scholarly journals Behaviourally-mediated interactions of landscape pattern shape predator-prey dynamics in highly altered landscapes

2016 ◽  
Author(s):  
Craig DeMars ◽  
Greg A Breed ◽  
Jonathan Potts ◽  
Robert Serrouya ◽  
Stan Boutin
Keyword(s):  
Landscape Structure ◽  
Boreal Forests ◽  
Rangifer Tarandus ◽  
Spatial Configuration ◽  
Anthropogenic Impacts ◽  
Population Declines ◽  
Linear Features ◽  
Encounter Rates ◽  
Predator Prey ◽  
Management Actions

Landscape structure plays a fundamental role in shaping predator-prey dynamics, often being a key determinant of predator-prey coexistence. Rapid alteration of landscape structure, however, can lead to changes in predator-prey interactions with the magnitude of such changes dependent upon the scale and intensity of alteration and animal behavioural responses to novel environmental stimuli. In the boreal forests of western Canada, linear features (e.g. roads, seismic lines and pipelines) from industrial activity are a ubiquitous form of landscape alteration and increasing evidence suggests their presence has impacted interactions between wolves (Canis lupus) and boreal caribou (Rangifer tarandus caribou), leading to caribou population declines. Using simulation analyses parameterized by empirical data, we demonstrate how linear features affect the ability of wolves to predate caribou and evaluate how the spatial configuration and density of linear features interacts with animal behaviour to influence caribou-wolf encounter rates. Model outputs yield insights into the spatial requirements of caribou for effectively reducing predation risk and further illustrate behavioural strategies that are theoretically optimal for caribou. We discuss how our spatially explicit modelling of predator-prey encounter rates can inform management actions aimed at minimizing anthropogenic impacts within caribou range as well as in other predator-prey systems.

scholarly journals Behaviourally-mediated interactions of landscape pattern shape predator-prey dynamics in highly altered landscapes

2016 ◽  
Author(s):  
Craig DeMars ◽  
Greg A Breed ◽  
Jonathan Potts ◽  
Robert Serrouya ◽  
Stan Boutin
Keyword(s):  
Landscape Structure ◽  
Boreal Forests ◽  
Rangifer Tarandus ◽  
Spatial Configuration ◽  
Anthropogenic Impacts ◽  
Population Declines ◽  
Linear Features ◽  
Encounter Rates ◽  
Predator Prey ◽  
Management Actions

Landscape structure plays a fundamental role in shaping predator-prey dynamics, often being a key determinant of predator-prey coexistence. Rapid alteration of landscape structure, however, can lead to changes in predator-prey interactions with the magnitude of such changes dependent upon the scale and intensity of alteration and animal behavioural responses to novel environmental stimuli. In the boreal forests of western Canada, linear features (e.g. roads, seismic lines and pipelines) from industrial activity are a ubiquitous form of landscape alteration and increasing evidence suggests their presence has impacted interactions between wolves (Canis lupus) and boreal caribou (Rangifer tarandus caribou), leading to caribou population declines. Using simulation analyses parameterized by empirical data, we demonstrate how linear features affect the ability of wolves to predate caribou and evaluate how the spatial configuration and density of linear features interacts with animal behaviour to influence caribou-wolf encounter rates. Model outputs yield insights into the spatial requirements of caribou for effectively reducing predation risk and further illustrate behavioural strategies that are theoretically optimal for caribou. We discuss how our spatially explicit modelling of predator-prey encounter rates can inform management actions aimed at minimizing anthropogenic impacts within caribou range as well as in other predator-prey systems.

Moose, caribou, and fire: have we got it right yet?

2019 ◽  
Vol 97 (10) ◽  
pp. 866-879 ◽  
Author(s):  
C.A. DeMars ◽  
R. Serrouya ◽  
M.A. Mumma ◽  
M.P. Gillingham ◽  
R.S. McNay ◽  
...  
Keyword(s):  
Boreal Forests ◽  
Rangifer Tarandus ◽  
Community Dynamics ◽  
Spatial Scales ◽  
Natural Disturbance ◽  
Apparent Competition ◽  
Time Frame ◽  
Population Declines ◽  
Dominant Form ◽  
Demographic Response

Natural disturbance plays a key role in shaping community dynamics. Within Canadian boreal forests, the dominant form of natural disturbance is fire, and its effects are thought to influence the dynamics between moose (Alces alces (Linnaeus, 1758)) and the boreal ecotype of woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)). Boreal caribou are considered “threatened” and population declines are attributed, at least in part, to disturbance-mediated apparent competition (DMAC) with moose. Here, we tested a primary prediction of the DMAC hypothesis: that moose respond positively to burns within and adjacent to the caribou range. We assessed moose selection for ≤25-year-old burns (when selection is predicted to be strongest) at multiple spatial scales and evaluated whether moose density was correlated with the extent of ≤40-year-old burns (a time frame predicted to negatively affect caribou). Against expectation, moose showed avoidance and low use of ≤25-year-old burns at all scales, regardless of burn age, season, and type of land cover burned. These findings mirrored the demographic response, as we found no correlation between ≤40-year-old burns and moose density. By contradicting the prevailing hypothesis linking fires to caribou population declines, our results highlight the need to understand regional variation in disturbance impacts on caribou populations.

