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A case study reporting a high diversity of native ants co-existing with imported fire ants is presented. Thirty-six species of ants were collected within one meter of the base and on the lower two meters of the trunk of a Quercus pagoda (cherry bark oak) in Tombigbee National Forest, Winston County, MS, on five dates during 2003 and 2004. Twenty-three of these species, including the imported fire ant hybrid, Solenopsis invicta x richteri, were nesting in the same area. A list of all species collected at the site is provided. Notes are given on the nesting habits of Polyergus lucidus longicornis and its slave, Formica dolosa, and also for other species in the area. Potential explanations for high diversity including the island effect of an isolated habitat, differing diets and foraging behaviors, habitat partitioning, and seasonal activity are discussed.
Arenivaga floridensis (Florida sand cockroach) is a fossorial insect restricted to scrub and sandhill communities on ancient ridges in peninsular Florida. Ecologically insular by nature, these ridge communities have experienced further fragmentation and significant reduction following conversion to citrus agriculture and subsequent urbanization. To assess the status of A. floridensis, we updated its known distribution by conducting an extensive field survey of scrub and sandhill habitats throughout the state. Roaches (n = 325) were collected at 47 localities, confirming the species' continued presence in nine out of eleven counties from which it has been reported, and providing 28 new localities for these nine counties. Moreover, we discovered 15 new populations representing six additional counties for which A. floridensis has either never been recorded (Gilchrist, Indian River, Martin, Palm Beach, and St. Lucie counties) or had records published (Orange County). We collected Arenivaga on 11 named peninsular ridges, including one major (Atlantic Coastal) and three minor (Bell, Gordonville, Orlando) ridges on which this species had not been previously reported. The nine new localities on the Atlantic Coastal Ridge constitute a significant range extension for A. floridensis, making it the most broadly distributed species of Florida's endemic ridge fauna.
Less than 4% of the once extensive Pinus palustris (longleaf pine) ecosystem remains today. Although longleaf pine habitats are recognized for their high species diversity, few published accounts document the vertebrate faunas of remaining tracts. Here we report on the vertebrate species richness of Ichauway, an 11,300-ha property in Baker County, GA. The property includes ca. 7300 ha of longleaf pine with native ground cover, along with more than 30 seasonal wetlands and ca. 45 km of riparian habitat associated with Ichawaynochaway Creek, Big Cypress Creek, and the Flint River. The fauna includes 61 species of fish, 31 amphibians, 53 reptiles, 191 birds, and 41 mammals. Despite the relative isolation of the property from other natural ecosystems, the vertebrate fauna of Ichauway is remarkably diverse and may offer an example of reference conditions to guide restoration of longleaf pine forests, associated seasonal wetlands, and riparian areas elsewhere in the southeastern US.
Habitat preferences for many woodpeckers are poorly known in many regions of North America. Seven woodpecker species use forested wetlands in peninsular Florida, yet no study has examined habitat use by woodpeckers in these forests. From September 1991 to August 1992, we used unlimited-distance point counts to sample birds at 32 stations in 2 forested wetland types (spring-fed and blackwater) in central Florida. We documented 1415 visual or aural woodpecker detections. Melanerpes carolinus (Red-bellied Woodpecker), Picoides pubescens (Downy Woodpecker), and Dyrocopus pileatus (Pileated Woodpecker) were common, accounting for 91% of all detections. Overall woodpecker abundance was greater in spring-fed forests than in blackwater forests. The relative abundance of 4 species was greatest during the fall and winter; this trend likely reflected shifts between habitats in response to fruit production as well as an influx of migrant Sphyrapicus varius (Yellow-bellied Sapsuckers). The relative abundance of Red-bellied and Pileated woodpeckers was greatest at sites surrounded by extensive forest cover. Unlike other studies, we found no relationship between woodpecker abundance and tree or snag basal area. The presence of Quercus spp. (oaks) also did not appear important to woodpeckers. Compared to other studies, snag density in the forests we sampled was high. This may have reduced the importance of snags to woodpeckers or made detecting relationships difficult. A high density of Sabal palmetto (sabal palm) may have provided additional foraging and nesting/roosting sites that further contributed to the lack of correlations between woodpecker detections and the presence of snags and oaks.
