scholarly journals Population growth, movements, and status of the Nushagak Peninsula Caribou Herd following reintroduction, 1988 - 2000

Rangifer ◽  
2003 ◽  
Vol 23 (5) ◽  
pp. 143 ◽  
Author(s):  
Gail H. Collins ◽  
Michael T. Hinkes ◽  
Andrew R. Aderman ◽  
James D. Woolington
Keyword(s):  
Population Dynamics ◽  
Population Density ◽  
Home Range ◽  
Body Condition ◽  
Canis Lupus ◽  
Rangifer Tarandus ◽  
Ursus Arctos ◽  
Range Condition ◽  
Calf Survival ◽  
Population Mortality

Barren ground caribou (Rangifer tarandus) were reintroduced to the Nushagak Peninsula, Alaska in February of 1988 after an absence of more than 100 years. Since reintroduction, herd growth and population dynamics have been monitored closely. At this time, there has been no significant dispersal from the herds' core range. The Nushagak Peninsula Caribou Herd (NPCH) grew rapidly from 146 reintroduced individuals to over 1000 in 13 years. Dramatic mean annual growth during the first 6 years (1988-1994) of 38% (r = 0.32) can be attributed to the high percentage of females in the initial reintroduction, high calf production and survival, exceptional range conditions, few predators, and no hunting. However, the populations' exceptional growth (peak counts of 1400) slowed and stabilized between 1996¬1998 and then decreased between 1998 and 2000. Size, body condition and weights of calves captured in 2000 were significantly lower than those captured in 1995 and 1997. Although calf production also decreased from close to 100% (1990-1995) to about 91% (1996-2000), overall calf survival continued to be high. Legal harvest began in 1995, and harvest reports have accounted for approximately 3% of population mortality annually. Although brown bears (Ursus arctos) and wolves (Canis lupus) are present, the extent of predation is unknown. Mean home range of the NPCH was 674 km2 and group sizes were greatest during post-calving aggregation in July (mean = 127). Caribou population density on the Nushagak Peninsula reached approximately 1.2 caribou/km2 in 1997 before declining to about 1.0 caribou/km2. A range survey in 1994 noted only trace utilization of lichens on the Nushagak Peninsula by caribou. A subsequent survey in 1999 found moderate to severe utilization in 46% of plots, suggesting the reintroduced herd was beginning to alter range condition. Between 1997 and 2000, both calf production and condition of 10-month-old calves declined. Calving has also been delayed in recent years. However, we suspect the reduced herd growth can be attributed to increasing hunting pressure and some dispersal of caribou from the Peninsula, not reduced range condition.

Displacement and dispersion of parturient caribou at calving as antipredator tactics

1987 ◽  
Vol 65 (7) ◽  
pp. 1597-1606 ◽  
Author(s):  
A. T. Bergerud ◽  
R. E. Page
Keyword(s):  
Snow Cover ◽  
Rangifer Tarandus ◽  
Forest Cover ◽  
Ursus Arctos ◽  
Early Years ◽  
Stochastic Variation ◽  
Spring Phenology ◽  
Calf Survival ◽  
Searching Ability ◽  
High Elevations

Survival of caribou (Rangifer tarandus) calves until 4 months of age was monitored for 8 years in four herds in northern British Columbia, Canada. The chief cause of mortality was predation by wolves (Canis lupus) and grizzly bears (Ursus arctos) and this mortality was correlated within years between all herds. More calves died in years with late springs when extensive snow patches remained during calving in June than in early springs when larger snow-free areas existed. Before calving and after birth, caribou cows sought to space themselves out on snow-free areas in small aggregations at high elevations above treeline. By placing themselves at high elevations, the females increased the distance between themselves and wolves and bears travelling in the valley bottoms, as well as the main alternate prey, moose (Alces alces), which calved only in forest cover at lower elevations. In addition, the reduced snow in early springs meant that there was more space for dispersion. The variation in calf survival for three herds was negatively correlated with the heterogeneity of the calving area. Snow cover disappeared in smaller patches in more rugged mountains regardless of spring phenology, thereby providing a more constant search area for predators from year to year. More uniform mountains had either extensive areas of snow cover (late years) or brown substrates (early years), thus greatly varying the space that predators had to search between years. As stochastic variation in snow cover at calving time alters the searching ability of predators, the aggregation responses of prey, and the spatial overlap between predators and prey, it promotes short-term stability of the prey and lessens the probability of extinction.

scholarly journals Movements of Subadult Male Grizzly Bears, Ursus arctos, in the Central Canadian Arctic

