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In encounters with predators, sclerosomatid harvestmen may employ a variety of defensive tactics including the voluntary detachment of legs (autotomy). The long-term costs of this evasive defense are not fully understood, but prior studies have documented negative consequences for terrestrial locomotion and foraging. In this study, we investigated the impact of leg loss upon locomotion in adult harvestmen (Leiobunum spp.). In southeastern Virginia, these harvestmen regularly climb vegetation and occupy perches on tree trunks, branches, and leaves that are often 1–2 m or more above the ground. In our study, we measured walking and climbing speeds for individuals with 5, 6, 7, and 8 legs. The results of our field surveys conducted over three seasons revealed relatively high frequencies (36–63%) of leg loss. We also found that individuals with six legs occupied perches that were significantly lower in the understory than those with eight legs. In the lab, we observed significantly slower walking speeds for individuals missing one or more legs. We also found that individuals with five legs climb significantly slower than individuals with eight legs. On the bases of the observed frequencies of leg loss in the field, we infer that leg autotomy is a common (and effective) evasive tactic used by harvestmen. However, the reduction in walking and climbing speeds resulting from leg loss may also affect habitat selection, (e.g., perch height) and may ultimately reduce the survivorship of individuals in future encounters with predators.
During 2003 and 2004, carabid beetles were collected from the 9 largest spruce-fir sites located in the southern Appalachian Mountains. Thirty-seven species were identified from 1817 individuals of Carabidae caught in these habitats. When adjusted for sample size, carabid beetle diversity was highest at Grandfather Mt., NC and lowest at Mt. Rogers, VA. Results from non-metric multi-dimensional scaling (NMS) ordination analysis indicate that carabid species found in spruce-fir forest cluster independently from those found in deciduous lower-elevation forests. There were no correlations between carabid species diversity and habitat area, isolation, and elevation.
Chiropteran mandibles from late Pleistocene/Holocene fossil cave localities in Hamilton County were identified in order to examine changes in bat species diversity and population trends over extended periods of time, providing insight into how bats in Southeast Tennessee have responded to major environmental changes over the past 10,000–20,000 years. Generic and species identifications were based on an unpublished key developed by the authors. Measurements of alveolar length (c1–m3) and total length measurements from the symphysis to the condyle were taken for all specimens identified as members of the genus Myotis in an attempt to identify species in this genus. The results of this study failed to confirm those of previous univariate morphological studies, suggesting that multivariate morphometric analyses may be needed to establish a means to differentiate among the species in this genus. Diversity data indicated two patterns of species abundance, with Eptesicus fuscus (Big Brown Bat) dominating some sites and Myotis sp. dominating others. The data suggest, but do not conclusively demonstrate, that a temporal replacement of older Eptesicus faunas by younger, Myotis-dominated faunas has occurred, connected with post-Pleistocene global warming. In addition, a correspondence between human disturbance and bat populations levels was observed. It is very likely that human disturbance has caused bat populations to become extinct in the caves under study, reinforcing the claim of previous researchers that bat population decline is a recent phenomenon that is tightly linked to human disturbance.
The Picayune Strand Restoration Project is being conducted as part of the Comprehensive Everglades Restoration Plan to restore hydrology and habitat in Southwest Florida. This study evaluated the success of the restoration activities by examining anuran species richness and relative abundance in relation to various restoration treatments, which included restored areas, un-restored areas, and natural wetlands. Anuran observations were conducted using nocturnal audible call surveys and dip netting. Univariate results indicated that: the lowest species richness and relative abundance values occurred within the un-restored areas, richness significantly increased in all restored areas relative to un-restored areas, abundance increased in some restored areas but not others, and highest richness and abundance were documented in the natural wetlands. Multivariate analysis confirmed these patterns and also indicated that the anuran species assemblages were significantly different between restoration treatments. Furthermore, the presence or absence of Lithobates sphenocephalus utricularius (Southern Leopard Frog), Gastrophryne carolinensis (Eastern Narrow-mouthed Toad), and Hyla femoralis (Pine Woods Treefrog) may be used to document restoration success or hydrologic disturbance, respectively. These findings suggest that the restoration activities can be effective and that anurans could be used as performance measures of restoration success.
