scholarly journals Trophic consequences of terrestrial eutrophication for a threatened ungulate

2021 ◽  
Vol 288 (1943) ◽  
pp. 20202811
Author(s):  
Robert Serrouya ◽  
Melanie Dickie ◽  
Clayton Lamb ◽  
Harry van Oort ◽  
Allicia P. Kelly ◽  
...  
Keyword(s):  
Primary Productivity ◽  
Rangifer Tarandus ◽  
Food Limitation ◽  
Species Traits ◽  
Apparent Competition ◽  
Habitat Alteration ◽  
Trophic Chain ◽  
Proximate Cause ◽  
Cascading Effects ◽  
Canadian Boreal Forest

Changes in primary productivity have the potential to substantially alter food webs, with positive outcomes for some species and negative outcomes for others. Understanding the environmental context and species traits that give rise to these divergent outcomes is a major challenge to the generality of both theoretical and applied ecology. In aquatic systems, nutrient-mediated eutrophication has led to major declines in species diversity, motivating us to seek terrestrial analogues using a large-mammal system across 598 000 km 2 of the Canadian boreal forest. These forests are undergoing some of the most rapid rates of land-use change on Earth and are home to declining caribou ( Rangifer tarandus caribou ) populations. Using satellite-derived estimates of primary productivity, coupled with estimates of moose ( Alces alces ) and wolf ( Canis lupus ) abundance, we used path analyses to discriminate among hypotheses explaining how habitat alteration can affect caribou population growth. Hypotheses included food limitation, resource dominance by moose over caribou, and apparent competition with predators shared between moose and caribou. Results support apparent competition and yield estimates of wolf densities (1.8 individuals 1000 km −2 ) above which caribou populations decline. Our multi-trophic analysis provides insight into the cascading effects of habitat alteration from forest cutting that destabilize terrestrial predator–prey dynamics. Finally, the path analysis highlights why conservation actions directed at the proximate cause of caribou decline have been more successful in the near term than those directed further along the trophic chain.

Is there a cost of parasites to caribou?

Parasitology ◽  
2008 ◽  
Vol 136 (2) ◽  
pp. 253-265 ◽  
Author(s):  
J. HUGHES ◽  
S. D. ALBON ◽  
R. J. IRVINE ◽  
S. WOODIN
Keyword(s):  
Rangifer Tarandus ◽  
Parasite Species ◽  
Negative Relationship ◽  
Apparent Competition ◽  
Range Shift ◽  
The Arctic ◽  
Contributory Factor ◽  
Ovibos Moschatus ◽  
Winter Range ◽  
Nematode Parasites

SUMMARYMacroparasites potentially play a significant but often ignored role in the ecology and dynamics of wild ruminant populations. In the Arctic, parasites may impact on host populations by exacerbating the effects of seasonal and limited forage availability on the condition, fecundity and survival of individuals. We studied the effects of abomasal nematode parasites and warble flies, Hypoderma tarandi, on condition and pregnancy of caribou Rangifer tarandus in the Dolphin-Union herd, Nunavut, Canada. By the end of winter, female caribou over 2 years old showed a significant decrease in body weight with increasing nematode burden, and a decrease in back fat depth with increasing warble abundance. These effects were exaggerated in the non-pregnant fraction of the population. High warble larvae burdens were also associated with significantly reduced probability of being pregnant. Our research demonstrates a negative relationship between parasites and caribou condition that may have consequences for their fitness. Additionally, we discuss the possibility that muskox Ovibos moschatus share some parasite species with the caribou and could lead to elevated burdens in the sympatric host. Parasites may have been a contributory factor in a previous winter range-shift of the caribou herd and this may reflect a form of apparent competition between the two ungulate species.

scholarly journals Studies in bank voles reveal strain differences between chronic wasting disease prions from Norway and North America

2020 ◽  
Vol 117 (49) ◽  
pp. 31417-31426 ◽  
Author(s):  
Romolo Nonno ◽  
Michele A. Di Bari ◽  
Laura Pirisinu ◽  
Claudia D’Agostino ◽  
Ilaria Vanni ◽  
...  
Keyword(s):  
North America ◽  
North American ◽  
Rangifer Tarandus ◽  
Chronic Wasting Disease ◽  
Strain Differences ◽  
Myodes Glareolus ◽  
Wasting Disease ◽  
Proximate Cause ◽  
Bank Voles ◽  
Regional Deposition

