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Paraxerus cepapi (A. Smith, 1836) is a rodent commonly called Smith's bush squirrel. Pelage color varies throughout its distribution, with grayer individuals in the western reaches of its distribution and more brown individuals in eastern areas. Paraxerus cepapi is 1 of 11 species in the genus Paraxerus and is found throughout sub-Saharan Africa. The International Union for the Conservation of Nature (IUCN) considers P. cepapi to be a species of "Least Concern" (LC), listing no major threats. [ABSTRACT FROM AUTHOR]

Short-term elevation of glucocorticoids (GCs) is one of the major physiological mechanisms by which vertebrates cope with challenging environmental or social factors (stressors). However, when exposure to stressors occurs repeatedly or over a prolonged period of time, animals may experience chronic elevation of GCs, which reduces the immune response efficiency and can lead to higher intensity of parasitic infection. Here, we used invasive gray squirrels Sciurus carolinensis introduced in Northern Italy and their 2 most prevalent gastrointestinal parasites, the nematode Strongyloides robustus and coccidia of the genus Eimeria , as a model to investigate relationships among macroparasite infection and concentrations of fecal glucocorticoid metabolites (FGMs), an integrated measure of circulating GCs. Our results revealed an association of FGMs with infection by St. robustus , but not with coccidia. Individuals with higher FGMs appear to be responsible for the greatest St. robustus egg shedding within gray squirrel populations, thus possibly acting as superspreaders. However, FGMs were negatively associated with adult St. robustus , suggesting that the abundance of adults of this nematode species does not induce elevation in FGMs, but is only affected by it through immune-mediated effects on its fecundity. Finally, the relationship between St. robustus (both eggs and adult parasites) and FGMs was not linear, suggesting that only high levels of physiological stress influence parasite infection. Our findings highlight that the direction and magnitude of the stress–infection relationship may depend not only on the specific host–parasite system, but also on the different life stages of the same parasite. [ABSTRACT FROM AUTHOR]

Knowledge of the spatiotemporal variability of abundance and vital rates is essential to the conservation of wildlife populations. In Pacific Northwest forests, previous small mammal research has focused on estimating abundance; few studies have focused on vital rates. We used robust design temporal symmetry models and live-trapping data collected 2011–2016 at nine sites to estimate apparent annual survival, population growth rate, and recruitment of Humboldt's flying squirrels (Glaucomys oregonensis) and Townsend's chipmunks (Neotamias townsendii) in a late-successional forest of the Cascade Mountains of Oregon, United States. We also estimated the proportional contribution of apparent annual survival and recruitment to population growth rate. Covariates previously associated with abundance were also associated with vital rates for Townsend's chipmunks, but less so for Humboldt's flying squirrels. Apparent annual survival was nearly constant (range = 0.47 to 0.51) among years and sites for Humboldt's flying squirrels but was consistently lower and more variable among years for Townsend's chipmunks (range = 0.13 to 0.31). Recruitment was variable among years for both species. Apparent annual survival generally contributed more than recruitment to the population growth rate of Humboldt's flying squirrels. For Townsend's chipmunks, recruitment consistently contributed more than apparent annual survival to population growth rate. These findings suggest that life history strategies differed for these co-occurring species. This study demonstrates substantial temporal variation in vital rates and some differences in abundance and vital rate habitat associations, suggesting that habitat suitability inferences based on short time series or variation in abundance could be misleading. [ABSTRACT FROM AUTHOR]

Knowledge of the spatiotemporal variability of abundance and vital rates is essential to the conservation of wildlife populations. In Pacific Northwest forests, previous small mammal research has focused on estimating abundance; few studies have focused on vital rates. We used robust design temporal symmetry models and live-trapping data collected 2011–2016 at nine sites to estimate apparent annual survival, population growth rate, and recruitment of Humboldt's flying squirrels (Glaucomys oregonensis) and Townsend's chipmunks (Neotamias townsendii) in a late-successional forest of the Cascade Mountains of Oregon, United States. We also estimated the proportional contribution of apparent annual survival and recruitment to population growth rate. Covariates previously associated with abundance were also associated with vital rates for Townsend's chipmunks, but less so for Humboldt's flying squirrels. Apparent annual survival was nearly constant (range = 0.47 to 0.51) among years and sites for Humboldt's flying squirrels but was consistently lower and more variable among years for Townsend's chipmunks (range = 0.13 to 0.31). Recruitment was variable among years for both species. Apparent annual survival generally contributed more than recruitment to the population growth rate of Humboldt's flying squirrels. For Townsend's chipmunks, recruitment consistently contributed more than apparent annual survival to population growth rate. These findings suggest that life history strategies differed for these co-occurring species. This study demonstrates substantial temporal variation in vital rates and some differences in abundance and vital rate habitat associations, suggesting that habitat suitability inferences based on short time series or variation in abundance could be misleading. [ABSTRACT FROM AUTHOR]

