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Analysis of regurgitated pellets of Caracara cheriway (Northern Crested Caracara) at a site in south-central Florida produced a wide variety of insects and spiders from 34 families and at least 72 genera. Species identified occur in dung, on carrion, and in both aquatic and terrestrial habitats. Some taxa identified are known to be chemically protected, and their consumption exposes Northern Crested Caracaras to a broad diversity of chemical deterrents: 1,4-benzoquinones, isoprenoids, carboxylic acids, esters, aldehydes, an alcohol, and ammonia, for example. Other species identified in pellets indicate that Northern Crested Caracaras likely experience other noxious substances, such as those produced by species with dischargeable defensive glands (i.e., formic acid), plant-derived deterrents ejected when the insects are disturbed, and venom produced by those that sting (i.e., piperidine alkaloids). Our collection of pellets represents only part of one year; therefore, the list of noxious chemicals ingested by these raptors with their insect food may be even more extensive than is now evident. Further analysis of more pellets and from both breeding season and non-breeding season months is warranted to obtain a more complete picture of this raptor's insect diet.
Remote sensing, geographical information system applications, and ground and aerial assessments revealed a fragmented distribution of 44,933 ha of potential habitat for the endangered Ammodramus savannarum floridanus (Florida Grasshopper Sparrow) with most of this habitat (30,262 ha, 67%) located on conservation lands. A continued decrease in available habitat since 1996 was indicated. Searches of potential habitat and information from surveys at known locations found 278 male Florida Grasshopper Sparrows at seven sub-populations during 2004. No previously unknown breeding aggregations were found. The current distribution evinces a considerable contraction in range compared to historic distribution; however, other breeding aggregations may exist on private property (10,718 ha) where access was denied. Three formerly large sub-populations on Avon Park Air Force Range have declined and are now near extirpation. The low number of individuals and the paucity and fragmented distribution of suitable dry prairie will be limiting factors for recovery of this sedentary subspecies. Habitat expansion and management, and demographic improvements at existing locations may restore some Florida Grasshopper Sparrow sub-populations. Large areas (> 377 ha) of protected potential habitat in Manatee, DeSoto, and Glades counties offer the best opportunities for the establishment of additional sub-populations (> 50 pairs) to achieve recovery goals. The cooperative effort of public land managers from various agencies and of private landowners will be needed to prevent the extinction of this bird.
Sterna antillarum antillarum (Eastern Least Tern) historically nested on Atlantic Coast beaches and barrier island shores, but has moved inland to artificial habitats, such as dredge-spoil sites, as available natural habitat has been lost to development and increased human recreational activities. Least Terns readily nest on artificial sites, but the effects of different habitat characteristics and depredation conditions on reproductive success are unclear. We examined the effects of management strategies, disking and electric fencing, on daily survival rate (DSR) and 21-day survival rate (DSR21) of clutches, and on apparent nesting success on a dredge-spoil site in Georgia from 1993 through 1998. All 3 estimates of reproductive success increased as management intensity increased. Significantly (χ22 = 185.8, P < 0.001), DSR increased from 0.88 (1993, no management) to 0.97 (1998, disking in March to remove vegetation and enclosure with an electric fence). Corresponding DSR21 were 0.06 and 0.59, respectively. Artificial nesting sites can be improved by management actions, and such work may be increasingly important as natural habitat for beach-nesting birds continues to decline in availability and quality.
Rostrhamus sociabilis (Snail Kite) nesting success and productivity were studied at the recently colonized Lake Kissimmee and historically occupied Lake Okeechobee in Florida during 1987 to 1993. Mean (± SD) clutch size for all lake-years was 2.79 ± 0.49, with 3-egg clutches (75.2%) being most frequent. No significant difference was detected in the overall distribution of 2-, 3-, and 4-egg clutches between lakes. The mean number of fledglings for all lake-years was 0.79 ± 0.99 fledgling/nest. Only 44.1% of all nests were successful in fledging birds. Fledging success did not differ significantly among years at Lake Kissimmee. However, significant differences occurred among years at Lake Okeechobee due to the high frequency of failed nests in 1990 (72.2%) and 1991 (74.3%) during low lake levels. Productivity at Lake Kissimmee (0.88 ± 1.00 fledgling/nest) was significantly greater than at Lake Okeechobee (0.74 ± 0.98 fledgling/nest).
