Mammalian Biology

, Volume 94, Issue 1, pp 134–139 | Cite as

Supplementary feeding can attract red squirrels (Sciurus vulgaris) to optimal environments

  • Anna StarkeyEmail author
  • Javier delBarco-Trillo
Original investigation


A number of conservation approaches are used to manage threatened species. However, some of these approaches require intensive planning and can often be restricted by funding. Supplementary feeding is a non-invasive and cost-effective approach to manage vulnerable populations, but we lack data on its usefulness. Here we investigated the effects of supplementary feeding on a population of red squirrels (Sciurus vulgaris), a UK priority species which faces competition from the non-native grey squirrel (Sciurus carolinensis). The study took place October-December 2015, lasting 8 weeks. Twenty feeders were installed 1 week prior to the beginning of the study in a protected woodland free from grey squirrels, either containing food (full feeders) or no food (empty feeders), and squirrel abundance before and after feeding was recorded at each feeder (for a total of 27 feeding and recording events). Six times more squirrels were seen at full feeders, and numbers increased by 7 fold after feeding. We also observed that the activity of red squirrels in the vicinity of full feeders increased during the course of the study. Eighty-five hair samples were collected during the study, all of which were found at full feeders. Results demonstrate red squirrels can differentiate between full and empty feeders, suggesting their awareness increases when supplementary food is present. Increased abundance of squirrels at full feeders after feeding times not only implies that squirrels are attracted to and can benefit by supplementation, it also shows that food supplementation can be used to regulate the movement of individuals across habitats. Understanding how red squirrel populations are affected by supplementary feeding will contribute towards existing conservation efforts to improve this species future survival.


