Write a short summary (3-4 sentences) of an application of distance sampling, based on your own experience, or on a research paper or report
In your summary, answer these questions:
If you are summarising an online paper, please link to it so others can read it
Read some of the other contributions, and respond to any that particularly interest you
The overall goal of this conservation monitoring research is to accurately estimate and monitor the population densities of forest antelopes (both common and rare species) in order to support effective conservation planning and action in forest ecosystems like in the Central Forest Reserves. Because traditional transect surveys often miss animals in dense vegetation and underestimate true numbers, the study uses camera traps to collect more reliable detection data.
Distance sampling contributes by using the measured distances of animals captured on camera to estimate detection probability and species density, helping correct for animals that are present but not detected. The researchers also improve accuracy by adjusting for animal activity/behavior patterns and using body weight, breeding period to better estimate densities for rarer speciesā¦..doi:10.1017/S0030605320001209
I read this paper on a non-traditional application of distance sampling for estimating feral cat abundance in urban areas: https://onlinelibrary.wiley.com/doi/10.1002/ece3.4938
The goal was to estimate feral cat density, both across the sampling area and within specific units, to identify areas to target for intervention (euthanasia or trap-neuter-release) and evaluate the effectiveness on ongoing interventions in reducing feral cat populations. Feral cat predation can have a large impact on native species, particularly birds.
Distance sampling was highlighted as an important survey method for this due to the challenges of accessing private lands in a dense urban area and human interference. This allowed the researcher to leverage the grid of public roads to do transects without having to trespass on private property. While standard distance sampling techniques would discourage using roads for transects, it made sense for this study in surveying private property and with the assumption that thereās a low degree of variability across the sampling area in terms of terrain/feral cat habitat.
The incorporation of the āaverage distance to obstructionā in the modeling was an interesting covariate to consider in an urban environment, as buildings and other manmade objects often impede visual line of sight. A similar method could be used for natural areas where there are forests, cliffs, or other environmental factors that restrict viewing distance.
The chosen articleās main objective (Estimating forest antelope population densities using distance sampling with camera traps | Oryx | Cambridge Core) is to estimate the density of forest antelope populations in Dja Faunal Reserve (Cameroon).
Distance sampling enables to get an estimate of the density of the study species without the notable costs and detectability limitations that other traditional methoulds possess. The former include unpracticable hours of field work bearing the size and ruggedness of the study area whilst amongst the latter we find difficulty of identification of species bearing dense understory or shy and nocturnal behaviour of the study species.
I read an article titled āAssessing mammal population densities in response to urbanization using camera trap distance samplingā here: https://doi.org/10.1002/ece3.10634Digital Object Identifier (DOI)
The goal is to study the impacts of urbanization through comparing distance sampling findings from two invasive species (dogs and cats) and three native species (weasels, hedgehogs, and hares) in rural-urban Tianjin, China. This is so important because urbanization is negatively impacting crucial ecosystems and global biodiversity. With continued expansion and habitat fragmentation and loss, the study argues that we must understand spatiotemporal dynamics of wildlife in order to conserve them.
To begin to understand the dynamics, the study employed the distance sampling framework with camera traps. This was chosen for its suitability in habitats with dense vegetation and for mammals that are more elusive (eg:hedgehogs). They placed the cameras in parks, woodlands, wastelands, and riparian zones. The research team found that cat, weasel, and hedgehog population densities increased with urbanization. Another finding was that the invasive speciesā population densities were impacted by urban-related activities, while the native speciesā densities were impacted by both urban and nature-based variables.
@Byro_ns @JManas and @Morgan, the studies you chose are great examples of how we can combine the strengths of camera-trapping and distance sampling 
Camera trapping advantages:
Distance sampling advantages:
@matthron, I find the feral cat paper interesting because of their use of public roads for their transects, especially compared to @Morganās paper where they placed cameras in urban green spaces. Placing transects along roads is generally discouraged because of the risk of bias, if the species of interest either avoids or actively uses roads, breaking the Random placement assumption of distance sampling. From my quick read of the paper, they selected roads at random, and propose that the high density of roads, urban speciesā familiarity with roads, and their dependence on anthropogenic resources found along roads means that cats wouldnāt be affected by roads. Maybe the papers they cite have more evidence to support this?
I found an article titled āUsing distance sampling with camera traps to estimate the density of group-living and solitary mountain ungulatesā.
The overall goal of the monitoring was to determine density of mountain ungulates in the Himalayan mountains; specifically, the Himalayan musk deer and Himalayan blue sheep. Determining successful density counts are crucial for conservation management as these ungulates are threatened by various factors such as hunting, habitat loss and livestock competition. However, the rugged and steep terrain proves difficult for conventional techniques.
The researcher determined that using camera traps and extending the point transect method with distance sampling would be the best option. Their results showed that distance sampling with camera work can overcome constraint that comes with the rugged terrain and harsh weather that may affect other sampling methods. Given that this technique had not yet been tested in mountainous terrain at the time, the team acknowledged the advantages and disadvantages of the camera trap within this project. Overall, they found the distance sampling with camera trap approach could help improve abundance estimations for mountain ungulates.
Hello, I have chosen the article āEstimating density of secretive terrestrial birds (Siamese Fireback) in pristine and degraded forest using camera traps and distance samplingā from Science Direct.
The overall goal of this conservation research is to accurately estimate wildlife population density and abundance of the Siamese Fireback in North-East Thailand. The goal of the research is to monitor trends over time and to make informed conservation decisions. Distance sampling contributes to this goal by accounting for the fact that not all animals present are detected during surveys, especially because some of them ālack unique identification markingsā. Distance sampling, therefore, allows researchers to correct counts and produce more accurate population estimates.
