| experimental plague in the california ground squirrel. | in experiments to determine the current susceptibility to plague, it was demonstrated that 256 yersinia pestis (a local strain of high virulence) were required to produce a 50% infectious dose (id50) in california ground squirrels (spermophilus beecheyi) that had been collected in southeastern monterey county, california; 6,070 y. pestis were required to produce a 50% lethal dose (ld50). (the ld50 was about 24 times the id50.) the frequency of serologic response to the specific fraction 1 antige ... | 1979 | 512421 |
| survey of q-fever agglutinins in birds and small rodents in northern california, 1975-76. | serum samples from 15 species of rodents and 33 species of birds were tested for agglutinins against coxiella burnetii by the microagglutination test. of 759 rodents tested, 21 (3%) were seropositive. antibody positive rodents included muskrats, ondatra zebethica, (11%), rattus spp. (10%), beechey ground squirrels, otospermophilus beecheyi, (6%), wood rats, neotoma fuscipes, (5%), and peromyscus spp. (2%). of 583 birds tested, 118 (20%) were seropositive. this included white crowned sparrows, zo ... | 1979 | 522220 |
| behavioral and electrophysiological sensitivity to temporally modulated visual stimuli in the ground squirrel. | behavioral and electrophysiological methods were used to measure sensitivity to flickering lights in a dichromatic species, the california ground squirrel (spermophilus beecheyi). discrimination tests were used to determine spectral sensitivity at stimulus frequencies from 5-50 hz and increment threshold spectral sensitivity. the contributions of retinal mechanisms to these capacities were assessed by recording the responses of optic nerve fibers to temporally modulated monochromatic lights. in ... | 1991 | 1883764 |
| hepadnaviruses and hepatocellular carcinoma (hcc). | members of the hepadnavirus family share properties of virion structure, genome structure and replication, epidemiologic behavior, and pathogenic effects. persistent infections with hepatitis b virus (hbv) in man, woodchuck hepatitis virus (whv) in marmota monax, ground squirrel hepatitis virus (gshv) in spermophilus beecheyi, and duck hepatitis b virus (dhbv) in domestic ducks of china are associated with development of hepatocellular carcinoma (hcc). epidemiological evidence implicating hepadn ... | 1989 | 2559799 |
| the ecology of western equine encephalomyelitis virus in the central valley of california, 1945-1985. | reeves' concept of the summer transmission cycle of western equine encephalomyelitis virus in 1945 was that the virus was amplified in a silent transmission cycle involving mosquitoes, domestic chickens, and possibly wild birds, from which it could be transmitted tangentially to and cause disease in human and equine populations. extensive field and laboratory studies done since 1945 in the central valley of california have more clearly defined the specific invertebrate and vertebrate hosts invol ... | 1987 | 3318522 |
| purification and partial characterization of prolactin from the california ground squirrel (spermophilus beecheyi). | prolactin (prl) secreted by cultured ground squirrel (spermophilus beecheyi) pituitaries (sbprl) was purified by gel filtration on sephadex g-100 and ion-exchange chromatography on polybuffer exchanger 94. purification from culture medium from 190 pituitaries yielded 1.1 mg of purified sbprl. the sbprl has an apparent molecular weight of 27,000 by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate, an isoelectric point of 6.3, and does not contain any asparagine-linked ... | 1987 | 3593848 |
| human and sylvatic trypanosoma cruzi infection in california. | in august 1982, a 56-year-old woman from lake don pedro, california, developed acute chagas' disease (american trypanosomiasis). she had not traveled to areas outside the united states with endemic chagas' disease, she had never received blood transfusions, and she did not use intravenous drugs. trypanosoma cruzi cultured from the patient's blood had isoenzyme patterns and growth characteristics similar to t. cruzi belonging to zymodeme z1. triatoma protracta (a vector of trypanosoma cruzi) infe ... | 1985 | 3919598 |
| hbv and hdv replication in experimental models: effect of interferon. | the use of hbv and hdv experimental models has significantly contributed to understand the viral life cycle and to systematically test antiviral effects of various drugs on a pre-clinical level. similar replication strategies of related hepadna viruses permit the use of chimpanzees (pan troglodytes), woodchucks (marmota monax), ground and tree squirrels (spermophilus beecheyi) or pekin ducks (anas domesticus) as appropriate animal models. cell culture systems for in vitro infection or transfecti ... | 1994 | 7526786 |
| factors affecting the seasonal abundance of ground squirrel and wood rat fleas (siphonaptera) in san diego county, california. | abiotic and biotic factors affecting the seasonal abundance of 3 species of sylvatic fleas on their hosts were examined at 7 sites in san diego county, california. indices for oropsylla (diamanus) montana (baker) were usually highest on spermophilus beecheyi nudipes (huey) when < 18.4 degrees c (october-december), whereas those for hoplopsyllus anomalus (baker) were highest when > 18.4 degrees c (july-september). o. montana was affected most by ambient temperature (inversely for the coastal site ... | 1996 | 8840686 |
| age differences in the response of california ground squirrels (spermophilus beecheyi) to avian and mammalian predators. | the antipredator behavior of juvenile and adult california ground squirrels (spermophilus beecheyi) was videotaped in experiment 1 to measure the effects of age on assessment of a briefly presented live dog and a model red-tailed hawk (buteo jamaicensis) in simulated flight. adult squirrels treated the hawk as more dangerous than the dog, whereas juvenile squirrels showed less differentiation of the predator types. juvenile squirrels also perceived the dog as a more immediate danger than adult s ... | 1997 | 9170282 |
| olfactory bulb uptake and determination of biotransfer factors in the california ground squirrel (spermophilus beecheyi) exposed to manganese and cadmium in environmental habitats. | manganese (mn) and cadmium (cd) profiles in olfactory bulbs of california ground squirrels (spermophilus beecheyi) trapped at lawrence livermore national laboratory's site 300 facility in california were determined with proton induced x-ray emission (pixe). as a reference, mn profiles in olfactory bulbs from laboratory rats exposed via nose-only inhalation to 0.53 mg/m3 mn in the form of mncl2 were also determined with pixe. atomic absorption spectrophotometry was used to measure soil mn and cd ... | 2001 | 11347597 |
| laboratory techniques for rearing the fleas (siphonaptera: ceratophyllidae and pulicidae) of california ground squirrels (rodentia: sciuridae) using a novel nest box. | three species of fleas, oropsylla montana (baker), hoplopsyllus anomalus (baker), and echidnophaga gallinacea (westwood), occur seasonally on the california ground squirrel, spermophilus beecheyi (richardson). few studies have focused on the biology and ecology of these fleas despite their importance in the epidemiology of sylvatic plague. to best duplicate a natural parasite-host relationship in the laboratory, a novel nest box was developed that facilitated housing wild-caught s. beecheyi, was ... | 2001 | 11372977 |
