Temporal refuges differ between anthropogenic and natural top down pressures in a subordinate carnivore

ABSTRACTApex predators structure communities through consumptive and non-consumptive pathways. In the carnivore guild, this can result in a within-guild cascade through the suppression of mesocarnivores. As the top-down influences of apex predators wane due to human-driven declines, landscape level anthropogenic pressures are rising. Human impacts can be analogous to apex predators in that humans can drive increased mortality in both prey species and carnivores, and impact communities through indirect fear effects and food subsidies. Here, we evaluate whether anthropogenic top-down pressures can structure communities in a similar manner as apex predators in shaping the interactions of mesocarnivores. Specifically, we expect anthropogenic forces to induce comparable effects as occurrence of apex predators in driving spatiotemporal partitioning between two mesocarnivores. Using multiple camera-trap surveys, we compared the temporal response of a small carnivore, the raccoon (Procyon lotor), to the larger coyote (Canis latrans) at four sites across Michigan that represented opposing gradients of pressure from humans and apex predators. Contrary to our expectations, we found that raccoons shifted their activity pattern in response to coyotes at sites with higher anthropogenic pressures and exhibited no temporal response at sites with apex predators. Temporal shifts were characterized by raccoons being more diurnal in areas of high coyote activity. We conclude that despite superficial similarities, anthropogenic forces do not replace the function of native apex predators in structuring the mesocarnivore guild. As such, an intact and functioning native predator guild remains necessary to preserve spatiotemporal community structure, in natural and disturbed systems alike.

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Temporal refuges differ between human and natural top-down pressures in a subordinate carnivore

10.22541/au.163670605.54862056/v1 ◽

2021 ◽

Author(s):

Rumaan Malhotra ◽

Samantha Lima ◽

Nyeema Harris

Keyword(s):

Time Use ◽

Species Interactions ◽

Human Impacts ◽

Apex Predators ◽

Top Down ◽

Anthropogenic Pressures ◽

Multiple Camera ◽

Urban Rural ◽

Food Subsidies ◽

Rural Sites

Animals exhibit variation in their space and time use across an urban-rural gradient. As the top-down influences of apex predators wane due to human-driven declines, landscape level anthropogenic pressures are rising. Human impacts can be analogous to apex predators in that humans can drive increased mortality in both prey species and carnivores, and impact communities through indirect fear effects and food subsidies. Here, we evaluate the time use of a common mesocarnivore across an urban rural gradient, and test whether it is influenced by the intensity of use of a larger carnivore. Using multiple camera-trap surveys, we compared the temporal response of a small carnivore, the raccoon (Procyon lotor), to the larger coyote (Canis latrans) at four sites across Michigan that represented a gradient of pressure from humans. We found that raccoon time use varied by site and was most unique at the rural extreme. Raccoons consistently did not shift their activity pattern in response to coyotes at the site with the highest anthropogenic pressures despite considerable interannual variation, and instead showed the stronger responses to coyotes at more rural sites. Temporal shifts were characterized by raccoons being more diurnal in areas of high coyote activity. We conclude that raccoons do partition time to avoid coyotes. Our results highlight that the variation in raccoon time use across the entirety of the urban-rural gradient needed to be considered, as anthropogenic pressures may dominate and obscure the dynamics of this interaction. In an increasingly anthropocentric world, to understand species interactions, it is imperative that we consider the entire spectrum of human pressures that it may occur within.

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Reintroduced wolves and hunting limit the abundance of a subordinate apex predator in a multi-use landscape

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2020.2202 ◽

2020 ◽

Vol 287 (1938) ◽

pp. 20202202

Author(s):

L. Mark Elbroch ◽

Jake M. Ferguson ◽

Howard Quigley ◽

Derek Craighead ◽

Daniel J. Thompson ◽

...

