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trivittatus virus infections in wild mammals and sentinel rabbits in central iowa.a serological survey was conducted in iowa to determine the prevalence rate of california group virus antibodies in sera of several vertebrate species. serum specimens were assayed for infectivity-neutralizing antibody in a microneutralization system with baby hamster kidney cell culture. of 77 sera assayed, 21 (27%) neutralized trivittatus (tvt) virus infectivity. the antibody prevalence rate was highest for eastern cottontail rabbits inasmuch as 46% (10/22) of the serum specimens form this spe ...19751200251
delayed response with different delay conditions by squirrel monkeys and fox squirrels. 19684970665
synaptic arrangements in the ventral posterolateral nucleus of the squirrel.because murine rodents have no complex synaptic arrangements in the ventral posterolateral nucleus (vpl), we sought to determine if the lack of complexity was a characteristic common to all rodents. we studied the synaptology of vpl in the fox squirrel, sciurus niger, using electron microscopy. we found vesicle-containing dendrites and complex synaptic arrangements in the squirrel vpl. therefore, the relative simplicity of the rat and mouse vpl is not a general feature of the rodent somatosensor ...19836616170
ticks (acari: ixodidae) collected from small and medium-sized kansas mammals.seven species of hard-bodied ticks were collected from 20 species of small and medium-sized mammals in kansas; amblyomma americanum l., dermacentor variabilis (say), haemaphysalis leporispalustris (packard), ixodes cookei packard, i. kingi bishopp, i. sculptus neumann, and i. texanus banks. dermacentor variabilis was found statewide, a. americanum only in the eastern one-third of the state, and the ixodes spp. and h. leporispalustris were widely scattered. the most common tick found was d. varia ...19948057327
ixodes dammini (acari: ixodidae) infestation on medium-sized mammals and blue jays in northwestern illinois.high prevalence of infestation of five species of medium-sized mammals and blue jays, cyanocitta cristata (l.), by immature ixodes dammini spielman, clifford, piesman and corwin was found in castle rock state park in northwestern illinois during may-august 1991. raccoons, procyon lotor l., and opossums, didelphis virginiana kerr, were infested with the highest larval densities and were trapped primarily in bottomland forest and ecotone habitats. all species had similar nymphal densities, except ...19938254647
lack of seroreactivity to ehrlichia chaffeensis among rodent populations.a retrospective serosurvey for antibodies to ehrlichia chaffeensis was conducted on eight species of wild rodents (mus musculus, oryzomys palustris, peromyscus leucopus, rattus norvegicus, reithrodontomys humulis, sciurus carolinensis, sciurus niger, and sigmodon hispidus) from the southeastern united states. serum samples (n = 281) collected between 1973 and 1993 were evaluated using an indirect fluorescent antibody test. all samples, screened at a dilution of 1:32, were negative for antibodies ...19989577793
serologic evidence of exposure of wild mammals to flaviviruses in the central and eastern united states.serosurveys were conducted to obtain flavivirus and west nile virus (wnv) seroprevalence data from mammals. sera from 513 small- and medium-sized mammals collected during late summer and fall 2003 from colorado, louisiana, new york, ohio, and pennsylvania were screened for flavivirus-specific antibodies. sera samples containing antibody to flaviviruses were screened for wnv-specific antibodies by epitope-blocking enzyme-linked immunosorbent assays and confirmed with plaque reduction neutralizati ...200515891139
experimental infection of fox squirrels (sciurus niger) with west nile virus.tree squirrels (sciurus spp.) have exhibited high seroprevalence rates, suggesting that they are commonly exposed to west nile virus (wnv). many characteristics of wnv infections in tree squirrels, such as the durations and levels of viremia, remain unknown. to better understand wnv infections in fox squirrels (s. niger), we subcutaneously inoculated fourteen fox squirrels with wnv. peak viremias ranged from 10(4.00) plaque-forming units (pfu)/ml of serum on day 2 post-infection (dpi) to 10(4.98 ...200617038697
importance of fragmentation-tolerant species as seed dispersers in disturbed landscapes.forest fragmentation can negatively affect plants if animal seed-dispersers become locally extinct in fragments. we conducted a 2-year experiment to evaluate the importance of tree squirrels (sciurus) as seed dispersers for quercus, carya, and juglans, and to assess dispersal consequences in patches where fragmentation-sensitive eastern gray squirrels (sciurus carolinensis) are absent. we accounted for fates of approximately 15,700 seeds from five tree species in four exclosure treatments at 18 ...200717180374
fox squirrel (sciurus niger) associations with west nile virus.tree squirrels (sciurus spp.) have been recently shown to be commonly exposed to west nile virus (wnv). many characteristics of wnv infections in tree squirrels are unknown. to better understand wnv associations in fox squirrels (s. niger), we conducted mark-recapture sampling (n = 72) and radio telemetry to study the longitudinal seroprevalence, seroconversions, and ectoparasites of these animals during 2005-2006 in northern colorado. five seroconversions were documented during this study. the ...200717426187
