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During the winter, Trichechus manatus latirostris (Florida Manatee) depends on long periods of rest in comparatively warm thermal refuges to help conserve energy and maintain stable body temperatures. Pterygoplichthys disjunctivus (Vermiculated Suckermouth Sailfin Catfish) has been observed attached to, and grazing algae from, Florida Manatee in Volusia Blue Spring. We hypothesized that the disturbance caused by grazing armored catfish would significantly alter Florida Manatee behavior. Analyses of 6 hours of underwater video of Florida Manatee behavior, with and without attached armored catfish, revealed that during each observation period, Florida Manatees with attached catfish demonstrated significantly higher activity levels and numbers of active behaviors. Increased Florida Manatee activity caused by the armored catfish may compound the impact of other known threat effects.
Florida springs are generally characterized as static ecosystems with unique faunal and floral assemblages that persist under relatively stable physical and chemical conditions. We sampled the fish fauna of Volusia Blue Spring to determine whether this presumption would withstand scrutiny at a higher temporal resolution and over time. We sampled by seining or snorkeling at five stations along the 320-m run weekly or bimonthly from October 2000 to September 2004. This four-year study consisted of 1152 samples that produced approximately 164,000 observations of 30 species of fish on 72 sampling trips. Concurrent water quality samples were collected at 14 sites along the center of the run and at each of the seine sites. Virtually anoxic water discharged from the spring head, but this water accumulated oxygen as it traveled the run. Fish density and species composition also changed dramatically along the length of the run. Species that tolerate low oxygen concentrations, such as poeciliids, dominated the assemblage at the spring head. Species that use patches of algae or small backwater areas, such as fundulids, were prominent in the middle reach of the run. Larger species, such as centrarchids and Lepisosteus spp., were abundant in the lower reach of the run. Within these broad patterns, most species exhibited great variability in density, probably due to the influence of variable emigration of potential predators, and also perhaps smaller species, from the St. Johns River.
The ecology of Notropis atrocaudalis (Blackspot Shiner) including habitat associations, population age structure, reproduction, and food habits were examined in two east Texas streams from November 2001 through October 2002. Blackspot Shiner were generally found in relatively shallow, slow-flowing runs, but exhibited no strong seasonal habitat associations. The population consisted of four age groups (ages 0, 1, 2, and 3) present within a year, and estimated maximum life span was 3 years. Reproductively mature individuals were observed from March through August and temporal patterns in ovarian development, gonadosomatic index, and ova development indicated that Blackspot Shiner spawns multiple clutches of eggs over an extended spawning period. Blackspot Shiner diets consisted primarily of aquatic insects including Ephemeroptera, Trichoptera, and Coleoptera larvae.
Aspects of the life-history of Etheostoma scotti (Cherokee Darter) were investigated using 12 monthly collections from Hickory Log Creek (Etowah River Drainage) in Cherokee County, GA. Specimens were collected from riffles, runs, and pools with slow current and examined to illuminate age, growth, food habits, and reproductive characters. The bulk of the diet consisted of Chironomidae larvae, with mollusks, detritus, branchiopods, and other aquatic insects as smaller components. Peak feeding occurred in late winter and spring and immediately preceded gamete production for a single spring spawning season peaking in April. Gravid females, collected from March to June, contained 2–256 mature oocytes, ranging from 0.7 to 1.2 mm in diameter. Sexual maturity occurred at age 1, and maximum age was 2 years. The largest specimen collected was a male 49.1 mm SL and 2.0 g total weight. Males were larger than females and were outnumbered 1:1.56. Only about half of the adult-sized males appeared to be in nuptial condition during the spawning season in the study population. These findings provide a greater understanding of the biology of this imperiled species and may allow for more focused and effective conservation efforts.
We describe physical and environmental characteristics associated with Micropterus notius (Suwannee Bass) spawning in the Ichetucknee River, FL. We located 24 Suwannee Bass nests from March to June (75% found May and June). Nests were found in relatively shallow waters (mean = 95 cm) with substrates dominated by organic material (63%). Suwannee Bass nests were located near cover, in low-flow areas (mean velocity = 0.01 m/s), and at a mean temperature of 21.7 °C. We did not detect any relationships from regressions between the frequency of nesting and temperature, photoperiod, river stage, discharge or lunar cycle. Ninety-two percent of nests contained submerged aquatic vegetation (SAV), which are likely important to nesting areas as stream-velocity refuges that reduce sediment wash-in and egg disturbance during spawning. Descriptions of spawning habitat of this range-restricted species have implications for conservation and management decisions.
