scholarly journals Predation rate by wolves on the Porcupine caribou herd

Rangifer ◽  
2000 ◽  
Vol 20 (5) ◽  
pp. 51 ◽  
Author(s):  
Robert D. Hayes ◽  
Donald E. Russell
Keyword(s):  
Canis Lupus ◽  
Rangifer Tarandus ◽  
Predation Rate ◽  
Herd Size ◽  
The Arctic ◽  
Wolf Predation ◽  
Weather Events ◽  
Constant Rate ◽  
Predatory Strategy ◽  
Dependent Model

Large migratory catibou {Rangifer tarandus) herds in the Arctic tend to be cyclic, and population trends are mainly driven by changes in forage or weather events, not by predation. We estimated daily kill rate by wolves on adult caribou in winter, then constructed a time and space dependent model to estimate annual wolf (Canis lupus) predation rate (P annual) on adult Porcupine caribou. Our model adjusts predation seasonally depending on caribou distribution: Pannual = SIGMAdaily* W *Ap(2)*Dp. In our model we assumed that wolves killed adult caribou at a constant rate (Kdaily, 0.08 caribou wolf1 day1) based on our studies and elsewhere; that wolf density (W) doubled to 6 wolves 1000 km2-1 on all seasonal ranges; and that the average area occupied by the Porcupine caribou herd (PCH) in eight seasonal life cycle periods (Dp ) was two times gteater than the area described by the outer boundaries of telemetry data (Ap /1000 km2). Results from our model projected that wolves kill about 7600 adult caribou each year, regardless of herd size. The model estimated that wolves removed 5.8 to 7.4% of adult caribou as the herd declined in the 1990s. Our predation rate model supports the hypothesis of Bergerud that spacing away by caribou is an effective anti-predatory strategy that greatly reduces wolf predation on adult caribou in the spring and summer.

Kill rate by wolves on moose in the Yukon

2000 ◽  
Vol 78 (1) ◽  
pp. 49-59 ◽  
Author(s):  
R D Hayes ◽  
A M Baer ◽  
U Wotschikowsky ◽  
A S Harestad
Keyword(s):  
Canis Lupus ◽  
Snow Depth ◽  
Prey Density ◽  
Large Scale ◽  
Rangifer Tarandus ◽  
Prey Selection ◽  
Ecological Factors ◽  
Predation Rate ◽  
Wolf Predation ◽  
Kill Rate

We studied the kill rate by wolves (Canis lupus) after a large-scale wolf removal when populations of wolves, moose (Alces alces), and woodland caribou (Rangifer tarandus caribou) were all increasing. We followed a total of 21 wolf packs for 4 winters, measuring prey selection, kill rates, and ecological factors that could influence killing behavior. Wolf predation was found to be mainly additive on both moose and caribou populations. Kill rates by individual wolves were inversely related to pack size and unrelated to prey density or snow depth. Scavenging by ravens decreased the amount of prey biomass available for wolves to consume, especially for wolves in smaller packs. The kill rate by wolves on moose calves was not related to the number of calves available each winter. Wolves did not show a strong switching response away from moose as the ratio of caribou to moose increased in winter. The predation rate by wolves on moose was best modeled by the number and size of packs wolves were organized into each winter.

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.

Wolf predation in a multiple-ungulate system in northern British Columbia

1998 ◽  
Vol 76 (8) ◽  
pp. 1551-1569 ◽  
Author(s):  
A T Bergerud ◽  
J P Elliott
Keyword(s):  
British Columbia ◽  
Canis Lupus ◽  
Birth Rate ◽  
Rangifer Tarandus ◽  
Adult Mortality ◽  
Recruitment Rate ◽  
Wolf Predation ◽  
Rate Of Increase ◽  
Ovis Dalli ◽  
Hunting Statistics

Caribou (Rangifer tarandus), elk (Cervus canadensis), moose (Alces alces), and Stone's sheep (Ovis dalli stonei) were either decreasing or stable in numbers in two areas in northeastern British Columbia in 1981-1982, prior to reductions in wolf (Canis lupus) numbers. Following the reduction of wolf numbers, recruitment improved 2-5 times for all four species, and all populations increased, based on either hunting statistics, census results, and (or) recruitments greater than 24 offspring at 9 months of age per 100 females. Recruitment of offspring at 9 months of age, when regressed against wolf numbers, declined with decelerating slopes for all four species. This inverse functional response is hypothesized to result from the preparturient spacing of females to reduce predation risk, and in this regard moose seem the least secure and sheep the most effectively spaced. For the four species, mean recruitment at 9 months of age that balanced adult mortality and provided a finite rate of increase of 1.00 was 24.16 ± 0.91 offspring/100 females (n = 11, coefficient of variation = 12.5%). The predicted recruitment rate for all four species in the absence of wolves was 53-57 offspring/100 females. But the birth rate of moose was much higher than those of the other species, indicating greater loss to other factors of which bear predation may be the greatest. Following wolf reductions of 60-86% of entire travelling packs, the wolves quickly recolonized the removal zones, with rates of increase ranging from 1.5 to 5.6.

