Assumptions about fence permeability influence density estimates for brown hyaenas across South Africa

Williams, Kathryn S.; Williams, Samual T.; Welch, Rebecca J.; Marneweck, Courtney J.; Mann, Gareth K.H.; Pitman, Ross T.; Whittington-Jones, G.M.; Balme, Guy A.; Parker, Daniel M.; Hill, Russell A.

doi:10.1038/s41598-020-77188-7

Cited by 8 publications

(11 citation statements)

References 64 publications

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“…The highest recorded densities are from reserves in Namibia (Okonjima Nature Reserve; Edwards et al, 2019), South Africa (Kwandwe Nature Reserve; Welch & Parker, 2016), and the central Tuli block, Botswana (Vissia et al, 2021). These far exceed our density estimate (Supplementary Table 2), although assumptions about fence permeability may account for some of these differences (Williams et al, 2021). Although there are challenges in comparing density estimates given some of the methods used (occupancy models and track counts; Balme et al, 2009; Rich et al, 2014; Rogan et al, 2019), our densities are similar to brown hyaena densities in similar habitats where spatial capture–recapture methods have been used (Williams et al, 2021; Fig.…”

Section: Discussioncontrasting

confidence: 67%

Estimates of carnivore densities in a human-dominated agricultural matrix in South Africa

Faure

Swanepoel²,

Cilliers³

et al. 2021

Oryx

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Populations of carnivore species outside protected areas may be of considerable importance for conservation, as many protected areas do not provide sufficient space for viable populations. Data on carnivore population sizes and trends are often biased towards protected areas, and few studies have examined the role of unprotected areas for carnivore conservation. We used camera-trapping data and spatial capture–recapture models to estimate population densities for four sympatric carnivores: the African leopard Panthera pardus, spotted hyaena Crocuta crocuta, brown hyaena Parahyaena brunnea and African civet Civettictis civetta in Platjan, a predominantly agricultural, mixed land-use system, South Africa. Mean densities per 100 km2 for the leopard were 2.20 (95% CI 1.32–3.68) and 2.18 (95% CI 1.32–3.61) for left and right flank data, respectively; spotted hyaena, 0.22 (95% CI 0.06–0.81); brown hyaena, 0.74 (95% CI 0.30–1.88); and African civet 3.60 (95% CI 2.34–5.57; left flanks) and 3.71 (95% CI 2.41–5.72; right flanks). Our results indicate that although densities are lower than those reported for protected areas, humans and predators coexist in this unprotected agricultural matrix. We suggest that increased conservation effort should be focused in such areas, to mitigate human–carnivore conflicts. Our study improves the knowledge available for carnivore populations on privately owned, unprotected land, and may benefit conservation planning.

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Section: Discussioncontrasting

confidence: 67%

Estimates of carnivore densities in a human-dominated agricultural matrix in South Africa

Faure

Swanepoel²,

Cilliers³

et al. 2021

Oryx

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“…Although our analysis was based on the BVC fence being impermeable, we are confident that our results were not affected by this bias as the fence is checked and maintained on a daily basis. In addition, the size of the Main Conservancy is >1000 km 2 , a supporting factor considering that the degree of overestimation was found to be inversely proportional to reserve size (Williams et al, 2021). In the case of Ripple Creek, estimated abundance was the same as the number of separate individuals identified in the identification process.…”

Section: Discussionmentioning

confidence: 96%

“…Thus, we are confident that any potential bias is likely to be negligible. Recent research on the effect of fence permeability assumptions on brown hyaena density estimates has also highlighted how density can be significantly overestimated when fences are incorrectly assumed to be impermeable (Williams et al, 2021). Although our analysis was based on the BVC fence being impermeable, we are confident that our results were not affected by this bias as the fence is checked and maintained on a daily basis.…”

Section: Discussionmentioning

confidence: 99%

“…Because of this, detection histories were created for each site based on either left side or right side images only, depending on which side yielded the most number of unique individuals for each section. This approach avoids overestimating the number of individuals captured when left and right flanks from the same individual are thought to be two separate individuals (Satter et al, 2019; Williams et al, 2021).…”

