scholarly journals Selection of Agricultural Foods by Eastern Grey Squirrels (Sciurus carolinensis): Implications for a New Introduction in British Columbia

2016 ◽  
Vol 130 (3) ◽  
pp. 202
Author(s):  
Jillian M McAllister ◽  
Valerie Law ◽  
Karl W Larsen
Keyword(s):  
British Columbia ◽  
Local Scale ◽  
Sciurus Carolinensis ◽  
Grey Squirrel ◽  
Food Items ◽  
South Central ◽  
Fruit Growing ◽  
Free Ranging ◽  
Grey Squirrels ◽  
Selection Of

The recent introduction of the Eastern Grey Squirrel (Sciurus carolinensis) into south-central British Columbia occurred within an important agricultural zone. As repercussions for the fruit-growing sector are currently unknown, we conducted trials with captive squirrels to understand the range of fruits consumed and their references. The squirrels consumed a portion of every food item offered, although the order in which the foods were used was inconsistent (with sharp contrasts between animals). Of the fruit types offered, apples appeared to be of greatest overall interest. However, seeds and nuts tended to be used first when presented in combination with fruit, suggesting opportunities to use these food types to deflect or remove Eastern Grey Squirrels from orchard crops. We caution that our results may not reflect the food items that free-ranging Eastern Grey Squirrels will target or disregard once densities in the introduced population become higher and the availability of food on a local scale begins to exert an effect.

scholarly journals A Test of Interspecific Effects of Introduced Eastern Grey Squirrels, Sciurus carolinensis, on Douglas's Squirrels, Tamiasciurus douglasii, in Vancouver, British Columbia

2006 ◽  
Vol 120 (1) ◽  
pp. 10 ◽  
Author(s):  
Yeen Ten Hwang ◽  
Serge Larivière
Keyword(s):  
British Columbia ◽  
Body Mass ◽  
Home Ranges ◽  
Sciurus Carolinensis ◽  
Grey Squirrel ◽  
Negative Effects ◽  
Competition Hypothesis ◽  
Ecological Reserve ◽  
Grey Squirrels ◽  
Stanley Park

We compared the effects of absence and presence introduced Eastern Grey Squirrels (Sciurus carolinensis) on the demography of native Douglas’s Squirrels (Tamiasciurus douglasii) in two urban parks in Vancouver, British Columbia: Ecological Reserve #74 in Pacific Spirit Regional Park (Douglas’s Squirrel only) and Stanley Park (Douglas’s and Eastern Grey squirrels). Based on the exploitative competition hypothesis, we predicted that in the presence of introduced Eastern Grey squirrels, Douglas’s Squirrels would occur at lower densities, have larger home ranges, lower body mass, and poorer reproduction. Using mark-recapture methods, we found no differences in density, home range, or body mass of Douglas’s Squirrel between parks. However, the proportion of breeding Douglas’s Squirrels was higher in Ecological Reserve #74 in the absence of Eastern Grey Squirrel, than in Stanley Park. We found no evidence that Eastern Grey Squirrels are displacing Douglas’s Squirrels in Stanley Park, but less conspicuous negative effects such as reduced breeding propensity may still reflect the competitive interactions of the two squirrel species.

scholarly journals The Distribution and Habitat Selection of Introduced Eastern Grey Squirrels, Sciurus carolinensis, in British Columbia

2005 ◽  
Vol 119 (3) ◽  
pp. 343 ◽  
Author(s):  
Emily K. Gonzales
Keyword(s):  
British Columbia ◽  
Habitat Selection ◽  
Coniferous Forests ◽  
Sciurus Carolinensis ◽  
Conifer Forests ◽  
Residential Land ◽  
Bodies Of Water ◽  
Land Types ◽  
Grey Squirrels ◽  
Selection Of

Eastern Grey Squirrels were first introduced to Vancouver in the Lower Mainland of British Columbia in 1909. A separate introduction to Metchosin in the Victoria region occurred in 1966. I surveyed the distribution and habitat selection of Eastern Grey Squirrels in both locales. Eastern Grey Squirrels spread throughout both regions over a period of 30 years and were found predominantly in residential land types. Some natural features and habitats, such as mountains, large bodies of water, and coniferous forests, have acted as barriers to expansion for Eastern Grey Squirrels. Given that urbanization is replacing conifer forests throughout southern British Columbia, it is predicted that Eastern Grey Squirrels will continue to spread as habitat barriers are removed.

