Locating species range frontiers: a cost and efficiency comparison of citizen science and hair-tube survey methods for use in tracking an invasive squirrel
Emily A. Goldstein A B C D , Colin Lawton C , Emma Sheehy C and Fidelma Butler B
+ Author Affiliations
- Author Affiliations
A Environmental Research Institute, Lee Road, Cork, Ireland.
B School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland.
C Department of Zoology, National University of Ireland Galway, Galway, Ireland.
D Corresponding author. Email: emilyagoldstein@gmail.com
Wildlife Research 41(1) 64-75 https://doi.org/10.1071/WR13197
Submitted: 10 May 2013 Accepted: 9 April 2014 Published: 19 May 2014
Abstract
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.
References
Amori, G., Mortelliti, A., Guidarelli, G., Schiavano, A., and Luiselli, L. (2012). Detectability of the European red squirrel (Sciurus vulgaris) in a Mediterranean area. Rendiconti Lincei 23, 203–206.| Detectability of the European red squirrel (Sciurus vulgaris) in a Mediterranean area.Crossref | GoogleScholarGoogle Scholar |
Barea-Azcón, J. M., Virgós, E., Ballesteros-Duperón, E., Moleón, M., and Chirosa, M. (2007). Surveying carnivores at large spatial scales: a comparison of four broad-applied methods. Biodiversity and Conservation 16, 1213–1230.
| Surveying carnivores at large spatial scales: a comparison of four broad-applied methods.Crossref | GoogleScholarGoogle Scholar |
Bertolino, S. (2009). Animal trade and non-indigenous species introduction: the world-wide spread of squirrels. Diversity & Distributions 15, 701–708.
| Animal trade and non-indigenous species introduction: the world-wide spread of squirrels.Crossref | GoogleScholarGoogle Scholar |
Bertolino, S., and Genovesi, P. (2003). Spread and attempted eradication of the grey squirrel (Sciurus carolinensis) in Italy, and consequences for the red squirrel (Sciurus vulgaris) in Eurasia. Biological Conservation 109, 351–358.
| Spread and attempted eradication of the grey squirrel (Sciurus carolinensis) in Italy, and consequences for the red squirrel (Sciurus vulgaris) in Eurasia.Crossref | GoogleScholarGoogle Scholar |
Bertolino, S., Wauters, L., Pizzul, A., Molinari, A., Lurz, P., and Tosi, G. (2009). A general approach of using hair-tubes to monitor the European red squirrel: a method applicable at regional and national scales. Mammalian Biology 74, 210–219.
| A general approach of using hair-tubes to monitor the European red squirrel: a method applicable at regional and national scales.Crossref | GoogleScholarGoogle Scholar |
Bertolino, S., Montezemolo, N. C., Preatoni, D. G., Wauters, L. A., and Martinoli, A. (2014). A grey future for Europe: Sciurus carolinensis is replacing native red squirrels in Italy. Biological Invasions 16, 53–62.
| A grey future for Europe: Sciurus carolinensis is replacing native red squirrels in Italy.Crossref | GoogleScholarGoogle Scholar |
Bolger, D. T., Morrison, T. A., Vance, B., Lee, D., and Farid, H. (2012). A computer-assisted system for photographic mark–recapture analysis. Methods in Ecology and Evolution 3, 813–822.
| A computer-assisted system for photographic mark–recapture analysis.Crossref | GoogleScholarGoogle Scholar |
Bowers, M. A., and Breland, B. (1996). Foraging of gray squirrels on an urban–rural gradient: use of the Gud to assess anthropogenic impact. Ecological Applications 6, 1135–1142.
| Foraging of gray squirrels on an urban–rural gradient: use of the Gud to assess anthropogenic impact.Crossref | GoogleScholarGoogle Scholar |
Braschler, B. (2009). Successfully implementing a citizen-scientist approach to insect monitoring in a resource-poor country. Bioscience 59, 103–104.
| Successfully implementing a citizen-scientist approach to insect monitoring in a resource-poor country.Crossref | GoogleScholarGoogle Scholar |
Brown, K., Moller, H., Innes, J., and Alterio, N. (1996). Calibration of tunnel tracking rates to estimate relative abundance of ship rats (Rattus rattus) and mice (Mus musculus) in a New Zealand forest. New Zealand Journal of Ecology 20, 271–276.
