Applying and testing a novel method to estimate animal density from motion‐triggered cameras

Becker, Marcus; Huggard, David J.; Dickie, Melanie; Warbington, Camille H.; Schieck, Jim; Herdman, Emily; Serrouya, Robert; Boutin, Stan

doi:10.1002/ecs2.4005

Cited by 14 publications

(28 citation statements)

References 41 publications

(48 reference statements)

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“…Continuing advances in camera data analysis (e.g. Becker et al, 2022; Moeller et al, 2018) may allow for abundance or density estimations in the future.…”

Section: Discussionmentioning

confidence: 99%

Ungulate occurrence in forest harvest blocks is influenced by forage availability, surrounding habitat and silviculture practices

McKay¹,

Finnegan²

2023

Ecol Sol and Evidence

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Forest harvesting causes habitat loss and alteration and can change predator–prey dynamics. In Canada, forest harvesting has shifted the distribution and abundance of ungulates (deer, elk and moose) that prefer early seral forest, resulting in unsustainable caribou predation by shared predators (bears, cougars and wolves). Long‐term solutions for caribou recovery require management to reduce ungulate prey species within caribou ranges. Silviculture practices applied after forest harvesting directly affect the amount of forage available in harvested areas, and therefore influence ungulate distribution, but few studies have completed detailed assessments on how specific treatments of site preparation, planting and stand tending influence ungulate use of harvest blocks. We used camera traps, silviculture data, GIS‐derived habitat and disturbance data, and detailed vegetation data collected at field sites to investigate ungulate occurrence in harvest blocks in west‐central Alberta, Canada. We compared seasonal ungulate occurrence and investigated how site‐specific characteristics, the surrounding habitat and disturbance density, and fine‐scale silviculture treatments influenced ungulate occurrence in blocks. Deer, elk and moose occurrence was higher in summer compared to winter. Elk, moose and white‐tailed deer occurrence was higher in blocks with greater availability of specific forage species. Moose occurrence was higher in blocks with a lower road density in the surrounding area, and white‐tailed deer occurrence was higher in blocks further from seismic lines and with a lower proportion of harvest blocks in the surrounding area. Deer, elk and moose occurrence was higher in younger harvest blocks. Mule deer and white‐tailed deer occurrence was lower in blocks with higher planting densities of lodgepole pine, and mule deer occurrence was also lower in blocks that had been stand tended. Our study provides detailed information on ungulate response to fine‐scale silviculture methods used in Alberta, directly linking wildlife occurrence to forestry practices, and providing practical scientific information to inform sustainable forestry. Translating this research into practical landscape management decisions could benefit boreal biodiversity, including threatened species like caribou, and culturally and economically important species like deer, elk and moose.

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“…Continuing advances in camera data analysis (e.g. Becker et al, 2022; Moeller et al, 2018) may allow for abundance or density estimations in the future.…”

Section: Discussionmentioning

confidence: 99%

Ungulate occurrence in forest harvest blocks is influenced by forage availability, surrounding habitat and silviculture practices

McKay¹,

Finnegan²

2023

Ecol Sol and Evidence

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“…However, field verification of these models remains a work in progress and density estimates are very sensitive to study design and model assumptions (Villette et al . 2016, 2017; Becker et al . 2022).…”

Section: Discussionmentioning

confidence: 99%

“…components of detectability) calculated from the images. However, field verification of these models remains a work in progress and density estimates are very sensitive to study design and model assumptions (Villette et al 2016(Villette et al , 2017Becker et al 2022). A recent comparison of multiple models for estimating densities of lynx at Kluane showed five-fold difference in estimates among different models using camera trap data (Doran-Myers et al 2021).…”

Section: Fig 4 95% Bootstrapped Confidence Intervals For Different In...mentioning

confidence: 99%

Snow track counts for density estimation of mammalian predators in the boreal forest

O’Donoghue

Slough²,

Poole³

et al. 2022

Wildlife Res.

