scholarly journals Estimating forest antelope population densities using distance sampling with camera traps

Oryx ◽  
2021 ◽  
pp. 1-7
Author(s):  
Rajan Amin ◽  
Hannah Klair ◽  
Tim Wacher ◽  
Constant Ndjassi ◽  
Andrew Fowler ◽  
...  
Keyword(s):  
Survey Methods ◽  
Distance Sampling ◽  
Common Species ◽  
Camera Trap ◽  
Camera Traps ◽  
Individual Species ◽  
Survey Tool ◽  
Terrestrial Mammals ◽  
Detection Probabilities ◽  
The Status

Abstract Traditional transect survey methods for forest antelopes often underestimate density for common species and do not provide sufficient data for rarer species. The use of camera trapping as a survey tool for medium and large terrestrial mammals has become increasingly common, especially in forest habitats. Here, we applied the distance sampling method to images generated from camera-trap surveys in Dja Faunal Reserve, Cameroon, and used an estimate of the proportion of time animals are active to correct for negative bias in the density estimates from the 24-hour camera-trap survey datasets. We also used multiple covariate distance sampling with body weight as a covariate to estimate detection probabilities and densities of rarer species. These methods provide an effective tool for monitoring the status of individual species or a community of forest antelope species, information urgently needed for conservation planning and action.

Can camera trapping be used to accurately survey and monitor the Hastings River mouse (Pseudomys oralis)?

2016 ◽  
Vol 38 (1) ◽  
pp. 44 ◽  
Author(s):  
Paul D. Meek ◽  
Karl Vernes
Keyword(s):  
Small Mammals ◽  
Small Mammal ◽  
Survey Methods ◽  
Camera Trap ◽  
Camera Traps ◽  
Camera Trapping ◽  
Common Element ◽  
Computer Assisted ◽  
Survey Tool ◽  
Wide Range

Camera trapping is increasingly recognised as a survey tool akin to conventional small mammal survey methods such as Elliott trapping. While there are many cost and resource advantages of using camera traps, their adoption should not compromise scientific rigour. Rodents are a common element of most small mammal surveys. In 2010 we deployed camera traps to measure whether the endangered Hastings River mouse (Pseudomys oralis) could be detected and identified with an acceptable level of precision by camera traps when similar-looking sympatric small mammals were present. A comparison of three camera trap models revealed that camera traps can detect a wide range of small mammals, although white flash colour photography was necessary to capture characteristic features of morphology. However, the accurate identification of some small mammals, including P. oralis, was problematic; we conclude therefore that camera traps alone are not appropriate for P. oralis surveys, even though they might at times successfully detect them. We discuss the need for refinement of the methodology, further testing of camera trap technology, and the development of computer-assisted techniques to overcome problems associated with accurate species identification.

scholarly journals Long-term monitoring of margays (Leopardus wiedii): Implications for understanding low detection rates

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0247536
Author(s):  
Bart J. Harmsen ◽  
Nicola Saville ◽  
Rebecca J. Foster
Keyword(s):  
Detection Rate ◽  
Camera Trap ◽  
Wide Distribution ◽  
Camera Traps ◽  
Detection Rates ◽  
Terrestrial Mammals ◽  
Exclusive Territories ◽  
Carnivore Species ◽  
Density Population

Population assessments of wide-ranging, cryptic, terrestrial mammals rely on camera trap surveys. While camera trapping is a powerful method of detecting presence, it is difficult distinguishing rarity from low detection rate. The margay (Leopardus wiedii) is an example of a species considered rare based on its low detection rates across its range. Although margays have a wide distribution, detection rates with camera traps are universally low; consequently, the species is listed as Near Threatened. Our 12-year camera trap study of margays in protected broadleaf forest in Belize suggests that while margays have low detection rate, they do not seem to be rare, rather that they are difficult to detect with camera traps. We detected a maximum of 187 individuals, all with few or no recaptures over the years (mean = 2.0 captures/individual ± SD 2.1), with two-thirds of individuals detected only once. The few individuals that were recaptured across years exhibited long tenures up to 9 years and were at least 10 years old at their final detection. We detected multiple individuals of both sexes at the same locations during the same survey, suggesting overlapping ranges with non-exclusive territories, providing further evidence of a high-density population. By studying the sparse annual datasets across multiple years, we found evidence of an abundant margay population in the forest of the Cockscomb Basin, which might have been deemed low density and rare, if studied in the short term. We encourage more long-term camera trap studies to assess population status of semi-arboreal carnivore species that have hitherto been considered rare based on low detection rates.

