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 the other contributions, and respond to any that particularly interest you
Here is my quick summary!!
Distance sampling was used in 2012 by World Wildlife Fund in Cambodia’s Eastern Plains Landscape to survey the endangered banteng population, Bos javanicus. This was the first robust estimate for banteng population and density from areas of the species’ range and used distance-based transect sampling methods. Population estimates were important to inform conservation actions for WWF and for government partners, highlighting the importance of stronger protection efforts that would ensure these populations of banteng survive. The methodology involved 1310 km of observations from 110 1-4km line transects, a sample covering 3406 km2. The recommended protocol for observing ungulates was followed which used 2 observers walking the transects at dawn and dusk and recording the number of animals, the distance between the observer and the animal/group, the bearing to the observer and the bearing of the transect. These observations resulted in a banteng population estimate of 3200 across the 3406 km2 study area (95% confidence interval 1980-5170) suggesting that the Eastern Plains Landscape supported the majority of the global population of banteng at the time.
Thomas N. E. Gray, Sovanna Prum, Chanrattana Pin and Channa Phan (2012). Distance sampling reveals Cambodia’s Eastern Plains Landscape supports the largest global population of the Endangered banteng Bos javanicus. Oryx, 46, pp 563-566 doi:10.1017/S0030605312000567
Monitoring, managing and conserving coastal dolphins pose a challenge primarily due to their sparse population across a large geographic range. Indo-pacific bottlenose dolphin (Tursiops aduncus) and Australian humpback dolphin (Sousa sahulensis) are two sympatric populations of the Pilbara region of Western Australia that face serious anthropogenic risks from habitat loss/degradation, bycatch in trawl fisheries to climate change.
The overall goal of the study was to:
The authors (Raudino et al. 2023) used aerial line transect (via a fixed-wing aircraft) to survey a total area of 33,420 km2 in the austral winters of 2015, 2016, and 2017 across. The density surface modeling (DSM) approach they used to quantify spatio-temporal patterns in dolphin density helped minimize detection, availability and perception biases.
According to the authors, the DSM approach contributed to the goal in the following ways:
Source: Raudino HC, Bouchet PJ, Douglas C, Douglas R and Waples K (2023) Aerial abundance estimates for two sympatric dolphin species at a regional scale using distance sampling and density surface modeling. Front. Ecol. Evol. 10:1086686. doi: 10.3389/fevo.2022.1086686
I looked at this paper: Amin R, Klair H, Wacher T, et al. Estimating forest antelope population densities using distance sampling with camera traps. Oryx . 2022;56(3):345-351. https://doi:10.1017/S0030605320001209
This study used a distance sampling method with camera trapping, to estimate forest antelope population densities in the Dja Faunal Reserve in Cameroon. Populations of several forest antelope species have suffered significant decline as a result of the bushmeat trade in this area, and monitoring the status of these populations - a key aim of this research - is therefore crucial to conserving them.
Monitoring these species through direct sightings or signs is often difficult due to their cryptic and nocturnal habits, the dense vegetation in the area, and the difficulty of identifying to species level based on spoor or other signs. For this reason, camera trapping was used, following a point transect distance sampling methodology. In this approach, each camera in the survey was treated as a point transect, and programmed to record a set number of still images, at a fixed time interval between images, when triggered. During camera set-up, images were taken with a 1-metre pole at various distances from the camera, to be used as a reference when processing images to determine distance of the animal from the camera.
Overall, the study found that this was an effective method for population density estimates of these forest antelope species, but comparison with other sites was difficult due to a lack of data on forest antelope populations, and lack of standardisation of monitoring methods.
I looked at: Rainey HJ, Iyenguet FC, Malanda G-AF, et al. Survey of Raphia swamp forest, Republic of Congo, indicates high densities of Critically Endangered western lowland gorillas Gorilla gorilla gorilla. Oryx. 2010;44(1):124-132. doi:10.1017/S003060530999010X
In the 90s, a preliminary survey on the periphery of the Lac Télé Community Reserve, swamp forests in the northern Republic of Congo indicated that this area may contain high densities of endangered western lowland gorillas and these conservationists wanted to verify this.