Meleagris gallopavo silvestris (Eastern Wild Turkey) habitat was altered in the Southeast by the introduction of Pinus spp. plantations to agricultural areas through the Conservation Reserve Program. However, the preponderance of M. gallopavo silvestris research has focused on extensive Pinus spp. plantations that lack the cover-type diversity that typifies the Southeast. From May–July 1998 and 1999, we monitored 36 radio-tagged M. gallopavo silvestris in Burke County, GA to investigate habitat use in landscapes intensively managed for agriculture and silviculture. We used compositional analysis to ide.gify habitats selected by male and female M. gallopavo silvestris during summers. Proportions of habitat types within the home range were different from habitats at radio-locations of males and females. Hardwood stands and fields were the most-selected habitat types by M. gallopavo silvestris in the summer. However, within home ranges, males and females also selected closed-canopy Pinus spp. habitats. Hens with broods did not preferentially select planted Pinus spp. habitats, but their use of Pinus spp. stands was greater than use of agricultural fields. The replacement of agricultural fields by closed-canopy Pinus spp. plantations may have improved habitat quality for M. gallopavo silvestris in some areas of the Southeast by diversifying the landscape. Our results suggest that closed-canopy planted Pinus spp. cover types are not detrimental to M. gallopavo silvestris when well distributed with fields and mature hardwood drains.
We report the findings of stream-survey data, a length-at-age study, and host-fish determination for Villosa constricta (notched rainbow). Visual surveys were done for freshwater mussels at 44 bridge crossings in the upper Neuse River basin in North Carolina. Three surveyors, each searching a 1-m wide lane, covered a 600-m long stream reach at each site. All mussels found were ide.gified to species and measured, and females were checked for gravidity. Of the 24 sites where V. constricta occurred, the median number found was 3.5 (range = 1–54). We cut thin-sections of 71 individual shells collected from middens at 1 survey site and counted growth lines to determine mussel age. Shell ages ranged from 3 to 14 years. Lab trials determined that Etheostoma flabellare (fantail darter) served as a suitable host for this species.
Keowee Reservoir has supported an abundant population of native Micropterus coosae (redeye bass) for over 30 years. Recently, redeye bass abundance in this reservoir declined concomitantly with the establishment of angler-introduced Micropterus punctulatus henshalli (Alabama spotted bass). We suspected declines in redeye bass abundance may be related to their hybridizing with the Alabama spotted bass resulting in offspring that are difficult to differentiate from the Alabama spotted bass. Thus, we collected tissue for genetic analyses from what was thought to be pure redeye bass (Jocassee Reservoir, SC), the original source of Alabama spotted bass (Lake Lanier, GA) stocked in Lake Keowee, and suspected redeye bass x Alabama spotted bass hybrids (Keowee Reservoir, SC) to determine if hybridization might be occurring. These analyses confirmed that hybridization among species of Micropterus had occurred in Keowee Reservoir.
An earlier collection of monthly samples of presumed Desmognathus quadramaculatus from Union County, GA, revealed the presence a previously unknown, sympatric, sibling species. This new form was recently described as D. folkertsi. In this paper, we report on the reproductive life history of this new species from data taken during (1) a 14-month period in 1989–90 and (2) late spring of 1998. Adult males and females mature at approximately the same size (57–58 mm snout–vent length [SVL]), and males reach larger mean (72 versus 66 mm SVL) and maximum (81 versus 75 mm SVL) sizes. Metamorphosis apparently takes place at approximately two years of age, and reproductive maturity is reached at four or more years of age in both sexes. If number of lobes in the multi-lobed testis indicates age, as has previously been presumed in adult male Desmognathus, then the paucity of singly-lobed, presumably young male D. folkertsi in both sampling periods suggest a declining population. Relative measures of density, however, indicated that the population at the study site was stable for eight years between collections. Therefore, testis-lobe data do not appear to be valid estimators of age in desmognathines. Clutch size, estimated from the number of developing follicles, averages approximately 40 eggs and is positively related to female body size. Ova take more than a single year in which to develop to oviposition size. This does not mean, however, that females follow a strictly biennial reproductive cycle.
