Rangifer

Influence of wolf predation on population momentum of the Nushagak Peninsula caribou herd, southwestern Alaska

2019-06-21T09:31:08+02:00

We investigated wolf predation as a potential driver of population change in the Nushagak Peninsula caribou herd, southwestern Alaska. We investigated the time budgets of three wolf packs using the peninsula from 2007 through 2012, and thus potentially preying on caribou there, in order to make inferences on their likelihood of serving as an important population modifier for the Nushagak Peninsula caribou herd. We found that only one pack regularly used the peninsula. The pack using the peninsula spent an average of 35% of its time there. Its use of the peninsula was disproportionately high in late summer and fall, disproportionately low in winter, and proportional during the caribou calving season in early summer. Overall wolf use of the Nushagak Peninsula increased in direct response to increasing caribou abundance but was not a primary population driver.

Metric and non-metric guides for the determination between fore- and hindlimb phalanges of Rangifer tarandus

2019-07-04T09:32:06+02:00

Phalanges are a great untapped resource in the zooarchaeology of Rangifer tarandus. The utilization of this resource, however, is constrained by a current inability to consistently differentiate fore- from hindlimb phalanges in a mixed assemblage. The ability to separate and identify forelimb and hindlimb phalanx 1 (PI) and phalanx 2 (PII), as well as to recognize and identify other small bones of the hoof, leads to great opportunities for archaeologists. In large scale-analysis, this capacity allows a greater ability to determine minimum number of individuals and assess butchery and transport practices. In the examination of individual life histories of Rangifer tarandus, these designations allow a more precise study of pathology and entheseal change, which can shed light on adaptation, foraging strategy, and human-animal interactions. This study presents qualitative and quantitative methods for the differentiation of PI and PII of the fore- and hindlimbs and describes other bones of the hoof. Metric techniques were developed to differentiate fore- from hindlimb phalanges using non-invasive, non-destructive, and simple methods. The efficacy and accuracy of these methods were assessed using blind testing by students and staff. The average success rates of metric analysis yielded 87% accuracy for determinations of fore- versus hindlimb PI and 92% accuracy for determination of fore- versus hindlimb PII. These results show that this method could benefit researchers working with Rangifer tarandus remains.

Behavioural responses of southern mountain caribou to helicopter and skiing activities

2019-09-25T10:12:55+02:00

Helicopter- and snowcat-supported backcountry skiing is a unique industry that is widespread throughout southern mountain caribou habitat in British Columbia. We analyzed standardized caribou encounter data collected by operators under an agreement between the BC government and Helicat Canada. Average reported encounter rates were low for helicopters (0.6%) and skiing groups (0.1%); however, encounters were likely underreported due to factors that affect caribou sightability. Although helicopters encountered caribou more frequently than skiing groups, caribou were detected from helicopters at greater distances than by skiers. We used Bayesian network models to assess the independent contribution of different factors to the behavioural response of caribou to encounters. Encounter distance was the most important factor in both helicopter and skiing models. Larger groups of caribou responded strongly to skiers but not to helicopters, although the independent effect of this factor was small in both models. Larger helicopters elicited stronger reactions from caribou than smaller machines and was responsible for 25% of the modelled variation in caribou response. Encounters with helicopters at distances of 100–500m had a 78% probability of eliciting a concerned-to-very-alarmedresponse from caribou, while skiers at a similar distance had a 60% probability of eliciting the same response. The probability of concerned-to-very-alarmed responses dropped to <20% at encounter distances of >1000 m. These results indicate that initial encounter distance is the key variable to manage risk to caribou of helicopter and skiing encounters. Ongoing feedback on the effectiveness of management practices is critical to ensure the continued viability of industries operating in caribou habitat.

Aerial survey and telemetry data analysis of a peripheral caribou calving area in northwestern Alaska

2019-10-21T16:21:01+02:00

With industrial development expanding in the Arctic, there is increasing interest in quantifying the impacts of development projects on barren ground caribou (Rangifer tarandus granti). The primary data source to assess caribou distribution and predict impacts in remote areas of Alaska has shifted in recent decades from aerial survey data to telemetry data, but these techniques have different strengths and weaknesses. The ranges of two caribou herds, the Western Arctic Herd and the Teshekpuk Herd, overlap in northwest Alaska between Wainwright and Atqasuk, Alaska. Based on long-term telemetry data sets, this region was thought to be outside of the core calving ranges of both herds. Calving has long been reported to occur in this general area, but early reports assumed caribou were from the Western Arctic Herd and only one systematic aerial survey of caribou density and distribution during calving has been conducted in this area in recent decades. Following interest in industrial development in this area, we conducted aerial strip-transect surveys during early to mid-June 2013–2015 to directly assess the density and distribution of caribou in the area and we used existing telemetry data to compare our results to the seasonal distribution of both herds. Total caribou densities varied between 0.36 and 1.06 caribou/km² among years, and calf densities varied 0.04 and 0.25 calves/km² among years. Contrary to assumptions by early researchers in the area, telemetry data indicated that caribou in this area during early to mid-June were from the Teshekpuk Herd. The use of telemetry data alone underestimated the importance of this area for calving, but the combination of aerial surveys and telemetry data provided complementary information on caribou use of this area showing the importance of collecting the appropriate types of data for assessing potential impacts of development on caribou.