It was impossible to study the entire area, as the swamps are part of the largest wetland in Africa (covering 62,500 km2) and access is difficult (all travel is by boat which is not the most effective method of transport for gorilla sightings). Therefore a relatively small area of 1,029 km2 was selected and line transect distance sampling was use to estimate gorilla densities. The distance sampling line transect survey was conducted between March and May 2007 during the dry (low water) season, and to minimize impact on the forest, permanent transects were not cut. Observations of great ape nests were used as a proxy for individual sightings.
Results indicated that estimated density of gorillas in the Raphia swamp forest were among the highest recorded densities of apes in Central Africa. Such high gorilla densities were potentially linked to the availability of monocotyledons as food and the natural protection from hunting offered by the swamp terrain.
The results of this research are important for emphasising the need to conserve the natural forest habitat surrounding the swamp, amidst increasing threats from logging concessions, construction of new roads and an increasing human population.
Illegal exploitation, harvesting for consumption, conflict with humans, and conversion of mangroves to agriculture have led to population declines of saltwater crocodiles (Crocodylus porosus) in Myanmar, their range is now limited to Meinmahlakyun Wildlife Sanctuary (MKWS). Little contemporary data exists on their distribution and population size which hinders effective conservation and management.
Using a combination of spotlight surveys, measuring environmental parameters, and terrestrial camera traps the study aimed to:
1. estimate the proportion of areas occupied by saltwater crocodiles across the sampling sites
2. assess the regional environmental and anthropogenic covariates influencing the occurrence and abundance of crocodiles
3. provide site-specific population sizes of saltwater crocodiles in the Ayeyarwady delta
4. evaluate the current population size estimates of MKWS which were observed by different approaches with the previously reported population size.
The population size was determined to have decreased since 1999, and:
• Crocodiles were more likely to occupy the MKWS than nearby forest
• Crocodile abundance was lower in human settlements
• Occupancy reduced with increasing salinity (crocodiles breed in less saline water)
The study’s findings can feed into land-use planning around the MKWS to minimise human-crocodile conflict.
Than et al. (2020) Estimating population status and site occupancy of saltwater crocodiles Crocodylus porosus in the Ayeyarwady delta, Myanmar: Inferences from Spatial Modeling Techniques, Global Ecology and Conservation. Redirecting
Hi @fcampbell , interesting paper. Just curious,
Please advise was distance sampling used in the 90s plerimenary study?
Source: Cappelle N, Després‐Einspenner ML,
Howe EJ, Boesch C, Kühl HS. Validating camera trap distance
sampling for chimpanzees. Am J Primatol. 2019;81:e22962.
Link: https://www.eva.mpg.de/documents/Wiley-Blackwell/Cappelle_Validating_AmJPrim_2019_3030935.pdf
The overall goal of this research was to assess whether Camera trap distance sampling (CTDS) give accurate results to estimating the abundance of chimpanzees, a semiarboreal primate, in Taï National Park, Côte d’Ivoire.
This was possible as they already knew the estimated abundance in the project site. They compared the results from camera traps to line transects nest counts and spatially explicit capture recapture methods.
The CTDS approach was able to provide accurate, though imprecise, estimated densities measures for a semiarboreal species over a period of 10 months survey. They attribute this imprecision to the small number of locations and the nonrandom movement of the chimpanzees. Which could be easily corrected by increasing the number of sampling locations.
Hello! I chose an article I read a while ago and saved it because the survey was done in the area where I work.
The goal of the conservation research in this article is to estimate the population densities of mesocarnivores on commercial farmland in South Africa, providing data to guide long-term wildlife management. Understanding the abundance and distribution of these species is essential for managing ecosystems and addressing human-wildlife conflicts, especially in agricultural landscapes where interactions with wildlife are frequent. Accurate population estimates can inform more effective conservation strategies and help mitigate conflicts.