Hello, this paper āUse of aerial distance sampling to estimate abundance of tule elk across a gradient of canopy cover and comparison to a concurrent fecal DNA spatial capture-recapture surveyā combines distance sampling with aeral survey to estimate the abundance of Tule elk in California. Traditionally the aeral survey is used to obtain a minimum count indice, and in this paper they present the result of using the aereal survey using the distance sampling (multiple covariate distance sampling) and they compare the results and the costs to the results of fecal DNA spatial capture-recapture (SCR) surveys.
The overall goal of this research was to test a survey method, rather than the elk population survey itself, and I find it very interesting because the application of areal transect can be nowadays done with drones equipped with infrared cameras, and therefore reduce the costs and the human effort (and maybe increase detectability?).
In this case the distance sampling transect were done using an helicopter, 3 human observers and a distance tool (rangefinders, that prove to not be too accurate, so they results in using GPS points and then calculate the distance using satellite measurements).
This paper is from 2022, do you know any up-to-date papers that explore this method, maybe with drones?
Hello, a very interesting part of this study is the calibration process for the distance sampling with the cameratrap, I conduct some cameratrap deployment and we did the calibration in evergreen dense forest in mountain areas, we didināt use the calibration pole as they did in this study, we used a measuring tape and a small whiteboard and we record the distance from the camera at 1, 2, 3, 4, m and go on until the vegetation was too dense to pass. the challange of the vegetation and the slope was real, and the fieldwork condition sometimes made it very difficult to complete the calibration process. At the end a sloppy calibration did influenced negatively the outcome of the distance sampling.
So I guess an important thing to be considered when using distance sampling with cameratrap is the calibration process!
In the paper https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2664.2008.01480.x they use distance sampling to estimate bird population sizes for common and wide-spread species in the UK. Distance sampling provided a different estimate than other methods, as for example more habitats were sampled.
It was interesting to read as it is an older study (from 2008). They found that distance sampling resulted in much larger estimates of bird populations than previous estimates, partly because non-breeding individuals are more included.
The overall goal of conservation monitoring and research is to ensure that reliable information obtained on wildlife population size, density and trends so that informed management decisions can be made. To guild conservation efforts effectively includes detecting population changes, evaluating the effectiveness of conservation actions and prioritizing resources and efforts to species or areas that requires them the most.
In Kruger National Park, distance sampling produced sufficiently precise estimates for species such as giraffe, impala, kudu, zebra, white rhinoceros, and bull elephants, making it suitable for monitoring trends and informing management decisions. By modelling how detectability decreases with distance from transects, it allows comparisons over time and space, making it possible to monitor population trends. https://doi.org/10.1071/WR07084
Really interesting to see distance sampling combined with eDNA spatial-MR in Chiaraās example!
@Eve_Bohnett and @matthron can you recommend other papers for Chiara? @Chiara, WildLabs is a good place to ask this question too
Iām also curious about the use of UAVs and thermal imaging that @Eve_Bohnett has mentioned elsewhere, specifically how distances are calculated. I see multiple possibilities:
@majellinās paper contains a useful example of testing for sampling bias. The researchers compared the ruggedness of their camera locations with the landscape as a whole, allowing them to check they had sampled all types of terrain
The lack of unique marking makes distance sampling an obvious choice in Saraās study, while Capture-Mark-Recapture (CMR) can be better for density estimation where animals can be individually identified
Thank you Lucy!
I love when papers have a in-deep description of the methodology! it feels like the authors actually care about research and want people to be able to replicate their studies and learn from their mistakes rather than gatekeeping!
The overall goal of the research was to evaluate whether distance sampling provides accurate, unbiased estimates of reptile population density for conservation monitoring. Distance sampling contributes to this goal by modeling detection probability and producing absolute density estimates without requiring capture or marking. However, through hard validation against total removal and validated mark-recapture estimates, the study demonstrated that distance sampling substantially underestimated true population densities in forest habitats due to incomplete detection and species-specific visibility bias. Thus, its reliability for conservation monitoring of forest reptiles is questionable.
Paper tittle:
Distance Sampling of Forest Snakes and Lizards
Thanks for sharing this paper, @mimi.rezoana. Itās refreshing to read a paper that rigorously validates distance sampling against other methods of estimating density, and discusses why it failed in their particular situation
In this case, they believe the āDetection is certainā assumption was broken, because they failed to detect all squamates on the transect line (along the forest trail)
Here is a link to the paper (I assume this is the one you read?): https://www.researchgate.net/publication/292051026_Distance_sampling_of_forest_snakes_and_lizards
Delaney et al. (2025) ā Method matters: Use of ThermalāImaging Drones to Assess the Assumptions of Density Estimation Techniques published in Ecological Applications (2025). The study used thermalāimaging drones to examine the assumptions that underpin methods like distance sampling and related density estimation approaches for wildlife (whiteātailed deer in Iowa, USA). Drones equipped with thermal cameras flew systematic surveys at night to count deer and evaluate how detection probability changes with factors like vegetation, animal behavior, and distance from the observer. The authors discuss how UAV data can help validate and improve distance sampling protocols by quantifying detection biases and availability of animals across landscapes, which is critical for making density estimates more reliable. While the study didnāt only present a full distance sampling density estimate (thatās still emerging in the literature), it explicitly used droneābased surveys in the context of distance sampling model design and evaluation, showing how TIRāUAV data can help build or improve distance sampling workflows ā which is exactly the kind of applied conservation research youāre looking for.