Keyword(s):

Population Model ◽

Human Impacts ◽

Adult Survival ◽

Apex Predator ◽

Vital Rates ◽

Grey Wolf ◽

Apex Predators ◽

Negative Effects ◽

Top Down ◽

Species Abundances

Top-down effects of apex predators are modulated by human impacts on community composition and species abundances. Consequently, research supporting top-down effects of apex predators occurs almost entirely within protected areas rather than the multi-use landscapes dominating modern ecosystems. Here, we developed an integrated population model to disentangle the concurrent contributions of a reintroduced apex predator, the grey wolf, human hunting and prey abundances on vital rates and abundance of a subordinate apex predator, the puma. Increasing wolf numbers had strong negative effects on puma fecundity, and subadult and adult survival. Puma survival was also influenced by density dependence. Overall, puma dynamics in our multi-use landscape were more strongly influenced by top-down forces exhibited by a reintroduced apex predator, than by human hunting or bottom-up forces (prey abundance) subsidized by humans. Quantitatively, the average annual impact of human hunting on equilibrium puma abundance was equivalent to the effects of 20 wolves. Historically, wolves may have limited pumas across North America and dictated puma scarcity in systems lacking sufficient refugia to mitigate the effects of competition.

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Population dynamics of large and small mammals: Graeme Caughley's grand vision

Wildlife Research ◽

10.1071/wr08004 ◽

2009 ◽

Vol 36 (1) ◽

pp. 1 ◽

Cited By ~ 18

Author(s):

Charles J. Krebs

Keyword(s):

Population Dynamics ◽

Population Control ◽

Population Increase ◽

Control Mechanisms ◽

Relative Role ◽

Top Down ◽

Large Herbivores ◽

Disturbed Systems ◽

Herbivorous Mammals ◽

Grand Vision

Ecologists that study the population dynamics of large and small herbivorous mammals operate in two worlds that overlap only partly, and in this paper I address whether the conjecture that these worlds represent two distinct and valid paradigms is currently justified. I argue that large mammals fall into three groups depending on whether they have effective predators or not, and whether they are harvested by humans. Because of human persecution of large predators, more and more large herbivorous mammals are effectively predator-free and are controlled bottom-up by food. But in less disturbed systems, large herbivorous mammals should be controlled top-down by effective predators, and this can lead to a trophic cascade. Small herbivorous mammals have been suggested to be controlled top-down by predators but some experimental evidence has challenged this idea and replaced it with the notion that predation is one of several factors that may affect rates of population increase. Intrinsic control (territoriality, infanticide, social inhibition of breeding) appears to be common in small herbivorous mammals with altricial young but is absent in species with precocial young, in ecosystems with strong stochastic weather variation (deserts) and in areas of human-induced habitat fragmentation in agricultural monocultures. The extrinsic control of large herbivores with precocial young validates part of Graeme Caughley’s Grand Vision, but the relative role of intrinsic and extrinsic mechanisms for small herbivores with altricial young is still controversial. An improved knowledge of population control mechanisms for large and small herbivores is essential for natural resource management.

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Temporal partitioning and spatiotemporal avoidance among large carnivores in a human-impacted African landscape

PLoS ONE ◽

10.1371/journal.pone.0256876 ◽

2021 ◽

Vol 16 (9) ◽

pp. e0256876

Author(s):

Charlotte E. Searle ◽

Josephine B. Smit ◽

Jeremy J. Cusack ◽

Paolo Strampelli ◽

Ana Grau ◽

...

Keyword(s):