We monitored the herpetofauna of a large conservation area in peninsular Florida from 1990 to 2010, visiting the refuge on over 2000 different days in that period and using a variety of sampling techniques. Our goals were to evaluate the species richness and abundance of herpetofauna (amphibians and reptiles) on the site. During the course of our study, we documented 72 species (22 amphibian and 50 reptile species); thus, the site has impressive species richness relative to other conservation areas in the southeastern United States. Five of the 72 species (6.9%) we found were introduced species. Continued monitoring of the diverse herpetofauna of Lake Woodruff National Wildlife Refuge could facilitate a better understanding of ongoing changes in species abundances and community assemblages occurring in the ecosystems of peninsular Florida.
American Alligator (Alligator mississippiensis) food habit data are important when establishing management strategies, as diet can directly influence growth rates, body condition, behavior, and reproduction. Diets of American Alligators are hypothesized to vary among habitats as well as geographically; however, few diet studies have been conducted outside of Florida and Louisiana. To address this information gap, 62 diet samples were obtained from alligators ranging in size from 94.7 cm to 386.0 cm (total length) from June 2006–September 2008 in inland freshwater wetlands in East Texas. A total of 33 different prey items (comprising 670 individual prey items) and 1 parasite were identified. Irrespective of size class, sex, and study site, >85% of individual prey items were invertebrates. Nearly all diet samples contained some sort of organic by-catch and/or non-food items (i.e., woody debris, aquatic plants, seeds, rocks, fishing tackle, etc.). Although alligator diets were similar between sexes, non-breeding (<183.0 cm in total length) alligators consumed more invertebrate prey items by biomass and percent occurrence than breeding-size alligators. In general, alligators forage opportunistically; therefore, most habitat-based, local, or geographic variability in food habits among populations are most likely influenced by food availability. As such, regional differences in food availability likely result in geographic variability in life-history characteristics such as growth rates and condition, important factors to consider when establishing management strategies.
We conducted multiple surveys to determine the distribution of the non-native Herichthys cyanoguttatus (Rio Grande Cichlid) in the Greater New Orleans Metropolitan Area (GNOMA). First, in 2003–2004, we trapped H. cyanoguttatus in Lake Pontchartrain (an oligohaline estuary) to determine if this freshwater species occurred in estuarine habitats. Our goal was to test the prediction that H. cyanoguttatus used estuarine corridors to disperse. Second, we sampled and compared 16 GNOMA sites before and after the 2005 hurricanes to determine how H. cyanoguttatus populations responded. Finally, we monitored H. cyanoguttatus populations monthly over two years (2006–2007) at six sites within the GNOMA to determine if numbers continued to increase after the hurricanes. We confirmed that H. cyanoguttatus: 1) does occur in estuarine habitats (0 to 8 psu), 2) effectively survived the 2005 hurricanes, 3) has increased significantly from 2006 to 2007 at three of six GNOMA sites, 4) is currently found more often in urban sites, and 5) persisted through the atypically cold winter of 2009/2010.
We surveyed the Lower Mississippi Alluvial Valley of Arkansas (“the Delta”) during the breeding seasons of 2005 and 2006 using the national marshbird monitoring protocol for secretive marshbirds. We detected and documented breeding by Podilymbus podiceps (Pied-billed Grebe), Ixobrychus exilis (Least Bittern), Rallus elegans (King Rail), and Gallinula chloropus (Common Moorhen). We detected but did not document breeding by Botaurus lentiginosus (American Bittern), Porphyrula martinica (Purple Gallinule), and Fulica americana (American Coot), all of which have been documented to breed in the Delta. Our estimated occupancy rates for breeding marshbirds in the study area ranged from a low of 6% for the King Rail in 2006 to a high of 27% for the Least Bittern in 2005. The range of these occupancy rates are low and reflect the rarity of secretive marshbirds in the Delta. Secretive marshbird occupancy rates were higher in the southern third of the Delta, probably because wetlands were more abundant or of higher quality there.
