Abstract
The eastern grey squirrel (Sciurus carolinensis) is a North American tree squirrel species which has been introduced to several countries outside its native range. We made use of squirrels culled in Italy within control activities to establish hematological reference intervals for this invasive species, with the aim to broaden the current knowledge about its physiology. Blood from 104 individuals was analysed through a laser analyser. Manual leukocyte differential counts on blood films from a subset of 77 animals were used for validation of the automated counts, resulting in a fairly good agreement between the two methods for all variables excluding monocytes. Reference intervals and the 90% confidence interval of their limits were estimated for 19 hematological variables, partitioning by sex when statistically significant differences were detected. For most variables, our results were comparable with the few data available on the grey squirrel and on related species. An exception was represented by the hematocrit and mean corpuscular volume which were higher than values reported by other authors, and by the mean corpuscular hemoglobin concentration, which was instead lower. This study gathered valuable reference information for studies aimed at disclosing the mechanisms underlying grey squirrels’ invasiveness and for future research on tree squirrels’ physiology.
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Data availability
All data used for analyses have been made available as Supplementary Material (ESM2).
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Acknowledgements
We thank all the private estate owners for allowing field collection. Thanks also to Luc Wauters, Mattia Panzeri and all the people who helped with sampling and laboratory analyses.
Funding
This research is part of the project “Immune response of invasive species as a driver of parasite dynamics” funded by the Department of Veterinary Medicine, Università degli Studi di Milano (Piano di Sostegno alla Ricerca, Linea 2).
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Romeo C., Comazzi S. and Ferrari N. contributed to the study conception and design. Material preparation, data collection and analysis were performed by Romeo C., D’Alessandro S. and Bielli M. The first draft of the manuscript was written by Romeo C., and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.
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Romeo, C., D’Alessandro, S., Bielli, M. et al. Reference intervals for hematological variables in wild Eastern grey squirrels (Sciurus carolinensis). Eur J Wildl Res 67, 6 (2021). https://doi.org/10.1007/s10344-020-01443-5
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DOI: https://doi.org/10.1007/s10344-020-01443-5