Human Impacts ◽

Activity Patterns ◽

Species Conservation ◽

Travel Behaviour ◽

Sympatric Species ◽

Large Carnivores ◽

East African ◽

Anthropogenic Pressures ◽

Coexistence Mechanisms ◽

Wild Dog

Africa is home to some of the world’s most functionally diverse guilds of large carnivores. However, they are increasingly under threat from anthropogenic pressures that may exacerbate already intense intra-guild competition. Understanding the coexistence mechanisms employed by these species in human-impacted landscapes could help shed light on some of the more subtle ways in which humans may impact wildlife populations, and inform multi-species conservation planning. We used camera trap data from Tanzania’s Ruaha-Rungwa landscape to explore temporal and spatiotemporal associations between members of an intact East African large carnivore guild, and determine how these varied across gradients of anthropogenic impact and protection. All large carnivores except African wild dog (Lycaon pictus) exhibited predominantly nocturnal road-travel behaviour. Leopard (Panthera pardus) appeared to employ minor temporal avoidance of lion (Panthera leo) in all sites except those where human impacts were highest, suggesting that leopard may have been freed up from avoidance of lion in areas where the dominant competitor was less abundant, or that the need for leopard to avoid humans outweighed the need to avoid sympatric competitors. Lion appeared to modify their activity patterns to avoid humans in the most impacted areas. We also found evidence of avoidance and attraction among large carnivores: lion and spotted hyaena (Crocuta crocuta) followed leopard; leopard avoided lion; spotted hyaena followed lion; and lion avoided spotted hyaena. Our findings suggest that large carnivores in Ruaha-Rungwa employ fine-scale partitioning mechanisms to facilitate coexistence with both sympatric species and humans, and that growing human pressures may interfere with these behaviours.

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A METHOD FOR THE SPATIAL ANALYSIS OF ANTHROPOGENIC PRESSURES IN SPANISH MARINE WATERS

Coastal Engineering Proceedings ◽

10.9753/icce.v33.management.64 ◽

2012 ◽

Vol 1 (33) ◽

pp. 64 ◽

Cited By ~ 2

Author(s):

Isabel Moreno ◽

Irene Del Barrio ◽

Ana Lloret ◽

Ainhoa Pérez-Puyol

Keyword(s):

Human Activities ◽

Spatial Information ◽

Human Impacts ◽

Marine Waters ◽

Anthropogenic Pressures ◽

Marine Management ◽

Gis Tools ◽

Environmental Status ◽

Good Environmental Status ◽

Official Sources

In 2008, the European Community adopted the Marine Strategy Framework Directive, aiming to achieve or maintain good environmental status in the European marine environment by 2020, applying an ecosystem-based approach to the management of human activities. Spatial information of the distribution of the human activities and their related pressures is essential to accomplish this task successfully. After compiling the available data from official sources, the spatial extent of the land-based and ocean-based human activities that could have an impact on the Spanish marine waters were estimated and mapped using GIS tools. In addition, a series of indexes were created in order to develop a cumulative analysis, taking into account the different relevance of pressures and that single pressures have different intensities. The identification of areas with an accumulation of pressures revealed that it is in coastal waters around big cities where the greater part of the pressures concentrates for each of the five Spanish marine districts. Human impacts emanating from the identified pressures could not be evaluated and this task is proposed to be accomplished in further projects. Nonetheless, the resulting information is considered very useful for managers and technical staff to support not only marine management but also other planning and decision making in Spain.

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Conflicts in the coastal zone: human impacts on commercially important fish species utilizing coastal habitat

ICES Journal of Marine Science ◽

10.1093/icesjms/fsx237 ◽

2018 ◽

Vol 75 (4) ◽

pp. 1203-1213 ◽

Cited By ~ 13

Author(s):

Elliot J Brown ◽

Rita P Vasconcelos ◽

Håkan Wennhage ◽

Ulf Bergström ◽

Josianne G Støttrup ◽

...

Keyword(s):

Fish Species ◽

Human Activities ◽

Human Impacts ◽

Coastal Development ◽

Life History Stage ◽

Coastal Habitat ◽

Anthropogenic Pressures ◽

Coastal Habitats ◽

Commercially Important ◽

Fishing Impacts

Abstract Coastal ecosystems are ecologically, culturally, and economically important, and hence are under pressure from diverse human activities. We reviewed the literature for existing evidence of effects of human-induced habitat changes on exploited fish utilizing coastal habitats. We focused on fish species of the Northeast Atlantic for which fisheries advice is provided by International Council for the Exploration of the Sea (ICES) and which utilize coastal habitats for at least one life-history stage (LHS). We found that 92% of these species are impacted by human activity in at least one LHS while utilizing coastal habitat and 38% in multiple stages. Anthropogenic pressures most commonly shown to impact these fish species were toxicants and pollutants (75% of species). Eutrophication and anoxia, invasive species, and physical coastal development affected about half of the species (58, 54, and 42% of species, respectively), while indirect fishing impacts affected a minority (17% of species). Moreover, 71% of the ICES advice species that utilize coastal habitats face impacts from more than one pressure, implying cumulative effects. Given that three-fourths of the commercial landings come from fish species utilizing coastal habitats, there is an obvious need for a better understanding of the impacts that human activities cause in these habitats for the development of ecosystem-based fisheries management.