Bryce, J., Johnson, P. J., and Macdonald, D. W. (2002). Can niche use in red and grey squirrels offer clues for their apparent coexistence? Journal of Applied Ecology 39, 875–887.
| Can niche use in red and grey squirrels offer clues for their apparent coexistence?Crossref | GoogleScholarGoogle Scholar |
Carey, M., Hamilton, G., Poole, A., and Lawton, C. (2007). ‘The Irish Squirrel Survey.’ (COFORD: Dublin, Ireland.) Available at http://www.coford.ie/media/coford/content/publications/projectreports/irishsquirrelsurvey2007 revised.pdf [verified 30 April 2014].
Catling, P. C., Burt, R. J., and Kooyman, R. (1997). A comparison of techniques used in a survey of the ground-dwelling and arboreal mammals in forests in north-eastern New South Wales. Wildlife Research 24, 417–432.
| A comparison of techniques used in a survey of the ground-dwelling and arboreal mammals in forests in north-eastern New South Wales.Crossref | GoogleScholarGoogle Scholar |
Cohn, J. P. (2008). Citizen science: can volunteers do real research? Bioscience 58, 192–197.
| Citizen science: can volunteers do real research?Crossref | GoogleScholarGoogle Scholar |
Cooper, C. B., Dickinson, J., Phillips, T., and Bonney, R. (2007). Citizen science as a tool for conservation in residential ecosystems. Ecology and Society 12, 11.
Courchamp, F., Chapuis, J. L., and Pascal, M. (2003). Mammal invaders on islands: impact, control and control impact. Biological Reviews of the Cambridge Philosophical Society 78, 347–383.
| Mammal invaders on islands: impact, control and control impact.Crossref | GoogleScholarGoogle Scholar | 14558589PubMed |
Crosbie, S. P., Koenig, W. D., Reisen, W. K., Kramer, V. L., Marcus, L., Carney, R., Pandolfino, E., Bolen, G. M., Crosbie, L. R., and Ernest, H. B. (2008). Early impact of the West Nile virus on the yellow-billed magpie (Pica nuttalli). The Auk 125, 542–550.
| Early impact of the West Nile virus on the yellow-billed magpie (Pica nuttalli).Crossref | GoogleScholarGoogle Scholar |
CSO (2011). ‘Population of Each Province, County and City, 2011.’ (Central Statistics Office: Cork, Ireland.) Available at http://www.cso.ie/en/statistics/population/populationofeachprovincecountyandcity2011/. [Accessed 30 October 2013]
Davis, M. A., Thompson, K., and Grime, J. P. (2001). Charles S. Elton and the dissociation of invasion ecology from the rest of ecology. Diversity & Distributions 7, 97–102.
| Charles S. Elton and the dissociation of invasion ecology from the rest of ecology.Crossref | GoogleScholarGoogle Scholar |
Delaney, D., Sperling, C., Adams, C., and Leung, B. (2008). Marine invasive species: validation of citizen science and implications for national monitoring networks. Biological Invasions 10, 117–128.
| Marine invasive species: validation of citizen science and implications for national monitoring networks.Crossref | GoogleScholarGoogle Scholar |
Devictor, V., Whittaker, R. J., and Beltrame, C. (2010). Beyond scarcity: citizen science programmes as useful tools for conservation biogeography. Diversity & Distributions 16, 354–362.
| Beyond scarcity: citizen science programmes as useful tools for conservation biogeography.Crossref | GoogleScholarGoogle Scholar |
Dickinson, J., Zuckerberg, B., and Bonter, D. N. (2010). Citizen science as an ecological research tool: challenges and benefits. Annual Review of Ecology Evolution and Systematics 41, 149–172.