scholarly journals Pack Size of Wolves, Canis lupus, on Caribou, Rangifer tarandus, Winter Ranges in Westcentral Alberta

2006 ◽  
Vol 120 (3) ◽  
pp. 313 ◽  
Author(s):  
Gerald W. Kuzyk ◽  
Jeff Kneteman ◽  
Fiona K. A. Schmiegelow
Keyword(s):  
Canis Lupus ◽  
Landscape Change ◽  
Rangifer Tarandus ◽  
Prey Size ◽  
Rocky Mountain ◽  
Predation Pressure ◽  
Resource Extraction ◽  
Rangifer Tarandus Caribou ◽  
Pack Size ◽  
Wolf Predation

We studied pack size of Wolves (Canis lupus) on Woodland Caribou (Rangifer tarandus caribou) winter ranges in westcentral Alberta. These Caribou winter ranges are experiencing increasing pressure from resource extraction industries (forestry, energy sector) and concerns have been raised regarding increased Wolf predation pressure on Caribou in conjunction with landscape change. Thirty-one Wolves, from eight Wolf packs, were fitted with radiocollars on two Caribou winter ranges in the Rocky Mountain foothills, near Grande Cache, Alberta (2000-2001). There was a mean of 8.2 Wolves/pack and between 30 and 39 Wolves on each of the RedRock/Prairie Creek and Little Smoky Caribou ranges. The average pack size of Wolves in this region does not appear to have increased over that recorded historically, but the range (5-18) in the number of Wolves per pack varied considerably over our study area. Wolves preyed predominately on Moose (Alces alces), averaging one Moose kill every three to five days. There was some indication that pack size was related to prey size, with the smallest pack preying on Deer (Odocoileus spp.). It was clear that Caribou could not be the primary prey for Wolves, due to their low numbers, and relative to the pack size and Wolf kills we observed.

Wolf functional response and regulation of moose in the Yukon

2000 ◽  
Vol 78 (1) ◽  
pp. 60-66 ◽  
Author(s):  
R D Hayes ◽  
A S Harestad
Keyword(s):  
Functional Response ◽  
Canis Lupus ◽  
Response Curve ◽  
Predation Rate ◽  
Type Ii ◽  
Prey Switching ◽  
East Central ◽  
Wolf Predation ◽  
Interior Alaska ◽  
Moose Population

We studied kill rates by wolves (Canis lupus) on a rapidly growing moose population in the east-central Yukon. We added these data to the cumulative functional response curve obtained in other North American wolf studies. Our kill rates are higher than those predicted at low moose densities. The kill rate increases rapidly, reaching 2.4 moose per wolf per 100 days at 0.26 moose/km2 and remains constant at this level. No data are available below 0.2 moose/km2 to indicate the shape of the ascending curve. Based on moose distribution and the low prey-switching ability of wolves, we suggest that the functional response curve is of type II. Our wolf predation rate model predicts that moose are held to a low density equilibrium between 0.07 and 0.12/km2, slightly below densities observed in interior Alaska and the Yukon.

scholarly journals Predation and caribou populations

Rangifer ◽  
1991 ◽  
Vol 11 (4) ◽  
pp. 46 ◽  
Author(s):  
Dale R. Seip
Keyword(s):  
North America ◽  
Canis Lupus ◽  
Predator Avoidance ◽  
Rangifer Tarandus ◽  
Food Resources ◽  
Numerical Response ◽  
Population Differences ◽  
Annual Increment ◽  
Wolf Predation ◽  
The Impact

Predation, especially wolf (Canis lupus) predation, limits many North American caribou (Rangifer tarandus) populations below the density that food resources could sustain. The impact of predation depends on the parameters for the functional and numerical response of the wolves, relative to the potential annual increment of the caribou population. Differences in predator-avoidance strategies largely explain the major differences in caribou densities that occur naturally in North America. Caribou migrations that spatially separate caribou from wolves allow relatively high densities of caribou to survive. Non-migratory caribou that live in areas where wolf populations are sustained by alternate prey can be eliminated by wolf predation.