2004 ◽  
Vol 118 (2) ◽  
pp. 239 ◽  
Author(s):  
Robert J. Gau ◽  
Philip D. McLoughlin ◽  
Ray Case ◽  
H. Dean Cluff ◽  
Robert Mulders ◽  
...  
Keyword(s):  
Home Range ◽  
Long Range ◽  
Rangifer Tarandus ◽  
Ursus Arctos ◽  
Canadian Arctic ◽  
Grizzly Bears ◽  
Home Ranges ◽  
Adult Males ◽  
Subadult Male ◽  
Daily Movement

Between May 1995 and June 1999, we equipped eight subadult male (3-5 yrs old) Grizzly Bears (Ursus arctos) with satellite radio-collars within a study area of 235,000 km2, centred 400 km northeast of Yellowknife, Northwest Territories, Canada. Subadult male annual home ranges were extraordinarily large (average = 11,407 km2, SE = 3849) due, in part, to their movement's occasional linear directionality. We believe their long-range linear movements may reflect some individuals tracking the migration of Caribou (Rangifer tarandus). Seasonal daily movement patterns were similar to adult males that were previously reported. The areas used by these bears are the largest ranges reported for any Grizzly Bears and the scale of their movements may put individual bears in contact with humans even when developments are hundreds of kilometres from the central home range of an animal.

Antipredator tactics of calving caribou: dispersion in mountains

1984 ◽  
Vol 62 (8) ◽  
pp. 1566-1575 ◽  
Author(s):  
A. T. Bergerud ◽  
H. E. Butler ◽  
D. R. Miller
Keyword(s):  
British Columbia ◽  
Canis Lupus ◽  
Rangifer Tarandus ◽  
Ursus Arctos ◽  
Unit Area ◽  
High Elevation ◽  
Nutrient Concentrations ◽  
Capture Success ◽  
Plant Associations ◽  
Provincial Park

The caribou (Rangifer tarandus) in Spatsizi Provincial Park, northern British Columbia, seek high south slopes in mountains as calving locations as an antipredator tactic. By being dispersed in heterogeneous and rugged mountains and away from moose (Alces alces), they force wolves (Canis lupus) and bears (Ursus arctos) to search large areas, reducing their capture success. By remaining at high elevation for 2–3 weeks in June, females with calves had to forego foraging in plant associations with high phytomass and nutrient concentrations. The antipredator tactic of dispersion in mountains was only relatively successful in 1976 and 1977; 90% of the calves still died prior to 6 months of age, largely from predation. The relatively recent invasion of moose into northern British Columbia in the early 1900's has resulted in more wolves per unit area than formerly and their combined searching has reduced the utility of leaving valley bottoms and being dispersed in mountains as a tactic to increasing the searching effort of predators.

Dynamics of caribou and wolves in northern British Columbia

1986 ◽  
Vol 64 (7) ◽  
pp. 1515-1529 ◽  
Author(s):  
A. T. Bergerud ◽  
J. P. Elliot
Keyword(s):  
British Columbia ◽  
Canis Lupus ◽  
Rangifer Tarandus ◽  
Alces Alces ◽  
Exponential Rate ◽  
Reduction Program ◽  
Calf Survival ◽  
Declining Populations

Major fluctuations in caribou (Rangifer tarandus) numbers have occurred since the settlement of European man in British Columbia. Caribou declined in the late 1930's and 1940's after moose (Alces alces) expanded their range and wolves (Canis lupus) increased. Following a wolf reduction program from 1949 to 1962, the caribou expanded until a high was reached in the late 1960's, after which the herds again diminished as wolf numbers increased and calf recruitment decreased. Three caribou populations were censused between 1976 and 1982, and an experiment was conducted on one of these areas (with the others as controls) to test the effect of wolf numbers on herd growth. The Spatsizi–Lawyers and Level–Kawdy populations inhabited ranges where wolf densities were near 9–10wolves/1000 km2;Spatsizi–Lawyers declined between 1977 and 1982(r = −0.13) and Level–Kawdy declined between 1977 and 1982(r = −0.12). We reduced wolves at the experimental Horseranch population from 10 to 1–4/1000 km2 and these caibou increased from 1977 to 1982 at an average exponential rate of 6% per year. None of the populations were heavily hunted; however, both declining populations had low calf survival with a mean of 55% of the calves dying within the first 2 weeks of life. Calf survival increased significantly at the Horseranch in the 3 years that wolves were reduced. In conclusion, we believe that the Spatsizi–Lawyers and Level–Kawdy populations declined as a result of predation on calves and adults. Yet, if wolves are managed to provide stabilizing recruitments for caribou, it should be possible to dampen the natural fluctuations of caribou and wolves that are frequent in unperturbed systems and maintain higher numbers of both species.

