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  • 1
    In: Mammal Review, Wiley, Vol. 53, No. 2 ( 2023-04), p. 49-64
    Abstract: Spatial patterns of and competition for resources by territorial carnivores are typically explained by two hypotheses: 1) the territorial defence hypothesis and 2) the searching efficiency hypothesis. According to the territorial defence hypothesis, when food resources are abundant, carnivore densities will be high and home ranges small. In addition, carnivores can maximise their necessary energy intake with minimal territorial defence. At medium resource levels, larger ranges will be needed, and it will become more economically beneficial to defend resources against a lower density of competitors. At low resource levels, carnivore densities will be low and home ranges large, but resources will be too scarce to make it beneficial to defend such large territories. Thus, home range overlap will be minimal at intermediate carnivore densities. According to the searching efficiency hypothesis, there is a cost to knowing a home range. Larger areas are harder to learn and easier to forget, so carnivores constantly need to keep their cognitive map updated by regularly revisiting parts of their home ranges. Consequently, when resources are scarce, carnivores require larger home ranges to acquire sufficient food. These larger home ranges lead to more overlap among individuals' ranges, so that overlap in home ranges is largest when food availability is the lowest. Since conspecific density is low when food availability is low, this hypothesis predicts that overlap is largest when densities are the lowest. We measured home range overlap and used a novel method to compare intraspecific home range overlaps for lions Panthera leo ( n  = 149) and leopards Panthera pardus ( n  = 111) in Africa. We estimated home range sizes from telemetry location data and gathered carnivore density data from the literature. Our results did not support the territorial defence hypothesis for either species. Lion prides increased their home range overlap at conspecific lower densities whereas leopards did not. Lion pride changes in overlap were primarily due to increases in group size at lower densities. By contrast, the unique dispersal strategies of leopards led to reduced overlap at lower densities. However, when human‐caused mortality was higher, leopards increased their home range overlap. Although lions and leopards are territorial, their territorial behaviour was less important than the acquisition of food in determining their space use. Such information is crucial for the future conservation of these two iconic African carnivores.
    Type of Medium: Online Resource
    ISSN: 0305-1838 , 1365-2907
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2023
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  • 2
    In: Animal Biotelemetry, Springer Science and Business Media LLC, Vol. 9, No. 1 ( 2021-10-16)
    Abstract: Understanding what animals do in time and space is important for a range of ecological questions, however accurate estimates of how animals use space is challenging. Within the use of animal-attached tags, radio telemetry (including the Global Positioning System, ‘GPS’) is typically used to verify an animal’s location periodically. Straight lines are typically drawn between these ‘Verified Positions’ (‘VPs’) so the interpolation of space-use is limited by the temporal and spatial resolution of the system’s measurement. As such, parameters such as route-taken and distance travelled can be poorly represented when using VP systems alone. Dead-reckoning has been suggested as a technique to improve the accuracy and resolution of reconstructed movement paths, whilst maximising battery life of VP systems. This typically involves deriving travel vectors from motion sensor systems and periodically correcting path dimensions for drift with simultaneously deployed VP systems. How often paths should be corrected for drift, however, has remained unclear. Methods and results Here, we review the utility of dead-reckoning across four contrasting model species using different forms of locomotion (the African lion Panthera leo , the red-tailed tropicbird Phaethon rubricauda , the Magellanic penguin Spheniscus magellanicus , and the imperial cormorant Leucocarbo atriceps ). Simulations were performed to examine the extent of dead-reckoning error, relative to VPs, as a function of Verified Position correction (VP correction) rate and the effect of this on estimates of distance moved. Dead-reckoning error was greatest for animals travelling within air and water. We demonstrate how sources of measurement error can arise within VP-corrected dead-reckoned tracks and propose advancements to this procedure to maximise dead-reckoning accuracy. Conclusions We review the utility of VP-corrected dead-reckoning according to movement type and consider a range of ecological questions that would benefit from dead-reckoning, primarily concerning animal–barrier interactions and foraging strategies.