west nile virus infection in tree squirrels (rodentia: sciuridae) in california, 2004-2005.west nile virus (wnv) transmission generally involves a mosquito vector and an avian reservoir host, with mammals as incidental hosts. although most mammalian wnv infections cause low or no morbidity or mortality, tree squirrels are susceptible to wnv-associated neurologic disease with infection prevalence comparable to that in dead birds. positive species included fox squirrel (sciurus niger), western gray squirrel (s. griseus), and eastern gray squirrel (s. carolinensis). kidney tissue (dissec ...200717488896
identifying the reservoir hosts of the lyme disease spirochete borrelia burgdorferi in california: the role of the western gray squirrel (sciurus griseus).we investigated the role of the western gray squirrel (sciurus griseus) as a reservoir host of the lyme disease spirochete borrelia burgdorferi. a survey of 222 western gray squirrels in california showed an overall prevalence of b. burgdorferi infection of 30%, although at a county level, prevalence of infection ranged from 0% to 50% by polymerase chain reaction. laboratory trials with wild-caught western gray squirrels indicated that squirrels were competent reservoir hosts of the lyme disease ...200818840740
antibodies to west nile virus in raccoons and other wild peridomestic mammals in iowa.surveillance for evidence of west nile virus (wnv) infection in small- and medium-sized wild mammals was conducted in iowa, usa, from may 2005 to june 2007. sera were collected from 325 mammals belonging to nine species and tested for antibodies to wnv and other flaviviruses by epitope-blocking enzyme-linked immunosorbent assay (elisa). all sera that had antibodies to flaviviruses by blocking elisa were further examined by plaque reduction neutralization test (prnt). thirteen mammals were seropo ...200919901390
coinfection of western gray squirrel (sciurus griseus) and other sciurid rodents with borrelia burgdorferi sensu stricto and anaplasma phagocytophilum in california.overlapping geographic distributions of tick-borne disease agents utilizing the same tick vectors are common, and coinfection of humans, domestic animals, wildlife, and ticks with both borrelia burgdorferi and anaplasma phagocytophilum has been frequently reported. this study was undertaken in order to evaluate the prevalence of both b. burgdorferi sensu stricto (hereinafter referred to as b. burgdorferi) and a. phagocytophilum in several species of sciurid rodents from northern california, usa. ...201020090047
remarkable diversity of tick or mammalian-associated borreliae in the metropolitan san francisco bay area, california.the diversity of lyme disease (ld) and relapsing fever (rf)-group spirochetes in the metropolitan san francisco bay area in northern california is poorly understood. we tested ixodes pacificus, i. spinipalpis, and small mammals for presence of borreliae in alameda county in the eastern portion of san francisco bay between 2009 and 2012. analyses of 218 borrelia burgdorferi sensu lato (bb sl) culture or dna isolates recovered from host-seeking i. pacificus ticks revealed that the human pathogen b ...201425129859
the safety of onrab® in select non-target wildlife.onrab(®) is a recombinant human adenovirus type 5 (had5) with the rabies glycoprotein gene incorporated into its genome. onrab(®) has been used in canada as an oral rabies vaccine in target wildlife species such as: red fox (vulpes vulpes), raccoon (procyon lotor), and striped skunk (mepthis mephitis). we evaluated the safety of onrab(®) in non-target wildlife species likely to contact the vaccine baits during oral rabies vaccine campaigns in the united states. we investigated the effects of ora ...201323831321
use of a public telephone hotline to detect urban plague cases.current methods for vector-borne disease surveillance are limited by time and cost. to avoid human infections from emerging zoonotic diseases, it is important that the united states develop cost-effective surveillance systems for these diseases. this study examines the methodology used in the surveillance of a plague epizootic involving tree squirrels (sciurus niger) in denver colorado, during the summer of 2007. a call-in centre for the public to report dead squirrels was used to direct animal ...201222429398
leptospirosis in fox squirrels (sciurus niger) of larimer county, colorado, usa.leptospirosis is a zoonotic disease caused by the bacterium leptospira interrogans. the organism is typically maintained within a geographic region by colonizing renal tubules of carrier animals and shed into the environment in urine. we assessed whether l. interrogans was present in fox squirrels (sciurus niger) in larimer county, colorado, usa, and whether it is associated with disease. twenty-two squirrels were trapped from 29 november 2011 to 15 december 2011 for use in an unrelated study. t ...201323778614