| Citizen science as an ecological research tool: challenges and benefits.Crossref | GoogleScholarGoogle Scholar |
Eraud, C., Boutin, J.-M., Roux, D., and Faivre, B. (2007). Spatial dynamics of an invasive bird species assessed using robust design occupancy analysis: the case of the Eurasian collared dove (Streptopelia decaocto) in France. Journal of Biogeography 34, 1077–1086.
| Spatial dynamics of an invasive bird species assessed using robust design occupancy analysis: the case of the Eurasian collared dove (Streptopelia decaocto) in France.Crossref | GoogleScholarGoogle Scholar |
Fimbel, C., and Freed, S. (2008). Monitoring western gray squirrels for landscape management in western Washington. Northwest Science 82, 299–308.
| Monitoring western gray squirrels for landscape management in western Washington.Crossref | GoogleScholarGoogle Scholar |
Finnegan, L., Hamilton, G., Perol, J., and Rochford, J. (2007). The use of hair tubes as an indirect method for monitoring red and grey squirrel populations. Biology and Environment: Proceedings of the Royal Irish Academy 107B, 55–60.
Fujisaki, I., Pearlstine, E. V., and Mazzotti, F. J. (2010). The rapid spread of invasive Eurasian collared doves Streptopelia decaocto in the continental USA follows human-altered habitats. The Ibis 152, 622–632.
| The rapid spread of invasive Eurasian collared doves Streptopelia decaocto in the continental USA follows human-altered habitats.Crossref | GoogleScholarGoogle Scholar |
Gaidet-Drapier, N., Fritz, H., Bourgarel, M., Renaud, P.-C., Poilecot, P., Chardonnet, P., Coid, C., Poulet, D., and Bel, S. (2006). Cost and efficiency of large mammal census techniques: comparison of methods for a participatory approach in a communal area, Zimbabwe. Biodiversity and Conservation 15, 735–754.
| Cost and efficiency of large mammal census techniques: comparison of methods for a participatory approach in a communal area, Zimbabwe.Crossref | GoogleScholarGoogle Scholar |
Galloway, A. W. E., Tudor, M. T., and Vander Haegen, W. M. (2006). The reliability of citizen science: a case study of Oregon white oak stand surveys. Wildlife Society Bulletin 34, 1425–1429.
| The reliability of citizen science: a case study of Oregon white oak stand surveys.Crossref | GoogleScholarGoogle Scholar |
Garden, J. G., McAlpine, C. A., Possingham, H. P., and Jones, D. N. (2007). Using multiple survey methods to detect terrestrial reptiles and mammals: what are the most successful and cost-efficient combinations? Wildlife Research 34, 218–227.
| Using multiple survey methods to detect terrestrial reptiles and mammals: what are the most successful and cost-efficient combinations?Crossref | GoogleScholarGoogle Scholar |
Gurnell, J. (1987) ‘The Natural History of Squirrels.’ (Facts on File: New York.)
Gurnell, J. (1996). The effects of food availability and winter weather on the dynamics of a grey squirrel population in southern England. Journal of Applied Ecology 33, 325–338.
| The effects of food availability and winter weather on the dynamics of a grey squirrel population in southern England.Crossref | GoogleScholarGoogle Scholar |
Gurnell, J., Lurz, P. W. W., Shirley, M. D. F., Cartmel, S., Garson, P. J., Magris, L., and Steele, J. (2004a). Monitoring red squirrels Sciurus vulgaris and grey squirrels Sciurus carolinensis in Britain. Mammal Review 34, 51–74.
| Monitoring red squirrels Sciurus vulgaris and grey squirrels Sciurus carolinensis in Britain.Crossref | GoogleScholarGoogle Scholar |
Gurnell, J., Wauters, L. A., Lurz, P. W. W., and Tosi, G. (2004b). Alien species and interspecific competition: effects of introduced eastern grey squirrels on red squirrel population dynamics. Journal of Animal Ecology 73, 26–35.
| Alien species and interspecific competition: effects of introduced eastern grey squirrels on red squirrel population dynamics.Crossref | GoogleScholarGoogle Scholar |
Gurnell, J., Lurz, P. W. W., and Halliwell, E. C. (2008). Red squirrel. In ‘Mammals of the British Isles: Handbook’. 4th edn. (Eds S. Harris and D. W. Yalden.) pp. 56–66. (The Mammal Society: Southampton, UK.)
