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Results for “Georgia Wildlife”

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At least 19 recordsLinked to original sources
USGS2018

Evaluation of vegetation-fire dynamics in the Okefenokee National Wildlife Refuge, Georgia, USA, with a Bayesian belief network

Vegetation response to wildfire has been studied extensively in upland ecosystems, but fire effects on temperate wetlands are less understood. We evaluated vegetation response to extensive wildfire in wetlands of Okefenokee National Wildlife Refuge (ONWR), USA, with a spatially explicit Bayesian belief network model informed with data recorded during 1990–2012. We assessed model accuracy and effects of fire frequency on vegetation composition with predictive scenarios of fire absence or a fire return interval (FRI) every 5 or 10 years during 2012–2032. In fire absence, shrubs increased 100%, primarily in the northern half of the Refuge, while the herbaceous class that was widespread in 2012 was eliminated. Areas dominated by forest during the past ~65 years were maintained with the 5- and 10-year FRI. Herbaceous-dominated areas maintained with the 5-year FRI decreased (90%) with the 10-year FRI. Shrub coverage increased with fire (17%, 5-year FRI; 20%, 10-year FRI), while scrub/shrub decreased (12%; 5-year FRI) or increased (6%; 10-year FRI). A 5-year FRI during conditions promoting severe fire may maintain the distribution of herbaceous and forested areas that followed an extensive drought and fires in 2011, and may limit scrub/shrub expansion that previously occurred with longer FRIs in the ONWR.

Georgia↗
USGS2017

A survey of the amphibians of Savannah National Wildlife Refuge, South Carolina and Georgia

From 2004 to 2006, we used a variety of sampling techniques to survey the amphibians of Savannah National Wildlife Refuge (SNWR), a large protected area straddling the lower portions of the Savannah River on the border between South Carolina and Georgia. We documented 22 amphibian species—15 frogs and 7 salamanders—with a possible 23rd species present. Species richness was lower than what might be expected from amphibian field guides of species inhabiting the adjacent Coastal Plain, likely due to a lack of specialized habitats, such as temporary ponds and upland pine forest. Amphibians occupied a variety of habitats and appeared tolerant of the mildly acidic and low-oxygen conditions of many of the wetlands. Although additional species may be found at SNWR, this initial survey provides a historic baseline for monitoring amphibian populations as areas adjacent to the refuge are disturbed, the climate changes, and multi-use management objectives are implemented within refuge boundaries.

Georgia, South Carolina↗
USGS1999

Abundance and reproduction of songbirds in burned and unburned pine forests of the Georgia Piedmont

We studied the abundance and productivity of songbirds in prescribed burned and unburned mature (>60 yr) pine forests at Piedmont National Wildlife Refuge, Georgia, during 1993-1995. We estimated species abundance, richness, and evenness using data from 312 point counts in 18 burned sites and six unburned sites. We measured gross habitat features in 0.04-ha circles centered on each point count station. We calculated productivity estimates at nests of seven of the most common nesting species. Habitat components we measured in 1-, 2-, and 3-yr post-burn sites were similar, but most components differed between burned and unburned sites. Although 98 species were detected during point counts, we report only on the 46 species that nested in the area and were detected >10% of the counts in either habitat class. Twenty-one species preferred burned sites and six preferred unburned sites. Avian species richness and evenness were similar for burned and unburned sites. Burned sites were preferred for nesting over unburned sites. Only nine nests of six species were found in unburned sites. Productivity estimates were low in burned sites. One or more eggs hatched in only 59 of 187 nests monitored, and an average of only 0.82 chicks per nest were estimated to have fledged. Predation was the most common probable cause for nest failure, ranging from 45% in the Northern Cardinal (Cardinalis cardinalis) to 64% in the Summer Tanager (Piranga rubra). Because the sources of predation at the refuge are unknown, future research should address this issue.