north american tree squirrels and ground squirrels with overlapping ranges host different cryptosporidium species and genotypes.wildlife-associated cryptosporidium are an emerging cause of cryptosporidiosis in humans. the present study was undertaken to determine the extent to which north american tree squirrels and ground squirrels host zoonotic cryptosporidium species and genotypes. fragments of the cryptosporidium 18s rrna and actin genes were amplified and sequenced from fecal samples obtained from three tree squirrel and three ground squirrel species. in tree squirrels, cryptosporidium was identified in 40.5% (17/42 ...201526437239
combining a dispersal model with network theory to assess habitat connectivity.assessing the potential for threatened species to persist and spread within fragmented landscapes requires the identification of core areas that can sustain resident populations and dispersal corridors that can link these core areas with isolated patches of remnant habitat. we developed a set of gis tools, simulation methods, and network analysis procedures to assess potential landscape connectivity for the delmarva fox squirrel (dfs; sciurus niger cinereus), an endangered species inhabiting for ...201020405797
distribution and diversity of borrelia burgdorferi sensu lato group bacteria in sciurids of california.california has a remarkable diversity of squirrel and chipmunk species (sciurids), and five named and several unnamed genospecies in the borrelia burgdorferi sensu lato group (bbsl) of bacteria as well, many of which utilize sciurids as reservoirs. we investigated the prevalence, spatial distribution, and diversity of bbsl in sciurids of california by literature search, pcr of 585 ear tissue samples from 15 sciurid species prospectively collected across 19 california counties, and dna sequencing ...201728976820
susceptibility of fox squirrels (sciurus niger) to west nile virus by oral exposure.fox squirrels (sciurus niger) (five of eight) were infected with west nile virus (wnv) when challenged by the oral route with 10(2.3) or 10(3.4) plaque forming units (pfu). the mean maximum serum wnv titer of infected fox squirrels was 10(5.1) pfu/ml and ranged from 10(4.6) to 10(5.6) pfu/ml. these levels of viremia are infectious for several mosquito vectors of wnv. this virus was also isolated from swabs of the oral and rectal cavities, and urine swabs between day 5 and 9 postexposure (p.e.) i ...201019402765
west nile virus infection in free-ranging squirrels in illinois.west nile virus (wnv) infection was diagnosed in 13 gray squirrels (sciurus carolinensis) and 3 fox squirrels (sciurus niger) that were observed with neurologic signs before death or found dead. all 16 had gliosis throughout all sections of the brain. most had lymphoplasmacytic encephalitis or meningoencephalitis, many with admixed neutrophils. neuronal necrosis and neuronophagia were also prominent features. west nile virus antigen was demonstrated in the brain, spleen, heart or kidney in 10 of ...200415152831
west nile virus infection in eastern fox squirrels (sciurus niger).since the initial outbreak of west nile virus (wnv) in the northeastern united states in 1999, the virus has rapidly spread westward and southward across the usa, causing high mortality in crows as well as sporadic mortality in horses, humans, and a wide variety of birds. in 2002 the epidemic widened as hundreds of equine and human cases and sporadic cases in other mammalian species were reported. this is the first report of wnv infection in three eastern fox squirrels (sciurus niger). neurologi ...200314608026
audiogram of the fox squirrel (sciurus niger).the behavioral audiograms of 2 fox squirrels (sciurus niger) were determined with a conditioned avoidance procedure. the squirrels were able to hear tones ranging from 113 hz to 49 khz at a level of 60 db sound-pressure level or less, with their best sensitivity of 1 db occurring at 8 khz. their ability to hear frequencies below 150 hz indicates that they have good low-frequency hearing, as do the 2 other members of the squirrel family (black-tailed and white-tailed prairie dogs) for which audio ...19979090140
a comparison of parasitic helminths and arthropods from two subspecies of fox squirrels (sciurus niger) in florida.the faunas of parasitic helminths and arthropods of 87 sherman's fox squirrels (sciurus niger shermani) and 32 big cypress fox squirrels (sciurus niger avicennia) collected from florida (usa) over a 6-yr period (1988 to 1993) were compared. one acanthocephalan, one cestode, nine nematodes, one flea, three sucking lice, three mites, one tick, and one dipteran larva were identified. citellinema bifurcatum and physaloptera massino were new records for florida and gongylonema pulchrum, neotrombicula ...19968827675
prevalence of cuterebra emasculator in squirrels in mississippi.between 1977 and 1979, 1,997 gray squirrels (scriurus carolinensis) and 290 fox squirrels (s. niger) were examined for cuterebra emasculator myiasis. approximately 19% of the gray and 5% of the fox squirrels were infested with 1.9 and 2.5 larvae per host, respectively. myiasis was seen between 14 august and 29 october. peak infestations occurred in the second week of september. adult and subadult squirrels had higher infestations than juveniles. multiple infestations occurred in 51% of the hosts ...19817253103