scholarly journals Incorporating Availability for Detection in Estimates of Bird Abundance

The Auk ◽  
2007 ◽  
Vol 124 (1) ◽  
pp. 96-106 ◽  
Author(s):  
Duane R. Diefenbach ◽  
Matthew R. Marshall ◽  
Jennifer A. Mattice ◽  
Daniel W. Brauning
Keyword(s):  
Survey Methods ◽  
Distance Sampling ◽  
Sampling Period ◽  
Bird Abundance ◽  
Point Counts ◽  
Variance Estimators ◽  
Bird Survey ◽  
Detection Probabilities ◽  
Ammodramus Henslowii ◽  
Further Development

Abstract Several bird-survey methods have been proposed that provide an estimated detection probability so that bird-count statistics can be used to estimate bird abundance. However, some of these estimators adjust counts of birds observed by the probability that a bird is detected and assume that all birds are available to be detected at the time of the survey. We marked male Henslow's Sparrows (Ammodramus henslowii) and Grasshopper Sparrows (A. savannarum) and monitored their behavior during May-July 2002 and 2003 to estimate the proportion of time they were available for detection. We found that the availability of Henslow's Sparrows declined in late June to <10% for 5- or 10-min point counts when a male had to sing and be visible to the observer; but during 20 May-19 June, males were available for detection 39.1% (SD = 27.3) of the time for 5-min point counts and 43.9% (SD = 28.9) of the time for 10-min point counts (n = 54). We detected no temporal changes in availability for Grasshopper Sparrows, but estimated availability to be much lower for 5-min point counts (10.3%, SD = 12.2) than for 10-min point counts (19.2%, SD = 22.3) when males had to be visible and sing during the sampling period (n = 80). For distance sampling, we estimated the availability of Henslow's Sparrows to be 44.2% (SD = 29.0) and the availability of Grasshopper Sparrows to be 20.6% (SD = 23.5). We show how our estimates of availability can be incorporated in the abundance and variance estimators for distance sampling and modify the abundance and variance estimators for the double-observer method. Methods that directly estimate availability from bird counts but also incorporate detection probabilities need further development and will be important for obtaining unbiased estimates of abundance for these species. Incorporación de la Disponibilidad para la Detección en las Estimaciones de Abundancia de Aves

Effects of different attractants and human scent on mesocarnivore detection at camera traps

2020 ◽  
Vol 47 (4) ◽  
pp. 338
Author(s):  
Bracy W. Heinlein ◽  
Rachael E. Urbanek ◽  
Colleen Olfenbuttel ◽  
Casey G. Dukes
Keyword(s):  
Fatty Acid ◽  
Castor Oil ◽  
Camera Trap ◽  
Camera Traps ◽  
Individual Species ◽  
Detection Rates ◽  
Capture Success ◽  
Affect Detection ◽  
Species Specific

Abstract ContextCamera traps paired with baits and scented lures can be used to monitor mesocarnivore populations, but not all attractants are equally effective. Several studies have investigated the efficacy of different attractants on the success of luring mesocarnivores to camera traps; fewer studies have examined the effect of human scent at camera traps. AimsWe sought to determine the effects of human scent, four attractants and the interaction between attractants and human scent in luring mesocarnivores to camera traps. Methods We compared the success of synthetic fermented egg (SFE), fatty acid scent (FAS) tablets, castor oil, and sardines against a control of no attractant in luring mesocarnivores to camera traps. We deployed each attractant and the control with either no regard to masking human scent or attempting to restrict human scent for a total of 10 treatments, and replicated treatments eight to nine times in two different phases. We investigated whether: (1) any attractants increased the probability of capturing a mesocarnivore at a camera trap; (2) not masking human scent affected the probability of capturing a mesocarnivore at a camera trap; and (3) any attractants increased the probability of repeat detections at a given camera trap. We also analysed the behaviour (i.e. speed and distance to attractant) of each mesocarnivore in relation to the attractants. Key resultsSardines improved capture success compared with the control treatments, whereas SFE, castor oil, and FAS tablets had no effect when all mesocarnivores were included in the analyses. Masking human scent did not affect detection rates in the multispecies analyses. Individually, the detection of some species depended on the interactions between masking (or not masking) human scent and some attractants. ConclusionsSardines were the most effective as a broad-based attractant for mesocarnivores. Mesocarnivores approached traps baited with sardines at slower rates, which allows for a higher success of capturing an image of the animal. ImplicationsHuman scent may not need to be masked when deploying camera traps for multispecies mesocarnivore studies, but researchers should be aware that individual species respond differently to attractants and may have higher capture success with species-specific attractants.