Chronic wasting disease (CWD) is a relentless epidemic disorder caused by infectious prions that threatens the survival of cervid populations and raises increasing public health concerns in North America. In Europe, CWD was detected for the first time in wild Norwegian reindeer (Rangifer tarandus) and moose (Alces alces) in 2016. In this study, we aimed at comparing the strain properties of CWD prions derived from different cervid species in Norway and North America. Using a classical strain typing approach involving transmission and adaptation to bank voles (Myodes glareolus), we found that prions causing CWD in Norway induced incubation times, neuropathology, regional deposition of misfolded prion protein aggregates in the brain, and size of their protease-resistant core, different from those that characterize North American CWD. These findings show that CWD prion strains affecting Norwegian cervids are distinct from those found in North America, implying that the highly contagious North American CWD prions are not the proximate cause of the newly discovered Norwegian CWD cases. In addition, Norwegian CWD isolates showed an unexpected strain variability, with reindeer and moose being caused by different CWD strains. Our findings shed light on the origin of emergent European CWD, have significant implications for understanding the nature and the ecology of CWD in Europe, and highlight the need to assess the zoonotic potential of the new CWD strains detected in Europe.

scholarly journals Diet of Grey Wolves (Canis lupus) During Calving in a Moose– Caribou System in Northern Ontario

2018 ◽  
Vol 131 (3) ◽  
pp. 215-220
Author(s):  
Rob Found ◽  
Ashley A. D. McLaren ◽  
Arthur R. Rodgers ◽  
Brent R. Patterson
Keyword(s):  
Canis Lupus ◽  
Rangifer Tarandus ◽  
Castor Canadensis ◽  
Northern Ontario ◽  
Southern Limit ◽  
Proximate Cause ◽  
Declining Populations ◽  
Dietary Component ◽  
A Minor ◽  
The Impact

Grey Wolves (Canis lupus) are a leading proximate cause of declining populations of Woodland Caribou (Rangifer tarandus), a threatened species. Although predation on adult caribou has been well documented, less is known about predation on neonatal calves. We used scat analysis to examine the diet of wolves in an area of Ontario overlapping the receding southern limit of caribou occurrence. Wolves consumed mostly Moose (Alces americanus; 82.7%), followed by American Beaver (Castor canadensis; 10.9%), caribou (3.1%), and Snowshoe Hare (Lepus americanus; 1.5%). This low use of caribou is consistent with other evidence suggesting that caribou are a minor dietary component of wolves in this system; however, because most caribou consumption consists of calves, the impact on this slowly reproducing species may still be significant.

Managing wolves (Canis lupus) to recover threatened woodland caribou (Rangifer tarandus caribou) in Alberta

2014 ◽  
Vol 92 (12) ◽  
pp. 1029-1037 ◽  
Author(s):  
Dave Hervieux ◽  
Mark Hebblewhite ◽  
Dave Stepnisky ◽  
Michelle Bacon ◽  
Stan Boutin
Keyword(s):  
Canis Lupus ◽  
Rangifer Tarandus ◽  
Apparent Competition ◽  
Provincial Government ◽  
Population Increase ◽  
Rangifer Tarandus Caribou ◽  
Wolf Population ◽  
Woodland Caribou ◽  
Population Reduction ◽  
Reduction Program

Across Canada, woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)) populations are declining because of human-induced changes to food webs that are resulting in apparent competition-induced increases in predator-caused caribou mortality. We tested the hypothesis that wolf (Canis lupus L., 1758) population reduction could reverse declines in a woodland caribou population following a BACI (before-after-control-impact) design conducted over a 12-year period in west-central Alberta, Canada. We monitored annual survival for 172 adult female caribou and calf recruitment from 2000 through 2012 and conducted a provincial government delivered wolf population reduction program annually during the winters of 2005–2006 to 2012 (inclusive) in an area centered on the Little Smoky range. Wolf removal translated to a 4.6% increase in mean population growth rate of the Little Smoky population mostly through improvements in calf recruitment. In contrast, the Red Rock Prairie Creek control population exhibited a 4.7% decline. Although the wolf population reduction program appeared to stabilize the Little Smoky population, it did not lead to population increase, however, with λ remaining approximately equal to 1. Therefore, we recommend, if required, predation management be combined with effective habitat conservation and long-term planning to effect the recovery of species, such as woodland caribou, which are declining as a result of habitat-mediated apparent competition.