Visual method for evaluating the state of sexual development in male grey squirrels (Sciurus carolinensis)

2006 ◽  
Vol 18 (3) ◽  
pp. 383 ◽  
Author(s):  
Mark Ferryman ◽  
Brenda A. Mayle ◽  
Geoff W. Morgan
Keyword(s):  
Sexual Development ◽  
Population Biology ◽  
Captive Breeding ◽  
Fertility Control ◽  
Sciurus Carolinensis ◽  
High Group ◽  
Visual Method ◽  
Epididymal Spermatozoa ◽  
Grey Squirrels ◽  
Selection Of

Stages of sexual development in grey squirrels were classified by scoring the presence of periscrotal hair and staining, as well as the position, size and colour of testes, to develop a visual breeding score (VBS). The VBS was a highly significant predictor of the presence and concentration of epididymal spermatozoa, which were produced from 12 months of age. Two classes of producers were identified: ‘high’ with spermatozoa levels >10 × 106 mL−1 and ‘low’ with spermatozoa levels <10 × 106 mL−1. Sperm motility was variable across all levels of productive males but was generally higher in the ‘high’ group, indicating that these were ‘functional’ males. Sexual regression was observed in two autumn periods. The VBS was less effective in determining states of regression and redevelopment; the confidence of classification improved when age class (adult or prepubertal) and date of capture was known. The use of the VBS to classify stages of sexual development in grey squirrels will improve selection of animals for studies of population biology and fertility control, and has potential application in captive breeding studies of rare Sciuridae species.

scholarly journals Natural strongholds for red squirrel conservation in Scotland

2021 ◽  
Vol 43 ◽  
pp. 93-108
Author(s):  
Andrew Slade ◽  
Andy White ◽  
Kenny Kortland ◽  
Peter W. W. Lurz
Keyword(s):  
Management Practice ◽  
Management Policy ◽  
Sciurus Carolinensis ◽  
Red Squirrel ◽  
Grey Squirrel ◽  
Case Scenario ◽  
Red Squirrels ◽  
Worst Case ◽  
Standard Management ◽  
Grey Squirrels

The Eurasian Red Squirrel (Sciurus vulgaris) is under threat from the invasive North American eastern Grey Squirrel (Sciurus carolinensis) with 80% of the remaining red squirrel populations in the British Isles found in Scotland. In this study we develop a spatially explicit mathematical model of the red and grey squirrel system and use it to assess the population viability of red squirrels across Scotland. In particular, we aim to identify existing forests – natural strongholds for red squirrels – that can successfully support red squirrels under UK Forestry Standard management and protect them from potential disease-mediated competition from grey squirrels. Our model results indicate that if current levels of grey squirrel control, which restrict or reduce the distribution of grey squirrels, are continued then there will be large expanses of forests in northern Scotland that support viable red squirrel populations. Model results that represent (hypothetical) scenarios where grey squirrel control no longer occurred indicated that grey squirrel range expansion and the process of red squirrel replacement would be slow. Model results for an assumed worst-case scenario where grey squirrels have expanded to all regions in Scotland identified forest regions – denoted natural strongholds – that could currently support red squirrels under UK Forestry Standard management practice. The results will be used to inform forest management policy and support a strategic review of red squirrel management by land management agencies and other stakeholders.

METABOLISM OF ANDROGENS BY THE ACTIVE AND INACTIVE PROSTATE GLAND, AND THE SEASONAL CHANGES IN SYSTEMIC ANDROGEN LEVELS IN THE GREY SQUIRREL (SCIURUS CAROLINENSIS GMELIN)

1981 ◽  
Vol 88 (3) ◽  
pp. 381-NP ◽  
Author(s):  
A. A. SIWELA ◽  
W. H. TAM
Keyword(s):  
Breeding Season ◽  
Seasonal Changes ◽  
Subcellular Fraction ◽  
Prostate Gland ◽  
Secretory Activity ◽  
Sciurus Carolinensis ◽  
Grey Squirrel ◽  
Androgen Level ◽  
Grey Squirrels ◽  
Androgen Levels