| quantitative shedding of two genotypes of cryptosporidium parvum in california ground squirrels (spermophilus beecheyi). | sixteen percent of california ground squirrels (spermophilus beecheyi) were found to be shedding an average of 53,875 cryptosporidium parvum oocysts/g of feces. male squirrels had a higher prevalence and higher intensity of shedding than did female squirrels. the majority of c. parvum isolates matched a bovine-murine genotype, with a few isolates resembling a porcine genotype. higher intensities of shedding by males may enhance dissemination and genotypic mixing of this protozoa given males' pro ... | 2001 | 11375204 |
| laboratory evaluation of fipronil and imidacloprid topical insecticides for control of the plague vector oropsylla montana (siphonaptera: ceratophyllidae) on california ground squirrels (rodentia: sciuridae). | two insecticides, fipronil and imidacloprid, were evaluated for efficacy and longevity against oropsylla montana (baker), the most important vector of plague in california. wild-caught california ground squirrels, spermophilus beecheyi (richardson), were individually housed in the laboratory to serve as natural hosts to o. montana and for on-animal insecticide trials. several concentrations oftechnical grade fipronil and imidacloprid in acetone were applied to samples of clean rodent bedding to ... | 2002 | 11931250 |
| flea, rodent, and plague ecology at chuchupate campground, ventura county, california. | chuchupate campground in ventura county, california, was closed to the public for 18 years (1982 to 2000) because of uncontrolled vector fleas and persistent plague antibody titers in rodents. the primary purpose of this study was to clarify the plague ecology of chuchupate campground by identifying involved rodents and their vector fleas and by determining many of their ecological parameters: abundance, flea and host preferences and diversities, and flea seasonality. rodents and fleas were iden ... | 2002 | 12125863 |
| experimental retinal detachment in the cone-dominant ground squirrel retina: morphology and basic immunocytochemistry. | the cellular responses of the cone-dominant ground squirrel retina to retinal detachment were examined and compared to those in rod-dominant species. retinal detachments were made in california ground squirrels. the retinas were prepared for light, electron, and confocal microscopy. tissue sections were labeled with antibodies to cone opsins, rod opsin, glial fibrillary acidic protein (gfap), vimentin, synaptophysin, cytochrome oxidase, and calbindin d 28k. wax sections were probed with the mib- ... | 2002 | 12507327 |
| bartonella strains from ground squirrels are identical to bartonella washoensis isolated from a human patient. | the most likely animal source of a human case of cardiac disease in washoe county, nev., was identified by comparison of dna sequences of three genes (citrate synthase glta, 60-kda heat shock protein gene groel, and 16s rrna gene) of bartonella washoensis cultured from the human patient in question and of bartonella isolates obtained from the following nevada rodents: peromyscus maniculatus (17 isolates), tamias minimus (11 isolates), spermophilus lateralis (3 isolates), and spermophilus beechey ... | 2003 | 12574261 |
| pattern of retinal projections in the california ground squirrel (spermophilus beecheyi): anterograde tracing study using cholera toxin. | the retinofugal pathways in the california ground squirrel, spermophilus beecheyi, were mapped after intravitreal injections of cholera toxin b-subunit. the results of the current study are consistent with work in other mammals and provide new details relevant to the organization and evolution of the visual system. all retinorecipient nuclei received bilateral input, with a contralateral predominance. the suprachiasmatic nucleus is heavily innervated, and sparse terminals were noted in other hyp ... | 2003 | 12820165 |
| isolation of bartonella washoensis from a dog with mitral valve endocarditis. | we report the first documented case of bartonella washoensis bacteremia in a dog with mitral valve endocarditis. b. washoensis was isolated in 1995 from a human patient with cardiac disease. the main reservoir species appears to be ground squirrels (spermophilus beecheyi) in the western united states. based on echocardiographic findings, a diagnosis of infective vegetative valvular mitral endocarditis was made in a spayed 12-year-old female doberman pinscher. a year prior to presentation, the re ... | 2003 | 14605197 |
| seasonal shedding of multiple cryptosporidium genotypes in california ground squirrels (spermophilus beecheyi). | twelve percent of 853 california ground squirrels (spermophilus beecheyi) from six different geographic locations in kern county, calif., were found to be shedding on average 44,482 oocysts g of feces(-1). the mean annual environmental loading rate of cryptosporidium oocysts was 57,882 oocysts squirrel(-1) day(-1), with seasonal patterns of fecal shedding ranging from <10,000 oocysts squirrel(-1) day(-1) in fall, winter, and spring to levels of 2 x 10(5) oocysts squirrel(-1) day(-1) in summer. j ... | 2004 | 15528541 |
| rodent-flea-plague relationships at the higher elevations of san diego county, california. | rodent-flea-plague relationships were examined at sites located at higher elevations of san diego county during 1991-2002. the most frequently sampled rodents were the california ground squirrel, spermophilus beecheyi, and white-footed mice, peromyscus spp. higher seasonal mean dependent variables (prevalences of squirrels and indices of o. montana), higher mean amounts of seasonal rainfall, and lower seasonal mean ambient temperatures were found at sites during 1991--1993 compared with 2000--20 ... | 2004 | 15707283 |
| rodenticide grain bait ingredient acceptance by norway rats (rattus norvegicus), california ground squirrels (spermophilus beecheyi) and pocket gophers (thomomys bottae). | vertebrate pest control in california is often accomplished through the use of rodenticide grain baits. these grain baits are composed of steam-rolled oats (sro), a toxicant, an indicator dye and an oil combination. a series of tests were performed to determine the effects of various dye and oil formulations on acceptance of grain bait by norway rats [rattus norvegicus (berk)], california ground squirrels [spermophilus beecheyi (richardson)] and pocket gophers (thomomys bottae eyd & gerv). seven ... | 2006 | 16718744 |
| ectoparasite diversity and exposure to vector-borne disease agents in wild rodents in central coastal california. | a survey of wild rodents was performed in the morro bay area of central coastal california to determine serological and polymerase chain reaction (pcr) prevalence of anaplasma phagocytophilum dumler, barbet, bekker, dasch, palmer, ray, rikihisa, and rurangirwa, borrelia burgdorferi johnson, schmidt, hyde, steigerwalt, and brenner, francisella tularensis mccoy, and yersinia pestis yersin; to describe the ectoparasitic fauna on important vector-borne disease hosts; and to determine whether pathoge ... | 2007 | 17427705 |
