damage to cavity-trees and the impact of hurricanes on Redcockaded Woodpeckers.
With the increase in urban development, forest fragments are becoming more prevalent. In urban areas, there is a tendency to hide power-lines within or on the edges of these fragmented forests; however, it is unknown how the maintenance of vegetation under and along power-lines impacts the forest composition and structure of an adjacent fragmented, urban forest. An urban, fragmented maple-oak-hickory forest is located on the Meredith College campus, Raleigh, NC. A 1-ha plot with a hundred 10- × 10-m subplots was established in 2007 to initiate a long-term project supporting undergraduate research. An adjacent meadow is cut and maintained regularly up to the forest and plot edge for power-line clearance and access. We identified, tagged, and measured all of the trees with a diameter at breast height (DBH) ≥ 5 cm in this permanent plot, and compared the tree species richness (S), Shannon-Weiner diversity index (H), Sorenson's similarity index (Ss), DBH, stem density, and basal area along the 100-m gradient from the forest edge. We also used a non-metric multidimensional scaling (NMS) analysis to describe how species composition changed along the gradient. Our findings showed that S, H, and Ss did not change along the 100-m gradient. The NMS confirmed that species composition was not different in the edge subplots (0–10 m from edge) compared to all other subplots and therefore was not impacted by continual, local disturbance along forest edges. However, we found that forest structure changed along the gradient with the exception of mean DBH; stem density and total basal area varied along the 100-m gradient. There was greater stem density along the edge of the forest (0–5 m and 10–20 m from edge) compared to the other interior subplots. Some of the interior subplots (10–20 m and 60–70 m from the edge) had a higher total basal area than the remaining plots. As expected, we also found that there was a negative linear relationship between DBH and stem density for all subplots. Our results confirm trends found in previous studies that community structure parameters (stand density and basal area) differ between forest edges and their respective forest interiors, but did not agree with previous research, which found species composition to be affected by edges. We believe the regular pruning of the forest edge adjacent to the power-lines explains our observed differences in forest structure, but tree species richness, diversity, similarity, and composition may be determined by the disturbance of larger-scale ecological processes. Our results show how power-line placement within a fragmented urban forest can affect the structure of the adjacent forest, and we recommend that the ecological effects of power-line corridors should be further investigated and incorporated into the larger body of literature on forest fragmentation.
Although male and female Odocoileus virginianus (White-tailed Deer) exhibit high site fidelity throughout the year, individuals occasionally leave their home ranges on short excursions during the fall and winter months. Although motives for these extraneous movements are difficult to discern, excursions are likely the function of the breeding season, food sources, limited escape cover, and/or human disturbances. From 2003–2007, we examined GPS collar locations of 32 adult male White-tailed Deer at Chesapeake Farms, MD. Seasonal excursions (n = 37), defined as movements lasting a minimum of 6 hours and venturing at least 0.5 km from 95% kernel home-range contours, were examined relative to possible motives related to food resources, breeding, and hunting pressure. Sixty-three percent (n = 20) of adult males made at least one excursion outside their home range immediately before or during breeding season. Based on the seasonal timing of excursions, breeding-season-related motives were likely the driving force behind the majority of adult male White-tailed Deer excursions, whereas hunting pressure and food resources were not a probable cause.
Cervus elaphus (Elk) were reintroduced into the Cumberland Mountains, Tennessee over a 3-year period beginning in December 2000. We radio-collared 159 Elk and monitored them by aerial telemetry from February 2001 to June 2003. Locations (n = 321) were used to develop a core herd home range (789-ha sampling area) to assess Elk seasonal forage use and availability. We monitored diet and resource availability from November 2003 to October 2004 by microhistological analysis of feces and vegetation sampling, respectively. We compared the relative availability of individual plant species (% cover) to the relative percentage of plant species found in fecal samples. A positive significant mean difference indicated plant species used in greater proportion to availability. Lolium arundinaceum (Tall Fescue) comprised 35.1% of the winter diet, and graminoids (65.9%) were the dominant forage class overall. The most selected graminoid was Andropogon gerardii (Big Bluestem). The diet shifted in the spring to a mixture of woody plants (28.1%), forbs (19.4%), and graminoids (38.4%). Carex spp. (sedges) and Juncus spp. (rushes) were the most selected graminoids. The highest seasonal use of forbs (45%) and legumes (23%) occurred during summer, with Impatiens spp. (jewelweed; 27%) as the dominant and most selected plant in the diet. The dominant fall forage class was woody plants (37.4%). Quercus spp. (oaks; vegetation and acorns 14.3%) were the most used woody plants with oak acorns comprising 9.7% of the Elk diet. We suggest that historic evidence, presence of native grasses, and Elk diets indicate that oak savannas could be an ideal habitat type for Elk in the reintroduction zone of Tennessee.
