Distance Sampling

Distance sampling is widely used for estimating the abundance of wild animal populations. St Andrews provides software implementing our methodologies for designing and analysing distance sampling surveys. This software has been downloaded by over 35,000 users in over 110 countries. The two most widely used forms of distance sampling are line and point transect sampling. In line transect sampling, an observer travels along a line, and records distances from the line of detected animals. A model for the probability of detection as a function of distance from the line is fitted, from which abundance is estimated. In point transect sampling, an observer visits points, and records distances of detected animals from each point. In the mural, the equation Pa = ... describes the average detection probability in the surveyed area for line transects.

How many dolphins are in the sea?

One of the big question in wildlife conservation is 'how many are there?' If you would like to know, for example, how many spinner dolphins are in the eastern tropical Pacific, it is easy to see that you cannot count them all. Hence, we use distance sampling methods to estimate the number (or abundance) of these dolphins. The way this works can be described in short (and very simplified): a ship with a team of observers travels on pre-defined transect lines across the study area covering a proportion of the total area. The observers scan the ocean all day during daylight hours and record each school of dolphins that they detect along with information on weather and sighting conditions. For each school of dolphins they also record how many dolphins are in the school, what species it is and, very importantly, how far these dolphins were from the transect line. Back in the office, we use this information on the distance of the schools from the line to estimate how many schools we missed in the area that we covered with our search and arrive at an estimate of how many dolphins there were in the covered area. We also know the proportion of the total area we covered and, hence, can scale up our our estimate of numbers in the covered area to an estimate of dolphins in the study area.


Related Publications

Borchers, D.L. and Cox, M.J. in press. Distance sampling detection functions: 2D or not 2D? Biometrics.

Potts, J.M., Buckland, S.T., Thomas, L. and Savage, A. in press. Estimating Key Largo woodrat abundance using spatially explicit capture-recapture and trapping point transects. Wildlife Society Bulletin.

Yuan, Y., Bachl, F.E., Lindgren, F., Borchers, D.L., Illian, J.B., Buckland, S.T., Rue, H. and Gerrodette, T. Point process models for spatio-temporal distance sampling data.

Buckland, S.T., Oedekoven, C.S. and Borchers, D.L. 2016. Model-based distance sampling. Journal of Agricultural, Biological and Environmental Statistics 21, 58-75.

Buckland, S.T., Rexstad, E., Thomas, L. and Borchers, D.L. 2016. Distance sampling surveys of population size: enabling better decision-making by wildlife managers. Pp. 45-51 in UK Success Stories in Industrial Mathematics, P.J. Aston, T.J. Mulholland and K.M.M. Tant (eds). Springer, New York.

Oedekoven, C.S., King, R., Buckland, S.T., Mackenzie, M.L., Evans, K.O. and Burger, L.W. 2016. Using hierarchical centering to facilitate a reversible jump MCMC algorithm for random effects models. Computational Statistics and Data Analysis 98, 79-90.

Borchers, D.L. and Langrock, R. 2015. Double-observer line transect surveys with Markov-modulated Poisson process models for animal availability. Biometrics 71, 1060-1069.

Borchers, D.L., Stevenson, B.C., Kidney, D., Thomas, L. and Marques, T.A. 2015. A unifying model for capture-recapture and distance sampling surveys of wildlife populations. Journal of the American Statistical Association 110, 195-204.

Buckland, S.T., Rexstad, E.A., Marques, T.A. and Oedekoven, C.S. 2015. Distance Sampling: Methods and Applications. Springer, New York.

Glennie, R., Buckland, S.T. and Thomas, L. 2015. The effect of animal movement on line transect estimates of abundance. PLoS ONE 10, e0121333.

Oedekoven C.S., J.L. Laake & H.L. Skaug. 2015. Distance sampling with a random scale detection function. Environmental and Ecological Statistics, 22:725-737

Burt, M.L., Borchers, D.L., Jenkins, K.J. and Marques, T.A. 2014. Using mark-recapture distance sampling methods on line transect surveys. Methods in Ecology and Evolution 5, 1180-1191.

Oedekoven, C.S., Buckland, S.T., Mackenzie, M.L., King, R., Evans, K.O. and Burger, L.W. 2014. Bayesian methods for hierarchical distance sampling models. Journal of Agricultural, Biological and Environmental Statistics 19, 219-239.

