| 1. |
- Abrham, Muzit, et al.
(author)
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Properties of vertebrate predator–prey networks in the high Arctic
- 2024
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In: Ecology and Evolution. - 2045-7758. ; 14:6
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Journal article (peer-reviewed)abstract
- Predation is an important ecological process that can significantly impact the maintenance of ecosystem services. In arctic environments, the relative ecological importance of predation is thought to be increasing due to climate change, partly because of increased productivity with rising temperatures. Therefore, understanding predator–prey interactions in arctic ecosystems is vital for the sustainable management of these northern regions. Network theory provides a framework for quantifying the structures of ecological interactions. In this study, we use dietary observations on mammalian and avian predators in a high arctic region, including isolated peninsulas on Ellesmere Island and north Greenland, to construct bipartite trophic networks. We quantify the complexity, specialization, and nested as well as modular structures of these networks and also determine if these properties varied among the peninsulas. Mammal prey remains were the dominant diet item for all predators, but there was spatial variation in diet composition among peninsulas. The predator–prey networks were less complex, had more specialized interactions, and were more nested and more modular than random expectations. However, the networks displayed only moderate levels of modularity. Predator species had less specialized interactions with prey than prey had with predators. All network properties differed among the peninsulas, which highlights that ecosystems often show complex responses to environmental characteristics. We suggest that gaining knowledge about spatial variation in the characteristics of predator–prey interactions can enhance our ability to manage ecosystems exposed to environmental perturbations, particularly in high arctic environments subject to rapid environmental change.
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| 2. |
- Angerbjörn, Anders, 1950-, et al.
(author)
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Evaluating the use of marine subsidies by Arctic foxes without direct coastal access; insights from stable isotopes
- 2024
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In: Polar Biology. - 0722-4060 .- 1432-2056.
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Journal article (peer-reviewed)abstract
- The trophic structures of tundra ecosystems are often viewed as a result of local terrestrial primary productivity. However, other resources can be brought in through long-distant migrants or be directly accessible in coastal areas. Hence, trophic structures may deviate from predictions based on local terrestrial resources. The Arctic fox (Vulpes lagopus) is a small canid that may use marine resources when available. We used stable isotope values in Arctic fox fur and literature data on potential prey to evaluate Arctic fox summer resource use in a mountain tundra without coastal access. The dietary contribution of local prey, presumably mostly rodents, declined with declining rodent abundance, with a subsequent increased contribution of migratory prey relying on marine resources. Stable isotope values did not differ between this terrestrial area and an area with direct coastal access during years of high rodent abundance, but isotope values during low rodent abundances suggested less marine input than in a coastal population feeding primarily on marine prey. Our study shows that marine resources may be used by animals in areas without any coastal access, and we highlight that such partial coupling of ecosystems must be included in the modeling and assessments of tundra environments.
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| 3. |
- Bashant, Janelle, et al.
(author)
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Facilitation or Competition? Effects of Lions on Brown Hyaenas and Leopards
- 2020
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In: Diversity. - : MDPI AG. - 1424-2818. ; 12:9
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Journal article (peer-reviewed)abstract
- Intra-guild interactions related to facilitation and competition can be strong forces structuring ecological communities and have been suggested as particularly prominent for large carnivores. The African lion (Panthera leo) is generally thought to be a dominant predator where it occurs and can be expected to have broad effects on sympatric carnivore communities. We used data from two small game reserves in northern South Africa to relate the presence of African lions to abundance, habitat use, diet, and prey selection of two sympatric large carnivores, brown hyaenas (Parahyaena brunnea) and leopards (Panthera pardus). Our results offered some support for the facilitative effects of lions on brown hyaenas, and competitive effects on leopards. However, differences between populations living without and with lions were restricted to broad diet composition and appear not to have permeated into differences in either prey selection, abundance or habitat use. Therefore, we suggest that the potential effects of lions on the predator–prey interactions of sympatric predators may have been context dependent or absent, and subsequently argue that lions may not necessarily influence the predator–prey dynamics in the landscapes they live in beyond those caused by their own predatory behaviour.
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| 4. |
- Belton, L. E., et al.
(author)
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Anthropogenic influences on spotted hyaena diet in the Kruger National Park, South Africa
- 2018
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In: Mammal Research. - : Springer Science and Business Media LLC. - 2199-2401 .- 2199-241X. ; 63:3, s. 315-323
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Journal article (peer-reviewed)abstract
- Rapid urban expansion has led to an increase in carnivores that live close to human dominated environments. Some carnivore species have successfully adapted to these novel conditions and taken advantage of opportunities associated with human habitation. Whilst many studies have compared carnivores living in protected areas to those in an urban setting, few have looked at the relationships between carnivores and human habitation within protected areas. In this study, we examined the effects ofhuman habitation on the diet of spotted hyaenas (Crocuta crocuta) in the Kruger National Park (KNP), South Africa. Our results suggested a limited effect of anthropogenic resources on spotted hyaena diet in the KNP. We found neither temporal nor spatial variation in the amount of, nor types of, anthropogenic material in spotted hyaena scats, despite observations of more road side litter close to large anthropogenic sites. We therefore suggest that anthropogenic resources may not have been utilised completely according to abundance. We encourage further research evaluating potential secondary effects of human activity and infrastructure on spotted hyaena diet and also stable isotope approaches that may provide further insights into the importance of anthropogenic food for spotted hyaenas inside the KNP.