The effect of survey method on the detection probabilities of frogs and tadpoles in large wetland complexes

2017 ◽  
Vol 68 (4) ◽  
pp. 686 ◽  
Author(s):  
Skye Wassens ◽  
Andrew Hall ◽  
Jennifer Spencer
Keyword(s):  
Survey Methods ◽  
Likelihood Estimation ◽  
Survey Method ◽  
Individual Species ◽  
Detection Probabilities ◽  
Poor Indicator ◽  
Frog Species ◽  
Species Combination ◽  
Bait Traps ◽  
Fyke Nets

Knowledge of the probability of detecting a species with a given survey effort is important when planning monitoring programs. The present paper compares detection probabilities for six survey methods: audio-visual transect surveys targeting adult frogs, and sweep netting, bait traps, small fyke nets, large fyke nets and seine netting targeting tadpoles. Data were drawn from repeat surveys of 16 wetlands over a 3-year period (2008–2011). Detection probabilities of each method and species combination were determined by maximum likelihood estimation. Audio-visual surveys targeting adults had a higher probability of detecting individual species than did methods targeting their tadpoles. However, the presence of adults was a reasonably poor indicator of the presence of their tadpoles on any given survey occasion. Of the methods employed to target tadpoles, large and small fyke nets had a significantly higher probability of detecting tadpoles of all species than did bait traps, seining or sweep nets. Differences in the detection probability of different methods demonstrated that the choice of survey method can bias towards particular groups of species and, in some cases, underestimate breeding activity by frog species in large waterbodies.

scholarly journals Horizontal or vertical? Camera trap orientations and recording modes for detecting potoroos, bandicoots and pademelons

2014 ◽  
Vol 36 (1) ◽  
pp. 60 ◽  
Author(s):  
Brendan D. Taylor ◽  
Ross L. Goldingay ◽  
John M. Lindsay
Keyword(s):  
Detection Probability ◽  
New South ◽  
Population Monitoring ◽  
Camera Trap ◽  
Probability Of Detection ◽  
Camera Traps ◽  
North East ◽  
South Wales ◽  
Detection Probabilities ◽  
The Stability

Camera traps can detect rare and cryptic species, and may enable description of the stability of populations of threatened species. We investigated the relative performance of cameras oriented horizontally or vertically, and recording mode (still and video) to detect the vulnerable long-nosed potoroo (Potorous tridactylus) as a precursor to population monitoring. We established camera traps for periods of 13–21 days across 21 sites in Richmond Range National Park in north-east New South Wales. Each camera trap set consisted of three KeepGuard KG680V cameras directed at a bait container – one horizontal and one vertical camera in still mode and one horizontal camera in video mode. Potoroos and bandicoots (Perameles nasuta and Isoodon macrourus) were detected at 14 sites and pademelons (Thylogale stigmatica and T. thetis) were detected at 19 sites. We used program Presence to compare detection probabilities for each camera category. The detection probability for all three taxa groups was lowest for the vertical still and similar for the horizontal cameras. The detection probability (horizontal still) was highest for the potoroos (0.43) compared with the bandicoots (0.16) and pademelons (0.25). We estimate that the horizontal stills camera could achieve a 95% probability of detection of a potoroo within 6 days compared with 8 days using a vertical stills camera. This suggests that horizontal cameras in still mode have great potential for monitoring the dynamics of this potoroo population.