Journal of Field Ornithology↗
USGS1998

Mercury in alligators (Alligator mississippiensis) in the southeastern United States

Mercury methylation may be enhanced in wetlands and humic-rich, blackwater systems that crocodiles and alligators typically inhabit. Given their high trophic level and long life-spans, crocodilians could accumulate significant burdens of Hg. Our objectives were to survey Hg concentrations in alligators from several areas in the southeastern United States to test their utility as sentinels of Hg contamination, to examine relationships among Hg concentrations in various tissues and to look for any differences in tissue Hg concentrations among locations. We measured total Hg concentrations in alligators collected in the Florida Everglades ( n =18), the Okefenokee National Wildlife Refuge, Georgia ( n =9), the Savannah River Site (SRS), South Carolina ( n =49) and various locations in central Florida ( n =21), sampling tissues including blood, brain, liver, kidney, muscle, bone, fat, spleen, claws and dermal scutes. Alligators from the Everglades were mostly juvenile, but Hg concentrations in tissues were high (means: liver 41.0, kidney 36.4, muscle 5.6 mg Hg/kg dry wt.). Concentrations in alligators from other locations in Florida were lower (means: liver 14.6, kidney 12.6, muscle 1.8 mg Hg/kg dry wt.), although they tended to be larger adults. Alligators from the Okefenokee were smallest and had the lowest Hg concentrations (means: liver 4.3, kidney 4.8, muscle 0.8 mg Hg/kg dry wt.). SRS alligators had the greatest size range and intermediate Hg levels (means: liver 14.9, muscle 4.8 mg Hg/kg dry wt.). At some locations, alligator length was correlated with Hg concentrations in some internal organs. However, at three of the four locations, muscle Hg was not related to length. Tissue Hg concentrations were correlated at most locations however, claw or dermal scute Hg explained less than 74% of the variation of Hg in muscle or organs, suggesting readily-obtained tissues, such as scutes or claws, have limited value for non-destructive screening of Hg in alligator populations.

Science of the Total Environment↗
USGS1998

Effects of radio transmitters on migrating wood thrushes

We quantified the effects of radio transmitters on Wood Thrushes (Hylocichla mustelina) using 4 yr of banding and telemetry data from Piedmont National Wildlife Refuge, Georgia. Flight performance models suggest that the 1.6-g transmitter shortens the migratory range of Wood Thrushes by only 60 km, and the estimated migratory range is adequate to accomplish migration even with limited fat stores. We used two strengths of line, 5- and 9-kg test-strength braided Dacron, to attach the transmitters using the thigh-harness method. We recaptured 13 returning radio-marked Wood Thrushes, seven of which were still marked. Six of the seven birds marked with the 5-kg test harnesses lost their transmitters within 1 yr while all six of the 9-kg test harnesses were still attached up to 21 mo later. Radio-marking did not reduce the return rates of adults and immatures, and the transmitters did not cause radio-marked birds to lose more mass than banded-only birds. Wood Thrushes can successfully carry a transmitter during migration with no detectable negative effects. We recommend continued use of the thigh-harness method, but we encourage the use of 5-kg cotton line.

Journal of Field Ornithology↗
USGS2006

Optimal regeneration planning for old-growth forest: addressing scientific uncertainty in endangered species recovery through adaptive management

Stochastic and structural uncertainties about forest dynamics present challenges in the management of ephemeral habitat conditions for endangered forest species. Maintaining critical foraging and breeding habitat for the endangered red-cockaded woodpecker (Picoides borealis) requires an uninterrupted supply of old-growth forest. We constructed and optimized a dynamic forest growth model for the Piedmont National Wildlife Refuge (Georgia, USA) with the objective of perpetuating a maximum stream of old-growth forest habitat. Our model accommodates stochastic disturbances and hardwood succession rates, and uncertainty about model structure. We produced a regeneration policy that was indexed by current forest state and by current weight of evidence among alternative model forms. We used adaptive stochastic dynamic programming, which anticipates that model probabilities, as well as forest states, may change through time, with consequent evolution of the optimal decision for any given forest state. In light of considerable uncertainty about forest dynamics, we analyzed a set of competing models incorporating extreme, but plausible, parameter values. Under any of these models, forest silviculture practices currently recommended for the creation of woodpecker habitat are suboptimal. We endorse fully adaptive approaches to the management of endangered species habitats in which predictive modeling, monitoring, and assessment are tightly linked.