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| 5. |
- Belton, Lydia E., et al.
(author)
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Social networks of spotted hyaenas in areas of contrasting human activity and infrastructure
- 2018
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In: Animal Behaviour. - : Elsevier BV. - 0003-3472 .- 1095-8282. ; 135, s. 13-23
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Journal article (peer-reviewed)abstract
- In group-living animals, the structure of social interactions among group members can have important consequences for individual fitness. Changes in resource abundance can influence social interactions with an expected weakening of social ties during times of resource scarcity. Although human activity and infrastructure often impose a disturbance on animal populations, they can also be a source of reliable resources that are relatively easy to access. We evaluated whether the social networks differed between four spotted hyaena, Crocuta crocuta, clans experiencing contrasting levels of human activity and infrastructure in the Kruger National Park, South Africa. The clan living in an area of high human activity and infrastructure had a less dense social network than the other clans, and the clan living in an area with limited human activity and infrastructure had shorter path lengths than the other clans, suggesting that it had more closely associated individuals. Our results did not support substantial differences between clans in the relative social network positions of animals from different age and rank classes. Contrary to our expectations, we suggest that anthropogenic resources may have weakened the social cohesiveness within spotted hyaena clans. We also argue that our study supports previous suggestions that there may be individual variation within broader classes of rank, age and sex in the position of individual animals in social networks.
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| 6. |
- Belton, Lydia E., et al.
(author)
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Spotted hyaena space use in relation to human infrastructure inside a protected area
- 2016
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In: PeerJ. - : PeerJ. - 2167-8359. ; 4
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Journal article (peer-reviewed)abstract
- Increasing human population growth has led to elevated levels of human-carnivore conflict. However, some carnivore populations have adapted to urban environments and the resources they supply. Such associations may influence carnivore ecology, behaviour and life-history. Pockets of urbanisation sometimes occur within protected areas, so that anthropogenic influences on carnivore biology are not necessarily confined to unprotected areas. In this study we evaluated associations between human infrastructure and related activity and space use of spotted hyaenas within one of the largest protected areas in South Africa, the Kruger National Park. Home range size was smaller for the dominant female of a clan living in close proximity to humans than that of the dominant female of a clan without direct access to human infrastructure. The home range including human infrastructure was also used less evenly during the night, presumably when the animals were active. Within this home range, a village area was preferred during the night, when the least modified areas within the village were preferred and administration and highly modified areas were avoided. During the day, however, there were no preference or avoidance of the village area, but all habitats except unmodified habitats within the village area were avoided. We suggest that human infrastructure and associated activity influenced hyaena space use, primarily through alterations in the spatial distribution of food. However, these effects may have been indirectly caused by habitat modification that generated favourable hunting habitat rather than a direct effect caused by access to human food such as garbage. Because of the often pivotal effects of apex predators in terrestrial ecosystems, we encourage further work aimed to quantify how human presence influences large carnivores and associated ecosystem processes within protected areas.
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| 7. |
- Belton, L. E., et al.
(author)
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Spotted hyaena visitation at anthropogenic sites in the Kruger National Park, South Africa
- 2018
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In: African Zoology. - : Informa UK Limited. - 1562-7020 .- 2224-073X. ; 53:3, s. 113-118
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Journal article (peer-reviewed)abstract
- Many large carnivores are attracted to anthropogenic sites, typically, because they offer easy access to anthropogenic resources, such as garbage. Such behaviour could lead to increased contacts between people and carnivores, with the potential for escalated conflicts. Within protected areas, carnivores experience limited risks of visiting anthropogenic sites. However, conflict could still arise, so that it is important to evaluate the drivers for visitation within protected areas. We tested how age, sex and social rank influenced seasonal visitation rates by spotted hyenas (Crocuta crocuta) at two sites with elevated human activity and infrastructure within the Kruger National Park, South Africa. Social rank did not influence visitation rates, and differences among age classes did not correspond to differences in abilities to procure native food. Instead, juveniles had higher visitation rates than older individuals, but only during the wet season. Visitation rates were not consistently higher during the dry season, nor was there more pronounced differences between age classes in the dry season. Our results suggest the anthropogenic sites were visited as part of exploratory behaviour coupled with occasional rewards. Our study also showed a large individual variation in tendencies towards visiting anthropogenic sites, but only for younger animals. We call for additional studies quantifying individual variation in tendencies to visit anthropogenic sites, and argue that deterrents and limitations in rewards of visiting anthropogenic sites might be efficient in preventing human-hyaena conflict within the Kruger National Park.