Sciurus vulgaris is a widespread, highly polytypic tree squirrel species, under which a large number of subspecies have been described. This study tests the robustness of the current subspecific classification by using geometric morphometrics to quantify morphological variation in mandible shape, along with canonical variates analysis to test hypotheses of morphological distinctiveness. Patterns of mandible allometry were examined in eight out of 16 currently recognized subspecies. The significance of the discriminate functions was tested statistically, and the iterative jackknife procedure was applied to evaluate stability of the subspecies-specific discriminant functions. Applying criteria that focus on shape diagnosability, rather than mean group differences, indicates that most regional subspecific groupings show intergradations and continuity in mandible shape and size and that allometric effects on mandible shape are negligible. Evidence of a distinct subspecies confined to the Iberian Peninsula (Sciurus vulgaris infuscatus) and a discrete group originating from an extinct, 19th century population in Dorset, UK were identified based on these mandibular data. All other regional subspecific groupings were not diagnosably different. These results suggest that most red squirrel subspecies might represent non-diagnosable morphological variants whose taxonomic validity seems doubtful. More generally, our results highlight the importance of applying objective, quantitative and reproducible criteria to the issue of subspecies delimitation. [ABSTRACT FROM AUTHOR]

Sciurus sanborni Osgood, 1944 is a rodent commonly called Sanborn's squirrel or ardilla de Sanborn. S. sanborni is a small squirrel with olive brown dorsum, buff eye rings, and usually, white underparts. S. sanborni is 1 of 28 species in the genus Sciurus, and a rare endemic of Peru that is found in lowland Amazonian forest between 300 and 580 m elevation. The Peruvian Ministry of the Environment classifies S. sanborni as "Vulnerable" and the International Union for Conservation of Nature and Natural Resources considers the species to be "Data Deficient;" habitat destruction is the main threat. [ABSTRACT FROM AUTHOR]

Sciurus aureogaster Cuvier, 1829 is a sciurid commonly called the red-bellied squirrel. It is a medium-bodied tree squirrel quite variable in color throughout its geographic distribution; partial and complete melanism are common. One of 28 species in the genus, S. aureogaster is endemic to Mexico and Guatemala, and introduced to the Florida Keys, United States. S. aureogaster inhabits a wide variety of ecosystems and plant communities, is diurnal, arboreal, and uses leaf nests and tree cavities for nesting. S. aureogaster feeds primarily on acorns (Quercus) and pine (Pinus) seeds throughout most of its distribution, but individuals are known to damage corn and other plantation crops including cacao. Litter size ranges between 1 and 4 young. S. aureogaster is listed as "Least Concern" by the International Union for Conservation of Nature and Natural Resources. [ABSTRACT FROM AUTHOR]

Tree squirrels are important components of ecosystems but to understand their role, we must learn how squirrels select and use habitat. Tree squirrel species richness is highest in the tropics and, according to the International Union for Conservation of Nature, is also where the greatest number of data deficient species occurs. The Neotropical pygmy squirrel (Sciurillus pusillus) is one of these species. In 2009 and 2010, we conducted distance sampling to estimate population density, we measured vegetation variables to investigate forest characteristics that influence habitat selection at 3 different scales, and conducted observations to obtain knowledge about activity patterns and behavior of Neotropical pygmy squirrels in igapó forest in the Peruvian Amazon. Density of squirrels was 0.10 and 0.14 individuals/ha, respectively, for each year. Squirrel activity peaked at 0800 h, individuals were found mainly in the canopy and never on the ground, and frequency of squirrel behaviors differed by time and story level. Squirrels mainly used high and low restinga and areas that had more trees that were ≥ 30 cm diameter at breast height (DBH)/ha compared to random areas in our site in igapó forest. Squirrels used trees that were larger in DBH, taller, and had a larger live crown compared to random trees. Neotropical pygmy squirrels are associated with features related to mature forests. [ABSTRACT FROM AUTHOR]