Conservation Feeders Food supplementation Invasive species Squirrel abundance 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Allan, J.D., McIntyre, P.B., Smith, S.D.P., Halpern, B.B., Boyer, G.L., Buchsbaum, A., Burton Jr, GA, Campbell, L.M., Chadderton, W.L., Ciborowski, J.J.H., Doran, P.J., Eder, T., Infante, D.M., Johnson, L.B., Joseph, C.A., Marino, A.L., Prusevich, A., Read, J.G., Rose, J.B., Rutherford, E.S., Sowa, S.P., Steinman, A.D., 2013. Joint analysis of stressors and ecosystem services to enhance restoration effectiveness. Proc. Natl. Acad. Sci. U. S.A. 110, 372–377.PubMedGoogle Scholar
  2. Bertolino, S., Wauters, L., Pizzul, A., Molinari, A., Lurz, P., Tosi, G., 2009. A general approach of using hair-tubes to monitorthe European red squirrel: a method applicable at regional and national scales. Mamm. Bio. 74, 210–219.Google Scholar
  3. Blanco, G., Lemus, J.A., García-Montijano, M., 2011. When conservation management becomes contraindicated: impact of food supplementation on health of endangered wildlife. Ecol. Appl. 21, 2469–2477.PubMedGoogle Scholar
  4. Boonstra, R., Krebs, C.J., 2006. Population limitation of the northern red-backed vole in the boreal forests of northern Canada. J. Anim. Ecol. 75, 1269–1284.PubMedGoogle Scholar
  5. Bryce, J.M., 2000. Habitat Use by Sympatric Populations of Red and Grey Squirrels: the Implications for Conservation Management. PhD Thesis. Oxford University.Google Scholar
  6. Bryce, J., Cartmel, S., Quine, C.P., 2005. Habitat Use by Red and Grey Squirrels: Result of Two Recent Studies and Implications for Management. Forestry Commission, Edinburgh, UK.Google Scholar
  7. Ceballos, G., Ehrlich, P.R., 2002. Mammal population losses and the extinction crisis. Science 3, 904–907.Google Scholar
  8. Clarke, D., Ayutthaya, S.S.N., 2010. Predicted effects of climate change, vegetation and tree cover on dune slack habitats at Ainsdale on the Sefton Coast, UK. J. Coast. Conserv. 14, 115–125.Google Scholar
  9. Clavero, M., García-Berthou, E., 2005. Invasive species are a leading cause of animal extinctions. Trends Ecol. Evol. 20, 110.PubMedGoogle Scholar
  10. Crawley, M.J., 2002. Statistical Computing: an Introduction to Data Analysis Using S-Plus. Wiley, Chichester, UK.Google Scholar
  11. Davies, M.A., 2003. Biotic globalization: does competition from introduced species threaten biodiversity? BioScience 53, 481–489.Google Scholar
  12. Di Febbraro, M., Martinoli, A., Russo, D., Preatoni, D., Bertolino, S., 2016. Modelling the effects of climate change on the risk of invasion by alien squirrels. Hystrix It. J. Mamm. 27 (11776).Google Scholar
  13. Finnegan, L., Hamilton, G., Perol, J., Rochford, J., 2007. The use of hair tubes as an indirect method for monitoring red and grey squirrel populations. Proc. R. Ir. Acad. Sect. B 107B, 55–60.Google Scholar
  14. Fischer, J., Lindenmayer, D.B., 2000. An assessment of the published results of animal relocations. Biol. Conserv. 96, 1–11.Google Scholar
  15. Fornasari, L, Casale, P., Wauters, L., 1997. Red squirrel conservation: the assessment of a reintroduction experiment. Ital.J. Zool. 64, 163–167.Google Scholar
  16. Gurevitch, J., Padilla, D.K., 2004. Are invasive species a major cause of extinctions? Trends Ecol. Evol. 9, 481–489.Google Scholar
  17. Gurnell, J., Lurz, P.W.W., McDonald, R., Pepper, H., 2009. Practical Techniques for Surveying and Monitoring Squirrels. Forestry Commission, Farnham, Surrey, UK.Google Scholar
  18. Gurnell, J., Lurz, P.W.W., Shirely, M.D.F., Cartmel, S., Garson, P.J., Magris, L., Steele, J., 2004a. Monitoring red (Sciurus vulgaris) and grey (Sciurus carolinensis) squirrels in Britain. Mammal. Rev. 34, 51–74.Google Scholar
  19. Gurnell, J., McDonald, R., Lurz, P.W.W., 2011. Making red squirrels more visible: the use of baited visual counts to monitor populations. Mammal. Rev. 41, 244–250.Google Scholar
  20. Gurnell, J., Pepper, H., 1993. A critical look at conserving the British red squirrel Sciurus vulgaris. Mammal. Rev. 23, 127–137.Google Scholar
  21. Gurnell, J., Wauters, LA., Lurz, P.W.W., Tosi, G., 2004b. Alien species and interspecific competition: effects of introduced eastern grey squirrels on red squirrel population dynamics. J. Anim. Ecol. 73, 26–35.Google Scholar
  22. Hoodless, A.N., Draycott, R.A.H., Ludiman, M.N., Robertson, P.A., 1999. Effects of supplementary feeding on territoriality, breeding success and survival of pheasants. J. Appl. Ecol. 36, 147–156.Google Scholar
  23. Jayne, K., Lea, S.E.G., Leaver, LA., 2015. Behavioural responses of Eastern grey squirrels, Sciurus carolinensis, to cues of risk while foraging. Behav. Process. 116, 53–61.Google Scholar
  24. Karmacharya, B., Hostetler, J.A., Conner, L.M., Morris, G., Oli, M.K., 2013. The influence of mammalian predator exclusion, food supplementation, and prescribed fire on survival ofGlaucomys volans. J. Mammal. 94, 672–682.Google Scholar
  25. Kenward, R.E., Holm, J.L., 1993. On the replacement of the red squirrel in Britain. A phytotoxic explanation. Proc. R. Soc. B 251, 187–194.PubMedGoogle Scholar
  26. Kenward, R.E., Hodder, K.H., Rose, R.J., Wallis, C.A., Parish, T., Holm, J.L, Morris, P.A., Walls, P.A., Doyle, F.I., 1998. Comparative demography of red squirrels (Sciurus vulgaris) and grey squirrels (Sciurus carolinensis) in deciduous and coniferous woodland. J. Zool. 244, 7–21.Google Scholar
  27. Klenner, W., Krebs, C.J., 1991. Red squirrel population dynamics. I. The effect of supplemental food on demography. J. Anim. Ecol. 60, 961–978.Google Scholar
  28. Lioy, S., Mori, E., Wauters, L.A., Bertolino, S., 2016. Weight operated see-saw feeding hoppers are not selective for red squirrels when greys are present. Mamm. Biol. 81, 365–371.Google Scholar
