Modeling influences on winter distribution of caribou in northwestern Alaska through use of satellite telemetry

I hypothesize that the distribution of barren-ground caribou (Rangifer tarandus granti) is affected by multiple, interrelated factors. These factors include, but are not limited to, terrain and snow characteristics as well as predation pressure and habitat. To test this hypothesis, I attributed caribou locations derived from satellite telemetry over a 6 year period with terrain (elevation, slope, aspect, and ruggedness), habitat characteristics, and moose density - potentially an index of wolf predation pressure. These locations were compared to random locations, attributed using the same data layers, using logistic regression techniques to develop resource selection functions (RSFs). I found that caribou moved significantly less during mid-winter than early- or late-winter and that cows moved significantly more in April than bulls due to their earlier departure on their spring migration. Distribution was different between cows and bulls. Terrain variables were important factors but were scale-dependent. Cows avoided forested areas, highlighting the importance of tundra habitats, and selected for dwarf shrub, with relatively high lichen cover, and sedge habitat types. Bulls selected for dryas, coniferous forest and dwarf shrub habitats but against lowland sedge, upland shrub and burned tundra. Cow distribution was negatively correlated with moose density at the scale of the Seward Peninsula. My results support the hypothesis that caribou distribution during winter in northwest Alaska is affected by multiple, interrelated factors. These results may be useful for researchers to track and/or model changes in future patterns of range use over winter

Winter Range Studies Of The Western Arctic Caribou Herd, Northwest Alaska

Thesis (Ph.D.) University of Alaska Fairbanks, 2011Climate change is likely to bring a myriad of interrelated changes to the Arctic. One change is warmer and drier conditions that could increase the prevalence of wildfire in northwest Alaska. Wildfires destroy terricolous lichens that Western Arctic Herd caribou (Rangifer tarandus ) rely on during winter; taking decades to recover. My goals were to assess the recent (1950--2007) fire regime within the herd's range, identify characteristics of habitat selected by overwintering caribou, and determine the potential impacts of climate change on the fire regime and caribou winter range. I used a combination of existing data and information collected at vegetation plots to conduct these analyses. I found that wildfires in the tundra were relatively common from 1950--2007, covering approximately 10% of northwest Alaska. Tundra was > 4.5 times more likely to re-burn than boreal forest. This novel, yet intuitive finding could have serious implications if fire starts to become more common in the Arctic. I found that the average annual area burned more than doubled in years where mean August temperatures exceeded 11.7�C (53�F). Caribou use tundra and forested during winter but avoided recently (< 58 years) burned areas in both habitat types likely because they contained < 1/4 of the abundance of forage lichen species than unburned habitats. I found that lichen abundance was 3 times greater in the herd's current winter range versus its historic range -- supporting the theory that caribou shift ranges to compensate for deteriorating grazing conditions. Stand age was the most consistent correlate with lichen abundance. Dwarf birch (Betula spp.) was more abundant in recent burns which may facilitate the intensification of the future fire regime in the region. My modeling efforts revealed that wildfire is likely to become more prevalent, especially on the herd's core winter range, which could have deleterious impacts on caribou winter range and provide quality habitat for moose ( Alces alces). My results should provide a solid foundation to develop a science-based fire management plan for the Western Arctic Herd

The effects of sampling regime on the analysis of movements of overwintering female caribou in east-central Alaska

Global Positioning System (GPS) technology enables research of animal movements at finer levels of spatial and temporal resolution than previous methodologies allowed. A feature of GPS collar technology is the capability to program the dates of (sample period) and time between successive relocations (sample interval). I investigated the effects of sampling regime, the combination of sample period and interval, on analyzing movements of female caribou (Rangifer tarandus granti) in the Fortymile Caribou Herd as a case study. Based on hourly relocations throughout the winter, caribou moved 260 meters per hour or 6.2 kilometers per day. Sample period influenced estimates of movement rates, as I detected both diurnal and seasonal variability. Caribou movement rates during daylight and twilight hours were significantly greater than during the nighttime. Movement rates were greater during twilight hours than during daylight, but only slightly. Mid-winter and late winter movement rates were virtually the same, however, both were significantly less than during early winter. As sample interval increased, estimates of movement rates decreased substantially. Estimates based on 2-hour sample intervals were 14% less than those based on one-hour sample intervals, with estimates declining to 65% of the one-hour sample interval estimates at 167-hour (weekly) intervals. Estimates of home range were also affected by using different sampling intervals, however, kernel and MCP estimates responded antithetically to increasing sample interval. Researchers need to be aware that decisions about sampling regime can affect the estimates of ecological parameters that are based on relocations, such as movement rate, habitat selection, and home range