| ground squirrels use an infrared signal to deter rattlesnake predation. | the evolution of communicative signals involves a major hurdle; signals need to effectively stimulate the sensory systems of their targets. therefore, sensory specializations of target animals are important sources of selection on signal structure. here we report the discovery of an animal signal that uses a previously unknown communicative modality, infrared radiation or "radiant heat," which capitalizes on the infrared sensory capabilities of the signal's target. california ground squirrels (s ... | 2007 | 17704254 |
| differential exposure to anaplasma phagocytophilum in rodent species in northern california. | anaplasma phagocytophilum is a zoonotic tick-borne rickettsial pathogen that causes granulocytic anaplasmosis (ga) in humans, horses, and dogs. in california, dusky-footed woodrats (neotoma fuscipes) are a putative reservoir host, and ixodes pacificus is a vector for transmission from rodents to humans, dogs, and horses. cases are clustered in coastal and sierra nevada foothill regions, but not necessarily in proximity to infected woodrats. this study was designed to compare exposures and active ... | 2008 | 18047398 |
| risk factors for toxoplasma gondii infection in wild rodents from central coastal california and a review of t. gondii prevalence in rodents. | sera from 523 wild rodents were tested for toxoplasma gondii antibodies using either an indirect fluorescent antibody test (ifat) (rats and mice, with titer >or=80 considered positive) or a latex agglutination test (lat) (voles, squirrels, and pocket mice, with titer >or=32 considered positive). seventeen percent (88/523) of the rodents, including 26% (85/328) of the peromyscus sp. and 8% (3/37) of spermophilus beecheyi, were seropositive. fourteen percent (23/161) of rodents captured in trap si ... | 2008 | 18605783 |
| evaluation of squirrels (rodentia: sciuridae) as ecologically significant hosts for anaplasma phagocytophilum in california. | granulocytic anaplasmosis (ga), caused by anaplasma phagocytophilum, is a potentially fatal, emerging rickettsial disease of humans, domestic animals, and wildlife. the purpose of this study was to determine whether sciurids from multiple areas of northern california were infested with ticks or exposed to or infected with a. phagocytophilum using polymerase chain reaction (pcr) and indirect-fluorescent antibody (ifa) serology. sciurids of nine different tree- and ground-dwelling species were ass ... | 2008 | 18714881 |
| detection of lawsonia intracellularis by real-time pcr in the feces of free-living animals from equine farms with documented occurrence of equine proliferative enteropathy. | the objective of this study was to determine whether lawsonia intracellularis was present in the feces of free-living animals collected on two equine premises with documented occurrence of equine proliferative enteropathy (epe). fresh feces from black-tailed jackrabbits (lepus californicus, n=100), striped skunks (mephitis mephitis, n=22), feral cats (felis catus, n=14), brewer's blackbirds (euphagus cyanocephalus, n=10), virginian opossums (didelphis virginiana, n=9), raccoons (procyon lotor, n ... | 2008 | 18957657 |
| use of a chitin synthesis inhibitor to control fleas on wild rodents important in the maintenance of plague, yersinia pestis, in california. | a study was designed to test the insect development inhibitors fluazuron and lufenuron for the control of fleas on sylvatic rodents as an adjunct to the control of plague. historical data of flea burden from 15 prior years of study at chuchupate campground, ventura county, ca, were compared to six years of treatment period data to determine if fluazuron and lufenuron were effective in controlling flea densities. the insect development inhibitors, delivered systemically via a feed cube, reduced f ... | 2008 | 19263847 |
| spatial analysis of plague in california: niche modeling predictions of the current distribution and potential response to climate change. | plague, caused by the bacterium yersinia pestis, is a public and wildlife health concern in california and the western united states. this study explores the spatial characteristics of positive plague samples in california and tests maxent, a machine-learning method that can be used to develop niche-based models from presence-only data, for mapping the potential distribution of plague foci. maxent models were constructed using geocoded seroprevalence data from surveillance of california ground s ... | 2009 | 19558717 |
| field efficacy of rodent bait containing the systemic insecticide imidacloprid against the fleas of california ground squirrels. | the efficacy of rodent bait containing the insecticide imidacloprid was evaluated for controlling fleas on the california ground squirrel, spermophilus beecheyi. the bait was designed to deliver an oral dose of insecticide resulting in flea mortality when obtaining a blood meal. during the five-week trial, performed at vandenberg air force base, santa barbara county, ca, a spot-baiting technique was used to apply bait to ground squirrel burrows. bait was applied six times throughout the trial. r ... | 2009 | 20836808 |
| comparative studies of diurnal and nocturnal rodents: differences in lifestyle result in alterations in cortical field size and number. | in this study we examine and describe the neuroanatomical organization of sensory cortex in four rodents: laboratory norway rats (long evans; rattus norvegicus), wild-caught norway rats (rattus norvegicus), wild-caught california ground squirrels (spermophilus beecheyi), and wild-caught eastern gray squirrels (sciurus carolinensis). specifically, we examined the myeloarchitecture and cytochrome oxidase reactivity for several well-identified areas in visual cortex (areas 17, 18, and 19), somatose ... | 2010 | 20886618 |
| seasonal and among-site variation in the occurrence and abundance of fleas on california ground squirrels (otospermophilus beecheyi). | an improved understanding of the ecology of fleas on california ground squirrels, otospermophilus beecheyi, is warranted given the role of fleas in the transmission, and perhaps persistence, of the plague-causing bacterium yersinia pestis. we sampled o. beecheyi on a seasonal basis from three study sites, each representing a different land use type (preserve, pasture, and agriculture) in the san joaquin valley, ca. overall, the abundance of fleas on squirrels was greatest in spring at the preser ... | 2011 | 21635649 |
| The Functional Organization and Cortical Connections of Motor Cortex in Squirrels. | Despite extraordinary diversity in the rodent order, studies of motor cortex have been limited to only 2 species, rats and mice. Here, we examine the topographic organization of motor cortex in the Eastern gray squirrel (Sciurus carolinensis) and cortical connections of motor cortex in the California ground squirrel (Spermophilus beecheyi). We distinguish a primary motor area, M1, based on intracortical microstimulation (ICMS), myeloarchitecture, and patterns of connectivity. A sensorimotor area ... | 2011 | 22021916 |
| bilateral and ipsilateral ascending tecto-pulvinar pathways in mammals: a study in the squirrel (spermophilus beecheyi). | the mammalian pulvinar complex is a collection of dorsal thalamic nuclei which have been related to several visual and integrative processes. previous studies have shown that the superficial layers of the superior colliculus project to multiple divisions of the pulvinar complex. while most of these works agree about the existence of an ipsilateral tecto-pulvinar projection arising from the stratum griseum superficialis, some others report a bilateral projection originating from this same tectal ... | 2011 | 22120503 |