Distance sampling with camera traps (CTDS) plays a crucial role in achieving this goal by offering a reliable method to estimate densities of unmarked species, which are often difficult to monitor with traditional techniques. By combining camera trapping with the precision of distance sampling, CTDS allows researchers to gather accurate data on elusive, nocturnal species like mesocarnivores. This method helps overcome challenges in tracking these species, providing important insights into their population dynamics and aiding in the development of better management practices.
I manged to read a research study titled " Distribution and population status of the African wild dog in Bicuar National Park, Angola: Insights from interview-based surveys and camera trapping"
See link below.
Summary.:
The overall goal was to extend existing knowledge relevant to the conservation of wild dogs calls by the Angolan National Institute of Biodiversity and Conservation Areas (INBAC) and IUCN/SSC (2015). The studies conducted in 2020 did not provide other relevant information, such as overall distribution, breeding occurrence, population estimates, or prey availability and was limited to the northern section of this protected area where road accessibility is higher.
Distance sampling contributes to this goal by providing a method best suited to study the Wild dogs as they are elusive species that usually occur at low densities and have large home ranges. To assess the availability of potential prey and competitors, as well as to gain additional evidence of residence and breeding of wild dog packs, we deployed 16 infrared camera traps from December 2016 to March 2017 in the northern and west area of Bicuar. This was triangulated with key informant interviews and recording of opportunistic presence records of wildlife species, including direct observations and indirect signs such as spoor tracks identified by experienced observers. They also intentionally visited other sites where park rangers reported frequent sightings or signs of wild dogs’ presence. Observations were mostly obtained when traversing the National Park to reach the vigilance posts. For each observation, species, the total number of individuals and geographic coordinates were recorded.
Comment.: I could not ascertain if the direct observations obtained when traversing their study area is also a distance sampling method.
A post was split to a new topic: Analysing sign instead of live sightings
Charmaille-Jammes, S., Valeix, M., Bourgarel, M., Murindagomo, F. and Fritz, H., 2009. Seasonal density estimates of common large herbivores in Hwange National Park, Zimbabwe.
The paper that I read estimated densities of ungulates in the late-dry and early wet seasons in a national park. The approach used involved recording distances of observed animals from transect lines (roads), angle from the road and angle North. The combined data was then analysed using distance software and densities were deduced. The main objective of the paper/research was to estimate densities of large ungulates and compare them over time (1999-2005).
Using roads as transacts was said to be questionable, but also said to work in large areas and in large species. In the study, existing roads were used. Habitat use by different species at different times of the year was established. Elephant densities were said to be high at 3individuals per sqkm in the late dry season, with up to 9individuals per sqkm in some years.
You’re always welcome to start a new Topic if you’d like to discuss something that diverges from our original discussion, @Morena_Rodriguez . I’ll move your question to a new topic now 
My research paper uses distance sampling to estimate the national population of common and widespread breeding birds in the UK, and then compares these estimates with other methods previously used, such as territory mapping and direct counts from sample areas.
The paper found a strong positive relationship between distance sampled estimates of national bird populations and estimates from previous methods. However quantitative differences did exist.
Firstly, the study also found that distance sampled estimates were lower than existing estimates in species that had marked sex biases in detectability. Secondly, it found distance sampled estimates were higher in species with a larger proportion of non-breeding individuals, as intense territory mapping aim to count breeding pairs only.
The paper highlights the need for more precise population estimates in relation to UK birds and the need to explicitly state whether the unit of interest is total population size or breeding population.
@Matt_Gudge I found the following findings from Newson et al. 2008 applicable to my classes and urban nature preserve monitoring work:
Using eBird data in combination with the BBS and other data is becoming commonplace to estimate bird population abundance specially in North American Studies.
One such Great Lakes study used 23 years (1997–2019) of GLMMP (the Great Lakes Marsh Monitoring Program), BBS, and eBird data to calculate abundance indices (Bianchini & Tozer, 2023).
