Epidemiological and postmortem findings in 262 red squirrels (<i>Sciurus vulgaris</i>) in Scotland, 2005 to 2009

LaRose, J. P.; Meredith, Anna; Everest, David J.; Fiegna, C.; McInnes, Colin J.; Shaw, Darren; Milne, Elspeth

doi:10.1136/vr.c4196

Cited by 32 publications

(37 citation statements)

References 20 publications

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“…In some cases a heavy ectoparasite burden probably contributed to mortality but this was considered secondary. This result is in contrast to that obtained by LaRose et al [9] in Scotland where starvation was the most common cause of mortality in juveniles and, at 9.8%, the fourth most common cause of death overall. A possible explanation for this is the additional laboratory procedures carried out in the present study.…”

Section: Discussioncontrasting

confidence: 99%

“…This result is consistent that obtained LaRose et al [9] in Scotland where 42.9% of mortality was caused by traffic. A slightly lower figure of 36% was recorded in 36 squirrels found dead on the island of Jersey [14].…”

Section: Discussionsupporting

confidence: 93%

“…In the study of red squirrels in Scotland [9] squirrelpox was the second most predominant cause of mortality (14.3%). However, squirrelpox does not occur on the IoW and was not seen in any of the squirrels submitted from other locations in this study.…”

Section: Discussionmentioning

confidence: 99%

“…Despite concerns that red squirrels may become extinct in Britain there has been only limited research into causes of mortality other than squirrelpox and much of the published data relates only to specific conditions [3-7]. Keymer [8] in 1983 was the first to describe the range of diseases affecting red squirrels in Britain but there were few comparable studies until 2010 when LaRose et al [9] conducted an extensive investigation in to causes of red squirrel mortality in Scotland. The purpose of the present study was, firstly, to investigate the causes of mortality and any associated pathological findings in red squirrels from geographically isolated populations in Britain, and secondly, to consider the factors that might influence the occurrence of disease in these populations.…”

Section: Introductionmentioning

confidence: 99%

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Causes of mortality and pathological lesions observed post-mortem in red squirrels (Sciurus vulgaris) in Great Britain

Simpson¹,

Hargreaves²,

Butler³

et al. 2013

BMC Vet Res

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BackgroundThe red squirrel population in Great Britain has declined dramatically in recent decades, principally due to squirrelpox. Concern exists that red squirrels may become extinct nationally and, as there has been limited research in to diseases other than squirrelpox, this study aimed to identify additional causes of mortality.ResultsPost-mortem examinations on 163 red squirrels found dead on Isle of Wight (IoW) England, in Scotland and at other locations in Great Britain showed that 41.7% (n = 68) were killed by road traffic and 9.2% (n = 15) by predators, principally domestic cats and dogs. The overall male/female ratio was 1.08/1. Fleas were recorded on 34.9% of IoW squirrels and on 43.8% of Scottish squirrels but sucking lice and ixodid ticks were only seen on Scottish squirrels. Bacterial infections were significant, particularly in association with respiratory disease (n = 16); two squirrels died of Bordetella bronchiseptica bronchopneumonia. Cases of fatal exudative dermatitis (n = 5) associated with a lukM-positive clone of Staphylococcus aureus occurred only on the IoW. Toxoplasmosis (n = 12) was also confined to IoW where it was responsible for almost one tenth (9.5%) of all deaths. Hepatozoonosis was common, especially in IoW squirrels, but was not considered a primary cause of mortality. Hepatic capillariasis affected four IoW squirrels and one from Scotland. Fungal infections included oral candidiasis, adiaspiromycosis and pulmonary phaeohyphomycosis. Neoplastic conditions diagnosed were: pulmonary carcinoma, gastric spindle cell tumour, renal papillary adenoma and trichoepithelioma. Epidermal hyperplasia of unknown aetiology was seen in squirrels showing crusty lesions of the ear pinnae on IoW (n = 3) and Brownsea Island (n = 1), associated in two cases with cutaneous wart-like growths. Miscellaneous diagnoses included chylothorax, electrocution, intussusception, suspected cholecalciferol rodenticide poisoning and foetal death and mummification. No cases of squirrelpox were diagnosed.ConclusionsRed squirrels in Britain suffer premature or unnatural mortality due to a number of conditions in addition to squirrelpox, many of which result, directly or indirectly, from human activities: road traffic trauma, pet predation, toxoplasmosis, trap injuries, rodenticide poisoning and electrocution accounted for 61% of all recorded mortality in this study. Red squirrels are also affected by several diseases of unknown aetiology which merit further research.