| deterioration of the gαo vomeronasal pathway in sexually dimorphic mammals. | in mammals, social and sexual behaviours are largely mediated by the vomeronasal system (vns). the accessory olfactory bulb (aob) is the first synaptic locus of the vns and ranges from very large in caviomorph rodents, small in carnivores and ungulates, to its complete absence in apes, elephants, most bats and aquatic species. two pathways have been described in the vns of mammals. in mice, vomeronasal neurons expressing gαi2 protein project to the rostral portion of the aob and respond mostly t ... | 2011 | 22039487 |
| resistance of california ground squirrels (spermophilus beecheyi) to the venom of the northern pacific rattlesnake (crotalus viridis oreganus): a study of adaptive variation. | recent studies have documented natural resistance to snake venom in a number of diverse mammalian species. the present paper documents for the first time variation in such resistance within one single species, the california ground squirrel (spermophilus beecheyi). this species is a frequent prey of the northern pacific rattlesnake (crotalus viridis oreganus) in certain habitats. venom resistance was tested directly in two populations of ground squirrels by injection of 1-40 mg/kg venom doses. o ... | 2012 | 3672545 |
| increment thresholds of the three spectral mechanisms in the retina of the california ground squirrel (spermophilus beecheyi). | increment threshold (it) functions were obtained for the electroretinogram (erg) and for single units in the optic nerve of the california ground squirrel. the three spectral mechanisms providing input to ganglion cells in this retina were isolated and their increment thresholds to large field, long-duration stimuli were examined. mean it functions for the 519 nm mechanism (irrespective of unit class), the 500 nm mechanism, and the erg all showed shallow log-log slopes between 0.52 and 0.63. the ... | 2013 | 3582531 |
| distribution and diversity of bartonella washoensis strains in ground squirrels from california and their potential link to human cases. | we investigated the prevalence of bartonella washoensis in california ground squirrels (otospermophilus beecheyi) and their fleas from parks and campgrounds located in seven counties of california. ninety-seven of 140 (69.3%) ground squirrels were culture positive and the infection prevalence by location ranged from 25% to 100%. in fleas, 60 of 194 (30.9%) oropsylla montana were found to harbor bartonella spp. when screened using citrate synthase (glta) specific primers, whereas bartonella dna w ... | 2016 | 27705539 |
| harderian gland neoplasms in captive, wild-caught beechey ground squirrels (spermophilus beecheyi). | harderian gland neoplasms were identified in 18 aged, adult beechey ground squirrels (spermophilus beecheyi) from the records of 167 wild-caught captive animals that were necropsied. all but one animal had tumors that were classified as carcinomas, with infiltrative growth and frequent metastases. this is the first detailed report of harderian gland neoplasia in wild sciuridae, although this neoplasm has been described in other rodent species. clinically, affected ground squirrels typically were ... | 2008 | 18487500 |
| hepatocellular carcinoma in richardson's ground squirrels (spermophilus richardsonii): evidence for association with hepatitis b-like virus infection. | during studies of seasonal obesity, a high frequency of hepatic neoplasms was observed in richardson's ground squirrels. of 12 richardson's ground squirrels examined thoroughly, 7 had mild or moderate degrees of chronic portal hepatitis and 6 (50%) had hepatocellular carcinoma. serological tests for hepadnavirus surface antigen, anti-core antibody and virion dna that recognize the ground squirrel hepatitis virus of california ground squirrels (spermophilus beecheyi) were uniformly negative. sout ... | 1991 | 1646762 |
| v1 connections reveal a series of elongated higher visual areas in the california ground squirrel, otospermophilus beecheyi. | for studies of visual cortex organization, mouse is becoming an increasingly more often used model. in addition to its genetic tractability, the relatively small area of cortical surface devoted to visual processing simplifies efforts in relating the structure of visual cortex to visual function. however, the nature of this compact organization can make some comparisons to the much larger non-human primate visual cortex difficult. the squirrel, as a highly visual rodent offers a useful means for ... | 2017 | 28078786 |
| the rattling sound of rattlesnakes (crotalus viridis) as a communicative resource for ground squirrels (spermophilus beecheyi) and burrowing owls (athene cunicularia). | animal communication involves very dynamic processes that can generate new uses and functions for established communicative activities. in this article, the authors describe how an aposematic signal, the rattling sound of rattlesnakes (crotalus viridis), has been exploited by 2 ecological associates of rattlesnakes: (a) california ground squirrels (spermophilus beecheyi) use incidental acoustic cues in rattling sounds to assess the danger posed by the rattling snake, and (b) burrowing owls (athe ... | 2002 | 12083617 |
| data from camera surveys identifying co-occurrence and occupancy linkages between fishers (pekania pennanti), rodent prey, mesocarnivores, and larger predators in mixed-conifer forests. | these data provide additional information relevant to the frequency of fisher detections by camera traps, and single-season occupancy and local persistence of fishers in small patches of forest habitats detailed elsewhere, "landscape fuel reduction, forest fire, and biophysical linkages to local habitat use and local persistence of fishers (pekania pennanti) in sierra nevada mixed-conifer forests" [10]. the data provides insight on camera trap detections of 3 fisher predators (bobcat [lynx rufus ... | 2016 | 26937448 |
| cryptosporidium rubeyi n. sp. (apicomplexa: cryptosporidiidae) in multiple spermophilus ground squirrel species. | previously we reported the unique cryptosporidium sp. "c" genotype (e.g., sbey03c, sbey05c, sbld05c, sltl05c) from three species of spermophilus ground squirrel (spermophilus beecheyi, spermophilus beldingi, spermophilus lateralis) located throughout california, usa. this follow-up work characterizes the morphology and animal infectivity of this novel genotype as the final step in proposing it as a new species of cryptosporidium. analysis of sequences of 18s rrna, actin, and hsp70 genes of addit ... | 2015 | 26543805 |
| rod photoreceptors and scotopic vision in ground aquirrels. | ground squirrel retinas contain a relatively small complement of rods (5--10% of all photoreceptors) which are thought to provide the basis for a weak scotopic visual capacity. in a previous investigation of the california ground squirrel (spermophilus beecheyi) involving the recording of a retinal gross potential, the electroretinogram (erg), electrophysiological evidence for a viable scotopic signal could be obtained from some, but not all of the ground squirrels examined. to further pursue th ... | 1980 | 7351444 |