The nuclear and cytoplasmic fractions derived from the actively secretory and inactive prostate of adult grey squirrels were incubated with radioactive testosterone and androstenedione. Testosterone was metabolized first to 5α-dihydrotestosterone and then 5 α-androstane-3α(β), 17β-diols. Testosterone could also be transformed into androstenedione and then to androsterone, but no 5α-dihydrotestosterone or diols could be synthesized from this pathway. Neither subcellular fraction of the inactive, non-secretory prostate could produce 5α-androstane-3α(β),17β-diols from testosterone either in the absence or presence of exogenous NADPH. The synthesis of androstenedione and 5α-dihydrotestosterone by the nuclear and cytoplasmic fractions of the inactive gland were significantly increased compared to that in fractions of the active prostate. The increase was unaffected by exogenous NADPH. The concentration of androgen (testosterone plus 5α-dihydrotestosterone) in systemic plasma was highest in December, the beginning of the breeding season. For the remainder of the breeding season, the androgen level was similar to that found in the non-breeding season. It is suggested that formation of 5α-androstane-3α(β),17β-diols was associated with the secretory activity of the prostate. The failure of the inactive prostate to synthesize these diols during sexual quiescence might be a means of ensuring the inactivity of the prostate.

scholarly journals Shades of Grey: Host Phenotype Dependent Effect of Urbanization on the Bacterial Microbiome of a Wild Mammal

2021 ◽  
Author(s):  
Mason R Stothart ◽  
Amy E.M. Newman
Keyword(s):  
Built Environment ◽  
Environmental Change ◽  
Habitat Heterogeneity ◽  
Spatial Scales ◽  
Coat Colour ◽  
Intestinal Microbiome ◽  
Rrna Gene ◽  
Sciurus Carolinensis ◽  
Grey Squirrel ◽  
Grey Squirrels

Abstract Background Host-associated microbiota are integral to the ecology of their host and may help wildlife species cope with rapid environmental change. Urbanization is a globally replicated form of severe environmental change which we can leverage to better understand wildlife microbiomes. Does the colonization of separate cities result in parallel changes in the intestinal microbiome of wildlife, and if so, does within-city habitat heterogeneity matter? Using 16S rRNA gene amplicon sequencing, we quantified the effect of urbanization on the microbiome of eastern grey squirrels (Sciurus carolinensis). Eastern grey squirrels are ubiquitous in rural and urban environments throughout their native range, across which they display an apparent coat colour polymorphism (agouti, black, intermediate). Results Grey squirrel microbiomes differed between rural and city environments; however, comparable variation was explained by habitat heterogeneity within cities. Our analyses suggest that operational taxonomic unit (OTU) community structure was more strongly influenced by local environmental conditions (rural and city forests versus human built habitats) than urbanization of the broader landscape (city versus rural). The bacterial genera characterizing the microbiomes of built-environment squirrels are thought to specialize on host-derived products and have been linked in previous research to low fibre diets. However, despite an effect of urbanization at fine spatial scales, phylogenetic patterns in the microbiome were coat colour phenotype dependent. City and built environment agouti squirrels displayed greater phylogenetic beta-dispersion than those in rural or forest environments, and null modelling results indicated that the phylogenetic structure of urban agouti squirrels did not differ greatly from stochastic expectations. Conclusions Habitat heterogeneity at fine spatial scales affects host-associated microbiomes, however, we found little evidence that this pattern was the result of similar selective pressures acting on the microbiome within environments. Further, this result, those of phylogeny-independent analyses, and patterns of beta-dispersion lead us to suggest that microbiota dispersal and ecological drift are integral to shaping the inter-environmental differences we observed. These patterns were partly mediated by squirrel coat colour phenotype. Given a well-known urban cline in squirrel coat colour melanism, grey squirrels provide a useful free-living system with which to study how host genetics mediate environment x microbiome interactions.

scholarly journals Locating species range frontiers: a cost and efficiency comparison of citizen science and hair-tube survey methods for use in tracking an invasive squirrel

