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.

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 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 Translocation and Recovery Efforts for the Telkwa Caribou, Rangifer tarandus caribou, Herd in Westcentral British Columbia, 1997-2005

2007 ◽  
Vol 121 (2) ◽  
pp. 155 ◽  
Author(s):  
Astrid Vik Stronen ◽  
Paul Paquet ◽  
Stephen Herrero ◽  
Seán Sharpe ◽  
Nigel Waters
Keyword(s):  
British Columbia ◽  
Habitat Use ◽  
Rangifer Tarandus ◽  
Initial Study ◽  
High Elevation ◽  
Rangifer Tarandus Caribou ◽  
Habitat Features ◽  
Lower Elevation ◽  
Significant Difference ◽  
High Elevations

During 1997–1999, 32 Woodland Caribou (Rangifer tarandus caribou) were translocated from the Sustut Herd to the Telkwa Mountains in westcentral British Columbia to augment recovery of the Telkwa Caribou Herd. The animals were fitted with radiocollars and located during 1997–2000 to determine selection of habitat features and terrain variables. Six Caribou calves were also collared to determine causes and timing of calf mortality during summer 1999. Defining available habitat for newly translocated animals is often arbitrary and subjective, and we based the analyses on ranks for habitat use and availability as this is less sensitive to the inclusion or exclusion of a questionable resource. This method represents some loss of information but provides indications of the relative importance of various habitat types without classifying any as avoided. High elevation habitat (> 1700 masl) on moderate slopes (16 – 45°) received the highest ranks, as did “warm” (136 – 315°) aspects and forests > 250 years old. Three calves died shortly after birth. One calf appeared to have been killed by predation, likely by a Golden Eagle (Aquila chrysaetos), and one calf was abandoned by the cow. Cause of death for the third calf is unknown. To assess habitat use associated with calving we compared summer locations with data obtained throughout the rest of 1999 for eight cows with calves and eight without calves. We found significant difference in use of elevation during calving time, when cows with calves remained at high elevations and barren cows generally descended to lower elevation habitat. Surveys conducted in 2005, five years after the completion of the initial study, produced a count of approximately 90 Caribou. This suggests that in the short term, the translocation was successful in re-establishing a self-sustaining Caribou population in the Telkwa Mountains.

scholarly journals Arboreal forage lichen response to partial cutting of high elevation mountain caribou range in the Quesnel Higland of east-central British Columbia

Rangifer ◽  
2007 ◽  
Vol 27 (4) ◽  
pp. 141 ◽  
Author(s):  
Michaela J. Waterhouse ◽  
Harold M. Armleder ◽  
Amanda F. Linnell Nemec
Keyword(s):  
British Columbia ◽  
Group Selection ◽  
Rangifer Tarandus ◽  
High Elevation ◽  
Partial Cutting ◽  
East Central ◽  
Engelmann Spruce ◽  
Dead Trees ◽  
Alectoria Sarmentosa ◽  
Feeding Zone

Group selection silvicultural systems have been recommended for managing mountain caribou (Rangifer tarandus caribou) habitat in high elevation Engelmann spruce – subalpine fir forests in east-central British Columbia. We measured the response of arboreal lichen (a key winter forage) to harvesting of 30% of the forested area using three partial cutting treatments, which created small (0.03 ha), medium (0.13 ha), and large (1.0 ha) openings, and a no-harvest treatment. Treatments were replicated on four sites, and monitored over a ten year post-harvest period. The short-term loss of lichen associated with removal of approximately one third of the trees was partially offset by a significant (P=0.01) increase in lichen abundance on trees in the caribou feeding zone (up to 4.5 m) in the three partial cutting treatments relative to trees in the uncut forest. Differences among treatments in the change in lichen composition, as measured by the percentage of Alectoria sarmentosa and Bryoria spp., were marginally significant (P=0.10). The partial cutting treatments showing a greater likelihood of shifting towards more Bryoria spp. than no-harvest treatment (P=0.04). In the year of harvest (1993), larger trees were found to hold more lichen than smaller trees (P=0.04), and live trees supported more lichen than dead trees (P=0.01), but lichen loading was similar among tree species (P=0.51). Tree fall rates were similar among treatments, based on the ten year average (0.6–0.8% of sample trees per year). The results indicate that caribou foraging habitat is maintained in the residual forest when group selection systems that remove only 30% of the trees are applied. Information on the distribution of lichen is useful for developing stand level prescriptions. Providing lichen bearing habitat meets just one of the needs of caribou. A comprehensive approach that considers all factors and their interactions is essential to maintain and recover the threatened mountain caribou.