Gurnell J, Lurz P, McDonald R, Pepper H (2009). ‘Practical Techniques for Surveying and Monitoring Squirrels. No. FCPN011’. (Forestry Commission: Surrey, UK.)
Harris, R. L., and Nicol, S. C. (2010). The effectiveness of hair traps for surveying mammals: results of a study in sandstone caves in the Tasmanian southern midlands. Australian Mammalogy 32, 62–66.
| The effectiveness of hair traps for surveying mammals: results of a study in sandstone caves in the Tasmanian southern midlands.Crossref | GoogleScholarGoogle Scholar |
Kenward, R. E., and Holm, J. L. (1993). On the replacement of the red squirrel in Britain. A phytotoxic explanation. Proceedings of the Royal Society of London. Series B, Biological Sciences 251, 187–194.
| On the replacement of the red squirrel in Britain. A phytotoxic explanation.Crossref | GoogleScholarGoogle Scholar | 1:STN:280:DyaK3s3jsVGrsw%3D%3D&md5=7b7ba61fcd855329f15cd15df45aa6f9CAS |
Kirkman, T. W. (1996) ‘Statistics to Use.’ Available at http://www.physics.csbsju.edu/stats. [Accessed 20 November 2012]
Koenig, W. D., Marcus, L., Scott, T. W., and Dickinson, J. L. (2007). West Nile virus and California breeding bird declines. EcoHealth 4, 18–24.
| West Nile virus and California breeding bird declines.Crossref | GoogleScholarGoogle Scholar |
Koprowski, J. L. (1994). Sciurus carolinensis. Mammalian Species 480, 1–9.
| Sciurus carolinensis.Crossref | GoogleScholarGoogle Scholar |
LaDeau, S. L., Kilpatrick, A. M., and Marra, P. P. (2007). West Nile virus emergence and large-scale declines of North American bird populations. Nature 447, 710–713.
| West Nile virus emergence and large-scale declines of North American bird populations.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD2sXmtFemu7o%3D&md5=9480aba618b851196f569061ba135c2fCAS | 17507930PubMed |
Lawton, C, Cowan, P, Bertolino, S, Lurz, PWW, and Peters, AR (2010). The consequences of introducing non-indigenous species: two case studies, the grey squirrel in Europe and the brushtail possum in New Zealand. Revue Scientifique et Technique – Office International des Epizooties 29, 287–298.
| 1:STN:280:DC%2BC3cfntFyrtw%3D%3D&md5=1de8126dabe22d8075826c1b5ef87aa3CAS |
Leung, B., Lodge, D. M., Finnoff, D., Shogren, J. F., Lewis, M. A., and Lamberti, G. (2002). An ounce of prevention or a pound of cure: bioeconomic risk analysis of invasive species. Proceedings. Biological Sciences 269, 2407–2413.
| An ounce of prevention or a pound of cure: bioeconomic risk analysis of invasive species.Crossref | GoogleScholarGoogle Scholar |
Lodge, D. M., and Shrader-Frechette, K. (2003). Nonindigenous species: ecological explanation, environmental ethics, and public policy. Conservation Biology 17, 31–37.
| Nonindigenous species: ecological explanation, environmental ethics, and public policy.Crossref | GoogleScholarGoogle Scholar |
Lurz, P. W. W., Gurnell, J., and Magris, L. (2005). Sciurus vulgaris. Mammalian Species 769, 1–10.
| Sciurus vulgaris.Crossref | GoogleScholarGoogle Scholar |
Lyra-Jorge, M. C., Ciocheti, G., Pivello, V. R., and Meirelles, S. T. (2008). Comparing methods for sampling large- and medium-sized mammals: camera traps and track plots. European Journal of Wildlife Research 54, 739–744.