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Bottom-up and top-down human impacts interact to affect a protected coastal Chilean marsh

Ecology ◽

10.1890/15-0327.1 ◽

2016 ◽

Vol 97 (3) ◽

pp. 640-648 ◽

Cited By ~ 6

Author(s):

José M. Fariña ◽

Qiang He ◽

Brian R. Silliman ◽

Mark D. Bertness

Keyword(s):

Human Impacts ◽

Top Down ◽

Bottom Up

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Historical geomorphic analysis of Someșul Mic River (NW Romania) channel spatial and temporal behavior, as a background for the assessment of present day morphological state of the river

Revista de Geomorfologie ◽

10.21094/rg.2019.018 ◽

2019 ◽

Vol 21 (1) ◽

pp. 59-76

Author(s):

Ioana PERȘOIU ◽

Maria HOSU

Keyword(s):

Human Impacts ◽

River Management ◽

Temporal Response ◽

Fluvial Systems ◽

Channel Dynamics ◽

The Past ◽

Management Actions ◽

Geological Conditions ◽

Decadal Scale ◽

Morphological State

In the context of the increased interest on integrating the complex spatial and temporal response of fluvial systems to human impacts into the process of assessing the ecological state of the rivers and in promoting a sustainable river management European countries have developed a multi–scalar, hierarchical, process based hydro–morphological framework focused on understanding the river functioning and evolution as a basis for interpreting current conditions. In this context, the goal of this paper is to demonstrate the usefulness of systematic historic and present day geomorphic analysis along channel reaches with distinct typologies in order to generate a better image of river morphology as a background for assessing its present morphological state. The historical geomorphic analysis of Someșul Mic River’s channel dynamics during the past 250 years has shown that the main controlling factor is climate through its centennial – decadal scale variations in magnitudes and amplitudes of flood events, while the local geological conditions and hydrotechnical works having subordinate effects. The reference condition in assessing the present day morphological state of the river was defined based on channel typology and dynamics between AD 1860 – AD 1970, reflecting a river state far from a pristine condition, but characterized trough human impacts maintained bellow the river sensitivity to disturbances. The Morphological Quality Index (MQI) was calculated for 17 distinct channel reaches. Its values indicate the high geomorphic degradation of the river induced by hydrotechnical interventions along the channel. Very poor conditions are concentrated mainly along the upper reaches of the river, while further downstream the river is in a dominantly moderate deterioration state. The resulted image has the potential to better identify the critical reaches along this river, and the main disturbatory elements acting on them, in order to support better projections on possible channel trajectories andsubsequently river management actions.

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Democracy, Justice, and the Welfare State: Reconstructing Public Care. By Julie Anne White. University Park: Pennsylvania State University Press, 2000. 173p. $35.00, cloth, $17.95 paper.

American Political Science Review ◽

10.1017/s0003055401302022 ◽

2001 ◽

Vol 95 (2) ◽

pp. 469-470

Author(s):

Russell L. Hanson

Keyword(s):

Social Services ◽

Welfare States ◽

State University ◽

Medical Assistance ◽

Pennsylvania State University ◽

Top Down ◽

Public Care ◽

Wide Range ◽

Food Subsidies ◽

The Welfare State

Modern welfare states offer cash payments, public housing, medical assistance, food subsidies, and a wide range of social services to needy individuals. The assistance is rendered by professional social workers and administrators who have the authority (and responsibility) to determine who is needy, what their needs are, and how those needs can be met equitably and efficiently. This top-down approach is both ineffective and paternalistic, according to Julie Anne White, who advocates a system of care based on democratic delib- eration rather than bureaucratic rationality.

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