Rallus longirostris (Clapper Rail) is considered a good indicator species for toxicants because of its strong site fidelity and predictable diet of benthic organisms. High levels of the rare PCB Aroclor 1268 have been found in Clapper Rail adults, chicks, and eggs from the marshes associated with the Linden Chemical Plant (LCP) in Brunswick, GA. Recently, sampling and testing feathers has successfully been used as a non-lethal tool to trace exposure and assimilation of Aroclor 1268 in rails from the LCP site. This approach allows us to infer how and when these birds are exposed to contaminants in the marsh due to predictable molting patterns coupled with the fact that a feather will accumulate the toxicant only at the time it is grown. This study is the start of a process to investigate the possibility that this ecosystem contamination is the foundation of an ecological trap for Clapper Rails at the LCP site. Aroclor 1268 was isolated in Clapper Rail feathers from all birds collected from the contaminated marsh. This finding suggests that these birds either hatched or resided in this system the previous year and thus were not new recruits, which would be expected if fitness was being compromised from the contamination. Based on samples taken during the same fall and winter from the LCP site and control areas, the ratios of hatch-year (HY) birds to adults were similar. However, based on samples taken during the spring and summer, the ratios of HY birds to adults from LCP were lower than reported previously in studies in the southeast. This result suggests that the population age structure may have been affected by the contamination. Future studies specifically focused on reproductive success and fitness are needed at LCP and throughout the Brunswick estuary.
Substantial declines in populations of Sialia sialis (Eastern Bluebird) have prompted a large movement throughout North America to construct human-made nest boxes to facilitate bluebird nesting. While large-scale habitat preferences of nesting bluebirds have been well-established, the factors that influence nest-box preference within relatively homogeneous habitats remain unclear. We tested the effects of vegetation height and nest-box orientation, comparing northeast-, southeast-, southwest-, and northwest-facing boxes, on nest-box occupancy in a population of Eastern Bluebirds in Athens, GA. Vegetation height surrounding nest boxes influenced nest-box preferences. Over 65% of boxes with little to no surrounding vegetation were occupied, as compared with only 21% of boxes surrounded by high vegetation. Nest-box orientation also influenced box selection. Over 68% of boxes facing northwest were occupied, compared with less than 34% of boxes facing all other directions. These findings differ from those in studies conducted at northern latitudes, suggesting that preference for box orientation may vary with latitude.
Relatively little information has been published on Coyotes in the eastern United States, particularly in the mid-Atlantic region, the last area of the contiguous US to be colonized by Coyotes. Increases in eastern Coyote distribution and abundance have been documented, and concerns about their impact on wildlife and livestock are growing. Information from published and unpublished manuscripts, theses, dissertations, and state wildlife agency records in the mid-Atlantic region were examined and synthesized. This review provides a comprehensive summary of Coyote ecology in the mid-Atlantic for natural resource managers and researchers.
Canis rufus (Red Wolf) is critically endangered, with the only wild population consisting of <150 individuals. Currently, little is known about the food habits of this population. Such information may be vital to managing for the population's long-term persistence. We collected scats of Red Wolves for two consecutive pup-rearing seasons from six packs, classified contents into prey categories, and assessed diet composition for each pack. Five of the six packs studied consumed only mammalian prey items. Adult Odocoileus virginianus (White-tailed Deer) and White-tailed Deer fawns accounted for 37–66% of diet of Red Wolves depending on the metric of diet composition. Adult White-tailed Deer and White-tailed Deer fawns accounted for 21–83% of the diet of individual packs of Red Wolves according to biomass consumed. Two packs regularly consumed foods associated with humans. Generalized linear modeling indicated that diet varied between packs and was not influenced by reproductive status, nor did diet vary between years.