| Comparing methods for sampling large- and medium-sized mammals: camera traps and track plots.Crossref | GoogleScholarGoogle Scholar |
Mack, R. N., Simberloff, D., Mark Lonsdale, W., Evans, H., Clout, M., and Bazzaz, F. A. (2000). Biotic invasions: causes, epidemiology, global consequences, and control. Ecological Applications 10, 689–710.
| Biotic invasions: causes, epidemiology, global consequences, and control.Crossref | GoogleScholarGoogle Scholar |
MacKenzie, D. I. (2005). What are the issues with presence-absence data for wildlife managers? The Journal of Wildlife Management 69, 849–860.
| What are the issues with presence-absence data for wildlife managers?Crossref | GoogleScholarGoogle Scholar |
MacKenzie, D. I., Nichols, J. D., Lachman, G. B., Droege, S., Andrew Royle, J., and Langtimm, C. A. (2002). Estimating site occupancy rates when detection probabilities are less than one. Ecology 83, 2248–2255.
| Estimating site occupancy rates when detection probabilities are less than one.Crossref | GoogleScholarGoogle Scholar |
McGoldrick, M. S. (2011). The vagility of an invasive species, the grey squirrel (Sciurus carolinensis) – studies of population genetic structure, control and recolonisation, range expansion and pox virus. Ph.D Thesis, Trinity College Dublin, Dublin, Ireland.
Mortelliti, A., and Boitani, L. (2008). Inferring red squirrel (Sciurus vulgaris) absence with hair tubes surveys: a sampling protocol. European Journal of Wildlife Research 54, 353–356.
| Inferring red squirrel (Sciurus vulgaris) absence with hair tubes surveys: a sampling protocol.Crossref | GoogleScholarGoogle Scholar |
Mortelliti, A., Cervone, C., Amori, G., and Boitani, L. (2010). The effect of non-target species in presence–absence distribution surveys: a case study with hair-tubes. The Italian Journal of Zoology 77, 211–215.
| The effect of non-target species in presence–absence distribution surveys: a case study with hair-tubes.Crossref | GoogleScholarGoogle Scholar |
Myers, J. H., Simberloff, D., Kuris, A. M., and Carey, J. R. (2000). Eradication revisited: dealing with exotic species. Trends in Ecology & Evolution 15, 316–320.
| Eradication revisited: dealing with exotic species.Crossref | GoogleScholarGoogle Scholar |
Newman, G., Wiggins, A., Crall, A., Graham, E., Newman, S., and Crowston, K. (2012). The future of citizen science: emerging technologies and shifting paradigms. Frontiers in Ecology and the Environment 10, 298–304.
| The future of citizen science: emerging technologies and shifting paradigms.Crossref | GoogleScholarGoogle Scholar |
O’Meara, D., Turner, P., Coffey, L., and O’Reilly, C. (2012). TaqMan assays for species identification of the red squirrel (Sciurus vulgaris) and the grey squirrel (Sciurus carolinensis). Conservation Genetics Resources 4, 603–604.
| TaqMan assays for species identification of the red squirrel (Sciurus vulgaris) and the grey squirrel (Sciurus carolinensis).Crossref | GoogleScholarGoogle Scholar |
O’Teangana, D. O., Reilly, S., Montgomery, W. I., and Rochford, J. (2000a). Distribution and status of the red squirrel (Sciurus vulgaris) and grey squirrel (Sciurus carolinensis) in Ireland. Mammal Review 30, 45–56.
| Distribution and status of the red squirrel (Sciurus vulgaris) and grey squirrel (Sciurus carolinensis) in Ireland.Crossref | GoogleScholarGoogle Scholar |
O’Teangana, D. O., Russ, J. M., Mathers, R. G., and Montgomery, W. I. (2000b). Habitat associations of the red squirrel Sciurus vulgaris and grey squirrel S. carolinensis in northern Ireland. Biology and Environment: Proceedings of the Royal Irish Academy 100B, 27–33.