Human population growth and development reduce the area and quality of natural communities and lead to a decline of associated wildlife populations. Sciurus niger avicennia (Big Cypress Fox Squirrel), a state-listed threatened subspecies endemic to south Florida, appears sensitive to habitat fragmentation and fire regime. This research assessed the distribution and habitat use of the Big Cypress Fox Squirrel from interviews with biologists, private land owners, and golf course managers and by transect sampling in natural areas on public and private lands in southwest Florida. Our findings indicate that the distribution of fox squirrel populations is influenced by land use and understory height. Conservation of this species in natural areas will require land management practices that maintain open landscapes.
Despite the ecological importance of bats, a lack of basic data, such as space-use needs, hinders management efforts. Therefore, we investigated home-range size in Nycticeius humeralis (Evening Bats) by radiotracking 14 individuals (5 females and 9 males) for 7–11 nights each in a pine-dominated landscape in southwestern Georgia during June–August 2008. We generated 95% and 50% adaptive kernel (AK) home ranges and 95% minimum convex polygon (MCP) home ranges and found that mean 95% AK home-range size was 155.7 ± 38.3 ha, with individual values ranging from 36.9 ha to 565.9 ha. Mean 95% MCP home-range size was 118.5 ± 29.5 ha, with individual values ranging from 33.6–456.2 ha. Home-range sizes did not differ between males and females (P = 0.35), but were larger in August (P = 0.004) than in June and July. Evening Bat home-range sizes on our study area were similar to previously documented home ranges in forested and rural landscapes. Although Evening Bats may be habitat generalists relative to foraging activity at the scale of habitat patches, multiple core areas of activity indicate selection within this scale that may be related to prey and roost availability.
The reproductive ecology of male Crotalus adamanteus Beauvois (Eastern Diamond-backed Rattlesnake) from southwestern Georgia (Joseph W. Jones Ecological Research Center, Baker County) was studied from 14 August 2003 to 14 August 2006. Few studies provide information on reproduction of free-living Eastern Diamondbacked Rattlesnakes, and no information is available on the seasonal relationship of plasma sex steroids of males to changes in the reproductive organs (e.g., mass of the testis and kidney) and the mating season. Here, the main goals were to determine whether: (i) males show variation in concentrations of plasma testosterone (T) during the active season (late March through November), (ii) males have elevated (peak) concentrations of plasma T during the single mating season, which has been documented to occur from late summer through early fall in nearby populations, and (iii) there are seasonal changes in length, width, and mass of the testis and kidney during the active season, particularly during the breeding period. There was a significant difference in mean concentrations of plasma T among seasons, with levels in summer significantly greater than those of spring, and levels in spring and fall were not significantly different. Testis mass and width, but not length, varied significantly across seasons. Testis mass paralleled elevated levels of plasma T, with peak mass occurring in the summer. Similarly, testis width was significantly greater in summer than in fall, but there was no significant difference between summer and spring, nor between spring and fall. We found no significant seasonal changes in any of the kidney measurements. Bisexual pairings were coincident or followed the occurrence of elevated levels of plasma T and changes in testis size; however, despite frequent observations, copulations were not observed. Nonetheless, our results support a mating season of late summer/early fall for the present population of Eastern Diamond-backed Rattlesnakes.
Larval stream salamanders are the numerically dominant predators in many headwater stream systems. Nonetheless, little is known about their activity patterns or the extent to which their movements are influenced by prevailing environmental conditions. In this study, we used capture rates from passive trapping as an index of activity level and sought to identify the environmental variables most responsible for fluctuations in larval stream salamander activity. Over the course of two months, we captured stream salamanders in aquatic funnel traps during both day- and night-trapping sessions at a first-order stream in the North Carolina Piedmont. Using an information-theoretic approach, we constructed models to elucidate the effects of (1) water temperature, (2) cloud cover, (3) days since last rainfall, and (4) time of day on larval salamander activity. We found that the model incorporating time of day and cloud cover was the best predictor of larval salamander activity. In our study, larval salamander activity was highest at night and also demonstrated a weak positive correlation with increasing cloud cover. Using model-averaging, we further determined that our time of day and cloud cover variables demonstrated a significant correlation with observed activity levels. This pattern of peak activity under low light conditions could be a behavioral adaptation that limits predation risk for larval salamanders.