scholarly journals Cougar (Puma concolor) predation on Northern Mountain Caribou (Rangifer tarandus caribou) in central British Columbia

2020 ◽  
Vol 134 (3) ◽  
pp. 265-269
Author(s):  
Shane C. White ◽  
Carolyn R. Shores ◽  
Leo DeGroot
Keyword(s):  
British Columbia ◽  
Rangifer Tarandus ◽  
Puma Concolor ◽  
Apparent Competition ◽  
Western Canada ◽  
Rangifer Tarandus Caribou ◽  
Feral Horses ◽  
The Status ◽  
Conservation Concern ◽  
Terrestrial Lichen

Caribou (Rangifer tarandus) populations are sympatric with Cougars (Puma concolor) in only a few areas, primarily in western Canada. Records of Cougar–Caribou interactions are limited and no published accounts describe Cougar predation on the shallow-snow, terrestrial-lichen-eating Northern Mountain Caribou (Rangifer tarandus caribou), referred to as Designatable Unit (DU) 7 by the Committee on the Status of Endangered Wildlife in Canada. In 2018 and 2019, two incidents of confirmed Cougar predation on radio-collared Caribou were documented in the declining Itcha-Ilgachuz subpopulation in west-central British Columbia. To the best of our knowledge, this is the first published record of Cougar predation on DU7 Northern Mountain Caribou. Increased landscape disturbance and climate change may be increasing apparent competition between deer (Odocoileus spp.), feral Horses (Equus ferus caballus), and Caribou, leading to Cougar predation in areas of Caribou range where it previously has not been documented. Cougar predation may become a conservation concern, as declining Caribou herds are susceptible to any increased predation pressure.

Timing and synchrony of activity in caribou

1998 ◽  
Vol 76 (11) ◽  
pp. 1999-2009 ◽  
Author(s):  
Julie AK Maier ◽  
Robert G White
Keyword(s):  
Rangifer Tarandus ◽  
Activity Patterns ◽  
Food Limitation ◽  
Late Winter ◽  
Activity Data ◽  
Alaska Range ◽  
Time Activity ◽  
Focal Animal ◽  
Limited Food ◽  
Free Ranging

Activity data were analyzed to assess activity patterns of caribou (Rangifer tarandus granti). We hypothesized that equal day and night activity, termed nychthemeral activity, would be expected if food constitutes a limiting resource for a highly gregarious species. To test this hypothesis, we investigated activity patterns of two caribou populations at the same latitude: one captive with no food limitation and the other wild and free-ranging in the Alaska Range in interior Alaska known to be at the end of a 3-year low plane of nutrition. For captive caribou, activity patterns were determined from focal-animal behavioural observations each month except May. Data were collected on wild caribou using activity-recording radio collars in each of three seasons: late winter, postcalving, and midsummer. Wild and captive caribou exhibited nychthemeral activity and did not time activity to sunrise or sunset. Wild caribou exhibited no among-group synchrony. Within-group synchrony was high in both herds. Wild caribou exhibited significantly fewer cycles of activity than captive caribou. Longer resting bouts in late winter, and longer active bouts postcalving and in midsummer for wild caribou, were interpreted as behavioural responses to ecological effects of limited food availability, with and without snow, and disturbance by insects.

Roads, logging, and the large-mammal community of an eastern Canadian boreal forest

2010 ◽  
Vol 88 (5) ◽  
pp. 454-467 ◽  
Author(s):  
Jeff Bowman ◽  
Justina C. Ray ◽  
Audrey J. Magoun ◽  
Devin S. Johnson ◽  
F. Neil Dawson
Keyword(s):  
Rangifer Tarandus ◽  
Deciduous Forest ◽  
Close Association ◽  
Coniferous Forest ◽  
Gray Wolf ◽  
The South ◽  
Road Density ◽  
The North ◽  
Canadian Boreal Forest ◽  
Mammal Communities