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Section: Discussioncontrasting

confidence: 99%

Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Causes of mortality and pathological lesions observed post-mortem in red squirrels (Sciurus vulgaris) in Great Britain

Simpson¹,

Hargreaves²,

Butler³

et al. 2013

BMC Vet Res

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“…The high feeding activity by the visitors of the park may therefore improve the survival of young individuals. In addition, causes of mortality such as predation [46] and road traffic [47], [48] probably have a low impact on the population of this park [23]. Under these circumstances, juvenile survival is likely to be high, close to 40-50%, as observed in other red squirrel populations [49], [50].…”

Section: Discussionmentioning

confidence: 99%

A Viable Population of the European Red Squirrel in an Urban Park

et al. 2014

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Whether urban parks can maintain viable and self-sustaining populations over the long term is questionable. In highly urbanized landscapes, urban parks could play a role in biodiversity conservation by providing habitat and resources to native species. However, populations inhabiting urban parks are usually small and isolated, leading to increased demographic stochasticity and genetic drift, with expected negative consequences on their viability. Here, we investigated a European red squirrel population located in an urban park close to Paris, France (Parc de Sceaux; 184 ha) to assess its viability. Using mitochondrial D-loop sequences and 13 microsatellite loci, we showed that the population presented high levels of genetic variation and no evidence of inbreeding. The size of the population was estimated at 100–120 individuals based on the comparison of two census techniques, Distance Sampling and Capture-Mark-Recapture. The estimated heterozygosity level and population size were integrated in a Population Viability Analysis to project the likelihood of the population's persistence over time. Results indicate that the red squirrel population of this urban park can be viable on the long term (i.e. 20 years) for a range of realistic demographic parameters (juvenile survival at least >40%) and immigration rates (at least one immigration event every two years). This study highlights that urban parks can be potential suitable refuges for the red squirrel, a locally threatened species across western European countries, provided that ecological corridors are maintained.

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Finite element analysis of feeding in red and gray squirrels (Sciurus vulgaris and Sciurus carolinensis)

Cox,

Watson

2024

The Anatomical Record

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Invasive gray squirrels (Sciurus carolinensis) have replaced the native red squirrel (Sciurus vulgaris) across much of Great Britain over the last century. Several factors have been proposed to underlie this replacement, but here we investigated the potential for dietary competition in which gray squirrels have better feeding performance than reds and are thus able to extract nutrition from food more efficiently. In this scenario, we hypothesized that red squirrels would show higher stress, strain, and deformation across the skull than gray squirrels. To test our hypotheses, we created finite element models of the skull of a red and a gray squirrel and loaded them to simulate biting at the incisor, at two different gapes, and at the molar. The results showed similar distributions of strains and von Mises stresses in the two species, but higher stress and strain magnitudes in the red squirrel, especially during molar biting. Few differences were seen in stress and strain distributions or magnitudes between the two incisor gapes. A geometric morphometric analysis showed greater deformations in the red squirrel skull at all bites and gapes. These results are consistent with our hypothesis and indicate increased biomechanical performance of the skull in gray squirrels, allowing them to access and process food items more efficiently than red squirrels.

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Epidemiological and postmortem findings in 262 red squirrels (Sciurus vulgaris) in Scotland, 2005 to 2009

Cited by 32 publications

References 20 publications

Causes of mortality and pathological lesions observed post-mortem in red squirrels (Sciurus vulgaris) in Great Britain

Causes of mortality and pathological lesions observed post-mortem in red squirrels (Sciurus vulgaris) in Great Britain

A Viable Population of the European Red Squirrel in an Urban Park

Finite element analysis of feeding in red and gray squirrels (Sciurus vulgaris and Sciurus carolinensis)

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