Functional Changes to the Slate Islands Provincial Park Ecosystem with Successive Arrival of Wolves, Canis lupus, from the Lake Superior Coast

2021 ◽  
Vol 134 (4) ◽  
pp. 342-352
Author(s):  
Arthur T. Bergerud ◽  
Brian E. McLaren ◽  
William Dalton ◽  
Lo Camps ◽  
Heather Butler ◽  
...  
Keyword(s):  
Canis Lupus ◽  
Indirect Effects ◽  
Rangifer Tarandus ◽  
Red Fox ◽  
Castor Canadensis ◽  
Direct And Indirect Effects ◽  
Red Foxes ◽  
Functional Changes ◽  
Snowshoe Hares ◽  
Provincial Park

Observations from 1974-2016 of Caribou (Rangifer tarandus) on the archipelago that comprises Slate Islands Provincial Park allowed us to infer direct and indirect effects of the arrival of Wolf (Canis lupus) pairs in winters of 1993-94 and 2003-04. Wolves created conditions that led to the near demise of Caribou from the islands, including some, but not all, behavioural changes in Caribou consistent with avoiding predators. Caribou on SIPP did not appear to return to calving locations near shoreline areas, nor use them to escape from Wolves by entering water. Shorelines and locations of Patterson Island near a Wolf-occupied Red Fox (Vulpes vulpes) den were the most common Caribou kill locations. Wolves also functionally shifted the ecosystem in Slate Islands Provincial Park via direct and indirect effects on North American Beavers (Castor canadensis), Red Foxes and Snowshoe Hares (Lepus americanus).

Major components of grizzly bear diet across North America

2006 ◽  
Vol 84 (3) ◽  
pp. 473-489 ◽  
Author(s):  
Garth Mowat ◽  
Douglas C Heard
Keyword(s):  
British Columbia ◽  
North America ◽  
Rangifer Tarandus ◽  
Ursus Arctos ◽  
Nitrogen Isotope ◽  
Grizzly Bears ◽  
Grizzly Bear ◽  
Carbon And Nitrogen ◽  
Skull Size ◽  
Meat Diet

We measured stable carbon and nitrogen isotope ratios in guard hair of 81 populations of grizzly bears (Ursus arctos L., 1758) across North America and used mixing models to assign diet fractions of salmon, meat derived from terrestrial sources, kokanee (Oncorhynchus nerka (Walbaum in Artedi, 1792)), and plants. In addition, we examined the relationship between skull size and diet of bears killed by people in British Columbia. The majority of carbon and nitrogen assimilated by most coastal grizzly bear populations was derived from salmon, while interior populations usually derived a much smaller fraction of their nutrients from salmon, even in areas with relatively large salmon runs. Terrestrial prey was a large part of the diet where ungulates were abundant, with the highest fractions observed in the central Arctic, where caribou (Rangifer tarandus (L., 1758)) were very abundant. Bears in some boreal areas, where moose (Alces alces (L., 1758)) were abundant, also ate a lot of meat. Bears in dryer areas with low snowfall tended to have relatively high meat diet fractions, presumably because ungulates are more abundant in such environments. Kokanee were an important food in central British Columbia. In areas where meat was more than about a third of the diet, males and females had similar meat diet fractions, but where meat was a smaller portion of the diet, males usually had higher meat diet fractions than females. Females reached 95% of their average adult skull length by 5 years of age, while males took 8 years. Skull width of male grizzly bears increased throughout life, while this trend was slight in females. Skull size increased with the amount of salmon in the diet, but the influence of terrestrial meat on size was inconclusive. We suggest that the amount of salmon in the diet is functionally related to fitness in grizzly bears.

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.

Factors limiting woodland caribou populations and their interrelationships with wolves and moose in southeastern British Columbia

1992 ◽  
Vol 70 (8) ◽  
pp. 1494-1503 ◽  
Author(s):  
Dale R. Seip
Keyword(s):  
British Columbia ◽  
Mortality Rate ◽  
Rangifer Tarandus ◽  
Adult Mortality ◽  
High Elevation ◽  
Limiting Factor ◽  
Predator Prey ◽  
Wolf Predation ◽  
Adult Females ◽  
Calf Survival

Caribou (Rangifer tarandus caribou), wolves (Canis lupus), and moose (Alces alces) were radio-collared and monitored in two areas of southeastern British Columbia to determine predator–prey interactions. Throughout the year, wolves and moose used similar areas and habitats, and moose were the primary prey of wolves. In winter most caribou used high-elevation habitats and were spatially separated from wolves and moose living in valley bottoms. In summer, caribou, wolves, and moose at Quesnel Lake used similar areas and habitats, whereas in Wells Gray Park most caribou migrated to rugged, mountainous areas, which kept them spatially separated from wolves and moose. The Quesnel Lake caribou population had a high adult mortality rate (29%/year), wolf predation being the major cause. Calf survival to October was low (2.5/100 adult females) when wolves were present and uncontrolled in the area, but was significantly greater (39/100 adult females) when wolves were reduced or absent. The Quesnel Lake caribou population was found to be declining by about 25%/year, and wolf predation appeared to be the major limiting factor. Caribou in Wells Gray Park had a low adult mortality rate (8%/year) and comparatively high calf survival to October (37/100 adult females). The Wells Gray caribou population was found to be slowly increasing, apparently because its migratory behavior kept it separated from wolves and moose throughout the year, resulting in low wolf predation on the caribou.

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.

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