comparative study of the forelimbs of the semifossorial prairie dog, cynomys gunnisoni, and the scansorial fox squirrel, sciurus niger.a comparative study of the forelimbs of the semifossorial prairie dog, cynomys gunnisoni , and the scansorial tree squirrel, sciurus niger, was focused on the musculoskeletal design for digging in the former and climbing in the latter. based on lever arm mechanics, it was expected that the forelimb of the prairie dog would show features appropriate to the production of relatively large forces and that of the fox squirrel to relatively great velocity. force and lever arm measurements were made of ...19846726818
uroporphyrinogen 3 cosynthetase activity in the fox squirrel (sciurus niger).the activity of uroporphyrinogen iii cosynthetase in hemolyzates and tissue extracts from fox squirrels is much less than in similar preparations from gray squirrels. low activity of this enzyme explains the production of large amounts of uroporphyrin i by the fox squirrel. members of this species thus provide a small-animal model for studies of congenital erythropoietic porphyria, a hereditary disease of man and cattle which is associated with a similar partial deficiency of uroporphyrinogen ii ...19715120867
erythropoietic porphyria of the fox squirrel sciurus niger.uroporphyrin i is found in high concentration in the bones, teeth, blood, soft tissues, and urine of the fox squirrel, sciurus niger. the concentration of uroporphyrin in fox squirrel spleen is much higher than in liver, kidney or bone marrow, probably because of accumulation from phagocytosed red cells. bleeding causes a marked increase in the uroporphyrin concentration of red cells and spleen, and a 3-8-fold increase in uroporphyrin excretion. urinary excretion of delta-aminolevulinic acid and ...19734682390
cysticerci of taenia mustelae in the fox squirrel.the liver of a fox squirrel (sciurus niger rufiventer) contained many clear, spherical cysts approximately 1 mm in diameter throughout the parenchyma. on dissection, most of these exhibited a dense, white area with four muscular suckers at a single point on the bladder. based on the size of the organisms, the characteristically tiny hooks on the scolex and the location of the cysts in this host, the parasites were identified as cysticerci of taenia mustelae. this is the first report in this host ...19902338737
leptospirosis in selected wild mammals of the florida panhandle and southwestern georgia.a group of 144 wild mammals, including white-tailed deer, cottontail rabbits, fox squirrels, gray squirrels, raccoons, opossums, a bobcat, and various small rodents was examined for cultural or serologic evidence of leptospiral infection. leptospires were isolated from 1 of 25 rabbits, 1 of 27 fox squirrels, 1 of 26 gray squirrels, 4 of 18 mice and rats, 8 of 21 raccoons, 7 of 17 opossums, and a bobcat. isolations were not made from 6 deer examined. serotypes isolated were leptospira interrogans ...19751176352
comparison of the its1 and its2 rdna in eimeria callospermophili (apicomplexa:eimeriidae) from sciurid rodents.the taxonomy of the coccidia has historically been morphologically based. the purpose of this study was to establish if conspecificity of isolates of eimeria callospermophili from 4 ground-dwelling squirrel hosts (rodentia: sciuridae) is supported by comparison of rdna sequence data and to examine how this species relates to eimerian species from other sciurid hosts. eimeria callospermophili was isolated from 4 wild-caught hosts, i.e., urocitellus elegans, cynomys leucurus, marmota flaviventris ...201121506777
fox squirrels (sciurus niger) develop west nile virus viremias sufficient for infecting select mosquito species.the west nile virus (wnv) viremia and shedding profiles of 11 adult fox squirrels (sciurus niger) infected by needle inoculation or mosquito bite were characterized. daily mean titers (95% confidence intervals) for all squirrels on days 1 through 6 postexposure (p.e.) were: 10(1.7 (1.32.1)), 10(4.4 (4.04.8)), 10(5.3 (5.05.6)), 10(4.4 (3.94.9)), 10(2.7 (2.03.4)), and 10(1.1 (0.52.1)) plaque-forming units (pfu)/ml. the highest wnv serum titers of individual squirrels infected by needle inoculation ...200818240969
mechanosensory projections to cuneate, gracile, and external cuneate nuclei in a tree squirrel (fox squirrel, sciurus niger).the distribution and organization of mechanosensory projections to the cuneate, gracile and external cuneate nuclei were mapped in tree squirrels anesthetized with ketamine and urethane. tungsten microelectrodes were used to record unit and unit cluster responses to mechanical stimulation. most responses in the gracile nucleus were to stimulation of skin and hairs of the tail, hind foot and leg, and trunk, in that order going from dorsal to ventral in the nucleus. a similar distribution of respo ...19836308501
occurrence of eimeria ontarioensis lee and dorney, 1971, in the fox squirrel, sciurus niger rufiventer, in indiana. 19734711674
scotopic and photopic visual capacitiesof an arboreal squirrel [ sciurus niger].behavior measurements of visualcapacities were made on fox squirrels [sciurus niger. spectal sensitivity functionsmeasured in the context of an increment-threshold task reveal the presence of a purkinjeshift in this species. under conditions of dark adaptation, the spectral sensitivityfunction is closely fit by a nomogram photpigment having a 500 nm maximum. under conditions of light adaptation, the spectral sensitivity function is bimodal in form with peaksat about 460 and 560 nm. several furth ...19751137813