| demodex sp. in california ground squirrels. | an undescribed species of demodex (acari: demodecidae) was observed in hair follicles and ducts of sebaceous glands in the ear canals of seven california ground squirrels (spermophilus beecheyi) from santa clara county, california (usa). the animals had died of unrelated causes and were submitted for necropsy between september 1994 and february 1996. similar mites were observed in the lumens of hair follicles and ducts of meibomian glands in the eyelids of two of these squirrels. microscopic cha ... | 1997 | 9131580 |
| disease surveillance of california ground squirrels ( spermophilus beecheyi ) in a drive-through zoo in oregon, usa. | rodents and other small wild mammals are often considered to be pests and vectors for disease in zoos that house small populations of valuable threatened and endangered animals. in 2005, three nonhuman primates at a drive-through zoo in oregon, us, acquired tularemia from an unknown source. due to an abundance of california ground squirrels ( spermophilus beecheyi ) on zoo grounds, we instituted serosurveillance of this species from july through september 2008 to determine the prevalence of anti ... | 2017 | 28418764 |
| retinal neurons of the california ground squirrel, spermophilus beecheyi: a golgi study. | although the optic nerve fibers of the cone-dominant ground squirrel retina have been well studied physiologically, the morphological details of the retinal neurons have not. to that end, retinal neurons of the california ground squirrel have been studied in golgi-impregnated wholemounts. two types of horizontal cell have been identified: h1 has an axon and axon terminal, whereas h2 is axonless. the dendritic field of h1 cells enlarges in a nonuniform manner with increasing displacement from the ... | 1996 | 8822165 |
| molecular epidemiology of bartonella species isolated from ground squirrels and other rodents in northern california. | bartonella spp. are endemic in wild rodents in many parts of the world. a study conducted in two northern california counties (sonoma and yolo) sampling california ground squirrels (otospermophilus beecheyi) and four other rodent species (peromyscus maniculatus, p. boylii, p. truei and neotoma fuscipes) led to the isolation of small gram-negative bacilli which were identified as bartonella spp. based on colony morphology, polymerase chain reaction-restriction fragment length polymorphism (pcr-rf ... | 2016 | 27245290 |
| prevalence and seasonality of fleas associated with california ground squirrels and the potential risk of tularemia in an outdoor non-human primate research facility. | ectoparasites at primate research centers may be difficult to control, e.g. without exposing non-human primates (nhps) to toxicants, but their impact on nhp health is poorly understood. in 2010, there was an epizootic of tularemia at the california national primate research center (cnprc) in yolo county, california that resulted in 20 confirmed and suspect clinical cases in outdoors housed rhesus macaques (macaca mulatta [zimmermann]) and a 53% seroprevalence in the southern section of the colon ... | 2017 | 29202201 |
| range instability leads to cytonuclear discordance in a morphologically cryptic ground squirrel species complex. | the processes responsible for cytonuclear discordance frequently remain unclear. here, we employed an exon capture data set and demographic methods to test hypotheses generated by species distribution models to examine how contrasting histories of range stability vs. fluctuation have caused cytonuclear concordance and discordance in ground squirrel lineages from the otospermophilus beecheyi species complex. previous studies in o. beecheyi revealed three morphologically cryptic and highly diverge ... | 2017 | 28734067 |
| coevolution of venom function and venom resistance in a rattlesnake predator and its squirrel prey. | measuring local adaptation can provide insights into how coevolution occurs between predators and prey. specifically, theory predicts that local adaptation in functionally matched traits of predators and prey will not be detected when coevolution is governed by escalating arms races, whereas it will be present when coevolution occurs through an alternate mechanism of phenotype matching. here, we analyse local adaptation in venom activity and prey resistance across 12 populations of northern paci ... | 2016 | 27122552 |
| isolation rearing reveals latent antisnake behavior in california ground squirrels (otospermophilus becheeyi) searching for predatory threats. | this study of california ground squirrels (otospermophilus beecheyi) investigated the long-term effects of isolation rearing on alarm-call recognition. six wild-caught squirrels, trapped as yearlings, and six laboratory-reared squirrels were maintained in solitary cages for approximately 3 years prior to the study. visual searching and olfactory searching were measured as squirrels emerged from their burrow-like nest box into a laboratory room after hearing repetitive playbacks of alarm calls or ... | 2015 | 25726178 |
| ground squirrel tail-flag displays alter both predatory strike and ambush site selection behaviours of rattlesnakes. | many species approach, inspect and signal towards their predators. these behaviours are often interpreted as predator-deterrent signals--honest signals that indicate to a predator that continued hunting is likely to be futile. however, many of these putative predator-deterrent signals are given when no predator is present, and it remains unclear if and why such signals deter predators. we examined the effects of one such signal, the tail-flag display of california ground squirrels, which is freq ... | 2012 | 22787023 |
| isolation and identification of a snake venom metalloproteinase inhibitor from california ground squirrel (spermophilus beecheyi) blood sera. | california ground squirrels (spermophilus beecheyi) show blood-based defenses to a variety of toxins in the venom of the northern pacific rattlesnake (crotalus oreganus oreganus). in this study we demonstrate the presence of an effective snake venom metalloproteinase inhibitor (svmpi) in s. beecheyi. the blood sera of california ground squirrels were effective at reducing the metalloproteinase activity of northern pacific (c. o. oreganus) and prairie rattlesnake (crotalus viridis viridis) venoms ... | 2011 | 21903126 |
| multiple unique cryptosporidium isolates from three species of ground squirrels (spermophilus beecheyi, s. beldingi, and s. lateralis) in california. | phylogenetic analyses of the 18s small-subunit (ssu) rrna and cryptosporidium oocyst wall protein (cowp) genes indicate that multiple unique cryptosporidium isolates are shed by separate species of spermophilus ground squirrels (s. beecheyi, s. beldingi, and s. lateralis) throughout california, despite some squirrel populations' being geographically isolated. the data support our assertion that spermophilus squirrels shed novel cryptosporidium species. | 2010 | 20971867 |