In Alligator mississippiensis (American Alligator), body length increases with age, but body length can be used as an accurate estimator of age only up to about 6–7 years, when growth rates slow considerably. Telomeres are repetitive DNA sequences that cap the ends of each chromosome. Telomeres shorten with age in most animals, but telomere shortening has not been examined in reptiles. We measured telomere length in erythrocytes of A. mississippiensis varying between ≈ 5 and 240 cm in body length and found a negative relationship between telomere length and body length (P < 0.01). Assuming that erythrocyte telomeres continue to shorten with time, even after growth rate declines, those individuals with the shortest telomeres should be the oldest members of the population. This method of estimating age, even in animals of similar body size, should allow questions about age structure and senescence to be addressed.
Apparent widespread declines in abundance of Anguilla rostrata (American eel) have reinforced the need for information regarding its life history and status. We used commercial eel pots and crab (peeler) pots to examine the distribution, condition, and abundance of American eels within the White Oak River estuary, NC, during summers of 2002–2003. Catch of American eels per overnight set was 0.35 (SE = 0.045) in 2002 and 0.49 (SE = 0.044) in 2003. There was not a significant linear relationship between catch per set and depth in 2002 (P = 0.31, depth range 0.9–3.4 m) or 2003 (P = 0.18, depth range 0.6–3.4 m). American eels from the White Oak River were in good condition, based on the slope of a length-weight relationship (3.41) compared to the median slope (3.15) from other systems. Estimates of population density from grid sampling in 2003 (300 mm and larger: 4.0–13.8 per ha) were similar to estimates for the Hudson River estuary, but substantially less than estimates from other (smaller) systems including tidal creeks within estuaries. Density estimates from coastal waters can be used with harvest records to examine whether overfishing has contributed to the recent apparent declines in American eel abundance.
Lynx rufus (bobcat) home-range sizes have been studied throughout the Southeast, but study duration is generally ≤ 2 years and number of bobcats sampled is often < 20. There have been even fewer studies dealing with spatial interactions of bobcats, and fewer still within a Pinus palustris (longleaf pine) ecosystem. Because both bobcat home-range sizes and the degree that space is shared by bobcats are highly variable, it is important to understand factors that influence bobcat home-range size and spatial organization within the various habitats where this species is found. Therefore, we determined seasonal and annual home-range sizes and spatial overlap of bobcats in a longleaf pine forest in southwestern Georgia. We monitored 44 radio-collared bobcats (17 M and 27F) during 2001–2004. Gender and year did not interact to affect bobcat annual home-range sizes (95% adaptive kernel), and annual differences in annual home-range sizes were insignificant. However, male bobcats had annual home-range sizes almost 2 times greater than those of females. Gender and season interacted to affect seasonal home-range sizes of bobcats; thus, we analyzed seasonal home-range sizes for each gender separately. Seasonal home-range sizes of male bobcats did not differ. However, for female bobcats, the greatest home-range sizes occurred during winter of 2003 and the smallest during summer of 2002. We examined 3 types of spatial overlap: male-male, female-female, and female-male. Home-range overlap differed among types; female-male overlap was approximately 1.6 times greater than female-female overlap and approximately 2.8 times greater than male-male overlap. Our home-range sizes were among the smallest reported in the Southeast. While intrasexual overlap is generally considered rare in bobcats, we observed sharing of space by male-male and female-female pairs. Furthermore, space shared by female-female pairs exceeded that of male-male pairs, contrary to hypotheses concerning land tenure of solitary carnivores. Land-management practices, such as prescribed burning and maintenance of food plots, provided abundant small prey for bobcats and best explain smaller home-range sizes of bobcats in this study relative to that reported in most other southeastern studies. We suggest that spatial exclusivity among male-male and female-female pairs is most likely when prey are moderately abundant, but that exclusivity of home ranges may be abandoned when prey are either abundant or rare. Further investigation into home-range overlap is needed to consider the effect of bobcat density on these variables.