According to producer-consumer models, consumers should follow pulsed resources with a time lag. This view has been challenged by studies demonstrating that individuals may anticipate future resource pulses by increasing reproduction just before the pulse. We studied population fluctuations and reproduction in European red squirrels, Sciurus vulgaris, in relation to seed masting of the main food resource (the Norway spruce) in boreal coniferous forests between 1979 and 2013. Red squirrels are pre-dispersal seed predators, and previous studies have shown that they can anticipate the coming seed mast. We did not find any indication that anticipation of masting (year) increased red squirrel reproduction in the preceding spring to early summer. Instead, the reproductive output of the squirrels was highest in the spring following the mast, indicating that the population had to be at its largest size in the autumn after the mast (year), when lots of subadults were around. However, we surmised, based on snow tracks and squirrel nest data, that the population crashed during the following winter (year). These data reflected the adult population during winter, which peaked at the same time as the resource pulse. We can therefore conclude that the time lag between the resource pulse and the attainment of the peak number of squirrels was less than one year, and that the resource crash affected more juveniles and subadults than adults. The population increase overlapped with the occurrence of masting, but there was also a lagged response, supporting the classical view of producer-consumer models. [ABSTRACT FROM AUTHOR]

Sciurus ignitus (Gray, 1867) is a Neotropical tree squirrel commonly known as the Bolivian squirrel. It is a small-bodied, understory and mid-canopy dweller that occurs within the evergreen lowland and montane tropical rain forests along the eastern slope of the Andes in Peru, Bolivia, and extreme northern Argentina, and the western Amazon Basin in Brazil and Peru between 200 and 2,700 m in elevation. S. ignitus is 1 of 28 species in the genus Sciurus, and 1 of 8 in the subgenus Guerlinguetus. The taxonomic status of this species, as with other small sciurids in Peru and Bolivia, remains ambiguous. S. ignitus is currently listed as 'Data Deficient' by the International Union for Conservation of Nature and Natural Resources. [ABSTRACT FROM AUTHOR]

Nests play a crucial role in the life history of tree squirrels, and can be a critical component of their biology that enables them to be a successful invasive species. Red-bellied squirrels (Sciurus aureogaster) were introduced to Elliott Key, Florida, in the late 1930s, and spread to nearby islands. Red-bellied squirrels were believed extirpated by Hurricane Andrew in 1992, but were rediscovered on Elliott Key in 2005. In 2006 and 2007, we surveyed for squirrel nests and measured vegetation to evaluate forest characteristics associated with nest-site selection by squirrels, and compared these data to measurements collected at random locations. Squirrels placed nests in large trees with more canopy linkages in mixed-hardwood forest, and the nest trees were in areas with large trees, high tree density and canopy cover, and lower recent hurricane damage. Red-bellied squirrels selected characteristics of nest trees and forest structure in similar ways to individuals in their native range, and to other species of tree squirrels in general. Results from our research allowed land managers to assess possible management actions and provided important information for them to develop an effective management strategy. Park officials are currently working toward complete eradication of the introduced population of red-bellied squirrels from the Florida Keys. We suggest that behaviors of individuals in native ranges may elucidate patterns for individuals introduced to novel environments; however, we also caution that care must be taken in further extrapolation. Our findings emphasize the importance of understanding ecology of introduced species for effective management. [ABSTRACT FROM AUTHOR]