As human populations encroach on more remote areas, tree plantations are frequently converted into suburban developments or conservation lands. The purpose of the current study was to compare the effects of restoration treatments on the abundance and biodiversity of two former pine plantations in northeast Florida. Restoration methods, which varied greatly in both environmental impact and effort from minimal (non-manipulated control plots) to thinned (removal of 90–97% of Slash Pines and exotic plant species) to cleared (mechanical removal of all vegetation to the substrate surface), were compared using replicated 100-m2 plots. Although sites exhibited variation in plant densities and relative guild abundance, restoration treatment produced a significant increase in plant abundance and relative composition of plant guilds. Plant abundance was 2–3 times higher in cleared plots compared to thinned and control plots, respectively; not surprisingly this was because cleared plots had large numbers of small herbaceous seedlings as well as a shift in their plant communities to graminoid species, which are typically less shade tolerant than other plant guilds. Moreover, the relative abundance of vines was substantially lower in cleared plots compared to control and thinned plots, which retained all or some of their tree and shrub cover, thereby providing support structure for climbing plants. While plant diversity (Shannon index) exhibited a significant time-by-treatment interaction because cleared plots initially had only 65–80% of the plant diversity compared to control and thinned plots, cleared plots reached or exceeded them in biodiversity by the last two sampling dates, although cleared plots at one site showed a large decline on the final sampling date. In general, both study sites reflected high levels of graminoids in cleared plots, while thinned plots showed more even increases across plant guilds. Lastly, pine tree diameter (i.e., plant growth rate) was greater and canopy cover was lower in thinned plots compared to controls, although the differences were only significant for one site. Results from this study indicate that thinning former pine plantations with selective removal of exotics will provide maximal plant biodiversity and tree growth rather than utilizing more cost- and labor-intensive clearing of sites.
Studies of local adaptation generally investigate plants growing in relatively stable habitats. We asked whether populations of the long-lived clonal grass Uniola paniculata (Sea Oats) are locally adapted to microhabitats in the southeastern US coastal dunes, a habitat characterized by dynamic environmental gradients spanning relatively small distances. Although vegetative zonation is well characterized across these gradients, little is known about intraspecific evolutionary responses of species spanning the gradients. Plants from the foredune and backdune areas of the gradient (<10 m and 40–60 m from the shoreline, respectively) were reciprocally transplanted into experimental plots in both habitats. Although foredune plots were washed away by storms before harvest, the foredune plants demonstrated no early advantage in stem diameter or height growth, and thus there was no support for local adaptation in foredune plants. In the backdune plots, the backdune plants demonstrated no early growth advantage, and additionally demonstrated no advantage in survival, nor in growth or total biomass of surviving plants at harvest. Thus, there was again no support for local adaptation. In frequently disturbed environments such as the coastal dunes, plants may be more likely to respond with phenotypic plasticity than through local adaptation.
Foraging preference of Odocoileus virginianus (White-tailed Deer) at ornamental plantings was compared amongst 11 wildflower species native to north Florida and south Georgia. Deer exhibited strong preference for Coreopsis floridana (Florida Tickseed), C. gladiata (Coastalplain Tickseed), C. integrifolia (Fringeleaf Tickseed), and Rudbeckia fulgida (Orange Coneflower). Browsing significantly reduced the height of Florida, Coastalplain, and Fringeleaf Tickseeds, and reduced the number of Florida and Fringeleaf Tickseed flowers. Browsing pressure remained high throughout the growing season; therefore, temporary exclosures are unlikely to offer a viable solution to damage caused by deer. Information on variation in deer preference between species and across seasons should help private landowners and public land managers make strategic decisions regarding which species to establish at residences, food plots, or roadside beautification projects.