2014 ◽  
Vol 41 (1) ◽  
pp. 64 ◽  
Author(s):  
Emily A. Goldstein ◽  
Colin Lawton ◽  
Emma Sheehy ◽  
Fidelma Butler
Keyword(s):  
Cost Effectiveness ◽  
Citizen Science ◽  
Habitat Management ◽  
Survey Methods ◽  
Geographic Region ◽  
Sciurus Carolinensis ◽  
Grey Squirrel ◽  
Species Invasions ◽  
The Face ◽  
Grey Squirrels

Context Improved knowledge of changing species distributions is critically important for conservation managers in the face of increasing species invasions, habitat disturbance and climate change. Efficient monitoring of the location of advancing species invasion frontiers is especially crucial for effective species community and habitat management. Aims To compare the cost-effectiveness and efficiency of two survey methods, a citizen science survey and a traditional hair-tube survey, in their abilities to locate the current southern invasion frontier of grey squirrels (Sciurus carolinensis) in Ireland. Methods In the citizen science survey, we collected sighting reports of the grey squirrel and its native congener, the red squirrel (S. vulgaris), from the geographic region of the invasion frontier from untrained members of the public over a 2-year period. Hair-tube surveys were carried out in 14 woodlands (≥30 ha) in the same geographic area to test the ability of this indirect field method to identify colonising grey squirrel populations. The costs, efficiency and cost-effectiveness of each method were compared. Key results The citizen science sighting reports resulted in the clear delineation of the southern frontier of the zone invaded by the grey squirrel. The hair-tube survey ascertained the presence of grey squirrels in 4 of 14 sites, but did not detect this species close to the invasion frontier defined by the citizen science survey. Even though the total cost of the citizen science survey was higher, it was more cost-effective and efficient on a per detection basis for the purposes of detecting the presence of grey and red squirrels. Conclusions The citizen science survey detected invasive squirrels in sites where the hair-tube survey did not. As such, the citizen science survey provided a more comprehensive snapshot of the location of the grey squirrel invasion frontier more efficiently and cost-effectively than did traditional field techniques. Implications In the face of increasing ecological and economic costs of biological invasions, we recommend straightforward citizen science surveys, over indirect field surveys, to managers and researchers seeking to efficiently track progressing invasions of readily observable animals cost-effectively.

Reproductive isolation between Urophora affinis and U. quadrifasciata (Diptera: Tephritidae) in British Columbia

1983 ◽  
Vol 61 (4) ◽  
pp. 787-791 ◽  
Author(s):  
D. E. Berube ◽  
Judith H. Myers
Keyword(s):  
British Columbia ◽  
Mate Selection ◽  
Reproductive Strategies ◽  
Species Recognition ◽  
Theoretical Models ◽  
Behavioral Differences ◽  
Centaurea Diffusa ◽  
Males And Females ◽  
Free Ranging ◽  
Selection Of

Observations were made of the reproductive behavior of free-ranging Urophora affinis and U. quadrifasciata on their host plant, Centaurea diffusa, near Kamloops, British Columbia. The behavior of both species is similar. Courting males of both species do not distinguish between conspecific males and females until attempted copulation. Males do discriminate between conspecific and non-conspecific females. Species recognition by males occurs at the time of prospective mate selection of during precopulatory displays. Recognition is apparently based on morphological and subtle behavioral differences between the two species. Some males did attempt copulation with non-conspecific females, and these were consistently rejected by the females. Differences in the male genitalia are probably important in female recognition of males. The behavior of these two species is discussed in relation to theoretical models of the evolution of reproductive strategies.

scholarly journals Diets and Food Selection of Female Mallards and Blue-Winged Teal During Spring Migration

2013 ◽  
Vol 4 (1) ◽  
pp. 63-74 ◽  
Author(s):  
Paul R. Tidwell ◽  
Elisabeth B. Webb ◽  
Mark P. Vrtiska ◽  
Andrew A. Bishop
Keyword(s):  
Food Availability ◽  
Food Selection ◽  
Isolated Wetlands ◽  
Barnyard Grass ◽  
Anas Discors ◽  
Food Items ◽  
South Central ◽  
Wintering Areas ◽  
Surrounding Landscape ◽  
Selection Of