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 carcass sampling. Staff used these reports to collect squirrel carcasses for the analysis of Yersinia pestis infection. This sampling protocol was analysed at the census tract level using Poisson regression to determine the relationship between higher call volumes in a census tract and the risk of a carcass in that tract testing positive for plague. Over-sampling owing to call volume-directed collection was accounted for by including the number of animals collected as the denominator in the model. The risk of finding an additional plague-positive animal increased as the call volume per census tract increased. The risk in the census tracts with >3 calls a month was significantly higher than that with three or less calls in a month. For tracts with 4-5 calls, the relative risk (RR) of an additional plague-positive carcass was 10.08 (95% CI 5.46-18.61); for tracts with 6-8 calls, the RR = 5.20 (2.93-9.20); for tracts with 9-11 calls, the RR = 12.80 (5.85-28.03) and tracts with >11 calls had RR = 35.41 (18.60-67.40). Overall, the call-in centre directed sampling increased the probability of locating plague-infected carcasses in the known Denver epizootic. Further studies are needed to determine the effectiveness of this methodology at monitoring large-scale zoonotic disease occurrence in the absence of a recognized epizootic. [ABSTRACT FROM AUTHOR]

Sciurus stramineus Eydoux and Souleyet, 1841, is a large-bodied squirrel commonly called the Guayaquil squirrel. S. stramineus is characterized by a distinct grizzled-gray pelage with dark feet and ears, a long tail, and a distinctive white ''collar'' behind the ears. It is native to the western slope of the Andes, occurring from dry or humid tropical forests at sea level to highelevation montane forests up to 2,000 m in Ecuador and Peru. S. stramineus is adaptable, adjusting to anthropogenic changes and living close to human settlements, in coffee plantations, with an introduced population in Lima, Peru. Because of a tolerance for living in proximity to humans, S. stramineus is also a concern for transmission of diseases such as leptospirosis and Chagas disease. [ABSTRACT FROM AUTHOR]

Cercartetus lepidus (Thomas, 1888) is a burramyid commonly called the little pygmy-possum. It is 1 of 4 species in the genus Cercartetus, which together with Burramys parvus form the marsupial family Burramyidae. This Lilliputian possum has a disjunct distribution, occurring on mainland Australia, Kangaroo Island, and in Tasmania. Mallee and heath communities are occupied in Victoria and South Australia, but in Tasmania it is found mainly in dry and wet sclerophyll forests. It is known from at least 18 fossil sites and the distribution of these reveal a significant contraction in geographic range since the late Pleistocene. Currently, this species is not listed as threatened in any state jurisdictions in Australia, but monitoring is required in order to more accurately define its conservation status. [ABSTRACT FROM AUTHOR]

The article focuses on a study which investigated the West Nile virus (WNV) infection in tree squirrels species (Rodentia, Sciuridae) in California in 2004 and 2005. The squirrels were necropsied at the California Animal Health and Food Safety Laboratories (CAHFS) in a biosafety cabinet. During the study period, the squirrels that were tested positive for WNV include the California fox squirrel (Sciurus niger), western gray squirrel (Sciurus griseus) and eastern gray squirrel (Sciurus carolinesis). Study authors concluded that the three squirrel species are susceptible to WNV, thus they are considered relevant to WNV surveillance in the state.

Abstract: The hibernation-specific HP-25 gene is expressed specifically in the liver of the chipmunk, a hibernating species of the squirrel family, and exists as a pseudogene in the tree squirrel, a nonhibernating species. Our previous studies have revealed two positively acting transcriptional regulatory regions in the 5′-flanking region of the chipmunk HP-25 gene, one from −260 to −80 and another from −80 to −59, and a pivotal role for hepatocyte nuclear factor-4 (HNF-4), which binds to the proximal regulatory region, in HP-25''s liver-specific transcription. A database search for transcription factor binding sites in the distal regulatory region indicated the presence of two potential binding sites for upstream stimulatory factor (USF): one between −161 and −156 and the other between −143 and −138. In an electrophoretic mobility shift assay (EMSA), in vitro-translated USF bound only to the sequence from −143 to −138. USF did not bind the corresponding sequence of the tree squirrel HP-25 gene, which has two base substitutions. Transient transfection studies in COS-7 cells showed that USF could activate the transcription of the chipmunk HP-25 gene, and that tree squirrel-type base substitutions in the USF-binding site aborted the transactivation by USF. By chromatin immunoprecipitation (ChIP) analysis, we confirmed that USF bound to the promoter region of the HP-25 gene in the chipmunk liver, and not in the kidney or heart. These results indicate that USF is involved in the transcriptional regulation of the chipmunk HP-25 gene in the liver, and that the base substitutions in the USF-binding site contribute to the lack of HP-25 gene expression in the tree squirrel. [Copyright &y& Elsevier]