Paull, D. J., Claridge, A. W., and Cunningham, R. B. (2012). Effective detection methods for medium-sized ground-dwelling mammals: a comparison between infrared digital cameras and hair tunnels. Wildlife Research 39, 546–553.
| Effective detection methods for medium-sized ground-dwelling mammals: a comparison between infrared digital cameras and hair tunnels.Crossref | GoogleScholarGoogle Scholar |
Peacock, D. S., Van Rensburg, B. J., and Robertson, M. P. (2007). The distribution and spread of the invasive alien common myna, Acridotheres tristis L. (Aves: Sturnidae), in southern Africa. South African Journal of Science 103, 465–473.
Perry, H. R., Garland, B. P., Barkalow, F. S., and Monroe, R. J. (1977). Factors affecting trap responses of the gray squirrel. The Journal of Wildlife Management 41, 135–143.
| Factors affecting trap responses of the gray squirrel.Crossref | GoogleScholarGoogle Scholar |
Pocock, M. J. O., and Jennings, N. (2006). Use of hair tubes to survey for shrews: new methods for identification and quantification of abundance. Mammal Review 36, 299–308.
| Use of hair tubes to survey for shrews: new methods for identification and quantification of abundance.Crossref | GoogleScholarGoogle Scholar |
Reiners, T. E., Encarnação, J. A., and Wolters, V. (2011). An optimized hair trap for non-invasive genetic studies of small cryptic mammals. European Journal of Wildlife Research 57, 991–995.
| An optimized hair trap for non-invasive genetic studies of small cryptic mammals.Crossref | GoogleScholarGoogle Scholar |
Roberts, N. J. (2011). Investigation into survey techniques of large mammals: surveyor competence and camera-trapping vs. transect-sampling. Bioscience Horizons 4, 40–49.
| Investigation into survey techniques of large mammals: surveyor competence and camera-trapping vs. transect-sampling.Crossref | GoogleScholarGoogle Scholar |
Sainsbury, A., Deaville, R., Lawson, B., Cooley, W., Farelly, S., Stack, M., Duff, P., McInnes, C., Gurnell, J., Russell, P., Rushton, S., Pfeiffer, D., Nettleton, P., and Lurz, P. (2008). Poxviral disease in red squirrels Sciurus vulgaris; in the UK: spatial and temporal trends of an emerging threat. EcoHealth 5, 305–316.
| Poxviral disease in red squirrels Sciurus vulgaris; in the UK: spatial and temporal trends of an emerging threat.Crossref | GoogleScholarGoogle Scholar | 18923872PubMed |
Schwingel, H., and Norment, C. (2010). Use of hair tubes to detect small-mammal winter activity in a northern forest habitat. Northeastern Naturalist 17, 531–540.
| Use of hair tubes to detect small-mammal winter activity in a northern forest habitat.Crossref | GoogleScholarGoogle Scholar |
Scotts, D., and Craig, S. (1988). Improved hair-sampling tube for the detection of rare mammals. Wildlife Research 15, 469–472.
| Improved hair-sampling tube for the detection of rare mammals.Crossref | GoogleScholarGoogle Scholar |
Sheehy, E., and Lawton, C. (2014). Population crash in an invasive species following the recovery of a native predator: the case of the American grey squirrel and the European pine marten in Ireland. Biodiversity and Conservation 23, 753–774.
| Population crash in an invasive species following the recovery of a native predator: the case of the American grey squirrel and the European pine marten in Ireland.Crossref | GoogleScholarGoogle Scholar |
Shorten, M. (1954). ‘Squirrels.’ (Collins: London.)