Evaluating Differences in Household Subsistence Harvest Patterns between the Ambler Project and Non-Project Zones

Western Alaska is one of largest inhabited, roadless areas in North America and, indeed, the world. Access, via a new road that would transverse Gates of the Arctic National Park and Preserve (GAAR), to a mining district in a vast roadless section of northwest Alaska has been proposed. Given the potential effects of the road on nearby communities, we analyzed how communities connected to the road system compare to their unconnected counterparts. Specifically, using zero inflated negative binomial models, we analyzed subsistence harvest data to understand factors that influence subsistence production at the household level. We found substantial difference in these factors between communities near the proposed road (project zone (PZ) communities and a comparable set of road accessible communities outside the region, and were affected by household characteristics such as the gender of the head of household, number of children, and income. Total subsistence production of project zone communities was 1.8 – 2.5 times greater than that of non-project zone communities. Communities with a higher percentage of Alaska Native residents had greater per capita subsistence harvests. Higher household income levels were associated with lower subsistence harvest levels. Roads can provide access for hunters from outside the region to traditional subsistence hunting grounds used by local residents that would not be very accessible if not for the road. Our proxy for competition (number of nonlocal moose hunters) indicates that resident moose harvest amounts are inversely related to the number of hunters in a particular area. If subsistence harvest patterns for project zone communities currently off the road changed to mirror existing non-project zone harvests due to the road, the financial cost would be USD $6,900 – 10,500 per household per year (assuming an$8/lb. ‘replacement’ cost for subsistence harvests). This represents about 33% of the median household income. Taken together, our results suggest that the proposed road should be expected to substantially impact subsistence production in communities that are not currently connected to the road system. The scale of our data did not allow for the comparison of the impacts of the different proposed routes but the impacts of different routes is likely minor in relation to the presence or absence of the proposed roadFigures / Tables / Abstract/Executive Summary / Acknowledgments / Introduction / The Proposed Road and Mine / Study Area / Communities / Background / Modeling Household Harvest / Conclusions / Literature CitedYe

Early fall and late winter diets of migratory caribou in northwest Alaska

Lichens are the primary winter forage for large herds of migratory caribou (Rangifer tarandus). Caribou select for lichens more than they are available across the landscape and they generally avoid, during winter, habitat that has been burned by wildfires for decades while lichen abundance recovers. However, the relative importance of lichens in the diet is subject to debate. From 2010-2013, we conducted one of the largest microhistological studies of the early fall (58 samples from 1 site) and late winter (338 samples from 58 sites) diets of barren-ground caribou. Lichens con­stituted ~ 71% of the late winter diets of caribou in northwest Alaska, whereas moss (11%) and shrubs (9%) were the next most common forage items. Early fall diets were very similar to late winter, perhaps because deciduous vegetation is senescent during both periods. Diets of males, non-pregnant females and pregnant females were not significantly different. Pregnancy was not associated with the abundance of any forage type during winter but was associated with higher physiological stress. This result was expected as fall body condition dictates conception, caribou are ‘capital’ breeders, and gestation can be energetically demanding. Caribou that migrated south (i.e., wintered south of 67.1°N) had lower levels of nutritional stress, higher levels of lichen in the diet, and lower levels of moss and shrubs compared to caribou that did not migrate south. Future investigations into the potential connection between lichen abundance in the winter diet and survivorship, as well as linking the late summer diets of individuals to their reproductive success, should be undertaken