Forest Science↗
USGS2009

Occurrence of viable avian influenza viruses in water and bed sediments from selected water bodies along the Atlantic Flyway, February and May 2006 and January 2007

Water and bed-sediment samples were collected from selected water bodies along the Atlantic Flyway and analyzed for the presence of viable avian influenza viruses. Samples were collected during February and May 2006 and January 2007 at U.S. Fish and Wildlife Service National Wildlife Refuges in Georgia, South Carolina, North Carolina, Virginia, and Maryland. Avian influenza viruses were detected in samples collected from the Savannah National Wildlife Refuge in Georgia during February 2006 and from the Santee National Wildlife Refuge in South Carolina and the Pee Dee National Wildlife Refuge in North Carolina during January 2007. Avian influenza virus was detected in water temperatures ranging from 11.8 to 12.7 degrees Celsius when birds were either present or had departed at least 10 days prior to sampling. Although the literature indicates that avian influenza virus persists in the environment more effectively at colder temperature regimes, these detections were made in a comparatively warmer climate at a time of the year when cooler water temperatures prevail.

Georgia, Maryland, North Carolina, South Carolina,↗
USGS2002

Wood Thrush movements and habitat use: Effects of forest management for Red-cockaded Woodpeckers

We monitored adult and juvenile breeding-season movements and habitat use of radio-tagged Wood Thrushes ( Hylocichla mustelina ) at the Piedmont National Wildlife Refuge, central Georgia, USA. We investigated the effects that management for Red-cockaded Woodpeckers ( Picoides borealis ), thinning and burning >30 year old loblolly pine ( Pinus taeda ) habitat, had on Wood Thrushes, a ground-foraging and midstory-nesting species. Adult Wood Thrush pairs regularly moved long distances between nesting attempts (range 1 to 17,388 m). The only experimental effect we found on adult movements was a decrease in weekly emigration rates (Ψ) from thinned and burned compartments after silvicultural management. Adult males preferred riparian hardwoods with sparse to moderate cover and those preferences increased following management. Juveniles remained near their nest site ( x̄ = 177 m, SE = 113) for an average 24 days (SE = 6.3), and then dispersed a mean 2,189 m (SE = 342). Before dispersal, juveniles preferred upland hardwood–pine mixed habitat ( P < 0.05) with moderate overstory cover ( P < 0.05). We found no management effects on dispersal distances or predispersal habitat use. However, juveniles from thinned and burned compartments dispersed to hardwood habitats with dense cover, whereas birds from control compartments dispersed to pine-dominated habitats with sparse cover. All juveniles dispersed to areas with habitat similar to what they used before dispersal. Small-scale thinning and burning for Red-cockaded Woodpeckers may have had little effect on Wood Thrush habitat use and movements because typical movements were often larger than the scale (stand or compartment) targeted for management.

The Auk↗
USGS2005

Use of radio-telemetry to reduce bias in nest searching

We used traditional searching, as well as radio-telemetry, to find 125 Wood Thrush ( Hylocichla mustelina ) nests during 1994–1996 at the Piedmont National Wildlife Refuge in Georgia, USA. We compared daily nest survival rates for 66 nests of radio-marked birds with 59 nests of birds found through systematic searching. By using radio-telemetry, we found Wood Thrush nests in higher elevation pine habitats, in addition to the more usual hardwood forests with moist soils. We found nests of radio-marked birds farther from streams than nests found by systematic searching. Thirty-two percent of radio-marked birds' nests were found at the tops of slopes, compared to 15% of the nests found by traditional searching. In addition, radio-marked birds generally moved up-slope for re-nesting attempts. Although the distribution of nests found with telemetry and searching varied, daily nest survival did not vary between the two groups. Radio-telemetry provided new information about Wood Thrush nesting habitats. We believe radio-telemetry can be a valuable addition to traditional searching techniques; it has the potential to provide a sample of nests free from a priori habitat biases.