The history of wildlife camera trapping as a survey tool in Australia

2015 ◽  
Vol 37 (1) ◽  
pp. 1 ◽  
Author(s):  
Paul D. Meek ◽  
Guy-Anthony Ballard ◽  
Karl Vernes ◽  
Peter J. S. Fleming
Keyword(s):  
Quantitative Research ◽  
Reaction Times ◽  
Historical Review ◽  
Camera Trap ◽  
Recent Change ◽  
Camera Traps ◽  
Camera Trapping ◽  
Survey Tool ◽  
Trapping Methods ◽  
Effective Models

This paper provides an historical review of the technological evolution of camera trapping as a zoological survey tool in Australia. Camera trapping in Australia began in the 1950s when purpose-built remotely placed cameras were used in attempts to rediscover the thylacine (Thylacinus cynocephalus). However, camera traps did not appear in Australian research papers and Australasian conference proceedings until 1989–91, and usage became common only after 2008, with an exponential increase in usage since 2010. Initially, Australian publications under-reported camera trapping methods, often failing to provide fundamental details about deployment and use. However, rigour in reporting of key methods has increased during the recent widespread adoption of camera trapping. Our analysis also reveals a change in camera trap use in Australia, from simple presence–absence studies, to more theoretical and experimental approaches related to population ecology, behavioural ecology, conservation biology and wildlife management. Practitioners require further research to refine and standardise camera trap methods to ensure that unbiased and scientifically rigorous data are obtained from quantitative research. The recent change in emphasis of camera trapping research use is reflected in the decreasing range of camera trap models being used in Australian research. Practitioners are moving away from less effective models that have slow reaction times between detection and image capture, and inherent bias in detectability of fauna, to more expensive brands that offer faster speeds, greater functionality and more reliability.

The status of non-volant mammals along a rainfall gradient in the south-west Kimberley, Western Australia

2012 ◽  
Vol 34 (1) ◽  
pp. 36 ◽  
Author(s):  
A. N. Start ◽  
A. A. Burbidge ◽  
M. C. McDowell ◽  
N. L. McKenzie
Keyword(s):  
Western Australia ◽  
Common Species ◽  
Current Status ◽  
Annual Rainfall ◽  
Mammal Species ◽  
Rainfall Gradient ◽  
Terrestrial Mammals ◽  
South West ◽  
The Status ◽  
High Level

To assess the current status of mammals in relation to mean annual rainfall and to improve knowledge of the original mammalian assemblages in tropical Western Australia, extant terrestrial mammals and subfossil mammalian remains were sought along a rainfall gradient in two parallel ranges in the Kimberley, Western Australia. As expected, extant mammal species richness decreased with decreasing rainfall. Data from other studies in higher-rainfall areas complemented this conclusion and a parallel decline in trap success implied an overall decline in abundance, although numbers of two rodents (Rattus tunneyi and Zyzomys argurus) were highly variable. Small rodents were rare. Subfossil deposits were biased by accumulation processes, with most attributable to tytonid owls. They largely consisted of rodent and, to a lesser extent, small dasyurid bones and there was a high level of consistency in the proportional composition of many common species across the rainfall gradient. Most deposits appear to predate the introduction of stock in the 1880s and some may be much older. All species persist in the study area except two Notomys spp. and three Pseudomys spp. Both the Notomys and one Pseudomys are apparently undescribed, extinct species. However, there were marked ratio differences between subfossil and modern assemblages. Although specimens of species larger than those taken by tytonid owls were scarce, their occurrences were broadly consistent with the modern understanding of distributions.

scholarly journals Large- and medium-bodied terrestrial mammals of the Upper Berbice region of Guyana

Check List ◽  
2020 ◽  
Vol 16 (5) ◽  
pp. 1229-1237
Author(s):  
Meshach A. Pierre ◽  
Leroy Ignacio ◽  
Evi A. D. Paemelaere
Keyword(s):  
Relative Abundance ◽  
Forest Ecosystems ◽  
Camera Trap ◽  
Camera Traps ◽  
Large Mammals ◽  
Sensitive Species ◽  
Terrestrial Mammals ◽  
Mammal Community ◽  
Eira Barbara ◽  
Brocket Deer

Large mammals are key contributors to forest ecosystems globally, but Neotropical mammal populations are understudied. We employed remotely triggered camera traps and track surveys to assess the mammal community in the newly accessible upper Berbice region of Guyana. In a cumulative 2,821 trap nights between two camps and 14 km of track surveys we recorded 18 species of mammals. Camera trap records showed that Red-Rumped Agouti (Dasyprocta leporina (Linnaeus, 1758)) featured the highest relative abundance at both camps, while Tayra (Eira barbara (Linnaeus, 1758)), Amazonian Brown Brocket Deer (Mazama nemorivaga (F. Cuvier, 1817)), Giant Anteater (Myrmecophaga tridactyla (Linnaeus, 1758)) and Giant Armadillo (Priodontes maximus (Kerr, 1792)) the lowest. We also report na&iuml;ve occupancy estimates. Detections of threatened and disturbance sensitive species indicate that the study site has a high biodiversity value. We provide recommendations for further study in this recently disturbed ecosystem and other understudied regions of Guyana.