| california ground squirrel (spermophilus beecheyi) defenses against rattlesnake venom digestive and hemostatic toxins. | previous studies have shown that some mammals are able to neutralize venom from snake predators. california ground squirrels (spermophilus beecheyi) show variation among populations in their ability to bind venom and minimize damage from northern pacific rattlesnakes (crotalus oreganus), but the venom toxins targeted by resistance have not been investigated. four california ground squirrel populations, selected for differences in local density or type of rattlesnake predators, were assayed for t ... | 2006 | 16525875 |
| california ground squirrel (spermophilus beecheyi) defenses against rattlesnake venom digestive and hemostatic toxins. | previous studies have shown that some mammals are able to neutralize venom from snake predators. california ground squirrels (spermophilus beecheyi) show variation among populations in their ability to bind venom and minimize damage from northern pacific rattlesnakes (crotalus oreganus), but the venom toxins targeted by resistance have not been investigated. four california ground squirrel populations, selected for differences in local density or type of rattlesnake predators, were assayed for t ... | 2005 | 16273425 |
| field efficacy of deltamethrin for rodent flea control in san bernardino county, california, usa. | a study was conducted to determine the initial and residual activity of deltamethrin (0.05% dust) applied to rodent burrows (at approximately 14 g/burrow) against fleas in the silverwood lake area of san bernardino county. in initial toxicity (2-d post-treatment), deltamethrin provided 97% flea control and in residual toxicity it resulted in 68% control of the rodent fleas at 15-d post-treatment. the flea fauna consisted of oropsylla montana (89.9%) and hoplopsylls anomalus (10.1%). all rodents ... | 2004 | 15707280 |
| choline acetyltransferase is expressed by non-starburst amacrine cells in the ground squirrel retina. | we have used immunostaining techniques to reveal a new type of amacrine cell that is immunoreactive for choline acetyltransferase (chat), the acetylcholine synthesizing enzyme, in the ground squirrel (spermophilus beecheyi) retina. cryostat sections and double immunostained wholemount preparations were examined by confocal microscopy. this new chat type iii cell is distinct in morphology and neurotransmitter content from the well know 'starburst' amacrine cells (types i and ii) that are so well ... | 2003 | 12573509 |
| cone photoreceptor recovery after experimental detachment and reattachment: an immunocytochemical, morphological, and electrophysiological study. | to compare the morphologic and functional recovery of the retina after detachment and reattachment in an animal with a cone-dominant retina, the ground squirrel. | 2003 | 12506104 |
| effect of diphacinone on blood coagulation in spermophilus beecheyi as a basis for determining optimal timing of field bait applications. | the effect was determined of a single dose of 2 mg kg-1 diphacinone on three blood-clotting parameters [prothrombin time (pt), partial thromboplastin time (ptt), and protein induced by vitamin k absence or antagonists (pivka)] over a 120-h period in california ground squirrels, spermophilus beecheyi. diphacinone resulted in elevated pt, ptt and pivka within 24 h of squirrels receiving the dose. the most significant change was observed 72 h after dosing. as time following diphacinone dosing incre ... | 2002 | 12146176 |
| age differences in arousal and vigilance in california ground squirrels (spermophilus beecheyi). | newly emerged pup, juvenile, and adult california ground squirrels (spermophilus beecheyi douglasii) were videorecorded at a seminatural field site in northern california. video data revealed age differences in the budgeting of ground squirrel behavior, habitat use, and physiological arousal as indicated by morphometric analyses of tail piloerection. adults and juveniles devoted their time to foraging in the open at feeding stations while displaying low to moderate levels of arousal, respectivel ... | 2001 | 11745313 |
| do california ground squirrels (spermophilus beecheyi) use ritualized syntactic cephalocaudal grooming as an agonistic signal? | animal communication theory holds that many signals have evolved from nonsignal precursors. this field and laboratory study of california ground squirrels (spermophilus beecheyi) provides evidence for the coexistence of such a precursor with its derived display. the precursor is an ancient, endogenously sequenced (syntactic) pattern of cephalocaudal grooming movements (ccgs) shared by all rodent suborders. the following evidence supports the hypothesis that a supernormal version of this pattern ... | 2000 | 10994844 |
| stress fever magnitude in laboratory-maintained california ground squirrels varies with season. | a previous study demonstrated that california ground squirrels (spermophilus beecheyi) living in the natural environment had, independent of season, a significantly higher mean diurnal body temperature (t(b)) (39.6 degrees c) than either summer (37.5 degrees c) or winter (36.5 degrees c) laboratory maintained animals. based upon the previous study it has been suggested that california ground squirrels living in the natural environment may have an elevated set-point for body temperature in a mann ... | 2000 | 10794961 |
| california ground squirrel (spermophilus beecheyi) blood sera inhibits crotalid venom proteolytic activity. | some california ground squirrels (spermophilus beecheyi) show limited necrosis following envenomation by northern pacific rattlesnakes (crotalus viridis oreganus). this study demonstrates that s. beecheyi blood sera inhibits venom proteases. sera from rattlesnake-abundant habitats inhibited c. v. oreganus venom more effectively than venom from two allopatric rattlesnake species, c. v. viridis and c. atrox, suggesting evolutionary specialization. the pattern of inhibition among squirrel populatio ... | 2000 | 10673162 |
| multiple somatosensory areas in the anterior parietal cortex of the california ground squirrel (spermophilus beecheyii). | multiunit electrophysiological recording techniques were used to explore the somatosensory cortex of the california ground squirrel (spermophilus beecheyii). cortex rostral and caudal to the primary somatosensory area (si) contained neurons that responded to stimulation of deep receptors and to muscle and joint manipulation. the region of cortex rostral to si was termed the rostral field (r) because of possible homologies with a similar field described in other mammals. cortex caudal to si had n ... | 2000 | 10660882 |
| assessment of rattlesnake dangerousness by california ground squirrels: exploitation of cues from rattling sounds. | we propose that the predator-prey relationship between california ground squirrels, spermophilus beecheyi beecheyi, and northern pacific rattlesnakes, crotalus viridis oreganus, offers a compelling analogy with the well-studied case of intraspecific fighting and assessment. because ground squirrels frequently place themselves at risk by harassing rattlesnakes, they stand to benefit from assessment strategies which serve to mediate risk. for example, larger and warmer snakes are more dangerous th ... | 1999 | 10373264 |