Georgia↗
USGS2022

Georgia and Landsat

Georgia’s nickname is “The Peach State” for its fruitful production, but it also could be called “The State of Abundance.” Georgia ranks in the top 10 States for population, at more than 10 million residents, and 6 million residents are in the greater Atlanta area. Georgia also ranks in the top 10 States for forest areas with 24 million acres, or about two-thirds of the State. Its trees vary from deciduous hardwoods and pines to cypress and magnolias. Georgia has diverse ecosystems, from the Blue Ridge Mountains in the northeast to the hilly, populous Piedmont region in the middle to the vast Coastal Plains that cover the southern half of the State with farms, forests, and wetlands. The State’s 14 major river basins, including the Chattahoochee and the Savannah, ultimately drain to the Atlantic Ocean or the Gulf of America. Millions of acres of wetlands include floodplain wetlands, freshwater swamps such as the Okefenokee Swamp, and coastal marshes. More than a dozen barrier islands lie off Georgia’s coastline. Wildlife in these myriad habitats include black bears, alligators, armadillos, manatees, sea turtles, and more than 40 species of snakes. The Landsat satellite imagery scale and its 50-year record of Earth observations make Landsat ideal for monitoring changes in these diverse environments and supporting decision-making by government officials and land managers.

Georgia↗
USGS2007

Presence and significance of chytrid fungus Batrachochytrium dendrobatidis and other amphibian pathogens at warm-water fish hatcheries in southeastern North America

Amphibian populations and species are declining or disappearing from many regions throughout the world (Stuart et al. 2004). No single cause has been demonstrated, although a number of emerging infectious diseases have been suggested as primary etiologic agents (Berger et al. 1998; Daszak et al. 2003; Lips et al. 2006). Several factors, including climate change, parasite infestation or compromised immune systems may interact locally or regionally to threaten species and populations (Carey and Bryant 1995; Parris and Beaudoin 2004; Pounds et al. 2006). Still, the disease model of amphibian decline may not be universally applicable (Daszak et al. 2005; McCallum 2005). The impacts of disease can devastate anuran populations, and declines due to disease, particularly amphibian chytrid fungus (Batrachochytrium dendrobatidis, &ldquo;BD&rdquo;) and ranaviruses (Berger et al. 1998; Chinchar 2002), are well documented (Daszak et al. 2003; Kiesecker et al. 2004). In addition to the better-known fungi and viruses, an undescribed Perkinsus-like organism also has had serious localized effects on populations of ranid frogs in southeastern North America (e.g. Rana sevosa in Mississippi, various Florida species; unpublished data). In North America, warm water fish hatcheries supply stock for sport fishing, ecological restoration, and endangered species management. Several million fish may be transported across multiple regions and river drainages in a single restocking event. For example, in 2004 three million bluegill (Lepomis macrochirus), originating from Orangeburg National Fish Hatchery (NFH), South Carolina were stocked at Harris Neck National Wildlife Refuge (NWR), Georgia as food for a nesting colony of endangered wood storks. This stocking in 2004 transported fish from the upper coastal plain across the Savannah River to the lower coastal plain, and may be responsible for mixing different larval phenotypes of Rana catesbeiana at Harris Neck (Dodd and Barichivich 2007). Our objective was to determine whether diseases known to have detrimental effects on amphibians (ranavirus, BD, mesomycetozoa, protozoa and helminths) are present in amphibian larvae living in warm-water fish hatcheries in the southeastern United States. We further examined hatchery records to assess the extent to which amphibian larvae have been transported throughout various regions and potentially contribute to spreading emerging infectious diseases.

Alabama, Florida, Georgia, North Carolina, South C↗
USGS1998

Experimental analysis and simulation modeling of forest management impacts on wood thrushes, Hylocichla mustelina