Abstract Waterfowl nutritional requirements and food availability at migration stopover habitats may differ from those at nesting or wintering areas. Although there is little information on factors that influence waterfowl diets and food selection during migration, we hypothesized that bird age and wetland density in the surrounding landscape would influence food selection. Thus, the objective of this study was to quantify mallard Anas platyrhynchos and blue-winged teal Anas discors diets during migration and evaluate effects of age and wetland density on waterfowl food selection. We collected 30 mallards and 29 blue-winged teal with food items present in esophagi from wetlands in south-central Nebraska during spring 2008 and 2009. Smartweed Polygonum spp. and barnyard grass Echinochloa spp. were the most common seeds found in both mallards and blue-winged teal, while Naididae and Chironomidae larvae were the most common invertebrates in mallard and blue-winged teal diets, respectively. Invertebrates were consumed by both species in greater proportion than available. Both mallards and blue-winged teal collected in wetland complexes selected some seeds over others, whereas birds in isolated wetlands foraged on foods in proportion to availability. After-hatch-year mallards also selected for some seeds over others, as compared with hatch-year birds, which foraged opportunistically on available foods. If after-hatch-year birds and birds in wetland complexes are able to be more selective in their diets relative to food availability at individual wetlands, they may be able to acquire and replenish lipids reserves more efficiently than hatch-year birds or birds in areas with lower wetland densities.

scholarly journals Shades of grey: Coat-colour dependent effect of urbanization on the bacterial microbiome of a wild mammal

2021 ◽  
Author(s):  
Mason R. Stothart ◽  
Amy E.M. Newman
Keyword(s):  
Built Environment ◽  
Environmental Change ◽  
Habitat Heterogeneity ◽  
Spatial Scales ◽  
Coat Colour ◽  
Intestinal Microbiome ◽  
Rrna Gene ◽  
Sciurus Carolinensis ◽  
Grey Squirrel ◽  
Grey Squirrels

AbstractBackgroundHost-associated microbiota can be fundamental to the ecology of their host and may even help wildlife species colonize novel niches or cope with rapid environmental change. Urbanization is a globally replicated form of severe environmental change which we can leverage to better understand wildlife microbiomes. Does the colonization of separate cities result in parallel changes in the intestinal microbiome of wildlife, and if so, does within-city habitat heterogeneity matter? Using 16S rRNA gene amplicon sequencing, we quantified the effect of urbanization on the microbiome of eastern grey squirrels (Sciurus carolinensis). Eastern grey squirrels are ubiquitous in both rural and urban environments throughout their native range, across which they display an apparent coat colour polymorphism (agouti, black, intermediate).ResultsGrey squirrel microbiomes differed between rural and city environments; however, comparable variation was explained by habitat heterogeneity within cities. Our analyses suggest that operational taxonomic unit (OTU) community structure was more strongly influenced by local environmental conditions (rural and city forests versus human built habitats) than urbanization of the broader landscape (city versus rural). Many of the bacterial genera identified as characterizing the microbiomes of built-environment squirrels are though to specialize on host-derived products and have been linked in previous research to low fibre diets. However, despite an effect of urbanization at fine spatial scales, phylogenetic patterns in the microbiome were coat colour phenotype dependent. City and built environment agouti squirrels displayed greater phylogenetic beta-dispersion than those in rural or forest environments, and null modelling results indicated that the phylogenetic structure of urban agouti squirrels did not differ greatly from stochastic phylogenetic expectations.ConclusionsHabitat heterogeneity at fine spatial scales affects host-associated microbiomes, however, we found little evidence that this pattern was the result of similar selective pressures acting on the microbiome within environments. Further, this result, those of phylogeny-independent analyses, and patterns of beta-dispersion lead us to suggest that microbiota dispersal and ecological drift are integral to shaping the inter-environmental differences we observed. These patterns were partly mediated by squirrel coat colour phenotype, and therefore putatively, host physiology. Given a well-known urban cline in squirrel coat colour melanism, grey squirrels provide an ideal free-living system with which to study how host genetics mediate environment x microbiome interactions.

Sign in / Sign up

Export Citation Format

Share Document