Translocation is often considered a viable conservation strategy, despite the absence of species-specific post-translocation data. Macrochelys temminckii (Alligator Snapping Turtle) populations have declined across their range and they may be considered candidates for translocation, but few studies have examined the response of individuals to movement events. I monitored M. temminckii with radiotelemetry in northwest Louisiana to provide baseline data regarding the species' response to translocation. I calculated average distances moved per day, measured water depths, and recorded growth of translocated and resident turtles. There was no observed mortality during the study, and translocated turtles gained mass and increased shell dimensions, indicating they effectively located resources after translocation. Resident individual shell dimensions increased, but some residents lost mass, possibly due to early recapture and reweighing dates. Movement distances were within the ranges reported by previous researchers. These data contribute baseline information concerning M. temminckii conservation biology.
The endangered Rostrhamus sociabilis plumbeus (Florida Snail Kite) has been the focus of several ecological studies emphasizing movements between and within wetland fragments. These studies have required the ability to trap and radiotag free-flying adults without significant risk of injury. We developed and tested a safe alternative to previous methods for trapping Snail Kites as part of a comparative study of VHF and satellite telemetry. The aquatic bal-chatri borrows from historical trap designs with modifications for trapping aquatic birds at the surface of the water. It consists of a square PVC frame with a series of parallel flourocarbon stringers and a mesh basket to restrain the lure species. Nooses are attached to the stringers and used to ensnare the toes of a predatory bird. The trap is held afloat by the PVC frame, with the mesh basket, stringers, and nooses positioned just beneath the surface of the water. After determining effective trap placement in relation to perched birds, we captured 11 kites in 13 days with native pomacea paludosa (Florida Apple Snail) and exotic Pomacea insularum (Island Apple Snail) as lures. Our results indicated that the aquatic bal-chatri can be used to target specific Snail Kites and recapture previously trapped individuals. This trap design is a safe, efficient, and low-cost alternative to methods previously used for capturing Snail Kites. Additionally, the aquatic bal-chatri is relatively easy to use and appears to have minimal impact on foraging behavior and breeding performance of Snail Kites.
Throughout their range, Haliaeetus leucocephalus (Bald Eagle) have experienced dramatic population increases, and breeding productivity has returned to levels observed prior to the impacts of DDT. To effectively manage growing Bald Eagle populations, habitat and anthropogenic characteristics influencing nest-site selection need to be quantified at multiple spatial scales. In this study, we examined local and landscape characteristics and anthropogenic features influencing nest-site selection by Bald Eagles in 3 National Forests in east Texas. On a local scale, Bald Eagles placed nests in large super-canopy coniferous trees, with nest sites surrounded by shorter and smaller trees than random sites. Bald Eagle nest sites were best predicted by basal area on a local level and distance to nearest human habitation on a landscape level, as determined by logistic regression. We suggest that conservation efforts for Bald Eagles in east Texas should include allowing forests to mature and reducing disturbance around large water bodies to conserve and create suitable nesting habitat on public and private lands.
Many cooperatively breeding birds exhibit fine-scale spatial genetic structure as a result of restricted dispersal and habitat specialization. Sitta pusilla (Brown-headed Nuthatch) is a cooperatively breeding bird restricted to mature pine-dominated forests of the southeastern United States and has been undergoing population declines across most of its range. We used five polymorphic microsatellite loci developed for this species to examine fine-scale spatial genetic structure within a site in northern Florida as well as broader genetic structure among this site and two other sites (a second in northern Florida and one in southern Georgia). Spatial autocorrelation analyses within the more densely sampled site detected positive spatial genetic autocorrelation up to 1300 m in males when auxiliary males were included, but no autocorrelation was found in females or in males when auxiliary males were excluded. At the broader scale, we found small but significant genetic differentiation among all three populations, including two sites that were separated by less than 40 km of suitable habitat. Our results suggest that both sexes of the Brown-headed Nuthatch exhibit limited dispersal, with philopatric male auxiliaries contributing to more pronounced genetic structure over small geographic distances compared to females. Our sampled populations were in a region where much suitable habitat remains, yet we still observed limited dispersal. This finding suggests that in more fragmented regions, populations may become isolated and at risk of extinction.
The overlap of external morphometric measurements between Peromyscus leucopus (White-footed Mouse) and P. gossypinus (Cotton Mouse) makes species determination challenging. Peromyscus were live-trapped at Poinsett State Park, Sumter County, SC, and identified using field and laboratory techniques. Our measurements for hind-foot length, total length, and tail length overlapped with published values for both species. Body mass, as measured in the field, was a good criterion that identified our animals as Cotton Mice (n = 29). This identification was confirmed by digital radiography, microsatellite DNA markers, and glucose phosphate isomerase analysis. Our results indicated that a combination of field and laboratory techniques is a valuable approach for positively identifying morphologically similar species.