Many crayfish species native to the southeastern United States are imperiled due to small range sizes and anthropogenic impacts such as habitat loss and introduction of non-native species. Furthermore, effective management of crayfish is limited by the scarcity of life-history and ecological data for many of these species. We report results of the first life-history study of the crayfish Cambarus hubbsi (Hubbs Crayfish). We collected 466 Hubbs Crayfish from the South Fork Spring River, AR throughout 2006 and recorded carapace lengths, wet weights, indicators of reproductive activity, and number of eggs on ovigerous females. Using length-frequency distributions, we identified four Hubbs Crayfish age classes and evaluated growth rates by plotting size by season (winter, spring, summer, autumn). Male Hubbs Crayfish were more common than females in all seasons except autumn, and males weighed more at equivalent lengths than females. Reproductive activity in Hubbs Crayfish peaked in late winter and spring, and ovigerous females were collected in March, April, and June. Ovigerous females were age II or III and carried few eggs relative to co-occurring crayfish of the genus Orconectes. Compared to these Orconectes species, Hubbs Crayfish is comparatively slow growing, long lived, with low reproductive potential, and as a result may be categorized as a K life-history strategist. Based on this species' life-history strategy and previously documented habitat specificity and taxonomic distinctiveness, Hubbs Crayfish may require monitoring and management attention normally reserved for species with smaller ranges.
Etheostoma proeliare is distributed in the Gulf Coastal Plain of southeastern North America from the Colorado River of eastern Texas through the Choctawhatchee River of eastern Alabama, north to the Fall Line, and upstream along the Arkansas River valley into eastern Oklahoma. Parsimony and Bayesian analysis of the ND2 gene from 28 populations recovered a monophyletic E. proeliare (PP: 1.0) containing a basal split between a novel clade of populations in the northern apex of the Mississippi embayment, from the Black and St. Francis rivers to the west of, through the Yazoo River to the east of, the main channel of the Mississippi River, and all other populations (PB:99, PP: 1.0). Southern populations are resolved into three clades: Trinity plus Neches Rivers (PB: 100, PP: 1.0), Sabine River east through western tributaries to the Mississippi River plus the Lake Pontchartrain drainage (PP: 1.0), and eastern tributaries to the Mississippi River east through the Escambia River (PP:0.99). The eastern clade is further divided into Pearl plus Big Black rivers (PB:97, PP: 1.0) and Mobile Basin plus Escambia River clades (PP:0.98). These results indicate that although the mainstem of the Mississippi River corresponds to some phylogeographic breaks in a lowland species, it is not an absolute barrier. Future studies of species in the region should further explore the placement of Lake Pontchartrain populations and the existence of divergent populations in the northern Gulf Coastal Plain.
We used lighted larval traps to assess reproduction by fishes inhabiting nine spring pools in the Barrens Plateau region of middle Tennessee between May and September 2004. The traps (n = 162 deployments) captured the larval or juvenile forms of Etheostoma crossopterum (Fringed Darter) (n = 188), Gambusia affinis (Western Mosquitofish) (n = 139), Hemitremia flammea (Flame Chub) (n = 55), the imperiled Fundulus julisia (Barrens Topminnow) (n = 10), and Forbesichthys agassizii (Spring Cavefish) (n = 1). The larval forms of four other species (Families Centrarchidae, Cyprinidae, and Cottidae) were not collected, despite the presence of adults. Larval Barrens Topminnow hatched over a protracted period (early June through late September); in contrast, hatching intervals were much shorter for Fringed Darter (mid-May through early June). Flame Chub hatching began before our first samples in early May and concluded by late-May. Juvenile Western Mosquitofish were collected between early June and late August. Our sampling revealed that at least two species (Flame Chub and Fringed Darter) were able to reproduce and recruit in habitats harboring the invasive Western Mosquitofish, while Barrens Topminnow could not.