Silvertown, J. (2009). A new dawn for citizen science. Trends in Ecology & Evolution 24, 467–471.
| A new dawn for citizen science.Crossref | GoogleScholarGoogle Scholar |
Simberloff, D. (2003). How much information on population biology is needed to manage introduced species? Conservation Biology 17, 83–92.
| How much information on population biology is needed to manage introduced species?Crossref | GoogleScholarGoogle Scholar |
Stanley, T. R., and Royle, J. A. (2005). Estimating site occupancy and abundance using indirect detection indices. The Journal of Wildlife Management 69, 874–883.
| Estimating site occupancy and abundance using indirect detection indices.Crossref | GoogleScholarGoogle Scholar |
Teacher, A. G. F., Griffiths, D. J., Hodgson, D. J., and Inger, R. (2013). Smartphones in ecology and evolution: a guide for the apprehensive. Ecology and Evolution 3, 5268–5278.
| Smartphones in ecology and evolution: a guide for the apprehensive.Crossref | GoogleScholarGoogle Scholar |
Teerink, B. J. (1991). ‘Hair of West-European Mammals.’ (Cambridge University Press: Cambridge, UK.)
Tulloch, A. I. T., and Szabo, J. K. (2012). A behavioural ecology approach to understand volunteer surveying for citizen science datasets. Emu 112, 313–325.
| A behavioural ecology approach to understand volunteer surveying for citizen science datasets.Crossref | GoogleScholarGoogle Scholar |
Tulloch, A., Possingham, H. P., and Wilson, K. (2011). Wise selection of an indicator for monitoring the success of management actions. Biological Conservation 144, 141–154.
| Wise selection of an indicator for monitoring the success of management actions.Crossref | GoogleScholarGoogle Scholar |
Tulloch, A. I., Possingham, H. P., Joseph, L. N., Szabo, J., and Martin, T. G. (2013a). Realising the full potential of citizen science monitoring programs. Biological Conservation 165, 128–138.
| Realising the full potential of citizen science monitoring programs.Crossref | GoogleScholarGoogle Scholar |
Tulloch, A. I. T., Mustin, K., Possingham, H. P., Szabo, J. K., and Wilson, K. A. (2013b). To boldly go where no volunteer has gone before: predicting volunteer activity to prioritize surveys at the landscape scale. Diversity & Distributions 19, 465–480.
| To boldly go where no volunteer has gone before: predicting volunteer activity to prioritize surveys at the landscape scale.Crossref | GoogleScholarGoogle Scholar |
van der Merwe, M., Brown, J. S., and Jackson, W. M. (2005). The coexistence of fox (Sciurus niger) and gray (S. carolinensis) squirrels in the Chicago metropolitan area. Urban Ecosystems 8, 335–347.
| The coexistence of fox (Sciurus niger) and gray (S. carolinensis) squirrels in the Chicago metropolitan area.Crossref | GoogleScholarGoogle Scholar |
Waters, C., and Lawton, C. (2011). ‘Red Squirrel Translocation in Ireland. Irish Wildlife Manuals.’ (National Parks and Wildlife Service, Department of the Environment, Heritage and Local Government: Dublin, Ireland.) Available at http://www.npws.ie/publications/irishwildlifemanuals/IWM51.pdf [verfied 30 April 2014].
Watt, H. B. (1923). The American grey squirrel in Ireland. Irish Naturalist 32, 95.
Wauters, L. A., Lurz, P. W. W., and Gurnell, J. (2000). Interspecific effects of grey squirrels (Sciurus carolinensis) on the space use and population demography of red squirrels (Sciurus vulgaris) in conifer plantations. Ecological Research 15, 271–284.
| Interspecific effects of grey squirrels (Sciurus carolinensis) on the space use and population demography of red squirrels (Sciurus vulgaris) in conifer plantations.Crossref | GoogleScholarGoogle Scholar |
Wheeler, S. S., Barker, C. M., Fang, Y., Armijos, M. V., Carroll, B. D., Husted, S., Johnson, W. O., and Reisen, W. K. (2009). Differential impact of West Nile virus on California birds. The Condor 111, 1–20.
| Differential impact of West Nile virus on California birds.Crossref | GoogleScholarGoogle Scholar | 20589226PubMed |
Wood, D. J. A., Koprowski, J. L., and Lurz, P. W. W. (2007). Tree squirrel introduction: a theoretical approach with population viability analysis. Journal of Mammalogy 88, 1271–1279.
| Tree squirrel introduction: a theoretical approach with population viability analysis.Crossref | GoogleScholarGoogle Scholar |