rabies in an eastern fox squirrel. 19724634526
special anatomical features of the cranial nerves of the fox squirrel, sciurus niger rufiventer (geoffroy). 195613394939
the accessory genital glands of male gray and fox squirrels correlated with age and reproductive cycles. 195513268330
the testis of the fox squirrel in relation to age and seasons. 195513268329
a new species of bothriocephalid cestode, from the fox squirrel (sciurus niger linn.). 195513252494
the helminths from a heavily parasitized fox squirrel, sciuris niger. 194918132290
a bad habit of the fox-squirrel (sciurus niger, var. ludovicianus). 188417759542
species of eimeria (apicomplexa: eimeriidae) from tree squirrels (sciurus niger) (rodentia: sciuridae) and analysis of the its1, its2, and 5.8s rdna.during the winter of 2004, 48 fecal samples were collected from live-trapped fox squirrels (sciurus niger) from central wyoming (natrona county) and examined for species of eimeria. two species, eimeria lancasterensis (prevalence, 65%) and eimeria ontarioensis (prevalence, 27%), were identified. genomic dna sequences its1 and its2 were amplified, cloned, and sequenced. additional sequences from e. lancasterensis isolated from a delmarva fox squirrel (sciurus niger cinereus) collected on chincote ...200919245280
bait development for oral delivery of pharmaceuticals to raccoons (procyon lotor) and striped skunks (mephitis mephitis).oral vaccination is one tool used to control wildlife diseases. a challenge to oral vaccination is identifying baits specific to target species. the us has been conducting oral vaccination against rabies since the 1990s. improvements in bait development will hasten disease elimination. in colorado, we examined a novel bait for oral vaccination and offered two different flavors, sweet and fish, to captive raccoons ( procyon lotor ) and striped skunks ( mephitis mephitis ) to assess consumption an ...201627505038
control of food handling by cutaneous receptor input in squirrels.in a complementary neuroanatomical study by brenowitz in 1980, it was shown that tree squirrels (sciurus niger) have a higher relative density of mechanoreceptors in their glabrous forepaw skin than do ground squirrels (spermophilus tridecemlineatus). the main purpose of this sudy was to test the prediction that tree squirrels would depend upon somatic sensory (cutaneous) input from their forepaws to a greater extent than would ground squirrels in food handling behavior. in addition, a series of ...19807437901
cutaneous mechanoreceptor distribution and its relationship to behavioral specializations in squirrels.the relationship between sensory specializations and behavioral specializations in two ecologically distinct species of squirrels was examined. it was predicted that the relative density of receptors in the glabrous forepaw skin of tree squirrels (sciurus niger), which are skilled climbers and manipulate food items extensively, would be higher than that in ground squirrels (spermophilus tridecemlineatus), which dig underground burrows. in addition to testing this prediction, several other aspect ...19807437898
the projection of cervical primary fibers to the dcn of the squirrel, sciurus niger: fiber sorting in the dorsal columns.the course and terminal distribution of cervical primary afferents in the dorsal column nuclei were studied in the fox squirrel, sciurus niger. unilateral rhizotomies were performed at cervical levels c3, c4, c5, c6 and c8. for all spinal levels studied except c8, degeneration in the medullary cuneate fasciculus was present within two distinct groups. they included a large oblique lateral lamina and a small superficial group of degeneration. the superficial group was horizontal, located medial t ...19836303492
animal model: normal porphyria of fox squirrels (sciurus niger). 1977851164
foci of altered hepatocytes in a fox squirrel (sciurus niger) with haemochromatosis.numerous minute milky white foci were distributed throughout the dark brown liver in an adult male fox squirrel. histologically, the hepatic focal lesions were composed of large eosinophilic granular hepatocytes, which were mostly positive for glutathione s-transferase mu antigen and proliferating cell nuclear antigen. electron microscopy demonstrated an increased number of mitochondria. these features corresponded to those in the eosinophilic type of foci of altered hepatocytes. berlin blue sta ...200415276864
quadrupedal locomotor performance in two species of arboreal squirrels: predicting energy savings of gliding.gliding allows mammals to exploit canopy habitats of old-growth forests possibly as a means to save energy. to assess costs of quadrupedal locomotion for a gliding arboreal mammal, we used open-flow respirometry and a variable-speed treadmill to measure oxygen consumption and to calculate cost of transport, excess exercise oxygen consumption, and excess post-exercise oxygen consumption for nine northern flying squirrels (glaucomys sabrinus) and four fox squirrels (sciurus niger). our results ind ...201020361193