Underwater observation is a widely used fish-sampling method, but capture efficiencies of this method are often unknown. For accuracy, survey counts require correction by measuring capture efficiencies of sampling protocols. Capture efficiencies for underwater observation were calculated for three small imperiled fishes—Etheostoma sitikuense (Citico Darter), Noturus flavipinnis (Yellowfin Madtom), and Noturus baileyi (Smoky Madtom)—using modified mark-recapture methods. Fishes were tagged with visual implant elastomer tags, released at sites within Abrams Creek in the Great Smoky Mountains National Park, and then recaptured. Efficiencies were calculated by comparing numbers of released individuals to recaptures. In the propagation facility, tag retention was 100 percent, and no post-tagging mortality was observed. Capture efficiency (CE = 0.12) was low for all species and potentially influenced by predation upon marked fish, emigration of fish from sites, or difficulty in sampling some habitats. Thus, population sizes may be larger than observed due to low capture efficiencies. Our results highlight challenges to estimating capture efficiencies for imperiled fishes when using underwater observational methods.
Dendroica cerulea (Cerulean Warbler) is a migrant songbird that has declined rangewide in recent decades. We surveyed 150 sites in 2006–2007 to determine if this species still occupied its former breeding range in Oklahoma. We located Cerulean Warblers at 5 sites and confirmed breeding on north slopes of two heavily forested ridges in the Ouachita Mountains. We did not encounter Cerulean Warblers in any bottomland hardwoods, despite the former widespread distribution and abundance of the species in such habitats. While habitat loss and degradation may limit occurrence of Cerulean Warbler in some areas, the pattern of decline for this species at the edge of its range in Oklahoma is also consistent with abandonment of peripheral range as the range-wide population declines.
We report on observations of parturition and maternal behavior of Corynorhinus rafinesquii (Rafinesque's Big-eared Bat) at a bridge in west-central Mississippi. Rafinesque's Big-eared Bats formed a maternity colony beneath the bridge in March, and parturition occurred from late May to early June. On 28 May 2004, a female Rafinesque's Big-eared Bat was observed giving birth in the breech position, which has not been previously reported for the species. On the same day, another adult female and her pup were found struggling on the ground due to entanglement of the umbilical cord around the mother's wing, and a third female was observed biting her pup. While important data were obtained during our observations, we emphasize the necessity of using extreme care when conducting repeated surveys at maternity roost sites.
Here we report the first record of the Eastern Hellbender in the Mobile River Basin (Cartecay River, Coosawattee River system) of northwest Georgia. Nearly all records of Eastern Hellbenders in the southeastern United States are from Tennessee or Ohio river drainages (Mississippi River Basin); a few historic records of presumably introduced origin are also known from the Savannah drainage (Atlantic Basin). We first captured this species in June 2009 while surveying for fishes. We then carried out Hellbender surveys at 6 sites and captured 2 individual Hellbenders in the Cartecay River within 1 river km of our first collection site. However, no more Hellbenders were found during additional fish surveys at 21 sites. Microsatellite data indicate an 84% probability of membership with a Hellbender population in the adjacent Toccoa River system (Tennessee drainage), suggesting either natural historic dispersal (e.g., via stream capture) or a more recent introduction from the Toccoa into the Cartecay system. Additional studies are needed to assess the full range, conservation status, and origin of this species in the Coosawattee River system.
Three of the 4 forms of albinism that occur in avifauna have been detected in Zenaida macroura (Mourning Dove). Albinism is rare in this species, and the incidence rate of each age and sex cohort is not well known. Consequently, we examined the pigmentation of Mourning Doves encountered in the Coastal Plain of South Carolina, and classified the age and sex of all individuals. One adult male Mourning Dove had unusually light coloration of some feathers and the upper mandible. This pigmentation is consistent with partial albinism. This was the only individual out of 10,749 examined that appeared to be albinistic. This low incidence rate of albinism supports the conclusion that this condition is relatively rare in Mourning Doves (Mirarchi 1993).
A melanistic morph of Sciurus carolinensis Gmelin (Eastern Gray Squirrel or Gray Squirrel) was observed on 17 and 27 September 2008 in the Georgia Piedmont, Athens-Clarke County, GA. This is a rare observation because we have found no reports of Gray Squirrel melanism located south of Virginia in the southeastern United States.
I observed a large Vespa crabro (European Hornet) steal prey from an Argiope aurantia (Yellow Garden Spider) in a forested housing development in northern Georgia. The hornet landed in the spider's web and in less than three minutes removed the prey previously captured by the spider. The spider made no attempt to attack or subdue the hornet. European Hornets may switch from predatory to scavenging habits in the fall of the year as the nesting season progresses, a trait documented in other vespines. To my knowledge, this is the first recorded incident of a hornet stealing prey from another predator.
The European land snails Discus rotundatus and Oxychilus draparnaudi were found in Washington, DC at Oxon Cove in March 2010. These constitute the first records of feral populations of these non-native species in the District of Columbia.