Molecular identification of Taenia spp. in wolves (Canis lupus), brown bears (Ursus arctos) and cervids from North Europe and Alaska

2011 ◽  
Vol 60 (3) ◽  
pp. 289-295 ◽  
Author(s):  
Antti Lavikainen ◽  
Sauli Laaksonen ◽  
Kimberlee Beckmen ◽  
Antti Oksanen ◽  
Marja Isomursu ◽  
...  
Keyword(s):  
Molecular Identification ◽  
Canis Lupus ◽  
Ursus Arctos ◽  
Brown Bears

Effects of crop sequence and rainfall on population dynamics of Fusarium solani f.sp. phaseoli in soil

1992 ◽  
Vol 70 (10) ◽  
pp. 2005-2008 ◽  
Author(s):  
Robert Hall ◽  
Lana Gay Phillips
Keyword(s):  
Population Dynamics ◽  
Phaseolus Vulgaris ◽  
Population Density ◽  
Fusarium Solani ◽  
Population Densities ◽  
Total Rainfall ◽  
Colony Forming Units ◽  
Bean Crop ◽  
Previous Summer ◽  
Crop Sequence

Evidence is presented that population dynamics of Fusarium solani f.sp. phaseoli in soil depend on the effects of crop sequence and rainfall on parasitic activities of the pathogen. In a rotation trial started in 1978 and conducted over 14 years, population densities (colony-forming units/g) of the fungus in soil remained below 50 in treatments (fallow, repeated corn, repeated soybean) where the preferred host plant (common bean, Phaseolus vulgaris) was not grown. Where bean was grown every 3rd year or every year, population densities reached 475 and 660, respectively, by 1984. Thereafter, population densities of the fungus fluctuated widely from year to year in both rotation and repeated bean treatments. In the rotation treatment, peaks in population density of the pathogen coincided with the years of bean production. In repeated bean plots between 1985 and 1991, population density of the fungus in June was significantly correlated (r = 0.77, p = 0.04) with total rainfall received during the previous summer (June–August). It is postulated that higher rainfall during the growing season of the bean crop stimulated root growth and root infection, leading to the accumulation of higher levels of potential inoculum in infected tissue and the release of higher levels of inoculum into the soil by the following June. Key words: Fusarium solani f.sp. phaseoli, bean, Phaseolus vulgaris, rainfall, crop rotation.

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.

PREDATION BY INSECTS AND SPIDERS INHABITING COLONIAL WEBS OF HYPHANTRIA CUNEA

1972 ◽  
Vol 104 (8) ◽  
pp. 1197-1207 ◽  
Author(s):  
R. F. Morris
Keyword(s):  
Population Dynamics ◽  
Nova Scotia ◽  
North America ◽  
Population Density ◽  
New Brunswick ◽  
Numerical Response ◽  
Initial Number ◽  
Hyphantria Cunea ◽  
The North ◽  
The Mean

AbstractThe number of predators inhabiting nests of Hyphantria cunea Drury was recorded annually for 13 years in four areas in New Brunswick and two areas on the coast of Nova Scotia. The most common groups were the pentatomids and spiders, which sometimes reproduced within the nests, but the mean number per nest was low in relation to the number of H. cunea larvae in the colonies. The rate of predation on fifth-instar larvae was low. Small or timid predators appeared to prey largely on moribund larvae or small saprophagans during the principal defoliating instars of H. cunea.No relationship could be detected between the number of larvae reaching the fifth instar and the number of predators in the colony; nor could any functional or numerical response of the predators to either the initial number of larvae per colony or the population density of colonies be found. It is concluded that the influence of the nest-inhabiting predators is small and relatively stable, and may be treated as a constant in the development of models to explain the population dynamics of H. cunea.H. cunea is a pest in parts of Europe and Asia, where it has been accidentally introduced from North America. The introduction to other continents of the North American predator, Podisus maculiventiis (Say), is discussed briefly.

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 Gray Wolves, Canis lupus, Killed by Cougars, Puma concolor, and a Grizzly Bear, Ursus arctos, in Montana, Alberta, and Wyoming

2008 ◽  
Vol 122 (1) ◽  
pp. 76 ◽  
Author(s):  
Michael D. Jimenez ◽  
Valpa J. Asher ◽  
Carita Bergman ◽  
Edward E. Bangs ◽  
Susannah P. Woodruff
Keyword(s):  
United States ◽  
Canis Lupus ◽  
Ursus Arctos ◽  
Puma Concolor ◽  
Western United States ◽  
Grizzly Bear ◽  
Grey Wolf ◽  
Gray Wolves ◽  
Large Predators

Four cases where large predators caused Grey Wolf (Canis lupus) mortality are recorded. We describe two incidents of Cougars (Puma concolar) killing Wolves in Montana and one incident of a Cougar killing a Wolf in Alberta. We report the first recorded incident of a Grizzly Bear (Ursus arctos) killing a Wolf in the western United States.

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