Okot Omoya, E., Mudumba, T., Buckland, S.T., Mulondo, P. and Plumptre, A.J. 2014. Estimating population sizes of lions Panthera leo and spotted hyaenas Crocuta crocuta in Ugandas savannah national parks using lure count methods. Oryx 48, 394-401.

Borchers, D.L., Zucchini, W., Heide-Jørgensen, M.P., Cañadas, A. and Langrock, R. 2013. Using hidden Markov models to deal with availability bias on line transect surveys. Biometrics 69, 703-713.

Cox, M.J., Borchers, D.L. and Kelly, N. 2013. Nupoint: an R package for density estimation from point transects in the presence of nonuniform animal density. Methods in Ecology and Evolution 4, 589-594.

Evans, K.O., Burger, L.W., Oedekoven, C.S., Smith, M.D., Riffell, S.K., Martin, J.A. and Buckland, S.T. 2013. Multi-region response to conservation buffers targeted for northern bobwhite. J. Wildlife Management 77, 716-725.

Langrock, R., Borchers, D.L. and Skaug, H. 2013. Markov-modulated nonhomogeneous Poisson processes for modeling detections in surveys of marine mammal abundance. Journal of the American Statistical Association 108, 840-851.

Marques, T.A., Buckland, S.T., Bispo, R. and Howland, B. 2013. Accounting for animal density gradients using independent information in distance sampling surveys. Statistical Methods and Applications 22, 67-80.

Oedekoven, C.S., Buckland, S.T., Mackenzie, M.L., Evans, K.O. and Burger, L.W. 2013. Improving distance sampling: accounting for covariates and non-independency between sampled sites. J. App. Ecol. 50, 786-793.

Plumptre, A.J., Sterling, E.J. and Buckland, S.T. 2013. Primate census and survey techniques. Pp. 10-26 in Primate Ecology and Conservation: A Handbook of Techniques. E.J. Sterling, N. Bynum and M.E. Blair (eds). Oxford University Press, Oxford.

Buckland, S.T., Burt, M.L., Rexstad, E.A., Mellor, M., Williams, A.E. and Woodward, R. 2012. Aerial surveys of seabirds: the advent of digital methods. J. App. Ecol. 49, 960-967.

Potts, J.M., Buckland, S.T., Thomas, L. and Savage, A. 2012. Estimating abundance of cryptic but trappable animals using trapping point transects: a case study for Key Largo woodrats. Methods in Ecology and Evolution 3, 695-703.

Cox, M.J., Borchers, D.L., Derner, D.A., Cutter, G.R. and Brierley, A.S. 2011. Estimating the density of Antarctic krill (Euphausia superba) from multi-beam echo-sounder observations using distance sampling methods. Applied Statistics 60, 301-316.

Summers, R.W. and Buckland, S.T. 2011. A first survey of the global population size and distribution of the Scottish crossbill Loxia scotica. Bird Conservation International 21, 186-198.

Borchers, D., Marques, T., Gunnlaugsson, T. and Jupp, P. 2010. Estimating distance sampling detection functions when distances are measured with errors. Journal of Agricultural, Biological and Environmental Statistics 15, 346-361.

Buckland, S.T., Laake, J.L. and Borchers, D.L. 2010. Double-observer line transect methods: levels of independence. Biometrics 66, 169-177.

Buckland, S.T., Plumptre, A.J., Thomas, L. and Rexstad, E.A. 2010. Line transect sampling of primates: can animal-to-observer distance methods work? International Journal of Primatology 31, 485-499.

Buckland, S.T., Plumptre, A.J., Thomas, L. and Rexstad, E.A. 2010. Design and analysis of line transect surveys for primates. International Journal of Primatology 31, 833-847.

Marques, T.A., Buckland, S.T., Borchers, D.L., Tosh, D. and McDonald, R.A. 2010. Point transect sampling along linear features. Biometrics 66, 1247-1255.

Russell, R.E., Lehmkuhl, J.F., Buckland, S.T. and Saab, V.A. 2010. Short-term responses of red squirrels to prescribed burning in the interior Pacific Northwest, USA. Journal of Wildlife Management 74, 12-17.

Thomas, L., Buckland, S.T., Rexstad, E.A., Laake, J.L., Strindberg, S., Hedley, S.L., Bishop, J.R.B., Marques, T.A. and Burnham, K.P. 2010. Distance software: design and analysis of distance sampling surveys for estimating population size. J. App. Ecol. 47, 5-14.

Related Links

The Distance Home Page

Research by Prof. Steve Buckland

Research by Dr. Len Thomas

Research by Dr. Cornelia Oedekoven

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