Estimated nest survivorship (Sday: nest age in days) combined for all years and both lakes was as follows: S28 (hatching) = 0.67 ± 0.14; S42 (2 weeks) = 0.58± 0.14; S56 (4 weeks) = 0.46 ± 0.20, and S70 (fledging) = 0.45 ± 0.03 (n = 641 nests). There was a higher probability of nest survivorship to hatching and fledging at Lake Kissimmee compared with Lake Okeechobee (S28 = 0.74 ± 0.11 and S70 = 0.53 ± 0.03 versus S28 = 0.63 ± 0.16 and S70 = 0.40 ± 0.02, respectively). Lake level and breeding date during early incubation had a significant effect on nest survivorship at both Lake Kissimmee and Lake Okeechobee.
A study was undertaken to compare the anatomy of the laminar floral parts with that of the spathes and leaves of Commelina erecta L. Each flower has two types of petals and two types of sepals. In contrast to the other organs, the petals have a completely open venation system whose vein endings consist solely of modified bundle-sheath cells. Bundle sheaths of leaves and spathes, but not the floral organs, contain sclerified cells for support. The high density of hook-shaped trichomes on the outer surface of the spathe and of glandular microhairs on the inner surface might indicate protective and secretory functions, respectively. Anomalous stomatal apparatuses are more common on floral organs than on spathes or leaves. Leaves and spathes appear to have a more detailed developmental program than sepals and petals.
The assemblage of microfungi associated with bark samples of healthy and damaged Fagus grandifolia (American beech), Abies fraseri (Fraser fir), and Tsuga canadensis (eastern hemlock) trees was evaluated during an All Taxa Biodiversity Inventory of the Great Smoky Mountains National Park in 2003 and 2004. Bark samples were collected from sampling points 0.3, 0.6, 0.9, and 1.2 m above the ground surface on the bole of each replicate tree. Patterns of species composition and diversity (species richness) were evaluated from bark samples over three sampling dates (May, July, and September) each year. A total of 4814 isolates were obtained, with greater than 95% belonging to the Deuteromycota. Over 94 species of fungi were identified from bark of the three tree species, which were either healthy or were damaged or under pressure from exotic pests. The most common genus was Trichoderma, for which a total of 13 species were identified during the two-year study. Frequencies of microfungi between healthy and damaged trees were similar across years, but when data was compared by year, frequencies were significantly greater in 2004 than 2003. Species richness was almost always significantly greater in September than in May and July. Frequencies of microfungi isolated from bark samples collected 1.2 m above the ground were significantly greater than in samples collected at 0.9, 0.6 and 0.3 m. Increased species richness at the higher bole positions was likely related to changes in microenvironment, as proposed by previous researchers. All other comparisons of species richness were similar.
Gully-eroded and steephead valleys on Eglin Air Force Base in the Florida panhandle were sampled for the abundance of four species of ravine-inhabiting, plethodontid salamanders in two separate periods, 25 years apart. In this interval, Desmognathus auriculatus (Southern Dusky Salamander) appears to have gone extinct and the abundance of D. cf. conanti (Spotted Dusky Salamanders) has decreased by about 68%. There was no change in the average abundance of Eurycea cirrigera (Two-lined Salamander). Pseudotriton ruber (Red Salamanders) declined in ravines from which larger populations of D. auriculatus disappeared, but increased in ravines from which smaller populations of D. auriculatus had disappeared. There was a slight increase in the average abundance of P. ruber in ravines that were inhabited by D. cf. conanti, but those changes in P. ruber abundance were unrelated to the changes in the abundance of D. cf. conanti. Declines in populations of D. auriculatus were also noted in Louisiana and Georgia; evidence suggests that all of these declines began in the mid-1970s. There are several potential causes of the regional declines, but no single explanation appears sufficient to explain declines in all populations. Feral pig rooting eliminates the larval seepage habitat of desmognathine salamanders and may be partly responsible for the declines on Eglin Air Force Base.