Effects of linear features on resource selection and movement rates of wood bison (Bison bison athabascae)

2020 ◽  
Vol 98 (1) ◽  
pp. 21-31
Author(s):  
C.A. DeMars ◽  
S.E. Nielsen ◽  
M.A. Edwards
Keyword(s):  
Boreal Forests ◽  
Native Species ◽  
Resource Selection ◽  
Rangifer Tarandus ◽  
Bison Bison ◽  
Weak Selection ◽  
Linear Features ◽  
Wood Bison ◽  
Using Data ◽  
Northeastern Alberta

Human-mediated disturbances can lead to novel environmental features that can affect native biota beyond simple habitat loss. In boreal forests of western Canada, linear features (LFs; e.g., pipelines, seismic lines, and roads) are known to alter behaviour, movements, and interactions among species. Understanding LF impacts on native species has therefore been a management priority. Here, we investigate how LFs affect the spatial behaviour of wood bison (Bison bison athabascae Rhoads, 1898), which are designated as “threatened” in Canada. Using data collected from the Ronald Lake population in northeastern Alberta, we assessed how LFs influenced habitat selection and movement of bison by testing support among three hypotheses explaining whether LFs (i) increased forage availability, (ii) enhanced movement efficiency, or (iii) increased predation risk. Results supported the movement efficiency hypothesis as bison were generally ambivalent toward LFs, showing weak selection or avoidance depending on land-cover type, but moved slightly faster when on them. These findings contrast with avoidance behaviours reported for sympatric woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)), which are also “threatened.” Our results should inform critical habitat decisions for wood bison, but we caution that further research is needed to understand the effects of LFs on bison demography.

scholarly journals Long-term nutrient reductions lead to the unprecedented recovery of a temperate coastal region

2018 ◽  
Vol 115 (14) ◽  
pp. 3658-3662 ◽  
Author(s):  
Jonathan S. Lefcheck ◽  
Robert J. Orth ◽  
William C. Dennison ◽  
David J. Wilcox ◽  
Rebecca R. Murphy ◽  
...  
Keyword(s):  
Chesapeake Bay ◽  
Structural Equation ◽  
Aquatic Vegetation ◽  
Structural Equation Models ◽  
Anthropogenic Impacts ◽  
Watershed Modeling ◽  
Unexpected Finding ◽  
Nutrient Loads ◽  
Management Actions ◽  
Successful Recovery

Humans strongly impact the dynamics of coastal systems, yet surprisingly few studies mechanistically link management of anthropogenic stressors and successful restoration of nearshore habitats over large spatial and temporal scales. Such examples are sorely needed to ensure the success of ecosystem restoration efforts worldwide. Here, we unite 30 consecutive years of watershed modeling, biogeochemical data, and comprehensive aerial surveys of Chesapeake Bay, United States to quantify the cascading effects of anthropogenic impacts on submersed aquatic vegetation (SAV), an ecologically and economically valuable habitat. We employ structural equation models to link land use change to higher nutrient loads, which in turn reduce SAV cover through multiple, independent pathways. We also show through our models that high biodiversity of SAV consistently promotes cover, an unexpected finding that corroborates emerging evidence from other terrestrial and marine systems. Due to sustained management actions that have reduced nitrogen concentrations in Chesapeake Bay by 23% since 1984, SAV has regained 17,000 ha to achieve its highest cover in almost half a century. Our study empirically demonstrates that nutrient reductions and biodiversity conservation are effective strategies to aid the successful recovery of degraded systems at regional scales, a finding which is highly relevant to the utility of environmental management programs worldwide.

