Anne Gunn

Voles, lemmings and caribou - population cycles revisited?

Although we may be confident that many caribou populations fluctuate, we have not made much progress in linking patterns of fluctuations with their underlying processes. Caribou abundance is relatively synchronized across continents and over decades which points to climatic variation as a causative factor. Progress on describing intrinsic and extrinsic factors for smaller-bodied and larger-bodied mammalian herbivore population dynamics also reveals the role of climatic variation and specifically decadal variations. Based on experience elsewhere, we can expect complex relationships between caribou, climatic variation and their forage rather than simple correlations. Caribou responses to decadal trends in climate likely accumulate through successive cohorts as changes in body mass which, in turn, leads to changes in lifetime reproductive success.

GENETIC VARIABILITY OF WOLVERINES (GULO GULO) FROM THE NORTHWEST TERRITORIES, CANADA: CONSERVATION IMPLICATIONS

Abstract Because of anthropogenic factors in the early 1900s that caused populations to decline dramatically, wolverines (Gulo gulo) currently are designated as endangered in eastern Canada and classified as vulnerable throughout the Holarctic Region by the International Union for Conservation of Nature and Natural Resources. Although numerous examples exist that illustrate the utility of genetic data for development of conservation plans, no study has investigated the genetic structure of natural populations of wolverines. We assessed allozymic and mitochondrial DNA (mtDNA) variability of wolverines within and among 5 sites from the Northwest Territories, Canada. Five of 46 presumptive allozyme loci were polymorphic. Estimates of heterozygosity (2.6%) and polymorphism (11.6%) were lower than values reported for most mammals but were within the range reported for Carnivora. To evaluate levels of variation in mtDNA, we sequenced the left domain of the control region. Six variable nucleotide sites were observed, resulting in 9 haplotypes of mtDNA. Within-site diversity of haplotypes (h) was high, but within-site diversity of nucleotides (π) was low, indicating little sequence divergence among the 9 haplotypes. Sequence data for mtDNA revealed considerably more genetic partitioning among sites (ϕST = 0.536) than did allozyme data (FST = 0.076). Based on fixation indices, gene flow estimates (Nm) were moderate for nuclear markers but low for mtDNA loci. These findings suggest that, although wolverines maintain large home ranges, they exhibit fidelity to discrete areas, gene flow is predominantly male-mediated, and most sites in the Northwest Territories are genetically independent and thus represent populations. Therefore, any conservation plan for wolverines in the Northwest Territories must consider preservation of populations if genetic diversity of this taxon is to be maintained.

Traditional behaviour and fidelity to caribou calving grounds by barren-ground caribou

Evidence for the fidelity of female barren-ground caribou (Rangifer tarandus spp.) of each herd to specific calving grounds is convincing. Involvement of learned behaviour in the annual return of those cows to the same calving grounds implies such actions are a form of «traditional» behaviour. Even wide variations in population size have not yet knowingly led to marked changes in size or location of calving grounds or prolonged abandonment of established ones. Rarely is the adoption of new calving grounds reported and emigration to another herds calving ground or interchange between calving grounds has not yet been unequivocally documented. The calving experience of individual caribou and environmental pressures may modify the cows use patterns of her calving grounds. The current definition of herds based on traditional calving grounds may require modification, if increasing caribou numbers result in changes in traditions. However, current data do not contradict either the fidelity to traditional calving grounds or the concept of herd identity based on that fidelity.

Estimating the zone of influence of industrial developments on wildlife: a migratory caribou Rangifer tarandus groenlandicus and diamond mine case study

Wildlife species may respond to industrial development with changes in distribution. However, discerning a response to development from differences in habitat selection is challenging. Since the early 1990s, migratory tundra Bathurst caribou Rangifer tarandus groenlandicus in the Canadian Arctic have been exposed to the construction and operation of two adjacent open-pit mines within the herds summer range. We developed a statistical approach to directly estimate the zone of influence (area of reduced caribou occupancy) of the mines during mid-July-mid-October. We used caribou presence recorded during aerial surveys and locations of satellite-collared cow caribou as inputs to a model to account for patterns in habitat selection as well as mine activities. We then constrained the zone of influence curve to asymptote, such that the average distance from the mine complex where caribou habitat selection was not affected by the mine could be estimated. During the operation period for the two open-pit mines, we detected a 14-km zone of influence from the aerial survey data, and a weaker 11-km zone from the satellite-collar locations. Caribou were about four times more likely to select habitat at distances greater than the zone of influence compared to the two-mine complex, with a gradation of increasing selection up to the estimated zone of influence. Caribou are responding to industrial developments at greater distances than shown in other areas, possibly related to fine dust deposition from mine activities in open, tundra habitats. The methodology we developed provides a standardized approach to estimate the spatial impact of stressors on caribou or other wildlife species.