scholarly journals Differences of terrestrial mammal species diversity between natural forest and edge forest areas in Batutegi Protected Forest, Lampung, Indonesia

2020 ◽  
Vol 1 (1) ◽  
pp. 33-39
Author(s):  
Robithotul Huda ◽  
Yossa Istiadi ◽  
Dolly Priatna
Keyword(s):  
Species Diversity ◽  
Sus Scrofa ◽  
Grid Cell ◽  
Camera Trap ◽  
Camera Traps ◽  
Core Area ◽  
Terrestrial Mammals ◽  
The Core ◽  
Research Areas ◽  
Muntiacus Muntjak

This research is an explorative quantitative survey by testing differences in species of terrestrial mammals found in natural forest (core) and edge forest (ecoton) areas. The data collection was obtained by using camera traps installed for 3 months based on a grid cell 2 x 2 km, with a total of 16 camera traps placed in core area and another 17 were in ecotone. The object of this research was medium (0.3 kg) to large terrestrial mammals. The t test was used to determine the differences the species diversity of mammals between two research areas. The study shows that there are 22 species of terrestrial mammals with a total of 552 individuals, which is distributed in both research areas. In the core area there are 18 species with 237 individuals, while in the ecotone there are 18 species with 315 individuals. Analyses the species richness index was 17.8171 for the core area while 17.8262 for the ecotone area. Similarity index in both study areas ranged from 0.7106 to 1. While the value of diversity index (Shannon-Wiener) in the core area H '= 2.2038 and in the ecotone area H' = 2.0541. Three species with the greatest relative abundance values are Porcupine (Hystrix brachyura), Barking Deer (Muntiacus muntjak), and Wild Boar (Sus scrofa). Based on the t tests of the two research areas, which are core area and ecotone, obtained tcount 0.41365 (p 0.05), it can be interpreted that the diversity of terrestrial mammals species in the core and ecotone areas is not the same.Penelitian ini merupakan penelitian kuantitatif survei eksploratif dengan melakukan pengujian perbedaan terhadap jenis mamalia teresterial yang ditemukan di wilayah hutan alam (inti) dan wilayah hutan tepi (ekoton). Pendataan mamalia teresterial menggunakan camera trap yang dipasang selama 3 bulan berdasarkan grid cell 2 x 2 km, dengan 16 camera trap dipasang di areal inti dan 17 lainnya di ekoton. Objek penelitian adalah mamalia teresterial berukuran sedang (0,3 kg) hingga mamalia besar. Uji t digunakan untuk menentukan perbadaan keragaman jenis mamalia teresterial pada dua areal penelitian. Hasil penelitian menunjukkan terdapat 22 jenis mamalia teresterial dengan total 552 individu, yang tersebar di kedua areal penelitian. Pada areal inti terdapat 18 jenis dengan 237 individu, sedangkan pada areal ekoton ditemukan 18 jenis dengan 315 individu. Analisis indeks kekayaaan jenis menunjukkan nilai 17,8171 untuk areal inti dan 17,8262 untuk areal ekoton. Indeks kemerataan pada kedua areal penelitian berkisar antara 0,7106 hingga 1.  Sedangkan nilai indeks keragaman (Shannon-Wiener) pada areal inti H’ = 2,2038 dan pada areal ekoton H’= 2,0541. Tiga jenis mamalia teresterial dengan kelimpahan relatif terbesar yaitu Landak (Hystrix brachyura), Kijang (Muntiacus muntjak), dan Babi hutan (Sus scrofa). Berdasarkan uji beda terhadap dua areal penelitian yaitu areal hutan alam (areal inti) dan areal tepi hutan (ekoton) didapatkan thitung 0,41365 (p 0,05), maka dapat diartikan bahwa keragaman jenis mamalia teresterial di areal inti dan ekoton tidak sama.

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