Surplus killing as exemplified by wolf predation on newborn caribou

1985 ◽  
Vol 63 (2) ◽  
pp. 295-300 ◽  
Author(s):  
Frank L. Miller ◽  
Anne Gunn ◽  
Eric Broughton
Keyword(s):  
Northwest Territories ◽  
Canis Lupus ◽  
Rangifer Tarandus ◽  
The Other ◽  
Wolf Predation ◽  
Barren Ground ◽  
Rangifer Tarandus Groenlandicus

We searched for newborn calf carcasses of migratory barren-ground caribou (Rangifer tarandus groenlandicus) in June 1982 in the Northwest Territories. On 17 June, we found 34 calves killed by wolves (Canis lupus), clumped in a 3-km2 area. The calves had been killed apparently within minutes of each other and about 24 h before being found. Wolves had not fed on 17 of the carcasses and had only partially eaten the other 17. Ground observations illustrate the speed of and efficiency with which wolves can kill calves: a single wolf killed three calves on one occasion and three and possibly four calves on a second occasion at average kill rates of 1 calf/min, and 1 calf/8 min or 1 calf/6 min between the first and last deaths. We attributed the surplus killing of newborn caribou calves to their high densities and their vulnerability on the calving grounds. We recommend that a distinction be made between "surplus killing" and "excessive killing" by predators.

scholarly journals Spatial variations in the warming trend and the transition to more severe weather in midlatitudes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Francisco Estrada ◽  
Dukpa Kim ◽  
Pierre Perron
Keyword(s):  
Radiative Forcing ◽  
Warming Trend ◽  
Severe Weather ◽  
Montreal Protocol ◽  
The Arctic ◽  
Extreme Weather Events ◽  
Jet Stream ◽  
Atmospheric Blocking ◽  
Regional Warming ◽  
Weather Events

AbstractDue to various feedback processes called Arctic amplification, the high-latitudes’ response to increases in radiative forcing is much larger than elsewhere in the world, with a warming more than twice the global average. Since the 1990’s, this rapid warming of the Arctic was accompanied by no-warming or cooling over midlatitudes in the Northern Hemisphere in winter (the hiatus). The decrease in the thermal contrast between Arctic and midlatitudes has been connected to extreme weather events in midlatitudes via, e.g., shifts in the jet stream towards the equator and increases in the probability of high-latitude atmospheric blocking. Here we present an observational attribution study showing the spatial structure of the response to changes in radiative forcing. The results also connect the hiatus with diminished contrast between temperatures over regions in the Arctic and midlatitudes. Recent changes in these regional warming trends are linked to international actions such as the Montreal Protocol, and illustrate how changes in radiative forcing can trigger unexpected responses from the climate system. The lesson for climate policy is that human intervention with the climate is already large enough that even if stabilization was attained, impacts from an adjusting climate are to be expected.

scholarly journals Observed and predicted effects of climate change on Arctic caribou and reindeer

2018 ◽  
Vol 26 (1) ◽  
pp. 13-25 ◽  
Author(s):  
Conor D. Mallory ◽  
Mark S. Boyce
Keyword(s):  
Climate Change ◽  
Rangifer Tarandus ◽  
The Arctic ◽  
Arctic Ecosystems ◽  
Global Trends ◽  
Warming Climate ◽  
The Many ◽  
Rapid Environmental Change ◽  
Full Consideration ◽  
Strong Concern

The ability of many species to adapt to the shifting environmental conditions associated with climate change will be a key determinant of their persistence in the coming decades. This is a challenge already faced by species in the Arctic, where rapid environmental change is well underway. Caribou and reindeer (Rangifer tarandus) play a key role in Arctic ecosystems and provide irreplaceable socioeconomic value to many northern peoples. Recent decades have seen declines in many Rangifer populations, and there is strong concern that climate change is threatening the viability of this iconic Arctic species. We examine the literature to provide a thorough and full consideration of the many environmental factors that limit caribou and reindeer populations, and how these might be affected by a warming climate. Our review suggests that the response of Rangifer populations to climate change is, and will continue to be, varied in large part to their broad circumpolar distribution. While caribou and reindeer could have some resilience to climate change, current global trends in abundance undermine all but the most precautionary outlooks. Ultimately, the conservation of Rangifer populations will require careful management that considers the local and regional manifestations of climate change.

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.

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