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Context Methods for estimating density of meso-carnivores in northern ecosystems are labour intensive and expensive to implement if mark–recapture and radio collaring are used. One alternative is to count tracks in the snow along transects as an index of density, but this method has been criticised as imprecise and lacking validation. Aims We aimed to examine the utility of track counts along snowmobile trails in the snow for measuring changes in populations of Canada lynx and coyotes in the boreal forest of north-western Canada. Methods We compared winter track counts of Canada lynx at three study sites and of coyotes at one site with concurrent estimates of density based on locations of radio-collared animals and estimates of numbers of uncollared animals from three 7–9-year studies in the Yukon and Northwest Territories, during a period of cyclical population fluctuations. Key results Snow track counts were positively correlated (r2 = 0.83) with density of Canada lynx, estimated by live trapping and radio collaring in the three survey areas. Coyotes also showed a clear relationship (r2 = 0.80) between known density and snow track counts, but track counts were strongly affected by season, with much higher counts in the early winter when snow was shallower. This indicates the need to control for season or snow depth when using track counts as indices of coyote abundance. We recommend sample sizes of at least 10 track counts per winter along a 25-km transect to maximise precision. Conclusions Snow track counts are a relatively simple, inexpensive method of concurrently tracking abundance of multiple species of meso-carnivores. These data indicate that track counts may be reliably used to monitor trends in numbers, but we suggest site-specific validation of the regressions reported here between tracks and animal abundance are required to translate these indices into estimates of density. Implications Track counts have the potential to be an affordable alternative to more intensive methods of monitoring trends in abundance of medium-sized mammals, for purposes such as management of harvest or to measure the success of programs to increase or reduce population abundance.

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“…The candidate models were then ranked using the Akaike information criterion corrected for small sample size (AICc) and their Akaike weights, with all models with ΔAICc <2 considered as competing models (Dyck et al, 2022). Model averaging and multimodel inference were conducted in the MuMIn package (Barton & Barton, 2015). We calculated Moran's I using the morans.I function from the R package ape to check the model residual for spatial autocorrelation across camera trap stations (Paradis & Schliep, 2019).…”

Section: Notementioning

confidence: 99%

Assessing mammal population densities in response to urbanization using camera trap distance sampling

Li,

Shi,

et al. 2023

Ecology and Evolution

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Environmental filtering is deemed to play a predominant role in regulating the abundance and distribution of animals during the urbanization process. However, the current knowledge about the effects of urbanization on the population densities of terrestrial mammals is limited. In this study, we compared two invasive mammals (dogs Canis lupus familiaris and cats Felis silvestris) and three indigenous mammals (Siberian weasels Mustela sibirica, Amur hedgehogs Erinaceus amurensis, and Tolai hares Lepus tolai) in response to urbanization using camera trap distance sampling (CTDS) in the rural–urban landscape of Tianjin, China. We used generalized additive mixed models (GAMMs) to test the specific responses of their densities to levels of urbanization. Invasive dogs (2.63 individuals/km2, 95% CI: 0.91–7.62) exhibited similar density estimations to cats (2.15 individuals/km2, 95% CI: 1.31–3.50). Amur hedgehogs were the most abundant species (6.73 individuals/km2, 95% CI: 3.15–14.38), followed by Tolai hares (2.22 individuals/km2, 95% CI: 0.87–5.68) and Siberian weasels (2.15 individuals/km2, 95% CI: 1.06–4.36). The densities of cats, Siberian weasels, and Amur hedgehogs increased with the level of urbanization. The population densities of dogs and cats were only influenced by urban‐related variables, while the densities of Siberian weasels and Amur hedgehogs were influenced by both urban‐related variables and nature‐related variables. Our findings highlight that the CTDS is a suitable and promising method for wildlife surveys in rural–urban landscapes, and urban wildlife management needs to consider the integrated repercussions of urban‐ and nature‐related factors, especially the critical impacts of green space habitats at finer scales.

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Applying and testing a novel method to estimate animal density from motion‐triggered cameras

Cited by 14 publications

References 41 publications

Ungulate occurrence in forest harvest blocks is influenced by forage availability, surrounding habitat and silviculture practices

Ungulate occurrence in forest harvest blocks is influenced by forage availability, surrounding habitat and silviculture practices

Snow track counts for density estimation of mammalian predators in the boreal forest

Assessing mammal population densities in response to urbanization using camera trap distance sampling

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