| use of orally administered chitin inhibitor (lufenuron) to control flea vectors of plague on ground squirrels in california. | the efficacy of orally administered lufenuron, a chitin inhibitor, to control fleas on california ground squirrels, spermophilus beecheyi (richardson), was evaluated during a 2-yr study in santa barbara county, ca. results demonstrated that use of a host-targeted feed cube containing lufenuron was effective in significantly reducing the burden of oropsylla montana (baker) and hoplopsyllus anomalus (baker) fleas on ground squirrels. a flea index that indicated a mean number of fleas per squirrel ... | 1999 | 10534949 |
| conflict and assessment in a predator-prey system: ground squirrels versus rattlesnakes. | adult california ground squirrels, spermophilus beecheyi beecheyi, actively confront and harass northern pacific rattlesnakes, crotalus viridis oreganus, which are the principal predator of ground squirrel pups. in this report we examine the roles of risk (snake size) and context (location of encounter and squirrel reproductive category) in rattlesnake assessment by ground squirrels. in interpreting the results, we borrow heavily from the well-developed conceptual framework applied in the analog ... | 1999 | 10328789 |
| california ground squirrel body temperature regulation patterns measured in the laboratory and in the natural environment. | body temperature (tb) was measured by telemetry in both laboratory maintained and natural environment california ground squirrels, spermophilus beecheyi. laboratory animals had a mean diurnal tb of 37.5 degrees c under conditions of ld 14:10, 20 degrees c and 36.5 degrees c under conditions of ld 10:14, 20 degrees c (p < 0.01). nocturnal mean tbs were 37.1 and 35.2 degrees c, respectively (p < 0.05). mean diurnal tbs for each animal in the natural environment ranged from 39.3 to 40.1 degrees c ( ... | 1998 | 9773514 |
| the topography of rod and cone photoreceptors in the retina of the ground squirrel. | the distributions of rod and cone photoreceptors have been determined in the retina of the california ground squirrel, spermophilus beecheyi. retinas were fixed by perfusion and the rods and cones were detected with indirect immunofluorescence using opsin antibodies. local densities were determined at 2-mm intervals across the entire retina, from which total numbers of each receptor type were estimated and isodensity distributions were constructed. the ground squirrel retina contains 7.5 million ... | 2008 | 9682870 |
| direction selectivity in the middle lateral and lateral (ml and l) visual areas in the california ground squirrel. | extracellular recordings obtained from the extrastriate cortex of the california ground squirrel, a diurnal sciurid, show that large receptive fields and a strong direction selectivity are present in the middle lateral area (ml) and the lateral area (l), located laterally to v2 and v3. direction selectivity was tested by presenting stimuli of varying dimensions, shapes and speeds at different locations in the visual field. most cells in ml and l (84%) were direction selective, with a preference ... | 1998 | 9651131 |
| ranging of male oropsylla montana fleas via male california ground squirrel (spermophilus beecheyi) juveniles. | we asked if fleas more frequently remain on those california ground squirrels (spermophilus beecheyi) that are likely to emigrate from their natal nest. in camp ohlone, alameda county, california, juvenile male squirrels were infested with more fleas (oropsylla montana) than were juvenile females, and juveniles of both sexes were infested with more fleas (o. montana and hoplopsyllus anomalus) than adults. there was no difference between the adult sexes in the number of fleas. the disproportionat ... | 1997 | 9379281 |
| seasonal fluctuations in hormones and behavior of free-living male california ground squirrels (spermophilus beecheyi). | plasma testosterone (t), prolactin (prl), and behavior were monitored concurrently in free-living male california ground squirrels (spermophilus beecheyi). male plasma t peaked in january, 2-3 months after males emerged from their annual period of estivation. prl peaked 6 to 10 weeks after t. temporal patterns of space use by males were directly correlated with plasma t levels, but seasonal maxima in rates of most monitored male behaviors occurred 4 weeks after the t peak. no monitored behavior ... | 1992 | 1563730 |
| seasonal variation in circulating testosterone and oestrogens of wild-caught california ground squirrels (spermophilus beecheyi). | blood samples were obtained each month for 18 months in 1984-85 from wild-caught california ground squirrels. circulating testosterone and total oestrogens were extracted from the plasma, measured by radioimmunoassay and compared with concurrent changes in plasma progesterone and prolactin in the same individuals. male plasma testosterone concentrations peaked in january, shortly before mating, whereas female testosterone concentrations were low throughout the year. female plasma oestrogen conce ... | 1991 | 1787461 |
| seasonal change in irradiance: a zeitgeber for circannual rhythms in ground squirrels. | 1. zeitgebers for circannual rhythms have been elusive. demonstration that an external factor is a zeitgeber requires proof of a phase-shift that endures for several years. 2. the california ground squirrel (spermophilus beecheyi) is an ideal subject. many features of behavior have circannual rhythms of which change in mass is the easiest to measure. the squirrels thrive in captivity for up to 10 years. the squirrels were kept in individual cages in an air conditioned room, fed lab chow ad lib, ... | 1991 | 1673890 |
| patterns of progesterone secretion in free-living california ground squirrels (spermophilus beecheyi). | during a long-term field study of a free-living population of california ground squirrels (spermophilus beecheyi), blood samples were drawn at regular intervals from marked females via femoral venipuncture, and plasma progesterone (p) and prolactin (prl) were measured by radioimmunoassay. marked fluctuations with season and reproductive condition occurred in circulating levels of both hormones, with peak levels occurring during the spring breeding season. two peaks in p concentrations were obser ... | 1988 | 3219378 |
| circulating prolactin in free-living california ground squirrels (spermophilus beecheyi). | during a long-term field study of a free-living population of california ground squirrels (spermophilus beecheyi), blood samples were drawn at regular intervals from marked animals via femoral venipuncture, and plasma prolactin (prl) was measured by homologous radioimmunoassay. marked fluctuations with season and reproductive condition occurred in circulating prl levels in both males and females, with peak levels occurring during the spring breeding season. peak prl levels in females were reache ... | 1988 | 3192071 |
| temporal properties of the short-wavelength cone mechanism: comparison of receptor and postreceptor signals in the ground squirrel. | temporal properties of the short-wavelength cone mechanism of the california ground squirrel (spermophilus beecheyi), a dichromat, were explored with single light pulses and pulse trains. both the electroretinogram (erg) and the isolated piii component of the retinal gross response were recorded under chromatic adaptation conditions that favored the detection of test lights by either the middle-wavelength mechanism or the short-wavelength mechanism. the erg b-wave generated by the short-waveleng ... | 1988 | 3257011 |