We radio-collared and tracked 16 (10 female, 6 male) Neotoma floridana smalli (Key Largo woodrats) from March–November 2002 and recorded a total of 631 locations. The average monthly ranges of individual male and female woodrats were 4756 (95% CI = 2376–7136) m2 and 2051 (95% CI = 1091–3011) m2, respectively. We found male and female ranges to be significantly different (P = 0.032). Female ranges varied with season (P = 0.032), while male ranges did not (P = 0.567). Spring (P = 0.033) and summer (P = 0.019) ranges were significantly different between sexes. At two spatial scales, Key Largo woodrats showed a preference for young habitat with selection ratios of 6.3 and 6.7. Six female ranges overlapped an average of 49% and 2 males overlapped an average of 8%. No woodrats were recorded crossing a major road. Study results suggest that N. f. smalli prefer early succession hammock, male woodrats should be introduced separately, and a major road is a barrier to woodrat movements.
Tree islands—small, wetland forest communities imbedded in a matrix of freshwater marsh—characterize Arthur R. Marshall Loxahatchee National Wildlife Refuge in South Florida. The establishment and spread of invasive exotic plant species were hypothesized to alter tree-island communities and prolong recovery times from hurricane disturbances. During the fall of 2004, two hurricanes, Frances and Jeanne, caused damage to these tree islands. We examined the spatial extent of damage to tree islands and tree species across the Refuge by sampling 74 islands. Each tree island was assigned an overall damage rating based on both the openness of the canopy and the type and quantity of damage received. Distance from the eye-wall of the hurricanes, tree-island size, average tree height on the island, and relative abundance of invasive exotic plants were examined as predictors of damage. Over 85% of the sampled tree islands had damage, with most of the damage occurring in the center of the Refuge. Most tree islands were found to have moderate damage, (i.e., snapped large branches and less than 50% canopy cover removed). Persea palustris (swamp bays) had more snapped trunks than Ilex cassine (dahoon holly) and Myrica cerifera (wax myrtle). Islands with larger trees had heavier damage than islands with shrubs or smaller trees. Fifty-eight percent of the tree islands sampled had either Lygodium microphyllum (lygodium) and/or Melaleuca quinquenervia (melaleuca). The only island with severe damage had abundant lygodium that appeared to have caused the entire canopy to collapse. These hurricanes present a unique opportunity to investigate recovery patterns of tree islands in an ecosystem impacted by invasive exotics. They also provide an opportunity to examine patterns of spread and recruitment of lygodium and melaleuca.
Over the last two decades, the northern Gulf of Mexico has undergone tremendous growth and development that has resulted in extensive and ongoing habitat modification. We had the opportunity to survey the main channels and bayous of three coastal estuarine basins for the presence and coverage of the invasive Phragmites australis (common reed). The occurrence and area of P. australis was highly variable among the lower Pascagoula River, Back Bay of Biloxi, and St. Louis Bay basins, with the largest amount of coverage (0.489 km2) found within the lower Pascagoula River basin and the smallest in Back Bay of Biloxi (0.0056 km2). Monospecific-stand coverage (47.2%) dominated both mixed-tree (27.2%) and mixed-marsh (26.6%) coverages in the lower Pascagoula River basin, whereas in the Back Bay of Biloxi, mixed-marsh coverage (71.4%) was greater than monospecific-stand (25.0%) and mixed-tree (3.6%) coverages. The only portion of St. Louis Bay containing P. australis (0.069 km2) was near the mouth of the Jourdan River, with monospecific-stand (62.3%) dominating the mixed-marsh (36.2%) and mixed-tree (1.5%) coverages. Although we were not able to survey all possible areas of each estuarine basin, the information gained in this study provides baseline data on the occurrence of this invasive species in the three main Mississippi coastal basins. Future monitoring of the spread of common reed, especially in the light of continued coastal development, is necessary if resource managers are to make informed decisions about which management action (water diversions and restoration scenarios) might positively influence this highly invasive native species.