North American Breeding Bird Survey data show that wood thrush (Hylocichla mustelina) populations in eastern U.S. forests have declined 1.8% per year during 1966-95. The declining quality of breeding forest tracts in North America is one possible cause for the apparent decline of some neotropical migratory birds, such as the wood thrush. In Georgia, however, wood thrush populations have declined during a period of increasing pine forest area and larger patch sizes. We hypothesized that forest management practices such as thinning and prescribed burning might create unsuitable habitat for wood thrushes. We conducted a four-year before/after, treatment/control experiment at the Piedmont National Wildlife Refuge in central Georgia to study to the effects of a treatment of thinning and prescribed burning on wood thrush demographic parameters. We simultaneously monitored wood thrush adults and juveniles with mark-recapture, radio-telemetry, nest searches, and plot-map surveys. Our analyses showed that wood thrushes were less likely to emigrate from the study compartments after the treatment, and wood thrushes exhibited some tendency to increase preference for hardwood habitats and decrease preference for pine habitats following the treatment. However, we observed no effects of treatment on nest success, adult survival, and adult and juvenile dispersal distances. We also found that female wood thrushes had lower survival rates than males during the breeding season, and we documented large-scale, within-year dispersal movements of adult (up to 17 km) and juvenile (up to 7 km) wood thrushes. We conclude that landscape level habitat quantity and quality must be considered during songbird management decisions. The documentation of sex- and age-specific wood thrush survival and movement rates was critical for construction of a set of population models. We used three stochastic models to learn more about wood thrush population dynamics and make predictions about population growth rates, reproductive success, and the effect of habitat changes on wood thrush populations. The simplest source/sink population model suggests that the Piedmont National Wildlife Refuge's wood thrush population is probably stable or increasing, and wood thrush populations in treated areas had higher growth rates than birds in untreated areas. We were able to use the individual-based model of wood thrush productivity to predict fecundity, a parameter that we could not measure directly in the field. Again, females on treated areas had higher fecundity than birds on untreated areas. Our spatially-based model predicted that wood thrush populations should respond positively to predicted changes in the age/size class structure of the Refuge's pine forests. Our model also showed that most wood thrushes leave the Refuge's forest compartments during the breeding season, and these dispersal movements are extremely important to understanding and managing wood thrush populations. The use of prescribed burning and retention shelterwood silviculture at the Piedmont National Wildlife Refuge does not appear to negatively affect the local wood thrush population. Continued use of the current management regime should result in adequate nesting, foraging, and escape habitats for wood thrushes. However, landscape-level habitat availability and quality, including lands outside the Refuge, must be considered when making management decisions that may affect wood thrushes.

Book↗
USGS2000

Effects of forest management on density, survival, and population growth of wood thrushes

Loss and alteration of breeding habitat have been proposed as causes of declines in several Neotropical migrant bird populations. We conducted a 4-year study to determine the effects of winter prescribed burning and forest thinning on breeding wood thrush ( Hylocichla mustelina ) populations at the Piedmont National Wildlife Refuge (PNWR) in Georgia. We estimated density, adult and juvenile survival rates, and apparent annual survival using transect surveys, radiotelemetry, and mist netting. Burning and thinning did not cause lower densities ( P = 0.25); wood thrush density ranged from 0.15 to 1.30 pairs/10 ha. No radiomarked male wood thrushes ( n = 68) died during the 4 years, but female ( n = 63) weekly survival was 0.981 ± 0.014 (SE) for females ( n = 63) and 0.976 ± 0.010 for juveniles ( n = 38). Apparent annual adult survival was 0.579 (SE = 0.173). Thinning and prescribed burning did not reduce adult or juvenile survival during the breeding season or apparent annual adult survival. Annual population growth (lambda) at PNWR was 1.00 (95% confidence interval = 0.32-1.63), and the considerable uncertainty in this prediction underscores the need for long term monitoring to effectively manage Neotropical migrants. Population growth increased on experimental compartments after the burn and thin (95% CI before = 0.91-0.97, after = 0.98-1.05), while control compartment declined (before = 0.98-1.05, after = 0.87-0.92). We found no evidence that the current management regime at PNWR, designed to improve red-cockaded woodpecker ( Picoides borealis ) habitat, negatively affected wood thrushes.

Georgia↗
USGS2000

Simultaneous use of mark-recapture and radiotelemetry to estimate survival, movement, and capture rates