We evaluated hypotheses concerning the distributions of large mammals in a 60 000 km2 study area that encompassed the contact zone between Ontario’s roadless north and the postlogging southern landscape. We estimated occurrence probability in 575 sample units for woodland caribou ( Rangifer tarandus caribou (Gmelin, 1788)), wolverine ( Gulo gulo (L., 1758)), gray wolf ( Canis lupus L., 1758), moose ( Alces alces (L., 1758)), and white-tailed deer ( Odocoileus virginianus (Zimmerman, 1780)). We used ordinations and spatial regressions to assess the contributions of parameters to species occurrence. Roads and cutovers were most abundant in the south, leading to an increased prevalence of deciduous forest. Mature coniferous forest, however, occurred most commonly in the north. Occurrence probabilities for moose and deer were greatest in the south, in close association with deciduous trees. Wolf occurrence was also greatest in the south, positively related to both deciduous forest and road density. Caribou occurrence, however, was positively related to mature coniferous forest and negatively related to both wolf occurrence and roads. Wolverine occurrence was negatively related to deciduous forest. Our surveys demonstrated distinct mammal communities in the northern and southern halves of our study area, a separation that appeared to be mediated by deciduous forest and roads.

scholarly journals Using predator-prey theory to predict outcomes of a broad-scale test of apparent competition

2020 ◽  
Author(s):  
R Serrouya ◽  
M Wittmann ◽  
B McLellan ◽  
Heiko Wittmer ◽  
S Boutin
Keyword(s):  
Rangifer Tarandus ◽  
Field Experiments ◽  
Puma Concolor ◽  
Field Studies ◽  
Apparent Competition ◽  
Ecological Communities ◽  
Predator Prey ◽  
Theoretical Predictions ◽  
Scale Test ◽  
The University

© 2015 by The University of Chicago. 0003-0147/2015/18505-55371$15.00. All rights reserved. Apparent competition is an important process influencing many ecological communities. We used predator-prey theory to predict outcomes of ecosystem experiments aimed at mitigating apparent competition by reducing primary prey. Simulations predicted declines in secondary prey following reductions in primary prey because predators consumed more secondary prey until predator numbers responded to reduced prey densities. Losses were exacerbated by a higher carrying capacity of primary prey and a longer lag time of the predator’s numerical response, but a gradual reduction in primary prey was less detrimental to the secondary prey. We compared predictions against two field experiments where endangered woodland caribou (Rangifer tarandus caribou) were victims of apparent competition. First, when deer (Odocoileus sp.) declined suddenly following a severe winter, cougar (Puma concolor) declined with a 1– 2-year lag, yet in the interim more caribou were killed by cougars, and caribou populations declined by 40%. Second, when moose (Alces alces) were gradually reduced using a management experiment, wolf (Canis lupus) populations declined but did not shift consumption to caribou, and the largest caribou subpopulation stabilized. The observed contrasting outcomes of sudden versus gradual declines in primary prey supported theoretical predictions. Combining theory with field studies clarified how to manage communities to mitigate endangerment caused by apparent competition that affects many taxa.

scholarly journals First record of herbivory of the invasive macrophyte Hedychium coronarium J. König (Zingiberaceae)

2013 ◽  
Vol 13 (4) ◽  
pp. 368-370 ◽  
Author(s):  
Wagner Antonio Chiba de Castro ◽  
Marcel Loyo Moitas ◽  
Gabriela Monteiro Lobato ◽  
Marcela Bianchessi da Cunha-Santino ◽  
Dalva Maria da Silva Matos
Keyword(s):  
Invasive Species ◽  
Food Resource ◽  
First Record ◽  
Apparent Competition ◽  
Aquatic Weed ◽  
Trophic Chain ◽  
Functional Changes ◽  
Hedychium Coronarium ◽  
Floodplain Area ◽  
Native Habitats

Invasive species can cause structural and functional changes in their non-native habitats, such as changes in the trophic chain. We describe ramet herbivory of butterfly ginger, an aggressive aquatic weed in Brazil, by capybaras in a floodplain area of a Cerrado reserve. This is the first record of herbivory of H. coronarium in invaded areas. Capybaras could be using the butterfly ginger as habitat and as a food resource, which could cause changes in apparent competition between these invasive and native macrophytes.

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