A systematic review into the suitability of urban refugia for the Eurasian red squirrel Sciurus vulgaris

• Published in: Mammal review 2022-01, Vol.52 (1), p.26-38
• Main Authors: Fingland, Kathryn, Ward, Samantha J., Bates, Adam J., Bremner‐Harrison, Samantha
• Format: Article
• Language: English
• Subjects: Animal diseases; Anthropogenic factors; Bird watching; conservation management; Environmental conditions; Eurasian red squirrel Sciurus vulgaris; Europe; Feral populations; Food; Food availability; Food sources; Gene flow; Green infrastructure; Habitats; Human populations; Mortality; Natural & organic foods; Nesting; Open spaces; Population; Population decline; Population density; Populations; Predation; Refugia; Rural areas; Sciurus vulgaris; Squirrels; supplementary feeding; Traffic accidents; Traffic accidents & safety; Urban areas; Urban development; urban ecology; Urban environments; urban greenspaces; Urban planning; Urban populations; Urban sprawl; Viral diseases; Wildlife; Wildlife habitats
• ISSN: 0305-1838; 1365-2907
• DOI: 10.1111/mam.12264

Urban growth and intensification are projected to increase as the global human population increases. Historically, urban areas have been disregarded as suitable wildlife habitat, but it is now known that these areas can be biodiverse and that wildlife species can adapt to the environmental conditions. One such urban‐dwelling species is the Eurasian red squirrel Sciurus vulgaris, which has suffered population declines in several countries throughout its range in recent decades. The current published literature was systematically reviewed to determine whether or not urban habitats are suitable refugia for red squirrels, through identifying and discussing key topics regarding the urban ecology of red squirrels. Urban environments can support higher population densities of red squirrels than rural areas, probably due to the widespread and reliable provision of anthropogenic supplemental food alongside natural food sources. The availability and quality of urban greenspaces are important determinants of the suitability of urban habitats for red squirrels, as they provide natural food sources and nesting sites. Despite the barriers present in urban landscapes (e.g. roads), red squirrels can still disperse and maintain gene flow at the population level. Road traffic accidents appear to be a significant cause of mortality in some urban red squirrel populations, and seasonal peaks of mortality occur during the autumn months. Diseases (e.g. squirrelpox virus) can also be a significant cause of mortality, although effects differ between populations and depend on whether grey squirrels Sciurus carolinensis are present. Many of the predation events that affect red squirrels appear to be due to free‐ranging domestic and feral cats Felis catus, although there is currently little evidence to suggest that predation is a limiting factor for urban red squirrel populations. We conclude that urban areas can be suitable refugia for red squirrels, provided that high‐quality greenspaces are maintained. Mitigation measures may also be necessary to reduce population mortality and to prevent disease outbreaks. Urbanisation is increasing as the global human population increases, so it is important to manage urban habitats to benefit both people and wildlife. We conducted a systematic review to investigate whether urban areas can be suitable habitat for the Eurasian red squirrel, which is a native species to the UK but has significantly declined in recent decades. Several key topics we