Australian waterbirds - time and space travellers in dynamic desert landscapes

2010 ◽  
Vol 61 (8) ◽  
pp. 875 ◽  
Author(s):  
R. T. Kingsford ◽  
D. A. Roshier ◽  
J. L. Porter
Keyword(s):  
Resource Availability ◽  
Environmental Flows ◽  
Anthropogenic Impacts ◽  
Aquatic Organisms ◽  
River Regulation ◽  
Population Declines ◽  
Time And Space ◽  
Regulated Rivers ◽  
Spatial And Temporal Scales ◽  
Resource Patches

Australia’s waterbirds are mostly nomadic, capitalising on highly variable aquatic resources in the arid interior (70% of the continent) for feeding and breeding. Waterbirds, unlike most aquatic organisms, can move between catchments, exploiting habitat wherever it occurs. In Australia, patterns of resource availability for waterbirds are mostly pulsed with peaks of productivity, coinciding with flooding and differing in time and space, affecting individuals, species and functional groups of waterbirds. Australian waterbirds are no different from waterbirds elsewhere, with their behaviour reflecting broad-scale resource availability. They respond to changing patterns of resource distribution, with rapid movements at spatial and temporal scales commensurate with the dynamics of the resource. The most serious conservation threat to waterbirds is a bottleneck in resource availability, leading to population declines, increasingly forced by anthropogenic impacts. River regulation and other threats (e.g. draining) reduce the availability of wetland habitat and decrease the probability of viable resource patches. It is axiomatic that waterbirds need water and such population bottlenecks may occur when the availability of water across the continent is limited. The rehabilitation of regulated rivers with environmental flows and protection of naturally flowing rivers in the arid region are essential for long-term sustainability of Australia’s waterbird populations.

Cryptic and cumulative impacts on the wintering habitat of the endangered black-faced spoonbill (Platalea minor) risk its long-term viability

2017 ◽  
Vol 45 (2) ◽  
pp. 147-154 ◽  
Author(s):  
EVAN J. PICKETT ◽  
MELANIE CHAN ◽  
WENDA CHENG ◽  
JOHN ALLCOCK ◽  
SIMBA CHAN ◽  
...  
Keyword(s):  
Climate Change ◽  
Habitat Loss ◽  
Population Change ◽  
Anthropogenic Impacts ◽  
Population Viability Analysis ◽  
Cumulative Impacts ◽  
Population Declines ◽  
Distribution Models ◽  
Waterbird Species

SUMMARYThe East Asian–Australasian flyway contains some of the most threatened habitats in the world, with at least 155 waterbird species reliant on the tidal habitats it comprises. The black-faced spoonbill (Platalea minor) is an iconic endangered species distributed across the coast of East Asia. Its population suffered a severe decline into the 1990s, but extensive monitoring and conservation interventions have aided a substantial recovery of the species. We used a population viability analysis based on data collected over the past two decades in conjunction with species distribution models to project spatially explicit models of population change for the next 35 years. Over nearly all scenarios of habitat loss and climate change, the global spoonbill population was projected to increase in the short-term due to low population numbers likely well below current population carrying capacities. However, climate change and habitat loss together threaten the recovery of the spoonbill population such that, by 2050, population declines are apparent as a consequence of these cumulative impacts. These threats are also cryptic and represent a challenge to the conservation of species recovering from anthropogenic impacts; observed population increases can hide large reductions in habitat suitability that threaten the long-term viability of species.

Prey Selection by Freshwater Predators with Different Foraging Strategies

1985 ◽  
Vol 42 (11) ◽  
pp. 1720-1732 ◽  
Author(s):  
Scott D. Cooper ◽  
Daniel W. Smith ◽  
James R. Bence
Keyword(s):  
Prey Selection ◽  
Foraging Strategies ◽  
Foraging Mode ◽  
Encounter Rates ◽  
Predator Prey ◽  
Anax Junius ◽  
Odonate Larvae ◽  
Selection For ◽  
Predator Foraging ◽  
Pachydiplax Longipennis

We observed several freshwater predators, including the odonate larvae Pachydiplax longipennis and Anax junius, the hemipterans Notonecta unifasciata and Buenoa scimitra, the dytiscid larva Acilius semisulcatus, and juvenile Gambusia affinis, feeding on a variety of microcrustacean prey and determined the frequency of the component parts of predator–prey interactions (encounter, attack, capture, ingestion). Encounter rates were the most important determinant of predator selectivity when predators were presented with a variety of microcrustacean prey. When only copepod species were used as prey, however, both encounter rates and capture success were important in determining predator diets. We used our data to test hypotheses concerning relationships between predator foraging mode and patterns of prey selection: mobile predators exhibited stronger selection for sedentary prey than did sit-and-wait predators; our own and literature data also indicated that macroinvertebrate sit-and-wait predators are better able to capture, and have higher selectivity for evasive prey than do mobile predators. A predator's attack acceleration, however, may be a better predictor of its selectivity for evasive versus nonevasive prey than its mean swimming speed.

scholarly journals Population Ecology of Caribou in British Columbia

Rangifer ◽  
1996 ◽  
Vol 16 (4) ◽  
pp. 73 ◽  
Author(s):  
D.R. Seip ◽  
D.B. Cichowski
Keyword(s):  
British Columbia ◽  
Canis Lupus ◽  
Rangifer Tarandus ◽  
Population Decline ◽  
Predation Rate ◽  
Mortality Rates ◽  
Geographic Range ◽  
Population Declines ◽  
Wolf Predation ◽  
Close Proximity