They found that:
Exclusive marsh breeders were detected more frequently and in precise numbers by the GLMMP as opposed to birds that preferred variable habitats. These studies provide crucial information on habitat-specific breeding characteristics and are fundamental to planning and implementation of any monitoring program.
Bianchini, Kristin, and Douglas Tozer. “Using Breeding Bird Survey and EBird Data to Improve Marsh Bird Monitoring Abundance Indices and Trends.” Avian Conservation and Ecology, vol. 18, no. 1, 2023, Using Breeding Bird Survey and eBird data to improve marsh bird monitoring abundance indices and trends - Avian Conservation and Ecology. Accessed 20 Feb. 2023.
@Nicorll , I think this depends on whether:
Thanks Sau. I’ll give the article a read. It’s nice to see citizen science like EBird being used like this.
A post was split to a new topic: Camera traps for distance sampling
Hello, i read a paper titled First insights into the spatio-temporal ecology of sympatric large carnivores in Niokolo-Koba National Park, Senegal
The link below
First insights into the spatio-temporal ecology of sympatric large carnivores in Niokolo-Koba National Park, Senegal | Oryx | Cambridge Core
They conducted a camera-trap survey during the dry season in Niokolo-Koba National Park, the largest terrestrial protected area in Senegal and the second largest in West Africa, to investigate the spatio-temporal ecology of the four large carnivores inhabiting the Park: the spotted hyaena Crocuta crocuta, leopard Panthera pardus, West African lion Panthera leo leo and African wild dog Lycaon pictus. They used 139 cameras covering one fifth of the park (1,523 km2), they chose micro placement remotely through satellite imagery to maximise carnivore detection by identifying areas with large carnivore spoors, scats and prey carcasses or proximity to water. When no sign of presence could be found, they deployed cameras along vehicle tracks and at the intersections of wildlife trails which carnivores usually prefer to use. They found out that the most frequently detected large carnivore was the spotted hyaena, followed by leopard, lion and African wild dog.
Their study is the first to focus on large carnivores in Niokolo-Koba National Park, Senegal, and is one of few such studies in West Africa. By providing new information on the ecology of large carnivores in West Africa, including where they range and which habitats are critical for their survival, this study will facilitate conservation planning. Robust baseline data are needed on the population sizes, distributions and ecological roles of large carnivores in this region, as well as the potential threats that they face. This information could then be used to develop targeted conservation strategies therefore there is urgent need of more research on these species in West Africa.
Hello, I managed to go through this paper ; Using distance sampling with camera traps to estimate the density of group-living and solitary mountain ungulateshttps://www.cambridge.org/core/journals/oryx/article/using-distance-sampling-with-camera-traps-to-estimate-the-density-of-groupliving-and-solitary-mountain-ungulates/C5D958932D21025637F461B7D3332AC4
Here is the summary;
Throughout the Himalaya, mountain ungulates are threatened by hunting for meat and body parts, habitat loss, and competition with livestock. Accurate population estimates are important for conservation management but most of the available methods to estimate ungulate densities are difficult to implement in mountainous terrain.
This study tested the efficacy of camera traps to estimate density of two mountain ungulates: the group-living Himalayan blue sheep or bharal Pseudois nayaur and the solitary Himalayan musk deer Moschus leucogaster in the in the trans-Himalayan part (Nilang valley) of Gangotri National Park, in the subalpine portion of the Park and Uttarkashi Forest Division within Uttarakhand State,India.
Camera traps were deployed in 2017–2018 for the bharal (summer: 21 locations; winter: 25) in the trans-Himalayan region (3,000–5,000 m) and in 2018–2019 for the musk deer (summer: 30 locations; winter: 28) in subalpine habitats (2,500–3,500 m) in the Upper Bhagirathi basin Uttarakhand, India. Although the ruggedness of the mountainous terrain proved difficult for using camera traps overall the approach proved to be advantageous for population estimates of remote dwelling and elusive species.