Alligator mississippiensis (American Alligators) demonstrated low hatch-rate success and increased adult mortality on Lake Griffin, FL, between 1998 and 2003. Dying Lake Griffin alligators with symptoms of poor motor coordination were reported to show specific neurological impairment and brain lesions. Similar lesions were documented in salmonines that consumed clupeids with high thiaminase levels. Therefore, we investigated the diet of Lake Griffin alligators and compared it with alligator diets from two lakes that exhibited relatively low levels of unexplained alligator mortality to see if consumption of Dorosoma cepedianum (gizzard shad) could be correlated with patterns of mortality. Shad in both lakes Griffin and Apopka had high levels of thiaminase and Lake Apopka alligators were consuming greater amounts of shad relative to Lake Griffin without showing mortality rates similar to Lake Griffin alligators. Therefore, a relationship between shad consumption alone and alligator mortality is not supported.
We radio-tracked nine Masticophis flagellum (Coachwhips) to determine home range, habitat use, and movements in eastern Texas from April to October 2000. Home ranges of Coachwhips contained more oak savanna macrohabitat than early-successional pine plantation or forested seep, based on the availability of these three macrohabitats in the study area. Likewise, within their individual home ranges, Coachwhips used oak savanna more than the other two macrohabitats, based on availability. An analysis of microhabitat use revealed that, relative to random sites within their home range, Coachwhips were found at sites with fewer pine trees and more herbaceous vegetation taller than 30 cm. Results of the two analyses, macrohabitat and microhabitat, were consistent: oak savannas contained relatively few pine trees but much herbaceous vegetation taller than 30 cm. Coachwhips made frequent long-distance moves, which resulted in large home ranges. Core activity areas, however, were small. These core activity areas were always within the oak savanna macrohabitat. Long movements, large home ranges, and small core activity areas likely were a result of the preferred oak savanna macrohabitat being patchily distributed in the landscape.
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.
Cryptobranchus alleganiensis (Hellbenders) are primarily nocturnal salamanders, emerging at night from their daytime rock retreats. Most populations exhibit infrequent diurnal activity, mainly during the breeding season or during overcast or rainy days. This paper reports on a population of Hellbenders from Transylvania County, NC, where 148 observations of diurnal activity were made during 51 person hours over a 3-yr period. Hellbenders were most diurnally active during the September breeding season (mean = 16.3 individuals/person hr), but also exhibited high levels of diurnal activity during summer months, especially in May (mean = 11.4 individuals/person hr). Diurnal activity was not correlated with cloud cover, water depth, or time of day when searches were conducted, but was positively correlated with water temperature. Previous literature and numerous surveys conducted by the author in other parts of the Hellbender's range suggest that this North Carolina population is unique in its diurnal activity, which is possibly related to factors such as prey availability, intraspecific competition, or predator threats.
Invasive species are one of the major threats to biological diversity. Invasive species of crayfish are known to negatively impact native species in aquatic ecosystems. We recently found that an Ozark endemic crayfish, Orconectes neglectus, has been introduced into the Spring River drainage of southern Missouri and northern Arkansas and appears to have the potential to negatively impact the native communities. We used quantitative kick netting along the Spring River and selected tributaries to determine the distribution and abundance of O. neglectus and its potential to impact native crayfish species. The native crayfishes Orconectes eupunctus, a species of special concern, and Cambarus hubbsi appear to no longer occur throughout much of their former range in the Spring River drainage where O. neglectus is now abundant. Orconectes eupunctus, C. hubbsi, and O. neglectus mainly used fast-flowing riffle and run habitats with a mix of gravel, cobble, and boulder, whereas the other common species collected, Orconectes punctimanus and Orconectes ozarkae, were more generalists in habitat use and were found at all sampled sites. Orconectes eupunctus and C. hubbsi were positively associated with each other, but negatively associated with O. neglectus, despite their similar habitat use. These results provide evidence that O. neglectus is expanding its range, possibly to the detriment of O. eupunctus and C. hubbsi. An intensive field survey and manipulative experiments would be required to confirm the disappearance of the native species, and the mechanisms involved.