Many small mammal species experience population declines following prescribed fire, presumably resulting from increased predation due to lack of cover. However, Peromyscus gossypinus (Cotton Mouse) typically shows a neutral or positive population response following fire. Because they typically spend diurnal hours in below-ground refuges, Cotton Mice may be less susceptible to predation following fire than other small mammals. We examined the effects of prescribed fire and exclusion of mammalian predators on selection of daytime refuges by Cotton Mice. We located daytime refuges of 12 radiotagged Cotton Mice in a fenced mesomammal-predator (hereafter, mesopredator) exclosure (23 refuge locations) and 9 Cotton Mice in an adjacent unfenced control plot (13 refuge locations) for one month prior to and one month after a prescribed fire in winter 2007. Refuge locations included Gopherus polyphemus (Gopher Tortoise) burrows (27.8%), other ground holes (44.4%), stump holes (25.0%), and holes at the base of trees (2.8%). Fire had little effect on refuge selection, likely because Cotton Mice primarily used below-ground refuges, which allowed them to avoid the direct effects of fire and predation following fire. Structure near the refuge, including burrows, stumps, and coarse woody debris, was important in selection of daytime refuges and was particularly important in the presence of mesopredators.
Discarded bottles were inspected for skeletal remains at 220 roadside sites along the southeastern Blue Ridge escarpment of North Carolina, South Carolina, and Georgia as a technique to examine the regional distributions of shrews. Vertebrate remains were found at approximately 63% of our study sites and in 4.5% of the open bottles we examined. Bottles collected a total of 553 specimens of small mammals representing 5 species of shrews and 6 species of rodents. The Northern Short-tailed Shrew (Blarina brevicauda) and the Smoky Shrew (Sorex fumeus) were abundant and distributed throughout the region, although Smoky Shrews were more strongly associated with mesic environments and higher altitudes ( = 940.1 m ± 25.4 m). The Masked Shrew (S. cinereus) and the Southeastern Shrew (S. longirostris) exhibited contiguous allopatry, with Masked Shrews occurring exclusively in mesic forest habitats at high elevations ( = 1126.7 ± 27.4 m), and Southeastern Shrews occurring only in xeric habitats at lower elevations ( = 503.7 ± 64.9 m). Our study demonstrates the utility of discarded bottles as a quick and effective alternative method for surveying shrews, without the added mortality that occurs from pitfall- or snap-trapping.
Two endangered Microtus pennsylvanicus dukecampbelli (Florida Salt Marsh Vole) were captured at a new location, in February of 2009, at Lower Suwannee National Wildlife Refuge. Since the species discovery in 1979, only 43 Florida Salt Marsh Voles (hereafter FSM Vole) have been captured. Outside of the type locality, this is only the second documented location for the FSM Vole. Given the difficulty in trapping this species and the lack of information about its life history, its discovery in a new location lends itself to the possibility that it is more widespread in the Central Florida Gulf Coast than previously thought. Although much of the salt marsh in the area is in public ownership, a good deal of it has already been altered by logging or development and is threatened by global climate change. More research is needed to adequately protect and manage the habitat for the FSM Vole. A study of FSM Vole coastal salt marsh habitat could also serve as a valuable monitoring tool for subtle changes in salt marsh habitats as global climate change progresses.
Odocoileus virginianus (White-tailed Deer) in Mississippi have been shown to respond morphometrically to soil resource area, but have not been evaluated for reproductive differences. We analyzed data from herd health checks (1978–2007) and fall harvests (1991–2007) to determine if soil resource area influenced reproductive parameters, and if assumed resource quality interacted with age. Ovulation rates approached unity and were similar across all soil resource areas and age classes, but there was some influence of soils and age class on number of corpora lutea. Pregnancy rate differed only between 2 of 8 soil resource areas, and was unaffected by age. Fetal counts increased with age class, and the incidence of twins among 1.5-year-old females was half that of females >2.5 years. Lactation rates differed among 1.5-year-olds by soil resource area, and reflected assumed soil quality among ≥3.5-year-olds. Because lactation occurs later in the reproduction cycle than ovulation or pregnancy, it is more indicative than other metrics of reproductive success. However, because lactation is a binary indicator, age-specific recruitment data is needed to determine potential effects of soil resource area on deer population dynamics.