    Type of Medium: Online Resource
    ISSN: 2050-3385
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
    detail.hit.zdb_id: 2711027-8
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  • 3
    In: Ecology, Wiley, Vol. 93, No. 6 ( 2012-06), p. 1297-1304
    Type of Medium: Online Resource
    ISSN: 0012-9658
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2012
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    detail.hit.zdb_id: 2010140-5
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  • 4
    In: Animal Biotelemetry, Springer Science and Business Media LLC, Vol. 9, No. 1 ( 2021-07-01)
    Abstract: Fine-scale data on animal position are increasingly enabling us to understand the details of animal movement ecology and dead-reckoning, a technique integrating motion sensor-derived information on heading and speed, can be used to reconstruct fine-scale movement paths at sub-second resolution, irrespective of the environment. On its own however, the dead-reckoning process is prone to cumulative errors, so that position estimates quickly become uncoupled from true location. Periodic ground-truthing with aligned location data (e.g., from global positioning technology) can correct for this drift between Verified Positions (VPs). We present step-by-step instructions for implementing Verified Position Correction (VPC) dead-reckoning in R using the tilt-compensated compass method, accompanied by the mathematical protocols underlying the code and improvements and extensions of this technique to reduce the trade-off between VPC rate and dead-reckoning accuracy. These protocols are all built into a user-friendly, fully annotated VPC dead-reckoning R function; Gundog.Tracks , with multi-functionality to reconstruct animal movement paths across terrestrial, aquatic, and aerial systems, provided within the Additional file 4 as well as online (GitHub). Results The Gundog.Tracks function is demonstrated on three contrasting model species (the African lion Panthera leo , the Magellanic penguin Spheniscus magellanicus , and the Imperial cormorant Leucocarbo atriceps ) moving on land, in water and in air. We show the effect of uncorrected errors in speed estimations, heading inaccuracies and infrequent VPC rate and demonstrate how these issues can be addressed. Conclusions The function provided will allow anyone familiar with R to dead-reckon animal tracks readily and accurately, as the key complex issues are dealt with by Gundog.Tracks . This will help the community to consider and implement a valuable, but often overlooked method of reconstructing high-resolution animal movement paths across diverse species and systems without requiring a bespoke application.
    Type of Medium: Online Resource
    ISSN: 2050-3385
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2021
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  • 5
    In: African Journal of Ecology, Wiley, Vol. 59, No. 4 ( 2021-12), p. 898-911
    Abstract: La surveillance biologique des aires protégées est essentielle aux prises de décision en matière de gestion, en particulier dans les petites réserves clôturées ( 〈 1 000 km 2 ) qui nécessitent une intervention intensive visant à maintenir les caractéristiques principales de l’habitat. Les estimations de la richesse en espèces et l’étude de la structure de la communauté fournissent des informations importantes aux fins de planification et l’évaluation des stratégies de conservation. La réserve faunique de Majete (MWR) est une petite réserve isolée (691 km 2 ) située dans l’écorégion de la forêt de Miombo, dans le sud du Malawi. Nous avons étudié la richesse en espèces et la structure de la communauté des mammifères terrestres de taille moyenne et grande au sein de la MWR, en nous appuyant sur une enquête normalisée et réalisée par piège photographique. Au cours de la saison sèche de l’année 2018, 140 emplacements d’appareils photo ont été échantillonnés pendant 40 jours chacun. Trente‐cinq espèces de mammifères ont été identifiées, et les estimateurs de richesse en espèces Chao 2, ICE et Jackknife 1 et 2 ont indiqué la présence de 36 à 41 espèces, ce qui correspond étroitement aux résultats des évaluations réalisées par le passé.. La non‐détection de certaines espèces est attribuée aux exigences particulières liées à l’habitat de ces dernières, auquel la méthode d’échantillonnage par piège photographique ne peut être appliquée. La structure de la communauté de mammifères, calculée à partir des indices d’abondance relative (IAR) des espèces détectées par l’appareil photo, était atypique pour la forêt claire de Miombo et mettait en évidence une sous‐représentation des éléphants. L’IAR dérivé des pièges photographiques était en corrélation positive avec les données de présence des espèces issues du recensement aérien réalisé en 2018. Ces résultats peuvent aider la Direction à affiner les techniques d’enquête et servir de référence aux fins de suivi des efforts de conservation.
    Type of Medium: Online Resource
    ISSN: 0141-6707 , 1365-2028
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2021
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  • 6
    In: Journal of The Royal Society Interface, The Royal Society, Vol. 19, No. 186 ( 2022-01)
    Abstract: The combined use of global positioning system (GPS) technology and motion sensors within the discipline of movement ecology has increased over recent years. This is particularly the case for instrumented wildlife, with many studies now opting to record parameters at high (infra-second) sampling frequencies. However, the detail with which GPS loggers can elucidate fine-scale movement depends on the precision and accuracy of fixes, with accuracy being affected by signal reception. We hypothesized that animal behaviour was the main factor affecting fix inaccuracy, with inherent GPS positional noise (jitter) being most apparent during GPS fixes for non-moving locations, thereby producing disproportionate error during rest periods. A movement-verified filtering (MVF) protocol was constructed to compare GPS-derived speed data with dynamic body acceleration, to provide a computationally quick method for identifying genuine travelling movement. This method was tested on 11 free-ranging lions ( Panthera leo ) fitted with collar-mounted GPS units and tri-axial motion sensors recording at 1 and 40 Hz, respectively. The findings support the hypothesis and show that distance moved estimates were, on average, overestimated by greater than 80% prior to GPS screening. We present the conceptual and mathematical protocols for screening fix inaccuracy within high-resolution GPS datasets and demonstrate the importance that MVF has for avoiding inaccurate and biased estimates of movement.
