• Barnes, R.F.W. (2001) How reliable are dung counts for estimating elephant numbers? African Journal of Ecology, 39, 19.
  • Barnes, R.F.W., Beardsley, K., Michelmore, F., Barnes, K.L., Alers, M.P.T. & Blom, A. (1997) Estimating forest elephant numbers with dung counts and a geographic information system. Journal of Wildlife Management, 61, 13841393.
  • Barnes, R.F.W. & Dunn, A. (2002) Estimating forest elephant density in Sapo National Park (Liberia) with a rainfall model. African Journal of Ecology, 40, 159163.
  • Blanc, J.J., Thouless, C.R., Hart, J.A., Dublin, H.T., Douglas-Hamilton, I., Craig, C.G. & Barnes, R.F.W. (2003) African Elephant Status Report 2002: An update from the African Elephant Database. IUCN/SSC African Elephant Specialist Group. IUCN, Gland, Switzerland and Cambridge, UK.
  • Clark, C.W. & Ellison, W.T. (2000) Calibration and comparison of the acoustic location methods used during the spring migration of the bowhead whale, Balaena mysticetus, off Part Barrow, Alaska, 1984–93. Journal of the Acoustical Society of America, 107, 35093517.
  • Frantz, A.C., Schaul, M., Pope, L.C., Fack, F., Schley, L., Muller, C.P. & Roper, T.J. (2004) Estimating population size by genotyping remotely plucked hair: the Eurasian badger. Journal of Applied Ecology, 41, 985995.
  • Gordon, K.M., Anderson, S.H., Gribble, B. & Johnson, M. (2001) Evaluation of the FLASH (Flashing Light Animal Sensing Host) System in Nugget Canyon, Wyoming. Report Number FHWA-WY-01/03F, PB2002101172. Wyoming Cooperative Fishery and Wildlife Research Unit, University of Wyoming, US Department of Transportation Federal Highway Administration, Laramie.
  • Greenwood, J.J.D. (1996) Basic techniques. Ecological Census Techniques: a Handbook (ed. W. J.Sutherland), pp. 11110. Cambridge University Press, Cambridge.
  • Günther, R.H., O'Connell-Rodwell, C.E. & Klemperer, S.L. (2004) Seismic waves from elephant vocalizations: a possible communication mode? Geophysical Research Letters, 31, L11602.
  • Hawk, H.L., Hawley, J.G., Portlock, J.M. & Scheibner, J.E. (1976) Seismic Intrusion Detector System. US Patent 3 984 803 5 October 1976.
  • Jachmann, H. & Bell, R.H.V. (1979) The assessment of elephant numbers and occupance by means of droppings counts in the Kasungu National Park, Malawi. African Journal of Ecology, 17, 231239.
  • Laing, S.E., Buckland, S.T., Burn, R.W., Lambie, D. & Amphlett, A. (2003) Dung and nest surveys: estimating decay rates. Journal of Applied Ecology, 40, 11021111.
  • Lee, R.D. (1973) Intruder Detection System. U.S. Patent 3 719 891 6 March 1973.
  • Payne, K.B., Thompson, M. & Kramer, L. (2003) Elephant calling patterns as indicators of group size and composition: the basis for an acoustic monitoring system. African Journal of Ecology, 41, 99107.
  • Plumptre, A.J. (2000) Monitoring mammal populations with line transect techniques in African forests. Journal of Applied Ecology, 37, 356368.
  • Prinzivalli, R.A. (1992) Investigating the use of infrared detectors to count elephants in a forest environment. African Journal of Ecology, 30, 346348.
  • Roca, A.L., Georgiadis, N., Pecon-Slattery, J. & O'Brien, S.J. (2001) Genetic evidence for two species of elephant in Africa. Science, 293, 14731477.
  • Ruette, S., Stahl, P. & Albaret, M. (2003) Applying distance-sampling methods to spotlight counts of red foxes. Journal of Applied Ecology, 40, 3243.
  • Seneviratne, L. & Rossel, G. (2001) Living next door to a national park. Sri Lanka Nature, 2001, 5156.
  • Ullrich, R. (1996) Building on and spinning off: Sandia National Lab's creation of sensors for Vietnam. Report no. SAND-96–2824C, CONF-9611112–1. History of Science Society Meeting, 8 November 8 1996, Atlanta, Georgia. US Department of Energy, Washington, DC.
  • Walsh, P.D. & White, L.J.T. (1999) What it will take to monitor forest elephant populations? Conservation Biology, 13, 11941202.
  • Walsh, P.D., White, L.J.T., Mbina, C., Idiata, D., Mihindou, Y., Maisels, F. & Thibault, M. (2001) Estimates of forest elephant abundance: projecting the relationship between precision and effort. Journal of Applied Ecology, 38, 217228.
  • Webbon, C.C., Baker, P.J. & Harris, S. (2004) Faecal density counts for monitoring changes in red fox numbers in rural Britain. Journal of Applied Ecology, 41, 768779.
  • Wing, L.D. & Buss, I.O. (1970) Elephants and forests. Wildlife Monographs, 19, 692.
  • Wood, J.D. (2003) Communication and spatial cohesion of the African elephant, Loxodonta africana. PhD Thesis, University of California, Davis.