Behavioural trade-offs in response to external stimuli: time allocation of an Arctic ungulate during varying intensities of harassment by parasitic flies

1. Macroparasites may be a major factor shaping animal behaviour. Tundra ecosystems inhabited by caribou and reindeer (Rangifer tarandus) are known for large concentrations of ectoparasites including mosquitoes (Culicidae) and black flies (Simuliidae), as well as endoparasitic oestrid flies (Oestridae). 2. Increased intensity and duration of insect harassment because of climatic warming is hypothesized as a potential factor in recent declines of Rangifer across the circumpolar north. Although there is a well-observed relationship between insect harassment and caribou/reindeer behaviour, the influence of ecto- relative to endoparasitic species is unclear. Climatic changes may favour the activity patterns, distribution or abundance of certain insect species; thus, understanding differential effects on the behaviour of Rangifer is important. 3. We recorded caribou behaviour using group scan and focal sampling methods, while simultaneously trapping insects and recording weather conditions on the postcalving/summer range of the Bathurst barren-ground caribou herd in Northwest Territories and Nunavut, Canada, during 2007-2009. 4. We developed statistical model sets representing hypotheses about the effects of insects, weather, habitat/location, and date/time on caribou behaviour. We used multinomial logistic regression models to explore factors affecting the relative dominance of behaviour types within groups of caribou and fractional multinomial logistic regression models to determine factors influencing time allocation by individual caribou. We examined changes in feeding intensity using fractional logistic regression. 5. Relative dominance of insect avoidance behaviour within caribou groups and time allocation to insect avoidance by individual caribou increased when oestrid flies were present or black flies were active at moderate-high levels. Mosquito activity had relatively little effect on caribou behaviour. Time spent feeding was reduced by the greatest degree when all three insect types were present in combination. Feeding intensity was influenced to a greater extent by the accumulation of growing degree days over the course of the postcalving/summer season than by insect activity. Changes in Arctic systems that increase the activity/abundance of ecto- and endoparasites could have implications for the productivity of Rangifer populations.

A Data-Driven Demographic Model to Explore the Decline of the Bathurst Caribou Herd

ABSTRACT The Bathurst herd of barren-ground caribou (Rangifer tarandus groenlandicus) in the Canadian central arctic declined from an estimated 203,800 to 16,400 breeding females from 1986 to 2009, with the most rapid decline from 2006 to 2009. A key research and management question was whether the decline was mainly due to decreases in productivity alone or also due to reduced adult female survival. Investigating causes of the decline was hampered by a lack of direct estimates of caribou demographic parameters. We developed a demographic model that could be objectively fitted to field data to explore the mechanisms for the Bathurst decline, with a focus on the recent accelerated decline from 2006 to 2009. Our modeling indicated that the decline was driven by increasing negative trends in adult female and calf survival rates and possibly reduced fecundity The effect of a constant hunter harvest on the declining herd was one potential cause for the recent accelerated decline in adult survival. The demographic model detected negative trends in adult female survival that were not detected using standalone analyses of collar-based survival data. The model allowed rigorous interpretation of trends in productivity by controlling for the simultaneous influence of trends in adult, calf, and yearling survival and adult fecundity on field-based calf—cow ratios. Stochastic simulations suggested that large increases in adult survival and productivity would be needed for the herd to recover. Our methods enable objective modeling of caribou demography that can assist in caribou management based upon all sources of available data.

Gauging climate change effects at local scales: weather‐based indices to monitor insect harassment in caribou

Climate change is occurring at an accelerated rate in the Arctic. Insect harassment may be an important link between increased summer temperature and reduced body condition in caribou and reindeer (both Rangifer tarandus). To examine the effects of climate change at a scale relevant to Rangifer herds, we developed monitoring indices using weather to predict activity of parasitic insects across the central Arctic. During 2007-2009, we recorded weather conditions and used carbon dioxide baited traps to monitor activity of mosquitoes (Culicidae), black flies (Simuliidae), and oestrid flies (Oestridae) on the post-calving and summer range of the Bathurst barren-ground caribou (Rangifer tarandus groenlandicus) herd in Northwest Territories and Nunavut, Canada. We developed statistical models representing hypotheses about effects of weather, habitat, location, and temporal variables on insect activity. We used multinomial logistic regression to model mosquito and black fly activity, and logistic regression to model oestrid fly presence. We used information theory to select models to predict activity levels of insects. Using historical weather data, we used hindcasting to develop a chronology of insect activity on the Bathurst range from 1957 to 2008. Oestrid presence and mosquito and black fly activity levels were explained by temperature. Wind speed, light intensity, barometric pressure, relative humidity, vegetation, topography, location, time of day, and growing degree-days also affected mosquito and black fly levels. High predictive ability of all models justified the use of weather to index insect activity. Retrospective analyses indicated conditions favoring mosquito activity declined since the late 1950s, while predicted black fly and oestrid activity increased. Our indices can be used as monitoring tools to gauge potential changes in insect harassment due to climate change at scales relevant to caribou herds.