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| 8. |
- Chizzola, Maddalena, et al.
(author)
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Landscape Level Effects of Lion Presence (Panthera leo) on Two Contrasting Prey Species
- 2018
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In: Frontiers in Ecology and Evolution. - : Frontiers Media SA. - 2296-701X. ; 6
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Journal article (peer-reviewed)abstract
- Due to the strong individual cost of being predated, potential prey species alter their behavior and physiology in response to predation risk. Such alterations may cause major indirect consequences on prey populations that are additive to the direct demographic effects caused by prey being killed. However, although earlier studies showed strong general effects of the presence of apex predators, recent data suggest that indirect effects may be highly context dependent and not consistently present. We combined behavioral data with data on endocrine stress and stable isotopes to assess landscape level effects of lion (Panthera leo) presence on two prey species in South Africa, impala (Aepyceros melampus) and blue wildebeest (Connochaetes taurinus). We also evaluated if there was any seasonal variation in such effects. In addition, we provide results from a physiological validation for an enzyme-linked immunoassay (EIA) that can be used for non-invasive monitoring of glucocorticoid stress metabolite concentrations in impala from fecal pellets. We did not find any significant differences in vigilance behavior, fecal glucocorticoid metabolite concentrations, delta C-13 values or isotope niche breadth between animals living with and without lions for either species. However, wildebeest living in a reserve with lions spent more time foraging compared to wildebeest in a lion-free environment, but only during the wet season. Values of fecal delta N-15 suggest a shift in habitat use, with impala and wildebeest living with lions potentially feeding in less productive areas compared to animals living without lions. For both species, characteristics of the social groups appeared to be more important than individual characteristics for both foraging and vigilance behavior. Our results highlight that antipredator responses may be highly dynamic and scale-dependent. We urge for further studies that quantify at what temporal and spatial scales predation risk is causing indirect effects on prey populations.
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| 9. |
- Clements, Harley S., et al.
(author)
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The bii4africa dataset of faunal and floral population intactness estimates across Africa's major land uses
- 2024
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In: Scientific data. - 2052-4463. ; 11:1
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Journal article (peer-reviewed)abstract
- Sub-Saharan Africa is under-represented in global biodiversity datasets, particularly regarding the impact of land use on species' population abundances. Drawing on recent advances in expert elicitation to ensure data consistency, 200 experts were convened using a modified-Delphi process to estimate 'intactness scores': the remaining proportion of an 'intact' reference population of a species group in a particular land use, on a scale from 0 (no remaining individuals) to 1 (same abundance as the reference) and, in rare cases, to 2 (populations that thrive in human-modified landscapes). The resulting bii4africa dataset contains intactness scores representing terrestrial vertebrates (tetrapods: ±5,400 amphibians, reptiles, birds, mammals) and vascular plants (±45,000 forbs, graminoids, trees, shrubs) in sub-Saharan Africa across the region's major land uses (urban, cropland, rangeland, plantation, protected, etc.) and intensities (e.g., large-scale vs smallholder cropland). This dataset was co-produced as part of the Biodiversity Intactness Index for Africa Project. Additional uses include assessing ecosystem condition; rectifying geographic/taxonomic biases in global biodiversity indicators and maps; and informing the Red List of Ecosystems.
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| 10. |
- Dalerum, Fredrik, et al.
(author)
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Arctic fox (Alopex lagopus) diet in Karupelv valley, East Greenland, during a summer with low lemming density
- 2000
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In: Arctic. - 0004-0843 .- 1923-1245. ; 53:1, s. 1-8
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Journal article (peer-reviewed)abstract
- We investigated the diet of arctic foxes (Alopex lagopus) in the Karupelv valley, East Greenland, during the summer of 1997. Despite a low density, lemmings were the most utilized prey, comprising 65.3% of dry fecal weight in fresh feces. This demonstrates the importance of lemming species as prey for arctic foxes all through a lemming cycle. Birds, arctic hare (Lepus arcticus), and insects also contributed to the diet. Arctic fox remains suggested that the foxes had scavenged their own species. Vegetation, muskoxen (Ovibos moschatus), and seal (Phocidae) were found in small amounts. We compared estimates of prey availability and diets of arctic foxes for a coastal area (<10 km from the shore) and an inland area (>10 km from the shore). Abundance of avian prey tended to be higher in the coastal area. Fresh feces indicated a significant overall difference in arctic fox diets between th: coastal and inland areas. Within prey categories, lemmings were significantly more represented in the inland area, while the coastal area had a more diverse diet overall. We also suggest that the existence of arctic foxes in East Greenland is dependent on regular peak years in lemming density.
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