ivermectin treatment of notoedric mange in two fox squirrels. 19846548999
phylogeny of six sciurus aberti subspecies based on nucleotide sequences of cytochrome b.the tassel-eared squirrel, sciurus aberti, is separated into six subspecies which occupy restricted and comparable habitats in ponderosa pine forests in the south-western united states and mexico. these forests and squirrel populations are currently isolated by large arid areas and, as such, s. aberti appears to offer an example of incipient speciation. we sequenced the complete mitochondrial cytochrome b gene to construct a molecular phylogeny for s. aberti and to determine whether subspecific ...19957663760
melanocortin 1 receptor (mc1r) gene sequence variation and melanism in the gray (sciurus carolinensis), fox (sciurus niger), and red (sciurus vulgaris) squirrel.sequence variations in the melanocortin 1 receptor (mc1r) gene are associated with melanism in many different species of mammals, birds, and reptiles. the gray squirrel (sciurus carolinensis), found in the british isles, was introduced from north america in the late 19th century. melanism in the british gray squirrel is associated with a 24-bp deletion in the mc1r. to investigate the origin of this mutation, we sequenced the mc1r of 95 individuals including 44 melanic gray squirrels from both th ...201424534267
scale-dependent neighborhood effects: shared doom and associational refuge.a resource's susceptibility to predation may be influenced by its own palatability and the palatability of its neighbors. we tested for effects of plant chemical defenses on seed survival by manipulating the frequency of palatable and less palatable sunflower seeds in food patches subject to harvest by fox squirrels (sciurus niger) and gray squirrels (sciurus carolinensis). we varied resource distributions at three scales: among stations (aggregates of patches ca. 50 m apart), among patches imme ...201221987268
notoedric mange in two fox squirrels. 19836643247
visual acuity and spatial contrast sensitivity in tree squirrels.the visual sensitivity of tree squirrels from three different species (two western gray squirrels, sciurus griseus; three fox squirrels, sciurus niger; and an eastern gray squirrel, sciurus carolinensis) was measured for spatial patterns defined by luminance differences. spatial contrast sensitivity functions were determined in behavioral discrimination experiments in which the stimuli were sinusoidally-modulated gratings. at an average luminance level of 3.4 cd/m(2) these squirrels were maximal ...198224923501
experimental transmission of eimeria confusa joseph 1969 to the fox squirrel.eimeria confusa joseph, 1969 from the gray squirrel sciurus carolinensis was transmitted to the fox squirrel sciurus niger rufiventer. this is the first report of the successful cross-transmission of a gray squirrel coccidium to the fox squirrel.19751152180
caching for where and what: evidence for a mnemonic strategy in a scatter-hoarder.scatter-hoarding animals face the task of maximizing retrieval of their scattered food caches while minimizing loss to pilferers. this demand should select for mnemonics, such as chunking, i.e. a hierarchical cognitive representation that is known to improve recall. spatial chunking, where caches with the same type of content are related to each other in physical location and memory, would be one such mechanism. here we tested the hypothesis that scatter-hoarding eastern fox squirrels (sciurus n ...201728989788
inaccessibility of reinforcement increases persistence and signaling behavior in the fox squirrel (sciurus niger).under natural conditions, wild animals encounter situations where previously rewarded actions do not lead to reinforcement. in the laboratory, a surprising omission of reinforcement induces behavioral and emotional responses described as frustration. frustration can lead to aggressive behaviors and to the persistence of noneffective responses, but it may also lead to new behavioral responses to a problem, a potential adaptation. we assessed the responses to inaccessible reinforcement in free-ran ...201627078081
big cypress fox squirrel (sciurus niger avicennia) ecology and habitat use in a cypress dome swamp-pine forest mosaic.forested wetlands are in decline, as are many species that are obligate residents. big cypress fox squirrels (bcfs; sciurus niger avicennia) are a threatened endemic to wet pine and cypress forests in southwestern florida. the region is characterized by development resulting in habitat loss, habitat fragmentation, and hydrological change that influence the quality of these wet forests. through radiotelemetry and field observations, we examined the ecology and habitat use of bcfs in a natural cyp ...201626989265
daily activity and nest occupation patterns of fox squirrels (sciurus niger) throughout the year.the authors investigated the general activity and nest occupation patterns of fox squirrels in a natural setting using temperature-sensitive data loggers that measure activity as changes in the microenvironment of the animal. data were obtained from 25 distinct preparations, upon 14 unique squirrels, totaling 1385 recording days. the animals were clearly diurnal, with a predominantly unimodal activity pattern, although individual squirrels occasionally exhibited bimodal patterns, particularly in ...201626963918