Seasonal changes in weight, condition and nutrition of free-ranging and captive muskox females

Wild muskoxen calve several weeks before snowmelt and begin costly lactation without access to green forage; retaining substantial body fat until late winter may be essential to reproductive success. Captive muskox females tend to regain body weight rapidly at the end of summer (White et aL, 1989) but little is known of seasonal changes in body reserves of wild muskoxen. We began a study of weight and body composition in female muskoxen in 1989, on Victoria Island, Northwest Territories (NWT). Our objectives were to assess seasonal changes in nutrition and body reserves of females, and to relate these changes to reproductive status, particularly to early lactation in late winter. The University of Saskatchewan keeps a small herd of tame muskoxen at Goodale Farm near Saskatoon. These animals are maintained through fall, winter and spring on grass hay supplemented with oat-hay pellets. In summer they graze a poor-medium quality pasture supplemented with hay and pellets. Our objective in this study was to determine whether an intrinsic seasonal cycle of weight change persisted in captive females despite nearly constant diet quality. Here we make a comparison of seasonal changes in wild and captive females. Collections on Victoria Island were conducted in Apr i l , May, August and November 1989, Apr i l , May, July, September and November 1990, and Apr i l and May 1991. Approximately 20 muskoxen, mostly adult females and calves, were shot by Inuit hunters during each collection. Measurements and notes on each animal included body weight, dressed carcass weight, depth of back fat (DBF), gastrocnemius muscle weight (an index of lean body mass), and reproductive status. Captive muskoxen at Goodale Farm were weighed weekly and the weekly weights were averaged for each month. Diet quality in wild muskoxen was estimated from analysis of nitrogen (N) in freeze-dried samples of rumen contents from shot animals. During studies of captive muskoxen, diet quality was kept constant by using the same quality of hay and pellets for 7-10 days prior to and during feed intake trials (Adamczewski et ai, 1991) and during blood sampling. Hay used during all trials was locally grown grass hay; it va-

Where the wild things are: Seasonal variation in caribou distribution in relation to climate change

In this study, we develop a method to analyse the relationships between seasonal caribou distribution and climate, to estimate how climatic conditions affect interactions between humans and caribou, and ultimately to predict patterns of distribution relative to climate change. Satellite locations for the Porcupine (Rangifer tarandus granti) and Bathurst (R. t. groenlandicus) caribou herds were analysed for eight ecologically-defined seasons. For each season, two levels of a key environmental factor influencing caribou distribution were identified, as well as the best climate data available to indicate the factors annual state. Satellite locations were grouped according to the relevant combination of season and environmental factor. Caribou distributions were compared for opposing environmental factors; this comparison was undertaken relative to hunting access for the Porcupine Herd and relative to exposure to mining activity for the Bathurst Herd. Expected climate trends suggest an overall increase in access to Porcupine caribou for Aklavik (NWT) hunters during the winter and rut seasons, for Venetie (Alaska) hunters during midsummer and fall migration and for Arctic Village (Alaska) during midsummer. Arctic Village may experience reduced availability with early snowfalls in the fall, but we expect there to be little directional shift in the spring migration patterns. For the Bathurst Herd, we expect that fewer caribou would be exposed to the mines during the winter, while more caribou would be exposed to the combined Ekati and Diavik mining zone in the early summer and to the Lupin-Jericho mining zone during the fall migration. If changes in climate cause an increased presence of caribou in the mining sites, monitoring and mitigation measures may need to be intensified.

YERSINIOSIS IN FREE-RANGING MUSKOXEN ON BANKS ISLAND, NORTHWEST TERRITORIES, CANADA

Sixty-seven muskox (Ovibos moschatus) carcasses, 53 skeletal remains and two sick muskoxen were seen during an aerial survey of the Thomsen River region, northern Banks Island, Northwest Territories, Canada in late July 1986. Complete necropsies were performed on 29 muskoxen estimated to have died within the previous 3 to 5 days. Twenty were diagnosed with acute yersiniosis due to Yersinia pseudotuberculosis serotype 1B and were in excellent body condition. A diagnosis could not be made on seven animals due to marked autolysis; however, these muskoxen also were in excellent body condition. The remaining two were aged, emaciated muskoxen. This report describes the first occurrence of yersiniosis in free-ranging muskoxen and the first documentation of large scale mortality due to this disease in a free-ranging population of wild ungulates.