| development of an homologous radioimmunoassay for secreted prolactin from the california ground squirrel (spermophilus beecheyi). | a sensitive homologous radioimmunoassay was developed for secreted prolactin from the california ground squirrel (spermophilus beecheyi). s. beecheyi plasma and pituitary extracts displaced 125i-labeled s. beecheyi prolactin in a parallel manner with s. beecheyi prolactin (sbprl). mean minimum sensitivity of the assay was 0.21 ng/ml, and mean intra- and interassay coefficients of variation were 4.1% and 14.5%, respectively. the assay was used to measure basal prolactin concentrations in male and ... | 1987 | 3620561 |
| disc shedding and autophagy in the cone-dominant ground squirrel retina. | the temporal pattern of cone outer-segment disc shedding was examined in the retina of the california ground squirrel, spermophilus beecheyi, under two different lighting conditions. squirrels were entrained to either 10-180 lx (room lighting) or 1,400 lx. cone shedding during the dark period was biphasic in both conditions, with increases occurring at 2-3 hr and 5-6 hr after light offset. entrainment to 1400 lx resulted in an increase in shedding at 2 hr after light offset and a slight advance ... | 1986 | 3758219 |
| directional filter characteristics of optic nerve fibers in california ground squirrel (spermophilus beecheyi). | directional units in the optic nerve of the california ground squirrel (spermophilus beecheyi) were studied with respect to their response to diffuse light, preferred directions of motion, tuning for preferred direction, the relationship between spatial and directional tuning characteristics, and receptive-field size and areal summating properties. directional units in the ground squirrel optic nerve are of the "on-off" type. no purely on or off units were encountered in a sample of 356 directio ... | 1984 | 6520632 |
| spatial filter characteristics of optic nerve fibers in california ground squirrel (spermophilus beecheyi). | the spatial response properties of single optic nerve fibers in the california ground squirrel (spermophilus beecheyi) were investigated. results are reported for each of several response classes. resolution limits determined for 165 spectrally nonopponent optic nerve fibers ranged from 0.1 to 4.2 cycles/degree (c/d), with a mean resolution limit of 1.49 c/d. directionally selective units possessed the highest resolution limits (mean = 1.91 c/d.) sustained and transient units possessed mean reso ... | 1984 | 6520631 |
| refractive state, depth of focus and accommodation of the eye of the california ground squirrel (spermophilus beecheyi). | retinoscopy and electrophysiological refraction were performed on 55 and 24 far-accommodated eyes of california ground squirrels (spermophilus beecheyi), respectively. these two indices were highly correlated, revealing the eye of this animal to be roughly emmetropic (-0.25 to -0.13 d). depth of focus was assessed by measuring the effect which defocusing produced on the spatial resolving power of 32 optic nerve fibers. depth of focus of the ground squirrel eye for a pupil diameter of 2.5 mm is e ... | 1984 | 6523746 |
| development of spectral mechanisms in the ground squirrel retina following lid opening. | the retina of the california ground squirrel (spermophilus beecheyi) contains three classes of photopigments (lambda max = 440, 500, 525 nm). from optic nerve recordings it was previously discovered that the effectiveness of signals from the 440 nm cone increase gradually over the weeks following lid opening. in this experiment several features of the electroretinogram (erg) were examined to assess developmental changes in signals originating in the outer retina. as judged by threshold sensitivi ... | 1984 | 6468555 |
| the distributions of photoreceptors and ganglion cells in the california ground squirrel, spermophilus beecheyi. | the topographical distributions of photoreceptors and ganglion cells of the california ground squirrel (spermophilus beecheyi) were quantified in a light microscopic study. the central retina contains broad, horizontal streaks of high photoreceptor density (40-44,000/mm2) and high ganglion cell density (20-24,000/mm2). the isodensity contours of both cell types are elliptical and oriented along the nasal-temporal axis. there are roughly five-fold decreases in both photoreceptor and ganglion cell ... | 1983 | 6655087 |
| differential signs of plague in young and old california ground squirrels (spermophilus beecheyi). | | 1983 | 6887441 |
| effects of photic environment on the development of spectral response properties of optic nerve fibers in the ground squirrel. | the california ground squirrel (spermophilus beecheyi) has two classes of cone photopigments (lambda max = 440 and 525 nm). under photopic conditions about 30% of all optic nerve fibers receives inputs from both cone classes, the remainder are driven solely by the 525 nm cone. recordings were made from optic nerves in young ground squirrels to trace the development of their spectral responsiveness. animals were reared from birth in one of three photic environments: white light, darkness, or red ... | 1983 | 6641841 |
| circannual rhythm of torpor and molt in the ground squirrel, spermophilus beecheyi. | using cool, white, fluorescent lamps photoperiods mimicking those in santa barbara, ca, entrain circannual rhythms of mass and torpor of spermophilus beecheyi so that maxima occur about september for 6 years. cycles with 12-hr photofractions or continuous light has short circannual periods of mass and torpor. after a phase-shift of 6 months, some squirrels entrained in about 3 years. squirrels kept 6 months on 10-hr and 6 months on 14-hr photofraction had weakly entrained circannual mass and mol ... | 1983 | 6138183 |
| a squamous cell carcinoma in a california ground squirrel (spermophilus beecheyi). | | 1981 | 7310949 |
| scotopic and photopic vision in the california ground squirrel: physiological and anatomical evidence. | the california ground squirrel is a highly diurnal species previously thought to have an all-cone retina. this issue was re-examined in physiological and anatomical experiments. the electroretinogram (erg) was used to measure the spectral sensitivity of the eye under different conditions of adaptation. the occurrence of a purkinje shift could be demonstrated, although there was some indication that not all members of this species show such a shift. spectral sensitivity of the dark-adapted eye of ... | 1976 | 1245613 |
| physiological correlates of burrow gas conditions in the california ground squirrel. | | 1974 | 4152025 |
| color vision and visual sensitivity in the california ground squirrel (citellus beecheyi). | | 1972 | 4636123 |
| serum electrophoretic patterns in the california ground squirrel. | | 1972 | 5020999 |
| adrenal gland size as an index of adrenocortical secretion rate in the california ground squirrel. | | 1972 | 4332519 |
| evaluation of an in vitro technique for quantitative assay of adrenocortical secretion in the california ground squirrel. | | 1972 | 4332518 |
| plague vector studies. ii. the role of climatic factors in determining seasonal fluctuations of flea species associated with the california ground squirrel. | | 1971 | 5160260 |
| electrophoretic variants of hemoglobin in the california ground squirrel, spermophilus beecheyi beecheyi (richardson). | | 1971 | 5116517 |