Although burial is known to have important effects on seed predation in a variety of habitats, the role of burial depth in affecting the removal of seeds in early-successional systems is poorly known. Phytolacca Americana (pokeweed) is a model species to examine the role of burial depth in affecting seed removal because it is common in early-successional habitats, studies suggest that seed removal is indicative of seed predation, and seed predation is related to the recruitment of mature plants. To determine how burial depth affects P. americana seed removal, 20 seeds of P. americana were buried at depths of 0, 1, or 3 cm in early-successional habitats at the Savannah River Site in South Carolina for over 6 weeks. The frequency with which seeds were encountered (as measured by the removal of at least one seed) and the proportion of seeds removed was significantly greater when seeds were on the soil surface (0 cm depth) compared to seeds that were buried 1 cm or 3 cm; there was no difference in encounter or removal between seeds at 1 cm or 3 cm. Our findings suggest that burial may have important consequences for P. americana population dynamics, because seed survival depends upon whether or not the seed is buried, and relatively shallow burial can yield large increases in seed survival. Because seed limitation is known to be an important determinant of plant community composition in early-successional systems, our work suggests that burial may play an unappreciated role in the dynamics of these communities by reducing predator-mediated seed limitation.
We developed a tail-mounted radio-transmitter for Myocastor coypus (nutria) that offers a practical and efficient alternative to collar or implant methods. The mean retention time was 96 d (range 57–147 d, n = 7), making this a practical method for short-term studies. The tail-mounts were less injurious to animals than collars and easier for field researchers to implement than either collars or surgically implanted transmitters.
Forty-eight Myotis grisescens (gray bat) maternity colonies in Missouri, Arkansas, and Oklahoma were monitored from 1978 to 2002 as recommended in the US Fish and Wildlife Service recovery plan for this endangered species. Seventy-nine percent of colonies were stable or increasing across 3 subpopulations in this portion of the species' range, and 9 of 14 (64%) actions required by the recovery plan in this region were entirely or partially completed. This study indicates that the dramatic decline in gray bat populations that led to its listing as endangered in 1976 may have halted and that gray bat populations appear to be recovering in the western portion of its range.
Gastropods in the family Ellobiidae are a cryptic and easily overlooked component of intertidal habitats in South Carolina salt marshes. Recent and archived collections reveal the presence of two ellobiid species, Microtralia ovula and Creedonia succinea, which are established and occasionally abundant in the mid- to upper-intertidal zone on oyster reefs and under wrack on washed shell banks. These species are previously known to occur only in Bermuda, southern Florida, the Bahamas, the Greater Antilles, and Mexico. This note reports a significant northward extension of their known range and acknowledges that similar distributional shifts are being more widely recognized for estuarine benthic fauna along the US Atlantic coast.
Speyeria diana (Diana fritillary) is a forest dwelling butterfly that has been eradicated from portions of its native habitat in North Carolina. This loss has been attributed to habitat destruction and pesticide use, resulting in its status as a species of special concern. During the spring and summer of 2003 and 2004, we conducted butterfly surveys on forested 10-ha plots in the southern Appalachians of North Carolina in which various forest management practices had been applied. During one survey (June 2004), we observed male Diana fritillary butterflies feeding on flowering Oxydendrum arboretum (sourwood) within plots that had been mechanically thinned and burned. These plots also had the greatest herbaceous plant cover. Our observations suggest that some forest management related disturbances, resulting in increased herbaceous plant cover, may help in conserving this species.
Carcharhinus isodon (finetooth shark) is a migratory shark found in coastal waters of the southeastern United States and is well documented in the waters of north Florida in both the Gulf of Mexico and the Atlantic Ocean. The southernmost reports are from Lemon Bay (27°N), just north of Charlotte Harbor on the west coast and from Port Salerno (27°N) on the east coast. Four C. isodon were captured on bottom-set longline in Florida Bay, just north of 25°N latitude, during routine sampling for Pristis pectinata (smalltooth sawfish). These captures extend the southern range of C. isodon in Florida to approximately 25°N and increase the likelihood of exchange between the Atlantic and Gulf stocks.