Reproductive success of the endangered Picoides borealis (Red-cockaded Woodpecker) is thought to be reduced by the presence of Glaucomys volans (Southern Flying Squirrels); hence, these squirrels are often removed when found inside woodpecker cavities. For this management practice to benefit Red-cockaded Woodpeckers, however, squirrel removal must both reduce the future probability of a flying squirrel re-occupying cavities and increase reproductive success for Red-cockaded Woodpeckers. In this study, using simulated Red-cockaded Woodpecker clusters (pseudo-clusters), we tested the first assumption regarding squirrels reoccupying nest cavities. We found no differences between removal and control pseudo-clusters in the amount of time that flying squirrels were present in pseudo-clusters, the proportion of nest boxes occupied by flying squirrels, or the mean number of total squirrels and individual squirrels (counting each squirrel only once in the analysis) present in the pseudo-clusters. Thus, removing flying squirrels from nest clusters did not reduce the future probability of a flying squirrel occupying either a cavity or a cluster. These results indicate a need to re-evaluate flying squirrel removal as a management technique to enhance Red-cockaded Woodpecker reproduction.
Osseus remains of Erethizon dorsatum (American or Common Porcupine) were recovered by archaeological excavations at the Charles Church Rockshelter site in Watauga County, NC. Two specimens were successfully radiocarbon-dated to between 7670 and 7460 years before present, confirming the presence of Porcupines in the mountains of North Carolina in the middle Holocene. Climatic events and human predation may have led to its extirpation from the southern Appalachians by AD 1000.
Laurel Wilt is caused by a recently identified fungal pathogen infecting plants in the Lauraceae. Laurel Wilt is transmitted by Xyleborus glabratus (Redbay Ambrosia Beetle), which was recently introduced to the southeastern United States from Asia. As the insect expands its range in the US, so too has the disease. A query of the NatureServe Explorer database was used to identify the conservation status of native plant species and recognized plant communities that may be affected by Laurel Wilt. Laurel Wilt affects at least nine plant species, and all fifteen species in the Lauraceae currently found in North America may ultimately prove to be hosts for the disease. Four of the twelve native lauraceous species had been identified as vulnerable to extirpation or extinction, prior to the introduction of Laurel Wilt. There are 55 plant communities in the US and Canada that have a member of the Lauraceae as a dominant or diagnostic species. The majority of these plant communities have been identified as vulnerable. Agricultural industries that are based upon Perseaamericana (Avocado) cultivation in Florida and California are threatened by Laurel Wilt as well. Given the potential impact of this disease on lauraceous plants and their associated communities, these taxa and assemblages should be monitored for the arrival and impact of Laurel Wilt.
Flowering times of some early-season plants vary with temperature. First flowering dates of 35 native spring herbs and one shrub (Lindera benzoin [Northern Spicebush]), recorded yearly from 1976 through 2008 in a common garden in western North Carolina, were analyzed to determine if they correlate with January or spring (February–May) temperature or show a trend over time. We also asked if species that flower earlier in the season are more tightly correlated with temperature than later-season species. One early-season (average flowering date = March 6) species, Carex plantaginea (Plantainleaf Sedge) and one later-season (average flowering date = April 11) species, Geranium maculatum (Spotted Geranium), showed a significant trend of flowering earlier over time; seven April-flowering species showed weak, statistically non-significant, trends of earlier flowering over time; and one species (Iris cristata) exhibited a weak trend of later flowering over time. Four mid-season (mid-March—early April) species showed a significant trend, and seven species showed a weaker, not significant trend, of earlier flowering in years with warmer January or spring temperatures. Overall, weak seasonal and longer-term responsiveness despite variation in soil and air temperatures over the site, multiple plantings for some species, and only a modest 0.28 °C increase in average January temperature over the 32-year observation period suggest flowering phenology of at least some plants in this common garden will track future climate change.
A once common butterfly found only in Florida, Cyclargus thomasi bethunebakeri (Miami Blue), declined to near extinction during the 1990s. On 26 November 2006, we discovered this species on Boca Grande Key, 76 km west of Bahia Honda Key. Previously, the butterfly was only known to survive on Bahia Honda Key. Over the following 8-month period, we searched periodically for this butterfly on islands in the Great White Heron National Wildlife Refuge (GWHWNR) and the Key West National Wildlife Refuge (KWNWR). The Miami Blue was not found on 6 islands in GWHNWR, but was present at 8 of 10 areas in KWNWR. Seven of the occupied sites were on islands in the Marquesas Keys. The number of Miami Blue adults varied greatly by island and season, but were highest at the two largest colonies when Pithecellobium keyense (Blackbead; both a larval host and adult nectar plant) was flowering and producing new leaves. Eight other plant species were visited by adult Miami Blues for nectar. Threats to the newly discovered colonies are discussed.
Alligator mississippiensis (American Alligator), ranging in size from 45.7–152.4 cm, have been identified as a Puma concolor coryi (Florida Panther) prey species. On 14 March 2008, we discovered a 269.2-cm Alligator that was killed and fed upon by a male Panther; this record is the largest one reported to date.