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

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.

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Natural strongholds for red squirrel conservation in Scotland

Nature Conservation ◽

10.3897/natureconservation.43.62864 ◽

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.

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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)

Journal of Endocrinology ◽

10.1677/joe.0.0880381 ◽

1981 ◽

Vol 88 (3) ◽

pp. 381-NP ◽

Cited By ~ 2

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.

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

The Canadian Field-Naturalist ◽

10.22621/cfn.v120i1.238 ◽

2006 ◽

Vol 120 (1) ◽

pp. 10 ◽

Cited By ~ 3

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.

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Comparisons of Line Transect and Point Count Survey Methods by Estimating Density of Grey Squirrel Sciurus Carolinensis

Journal of Environment and Ecology ◽

10.5296/jee.v7i1.9287 ◽

2016 ◽

Vol 7 (1) ◽

pp. 17 ◽

Cited By ~ 1

Author(s):

Mariwan Rahim

Keyword(s):

Survey Methods ◽

Line Transect ◽

Sciurus Carolinensis ◽

Animal Population ◽

Grey Squirrel ◽

Density Estimates ◽

East Anglia ◽

Point Count ◽

Point Counts ◽

Count Surveys

The methods have used to study animal population must be defined clearly at the beginning of the project. We compared line transect and point count survey methods to estimating the density of grey squirrel at University of East Anglia campus (UEA), Norwich-United Kingdom. Across the entire UEA campus we surveyed 0.43698 ha of the 146 ha of the campus area. A total of 21 squirrels were observed during survey between 21st-26th in December 2013. Nine individuals were observed during line transect and twelve individuals were observed during point counts. The average number of species detected was differing between the two methods. Density estimates of grey squirrel from the two methods were different. Densities of grey squirrel as estimated by point count surveys were higher than those by line transect count surveys. Our results indicate that it is important to account for different survey methods when comparing the two methods to estimate the grey squirrel.

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

10.21203/rs.3.rs-349195/v1 ◽

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.

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

The Canadian Field-Naturalist ◽

10.22621/cfn.v130i3.1880 ◽

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.

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

10.1101/2021.02.16.431540 ◽

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.

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Spacing behaviour, kinship, and population dynamics of grey squirrels in a newly colonized broadleaf woodland in Italy

Canadian Journal of Zoology ◽

10.1139/z01-109 ◽

2001 ◽

Vol 79 (9) ◽

pp. 1533-1543 ◽

Cited By ~ 17

Author(s):

John Gurnell ◽

Luc A Wauters ◽

Damiano Preatoni ◽

Guido Tosi

Keyword(s):

Home Range ◽

Home Range Size ◽

Core Area ◽

Adult Survival ◽

Sciurus Carolinensis ◽

Red Squirrel ◽

Grey Squirrel ◽

Colonization Process ◽

Juvenile Males ◽

Grey Squirrels

Eastern grey squirrels, Sciurus carolinensis, introduced to Britain and northern Italy are replacing the native Eurasian red squirrel, Sciurus vulgaris. We studied the pattern of colonization of a high-quality broadleaf woodland by grey squirrels by means of livetrapping and radio-tracking. The studies started in July 1996, when six grey squirrels (four males, two females) first colonized the woodland, and lasted until November 1998, when densities exceeded those of the local red squirrel population. Grey squirrel colonization was rapid, with a high proportion of adult and yearling females breeding. Juvenile recruitment was also higher than in stable populations in Britain. Adult survival was better in 1997 (83%) than in 1998 (47%), with predation accounting for 67% of losses in 1998. This indicates the effects of local predator communities on the colonization process. Densities of grey squirrels were moderate in 1998, with a maximum of 1.9 squirrels/ha and we expect density to increase further. Adult home range sizes were three to four times larger than those of subadults, and male ranges were larger than those of females. Body mass was positively correlated with both total home range size and core-area size. Core-area size for adults was inversely correlated with food availability. Juvenile female grey squirrels were philopatric, forming female kin groups, while most juvenile males settled outside the mother's home range.

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An Opportunistic Assessment of the Impact of Squirrelpox Disease Outbreaks upon a Red Squirrel Population Sympatric with Grey Squirrels in Wales

Animals ◽

10.3390/ani12010099 ◽

2022 ◽

Vol 12 (1) ◽

pp. 99

Author(s):

Craig M. Shuttleworth ◽

David Everest ◽

Paul Holmes ◽

Suzi Bell ◽

Rachel Cripps

Keyword(s):

Survival Rates ◽

Disease Outbreaks ◽

Sciurus Carolinensis ◽

Red Squirrel ◽

Grey Squirrel ◽

Red Squirrels ◽

Local Survival ◽

Temporal And Spatial ◽

The Impact ◽

Grey Squirrels

Native red squirrels (Sciurus vulgaris) persisted in the coastal mainland woodlands of northern Gwynedd whilst sympatric with an invasive grey squirrel (Sciurus carolinensis) population suppressed by culling. Squirrelpox disease in the red squirrel population was recorded in 2017 and 2020/21. An autumn 2020 outbreak was associated with only 17.4% of animals caught and marked in the preceding June known to be present in March 2021. Despite an opportunistic data collection lacking the rigour of empirical experimental design, we observed low local survival rates similar to previously published accounts reported during major squirrelpox outbreaks. The use of a conservation dog to detect red squirrel carcasses resulted in positive detection and confirmation of a temporal and spatial expansion of one disease outbreak. The study is the first in Wales to use conservation dogs and the findings reinforce the vital strategic importance of geographical isolation reducing sympatry of red with grey squirrels in European regions where the introduced congener is a source of the squirrelpox infection.

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Shades of grey: host phenotype dependent effect of urbanization on the bacterial microbiome of a wild mammal

Animal Microbiome ◽

10.1186/s42523-021-00105-4 ◽

2021 ◽

Vol 3 (1) ◽

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 (across three cities) on the microbiome of eastern grey squirrels (Sciurus carolinensis). 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 Squirrel microbiomes differed between city and rural environments, but differences of comparable magnitude were observed between land classes at a within-city scale. We did not observe strong evidence that inter-environmental differences were the result of disparate selective pressures. Rather, our results suggest that microbiota dispersal and ecological drift are integral to shaping the inter-environmental differences we observed. However, these processes 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.

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