The abundance and geographic range of woodland caribou (Rangifer tarandus caribou) decreased in many areas of British Columbia during the 1900's. Recent studies have found that predation during the summer is the major cause of mortality and current population declines. Increased moose {Alecs alces) populations may be related to past and current caribou declines by sustaining greater numbers of wolves (Canis lupus). Mortality rates were greater in areas where caribou calved in forested habitats, in close proximity to predators and moose. Caribou populations which had calving sites in alpine areas, islands, and rugged mountains experienced lower mortality and were generally stable or increasing. A predator-induced population decline in one area appeared to stabilize at low caribou densities, suggesting that the wolf predation rate may be density dependent.

scholarly journals Predator management and species at risk in Alberta

2016 ◽  
Author(s):  
Dave Hervieux
Keyword(s):  
Current Knowledge ◽  
Apparent Competition ◽  
Provincial Government ◽  
Management Approach ◽  
Population Declines ◽  
Woodland Caribou ◽  
Management Actions ◽  
Habitat Recovery ◽  
Predator Management ◽  
Anthropogenic Habitat

Alberta has employed lethal techniques to reduce predator populations in several wildlife-management situations, particularly in attempts to achieve goals and objectives for threatened or endangered species. Annual wolf populations reductions within and adjacent to woodland caribou population ranges in West Central Alberta are a notable example of this management approach. Almost all woodland caribou populations in Alberta are exhibiting ongoing population declines, with some populations declining at rapid rates. Current knowledge indicates that these declines are from apparent competition due to anthropogenic habitat changes, with resulting unsustainably high levels of wolf predation on woodland caribou populations. Delivery of annual wolf population reductions for two woodland caribou populations has resulted in stable or slightly increasing caribou population growth; in the absence of the wolf program at least one of the caribou populations would now be extirpated. The delivery of lethal wolf management for woodland caribou conservation and recovery in Alberta is enabled by a variety of provincial government approved management plans and policies. It is fully recognized that predator management for woodland caribou recovery must be predicated on management approaches and actions to improve caribou habitat conservation and recovery and thereby address the ultimate factors influencing apparent competition and unsustainably high levels of predation. Considerable effort is now being devoted to planning, policy revisions, regulatory adjustments, and management actions to address fundamental considerations related to caribou habitat. Progress on woodland caribou habitat will have little relevance; however, if the resident caribou population becomes extirpated before sufficient habitat recovery is achieved. Effective reductions in predation rates are needed immediately.

scholarly journals Bycatch mitigation could prevent strong changes in the ecological strategies of seabird communities across the globe

2021 ◽  
Author(s):  
Cerren Richards ◽  
Robert S. C. Cooke ◽  
Diana E. Bowler ◽  
Kristina Boerder ◽  
Amanda E. Bates
Keyword(s):  
Spatial Variation ◽  
Ecosystem Functioning ◽  
Species Traits ◽  
Fishing Effort ◽  
Population Declines ◽  
Ecological Strategies ◽  
Mass Generation ◽  
Management Actions ◽  
Distribution Ranges ◽  
Fisheries Bycatch

Fisheries bycatch, the incidental mortality of non-target species, is a major threat to seabirds worldwide. Mitigating bycatch is an important factor to reduce seabird population declines and consequent changes in ocean trophic dynamics and ecosystem functioning. However, it remains an open question how and where mitigating bycatch at a global scale may conserve seabird traits and the ecological strategies that traits represent. Here we combine a dataset of species traits and distribution ranges for 341 seabirds with spatially resolved fishing effort data for gillnet, longline, trawl, and purse seine gears to: (1) understand spatial variation in seabird community traits; and (2) test whether mitigating fisheries bycatch may prevent shifts in traits of seabird communities and loss of ecological strategies. We find distinct spatial variation in the community weighted mean of five seabird traits (clutch size, body mass, generation length, foraging guild, and diet guild). Furthermore, our analysis suggests that successful bycatch mitigation could prevent strong shifts in the traits of seabird communities across the globe particularly in the North Atlantic and Southern Oceans. Specifically, changes in dominant foraging and diet guilds, and shifts towards communities with faster reproductive speeds (larger clutch sizes and shorter generation lengths) and smaller body masses could be avoided. Therefore, bycatch mitigation may have important indirect benefits for sustaining ecosystem functioning, as mediated by species traits. Incorporating species traits into management actions will provide valuable tools for marine spatial planning and when evaluating the success of conservation initiatives.

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