    Type of Medium: Online Resource
    ISSN: 1742-5662
    Language: English
    Publisher: The Royal Society
    Publication Date: 2022
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  • 7
    In: Ecology, Wiley, Vol. 102, No. 5 ( 2021-05)
    Abstract: Competitively dominant carnivore species can limit the population sizes and alter the behavior of inferior competitors. Established mechanisms that enable carnivore coexistence include spatial and temporal avoidance of dominant predator species by subordinates, and dietary niche separation. However, spatial heterogeneity across landscapes could provide inferior competitors with refuges in the form of areas with lower competitor density and/or locations that provide concealment from competitors. Here, we combine temporally overlapping telemetry data from dominant lions ( Panthera leo ) and subordinate African wild dogs ( Lycaon pictus ) with high‐resolution remote sensing in an integrated step selection analysis to investigate how fine‐scaled landscape heterogeneity might facilitate carnivore coexistence in South Africa’s Hluhluwe‐iMfolozi Park, where both predators occur at exceptionally high densities. We ask whether the primary lion‐avoidance strategy of wild dogs is spatial avoidance of lions or areas frequented by lions, or if wild dogs selectively use landscape features to avoid detection by lions. Within this framework, we also test whether wild dogs rely on proactive or reactive responses to lion risk. In contrast to previous studies finding strong spatial avoidance of lions by wild dogs, we found that the primary wild dog lion‐avoidance strategy was to select landscape features that aid in avoidance of lion detection. This habitat selection was routinely used by wild dogs, and especially when in areas and during times of high lion‐encounter risk, suggesting a proactive response to lion risk. Our findings suggest that spatial landscape heterogeneity could represent an alternative mechanism for carnivore coexistence, especially as ever‐shrinking carnivore ranges force inferior competitors into increased contact with dominant species.
    Type of Medium: Online Resource
    ISSN: 0012-9658 , 1939-9170
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2021
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  • 8
    In: Journal of Mammalogy, Oxford University Press (OUP), Vol. 97, No. 2 ( 2016-03-23), p. 473-482
    Abstract: Human/carnivore conflicts are common across the globe, and with a growing human population, this conflict is likely to increase as the space available to large carnivores is reduced. In South Africa, many small ( & lt; 400 km 2 ), fenced protected areas have reintroduced persecuted carnivores, such as brown hyenas ( Hyaena brunnea ). These reserves have great potential to conserve brown hyena populations; consequently, understanding the limitations that small, fenced reserves impose on space use patterns is needed. We investigated the home range (95% fixed kernel utilization distributions) and landscape determinants of habitat selection using resource selection functions for 10 brown hyenas in 3 separate fenced reserves. Home range sizes were consistently smaller in 2 of the reserves when compared to the third. Considerable variation in the selection of habitat features exists among individual brown hyenas and reserves. The most important landscape determinant driving brown hyena space use was distance to roads, with brown hyenas observed closer to roads when compared to random locations within their ranges. If this relationship with roads holds outside of protected areas, it could represent a considerable threat to the species. Thus, obtaining a better understanding of the influence of roads on brown hyenas represents an important focus for future research.
    Type of Medium: Online Resource
    ISSN: 1545-1542 , 0022-2372
    RVK:
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2016
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    SSG: 12
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  • 9
    In: PLoS ONE, Public Library of Science (PLoS), Vol. 6, No. 9 ( 2011-9-7), p. e23607-
    Type of Medium: Online Resource
    ISSN: 1932-6203
    Language: English
    Publisher: Public Library of Science (PLoS)
    Publication Date: 2011
    detail.hit.zdb_id: 2267670-3
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  • 10
    In: South African Journal of Science, Academy of Science of South Africa, Vol. 113, No. 3/4 ( 2017-03-29), p. 3-
    Type of Medium: Online Resource
    ISSN: 1996-7489
    Language: Unknown
    Publisher: Academy of Science of South Africa
    Publication Date: 2017
    detail.hit.zdb_id: 2067033-3
    detail.hit.zdb_id: 2482725-3
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