Biologists often estimate separate survival and movement rates from radio-telemetry and mark-recapture data from the same study population. We describe a method for combining these data types in a single model to obtain joint, potentially less biased estimates of survival and movement that use all available data. We furnish an example using wood thrushes ( Hylocichla mustelina ) captured at the Piedmont National Wildlife Refuge in central Georgia in 1996. The model structure allows estimation of survival and capture probabilities, as well as estimation of movements away from and into the study area. In addition, the model structure provides many possibilities for hypothesis testing. Using the combined model structure, we estimated that wood thrush weekly survival was 0.989 ± 0.007 ( ± SE). Survival rates of banded and radio-marked individuals were not different ( α [ S radioed , S banded ] =log[ S radioed / S banded ]=0.0239 ± 0.0435). Fidelity rates (weekly probability of remaining in a stratum) did not differ between geographic strata ( Ψ = 0.911 ± 0.020; α [ Ψ 11 , Ψ 22 ]=0.0161 ± 0.047), and recapture rates ( p = 0.097 ± 0.016) banded and radio-marked individuals were not different ( α [ P radioed , P banded ]=0.145 ± 0.655). Combining these data types in a common model resulted in more precise estimates of movement and recapture rates than separate estimation, but ability to detect stratum or mark-specific differences in parameters was week. We conducted simulation trials to investigate the effects of varying study designs on parameter accuracy and statistical power to detect important differences. Parameter accuracy was high (relative bias [RBIAS] <2 %) and confidence interval coverage close to nominal, except for survival estimates of banded birds for the 'off study area' stratum, which were negatively biased (RBIAS -7 to -15%) when sample sizes were small (5-10 banded or radioed animals 'released' per time interval). To provide adequate data for useful inference from this model, study designs should seek a minimum of 25 animals of each marking type observed (marked or observed via telemetry) in each time period and geographic stratum.

Journal of Wildlife Management↗
USGS2007

Establishing a baseline and faunal history in amphibian monitoring programs: The amphibians of Harris Neck, GA

We conducted an intensive inventory of Harris Neck National Wildlife Refuge in coastal Georgia to determine the feasibility of establishing an amphibian monitoring program at this location. Thirteen semi-aquatic amphibian species were identified at 21 locations. Amphibian species richness at Harris Neck was similar to that of nearby barrier islands. The amphibian fauna of Harris Neck has long been affected by human-induced landscape changes, including the inadvertent introduction of tadpoles from distant fish hatcheries and the creation of artificial impoundments. Land-use history provides important information necessary to understand current amphibian distribution, especially when census data are used to establish a baseline from which to monitor future status and trends.

Southeastern Naturalist↗
USGS2001

Development of a bird banding recapture database

Recaptures (and resightings) constitute the vast majority of post-release data from banded or otherwise marked nongame birds. A powerful suite of contemporary analytical models is available for using recapture data to estimate population size, survival rates and other parameters, and many banders collect recapture data for their project specific needs. However, despite widely recognized, broader programmatic needs for more and better data, banders' recapture data are not centrally reposited and made available for use by others. To address this need, the US Bird Banding Laboratory, the Canadian Bird Banding Office and the Georgia Cooperative Fish and Wildlife Research Unit are developing a bird banding recapture database. In this poster we discuss the critical steps in developing the database, including: determining exactly which recapture data should be included; developing a standard record format and structure for the database; developing electronic means for collecting, vetting and disseminating the data; and most importantly, developing metadata descriptions and individual data set profiles to facilitate the user's selection of appropriate analytical models. We provide examples of individual data sets to be included in the database, and we assess the feasibility of developing a prescribed program for obtaining recapture data from banders who do not presently collect them. It is expected that the recapture database eventually will contain millions of records made available publicly for a variety of avian research and management purposes

Book chapter↗
USGS2004

Costs of detection bias in index-based population monitoring

Managers of wildlife populations commonly rely on indirect, count-based measures of the population in making decisions regarding conservation, harvest, or control. The main appeal in the use of such counts is their low material expense compared to methods that directly measure the population. However, their correct use rests on the rarely-tested but often-assumed premise that they proportionately reflect population size, i.e., that they constitute a population index. This study investigates forest management for the endangered Red-cockaded Woodpecker (Picoides borealis) and the Wood Thrush (Hylocichla mustelina) at the Piedmont National Wildlife Refuge in central Georgia, U.S.A. Optimal decision policies for a joint species objective were derived for two alternative models of Wood Thrush population dynamics. Policies were simulated under scenarios of unbiasedness, consistent negative bias, and habitat-dependent negative bias in observed Wood Thrush densities. Differences in simulation outcomes between biased and unbiased detection scenarios indicated the expected loss in resource objectives (here, forest habitat and birds) through decision-making based on biased population counts. Given the models and objective function used in our analysis, expected losses were as great as 11%, a degree of loss perhaps not trivial for applications such as endangered species management. Our analysis demonstrates that costs of uncertainty about the relationship between the population and its observation can be measured in units of the resource, costs which may offset apparent savings achieved by collecting uncorrected population counts.

Animal Biodiversity and Conservation↗