fox squirrels match food assessment and cache effort to value and scarcity.scatter hoarders must allocate time to assess items for caching, and to carry and bury each cache. such decisions should be driven by economic variables, such as the value of the individual food items, the scarcity of these items, competition for food items and risk of pilferage by conspecifics. the fox squirrel, an obligate scatter-hoarder, assesses cacheable food items using two overt movements, head flicks and paw manipulations. these behaviors allow an examination of squirrel decision proces ...201424671221
multiple introductions of the eastern fox squirrel (sciurus niger) in california.eastern fox squirrels (sciurus niger) have been introduced into california within the past 130 years. recently, their range has been expanding at an alarming rate. genetic diversity was assessed in 101 control region sequences of eastern fox squirrels from three geographic regions within california (los angeles county, alameda and contra costa counties and sacramento county) to determine if a single or multiple introductions occurred within california, as indicated by the detection of multiple h ...201524438286
assessing the influence of field- and gis-based inquiry on student attitude and conceptual knowledge in an undergraduate ecology lab.combining field experience with use of information technology has the potential to create a problem-based learning environment that engages learners in authentic scientific inquiry. this study, conducted over a 2-yr period, determined differences in attitudes and conceptual knowledge between students in a field lab and students with combined field and geographic information systems (gis) experience. all students used radio-telemetry equipment to locate fox squirrels, while one group of students ...200818765756
flexibility of cue use in the fox squirrel (sciurus niger).recent work on captive flying squirrels has demonstrated a novel degree of flexibility in the use of different orientation cues. in the present study, we examine to what extent this flexibility is present in a free-ranging population of another tree squirrel species, the fox squirrel. we trained squirrels to a rewarded location within a square array of four feeders and then tested them on transformations of the array that either pitted two cue types against one cue type, the majority tests, or a ...200818350324
peridomestic mammal susceptibility to severe acute respiratory syndrome coronavirus 2 infection.wild animals have been implicated as the origin of severe acute respiratory syndrome coronavirus 2 (sars-cov-2), but it is largely unknown how the virus affects most wildlife species and if wildlife could ultimately serve as a reservoir for maintaining the virus outside the human population. we show that several common peridomestic species, including deer mice, bushy-tailed woodrats, and striped skunks, are susceptible to infection and can shed the virus in respiratory secretions. in contrast, w ...202134286685
eimeria lancasterensis (apicomplexa: eimeriidae) from the eastern fox squirrel, sciurus niger (rodentia: sciuridae), in north-central texas.eimeria lancasterensis joseph, 1969, is reported for the first time from the feces of 10 of 11 (91%) eastern fox squirrels, sciurus niger ludovicianus, in dallas and johnson counties, texas. oocyst measurements were similar to those reported previously from the eastern gray squirrel, sciurus carolinensis carolinensis, in massachusetts. except for our observation of a substieda body, oocyst morphology was identical to the original description of e. lancasterensis.19892760777
comparison of the muscle mechanics of the forelimb of three climbers.the climbing behavior, muscle mechanics, and functional properties of selected forelimb muscles were examined to ascertain how three distantly related mammals may be adapted for climbing. to determine if features of the fox squirrel (stalheim-smith: j. morphol. 180:55-68, '84) are general or unique features for a climber, two distantly related climbers, the raccoon (procyon lotor) and the opossum (didelphis virginiana), were studied. muscle mechanics varied: the elbow flexors of the fox squirrel ...20082810372
insights on the host associations and geographic distribution of hymenolepis folkertsi (cestoda: hymenolepididae) among rodents across temperate latitudes of north america.synoptic data and an understanding of helminth parasite diversity among diverse rodent assemblages across temperate latitudes of north america remain remarkably incomplete. renewed attention to comprehensive survey and inventory to establish the structure of biodiverse faunas is essential in providing indicators and proxies for identifying the outcomes of accelerating change linked to climate warming and anthropogenic forcing. subsequent to the description of hymenolepis folkertsi in the oldfiel ...201627630100
powassan virus experimental infections in three wild mammal species.powassan virus (powv) is a tick-borne virus maintained in sylvatic cycles between mammalian wildlife hosts and ticks (primarily ixodes spp.). there are two currently recognized lineages, powv-lineage 1 (powv-l1) and deer tick virus (dtv; lineage 2), both of which can cause fatal neurologic disease in humans. increased numbers of human case reports in the northeastern and north central united states in recent years have fueled questions into powv epidemiology. we inoculated three candidate wildli ...202133534764