  29. López-Bao, J.V., Rodríguez, A., Palomares, F., 2008. Behavioural response of a trophic specialist, the Iberian lynx, to supplementary food: patterns of food use and implications for conservation. Biol. Conserv. 141, 1857–1867.Google Scholar
  30. López-Bao, J.V., Rodríguez, A., Palomares, F., 2010. Abundance of wild prey modulates consumption of supplementary food in the Iberian Lynx. Biol. Conserv. 143, 1245–1249.Google Scholar
  31. Magris, L., Gurnell, J., 2002. Population ecology of the red squirrel (Sciurus vulgaris) in a fragmented woodland ecosystem on the Island of Jersey, Channel Islands. J. Zool. 256, 99–112.Google Scholar
  32. Manchester, S.J., Bullock, J.M., 2000. The impacts of non-native species on UK biodiversity and the effectiveness of control. J. Appl. Ecol. 37, 845–864.Google Scholar
  33. McKinney, M.L., 1997. Extinction vulnerability and selectivity: combining ecological and paleontological views. Annu. Rev. Ecol. Syst. 28, 495–516.Google Scholar
  34. Molinari, A., Wauters, L.A., Airoldi, G., Cerinotti, F., Martinoli, A., Tosi, G., 2006. Cone selection by Eurasian red squirrels in mixed conifer forests in the Italian Alps. Acta Oecol. 30, 1–10.Google Scholar
  35. Newey, S., Allison, P., Thirgood, S., Smith, A.A., Graham, I.M., 2010. Population and individual level effects of over-winter supplementary feeding mountain hares. J. Zool. 282, 214–220.Google Scholar
  36. Newton, I., 1998. Population Limitation in Birds. Academic Press Limited, London, UK.Google Scholar
  37. Oro, D., Margalida, A., Carrete, M., Heredia, R., Donázar, J.A., 2008. Testing the goodness of supplementary feeding to enhance population viability in an endangered vulture. PLoS ONE 3, e4084.Google Scholar
  38. Pepper, H., Patterson, G., 1998. Red Squirrel Conservation. Forestry Commission, Edinburgh, UK.Google Scholar
  39. R Core Team, URL 2014. R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria Scholar
  40. Robb, G.N., McDonald, R.A., Chamberlain, D.E., Bearhop, S., 2008. Food for thought: supplementary feeding as a driver of ecological change in avian populations. Front. Ecol. Environ. 6, 476–484.Google Scholar
  41. Rushton, S.P., Lurz, P.W.W., Gurnell, J., Nettleton, P., Bruemmer, C., Shirley, M.D.F., Sainsbury, A.W., 2006. Disease threats posed by alien species: the role of a poxvirus in the decline of the native red squirrel in Britain. Epidemiol. Infect. 134, 521–533.PubMedGoogle Scholar
  42. Steen, R., Barmoen, M., 2017. Diel activity of foraging eurasian red squirrels (Sciurus vulgaris) in the winter revealed by camera traps. Hystryx It. J. Mamm. 28, 43–47.Google Scholar
  43. Tomkins, D.M., White, A.R., Boots, M., 2003. Ecological replacement of the native red squirrels by invasive greys driven by disease. Ecol. Lett. 6, 189–196.Google Scholar
  44. UK Biodiversity Action Plan Steering Group, 1995. Biodiversity: the UK Steering Group Report. HMSO, London.Google Scholar
  45. van der Merwe, M., Brown, J.S., Kotler, B.P., 2014. Quantifying the future value of cacheable food using fox squirrels (Sciurus niger). Isr. J. Ecol. Evol. 60, 1–10.Google Scholar
  46. Vander Wall, S.B., 1998. Foraging success ofgranivorous rodents: effects of variation in seed and soil water on olfaction. Ecology 79, 233–241.Google Scholar
  47. Wake, D.B., Vredenburg, V.T., 2008. Are we in the midst of the sixth mass extinction? A view from the world of amphibians. Proc. Natl. Acad. Sci. U. S.A. 105, 11466–11473.PubMedPubMedCentralGoogle Scholar
  48. Wauters, L.A., Gurnell, J., 1999. The mechanism of replacement of red squirrels by grey squirrels: a test of the interference competition hypothesis. Ethology 105, 1053–1071.Google Scholar
  49. Wauters, L.A., Gurnell, J., Preatoni, D., Tosi, G., 2001. Effects of spatial variation in food availability on spacing behaviour and demography of Eurasian red squirrels. Ecography 24, 525–538.Google Scholar
  50. Wauters, L.A., Githiru, M., Bertolino, S., Molinari, A., Yosi, G., Lens, L., 2008. Demography of alpine red squirrel populations in relation to fluctuations in seed crop size. Ecography 31, 104–114.Google Scholar
  51. Wauters, L.A., Vermeulen, M., Van Dongen, S., Bertolino, S., Molinari, A., Tosi, G., Matthysen, E., 2007. Effects of spatio-temporal variation in food supply on red squirrel Sciurus vulgaris body size and body mass and its consequences for some fitness components. Ecography 30, 51–65.Google Scholar
  52. White, A., Lurz, P.W., Bryce, J., Tonkin, M., Ramoo, K., Bamforth, L., Jarrott, A., Boots, M., 2016. Modelling disease spread in real landscapes: Squirrelpox spread in Southern Scotland as a case study. Hystrix It. J. Mamm. 27 (11657).Google Scholar
  53. Williamson, M., 1993. Invaders, weeds and the risk from genetically manipulated organisms. Experentia 49, 219–224.Google Scholar
  54. Wilson, H.B., Meijaard, E., Venter, O., Ancrenaz, M., Possingham, H.P., 2014. Conservation strategies for orangutans: reintroduction versus habitat preservation and the benefits of sustainably logged forest. PLoS ONE 9, e102174.Google Scholar
  55. WS Atkins Consultants Limited, 2004. Ainsdale Sand Dunes National Nature Reserve: Environmental Impact Assessment of Options for Management of Seaward Areas. WS Atkins Consultants Ltd, Warrington, UK.Google Scholar

Copyright information

© Deutsche Gesellschaft für Säugetierkunde 2019

Authors and Affiliations

  1. 1.School of Natural Sciences and PsychologyLiverpool John Moores UniversityLiverpoolUK
  2. 2.School of Biological, Earth and Environmental SciencesUniversity College CorkCorkIreland

Personalised recommendations