Section: Methodsmentioning

confidence: 99%

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Camera traps reveal a large population of brown hyaena on a fenced reserve in southern Zimbabwe

Gush¹,

Wijers

Comley

et al. 2022

Afr J Ecol

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Investigations into the demographics of cryptic carnivores such as the near‐threatened brown hyaena Parahyaena brunnea have been improved by recent developments in camera trap technology and survey methods. Here, we assess the population density and abundance of this species on the Bubye Valley Conservancy (BVC) in south‐west Zimbabwe, a largely unsurveyed portion of the brown hyaena's range. We estimated brown hyaena density from a camera trap survey across two sections of the BVC (namely Main Conservancy and Ripple Creek) using a spatially explicit capture‐recapture method from individually identifiable images. This resulted in population density estimates of 14.72 ± 0.99 per 100 km2 for the Main Conservancy and 6.39 ± 1.74 for the Ripple Creek. While similar results have been found in recent studies of small, fenced reserves in Southern Africa, to our knowledge, these high‐density findings are the first for a large (>1000 km2) fenced reserve. We estimated the brown hyaena population on the BVC to be in excess of 400 individuals. This considerable population size is likely due to the well‐protected nature of the reserve and the scavenging opportunities provided by the sympatric large carnivores on the BVC, suggesting that this is a key locale for the species' conservation.

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“…As bone scavengers often have large home ranges and opportunistically transverse fence boundaries, it is possible that some of the nutrients from lion carcasses are lost from the reserve. However, Williams et al (2021) showed that in reserves where fence integrity is high, scavengers such as brown hyaena generally remain within the reserve due to the abundance of sympatric predators and high levels of carrion, so the loss of nutrients via this vector is assumed negligible.…”

Section: Role Of Predators and Bone Scavengersmentioning

confidence: 99%

Large predators can mitigate nutrient losses associated with off‐site removal of animals from a wildlife reserve

Abraham

Webster

Prys-Jones

et al. 2021

Journal of Applied Ecology

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1. Animals concentrate key nutrients in their bodies. In fenced wildlife reserves where nutrient input and/or retention is low, the off-site removal of animals may constitute a significant loss of nutrients for the ecosystem.2. Here we add wildlife capture and removal into the phosphorus (P) and calcium (Ca) budget for a 121,700 ha fenced game reserve located in the southern Kalahari.We then use faecal P concentrations from 11 mammal herbivores >10 kg as an indicator of potential nutrient stress in this system to investigate whether the implications of nutrient loss via off-site wildlife removal may be cause for concern.Finally, we assess the role of natural predation as a mechanism to minimise the need for wildlife removal and concomitant nutrient loss.3. During the period 2009-2018, mean loss of P and Ca via wildlife removal was 2.9 and 6.2 kg km −2 year −1 , respectively. This compares to 1.0 and 2.1 kg km −2 year −1 of P and Ca added via the provision of mineral licks. If it is assumed that natural fluxes of these elements are in steady state, then anthropogenic activities have resulted in a net deficit of 18.5 kg/km 2 of P and 40.6 kg/km 2 of Ca over the decade. 4. We found that dry season herbivore faecal P concentrations are close to or below a widely cited minimum threshold of 2,000 mg/kg, below which most vertebrates begin suffering growth and reproductive issues. Large animals were more likely to be under this threshold. Prolonged continuation of off-site wildlife removal may result in nutrient losses that can lead to long-term ecological degradation. Natural predation levels were, however, found sufficient to mitigate the need for wildlife removal and present a management strategy whereby herbivore populations can be regulated without a loss of nutrients. Synthesis and applications.We find that the capture and permanent removal of large-bodied animals from wildlife reserves can be a significant cause of nutrient loss. Over time, in sites where nutrient input and/or retention is low, this may | 1361

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Assumptions about fence permeability influence density estimates for brown hyaenas across South Africa

Cited by 8 publications

References 64 publications

Estimates of carnivore densities in a human-dominated agricultural matrix in South Africa

Estimates of carnivore densities in a human-dominated agricultural matrix in South Africa

Camera traps reveal a large population of brown hyaena on a fenced reserve in southern Zimbabwe

Large predators can mitigate nutrient losses associated with off‐site removal of animals from a wildlife reserve

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