comparative analysis of microbiota along the length of the gastrointestinal tract of two tree squirrel species (sciurus aberti and s. niger) living in sympatry.microbiota inhabiting the gastrointestinal (gi) tract of animals has important impacts on many host physiological processes. although host diet is a major factor influencing the composition of the gut micro-organismal community, few comparative studies have considered how differences in diet influence community composition across the length of the gi tract. we used 16s sequencing to compare the microbiota along the length of the gi tract in abert's (sciurus aberti) and fox squirrels (s. niger) l ...201931871649
multiple origins of melanism in two species of north american tree squirrel (sciurus).while our understanding of the genetic basis of convergent evolution has improved there are still many uncertainties. here we investigate the repeated evolution of dark colouration (melanism) in eastern fox squirrels (sciurus niger; hereafter "fox squirrels") and eastern gray squirrels (s. carolinensis; hereafter "gray squirrels").201931296164
wildlife contact rates at artificial feeding sites in texas.given the popularity of feeding white-tailed deer (odocoileus virginianus) in texas and the increasing amount of corn that is distributed, more information is needed on the impacts of this activity on non-target wildlife. our objectives were to report visitation, intra- and interspecific contact, and contact rates of wildlife at artificial feeding sites in texas. our study was conducted at three sites in kleberg and nueces counties, texas. we trapped animals from february to april and august to ...201323609307
pooled whole-genome sequencing of interspecific chestnut (castanea) hybrids reveals loci associated with differences in caching behavior of fox squirrels (sciurus niger l.).dispersal of seeds by scatter-hoarding rodents is common among tropical and temperate tree species, including chestnuts in the genus castanea. backcrossed (bc) interspecific hybrid chestnuts exhibit wide variation in seed traits: as the parent species (castanea dentata and c. mollissima) have distinct seed phenotypes and tend to be handled differently by seed dispersers, phenotypic variation in bc trees is likely due to inheritance of genes that have undergone divergent evolution in the parent s ...201830519394
mortality due to toxoplasmosis in suburban eastern fox squirrels ( sciurus niger) in michigan, usa.three separate mortality events affecting wild eastern fox squirrels ( sciurus niger) were investigated in suburban areas within southeastern michigan, us over a 3-yr period from the summer of 2015 through the winter of 2017. a total of seven squirrels were submitted for investigation. the squirrels were generally in fair to good body condition with moderate fat deposits. the tissues that most commonly exhibited gross or histologic lesions included the lungs, liver, and heart, whereas spleen and ...201930096029
landscape-scale differences among cities alter common species' responses to urbanization.understanding how biodiversity responds to urbanization is challenging, due in part to the single-city focus of most urban ecological research. here, we delineate continent-scale patterns in urban species assemblages by leveraging data from a multi-city camera trap survey and quantify how differences in greenspace availability and average housing density among ten north american cities relate to the distribution of eight widespread north american mammals. to do so, we deployed camera traps at 56 ...202033141996
models for human porphyrias: have animals in the wild been overlooked?: some birds and mammals accumulate significant amounts of porphyrins in the body without showing the injurious symptoms observed in human porphyrias.humans accumulate porphyrins in the body mostly during the course of porphyrias, diseases caused by defects in the enzymes of the heme biosynthesis pathway and that produce acute attacks, skin lesions and liver cancer. in contrast, some wild mammals and birds are adapted to accumulate porphyrins without injurious consequences. here we propose viewing such physiological adaptations as potential solutions to human porphyrias, and suggest certain wild animals as models. given the enzymatic activity ...202033155299
a baylisascaris outbreak in fox squirrels (sciurus niger) and subsequent detection of francisella tularensis in kansas, usa.thorough epidemiologic investigations of wildlife mortality events are often challenging, in part because of the dynamic variables involved. in may 2011, six fox squirrels (sciurus niger) in clinton state park, kansas, us were euthanized after exhibiting clinical signs of neurologic disease. postmortem examination of two squirrels revealed that these individuals died of baylisascaris larva migrans, which resulted in meningoencephalitis and variable pneumonia and myocarditis. fecal flotation of r ...202031750777
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