Response of Overwintering Caribou to Burned Habitat in Northwest Alaska

Caribou (Rangifer tarandus granti) use lichens, when available, as primary forage on their winter range. In boreal forest habitats, wildland fires effectively destroy lichens, and overwintering caribou are known to avoid burned areas for decades while lichen communities regenerate. However, little has been published about caribou response to burned habitat in tundra ecosystems. To assess the relationship between winter caribou distribution and burned areas, we instrumented Western Arctic Herd caribou with satellite telemetry collars and evaluated their locations in relation to recent burns of known age (? 55 years old) across northwestern Alaska. We analyzed caribou distribution for different habitat types (tundra and boreal forest), age categories of burns, and possible edge effects. We also reanalyzed the data, limiting available habitat to a uniform traveling distance (5658 m) from daily satellite locations. Using selection indices that compared caribou use of burns and buffers to their availability, we found that caribou strongly selected against burned areas within the tundra ecosystem. Recent burns were selected against at both large (range-wide) and intermediate (5658 m) spatial scales. Caribou particularly selected against 26- to 55-year-old burns and the interior (core) portions of all burns. We found that caribou were more likely to select burned areas in the late fall and early spring than midwinter. Increased fires in northwestern Alaska could decrease the availability and quality of winter habitat available to the herd over the short term (up to 55 years), potentially influencing herd population dynamics and reducing sustainable harvest levels. We recommend that fire managers consider caribou midwinter range condition and extent: however, management that achieves a mosaic pattern of fire history may benefit a wide array of species, including caribou. A better understanding of the current regional fire regime and the distribution of available winter range will be required before practicable management recommendations can be developed for this herd.Le fourrage principal du parcours d’hiver du caribou (Rangifer tarandus granti) est le lichen, lorsque celui-ci se trouve à sa disposition. Dans les habitats de forêt boréale, les feux de broussailles détruisent les lichens, au point où les caribous évitent, pendant des décennies l’hiver, les régions qui ont été brûlées afin de laisser le temps au lichen de se régénérer. Cependant, peu d’information a été publiée à l’égard de la réaction du caribou envers l’habitat brûlé des écosystèmes de la toundra. Afin d’évaluer la relation entre la répartition du caribou d’hiver et les régions brûlées, nous avons posé à un troupeau de caribous de l’Arctique de l’Ouest des colliers émetteurs à télémétrie par satellite et évalué leur emplacement par rapport à des régions brûlées récemment dont on savait à quand remontaient les incendies (? 55 ans) et ce, aux quatre coins du nord-ouest de l’Alaska. Nous avons analysé la répartition du caribou en fonction de types d’habitats différents (la toundra et la forêt boréale), de catégories d’âge des régions brûlées et d’effets de lisière possibles. De plus, nous avons réanalysé les données en prenant soin de limiter l’habitat disponible à une distance de déplacement uniforme (5 658 m) à partir des emplacements satellites quotidiens. Grâce aux indices de sélection comparant l’utilisation faite par les caribous des régions brûlées et des zones tampons et leur disponibilité, nous avons remarqué que le caribou délaissait fortement les régions brûlées dans l’écosystème de la toundra. Les régions brûlées récemment étaient rejetées tant à la grande échelle spatiale (l’ensemble du parcours) qu’à l’échelle intermédiaire (5658 m). Plus particulièrement, le caribou se tenait loin des régions brûlées il y a 26 à 55 ans et des sections intérieures (au centre) de toutes les régions brûlées. Nous avons constaté que le caribou était plus susceptible d’opter pour les régions brûlées vers la fin de l’automne et au début du printemps qu’au milieu de l’hiver. Les incendies à la hausse dans le nord-ouest de l’Alaska pourraient avoir pour effet de diminuer la disponibilité et la qualité de l’habitat d’hiver à la disposition du troupeau à court terme (jusqu’à 55 ans), ce qui pourrait influencer la dynamique de la population du troupeau et réduire les taux de récoltes durables. Nous recommandons que les directeurs des incendies considèrent l’état et l’étendue du parcours du caribou en parcours d’hiver. Cela dit, une gestion donnant lieu à un dessin en mosaïque de l’historique des incendies pourrait avantager une vaste gamme d’espèces, dont le caribou. Il faudra avoir une meilleure compréhension du régime régional actuel des incendies et de la répartition du parcours d’hiver disponible avant que des recommandations de gestion réalisables puissent être faites pour ce troupeau

Denning Ecology of Wolves in East-Central Alaska, 1993–2017

 Dens are a focal point in the life history and ecology of gray wolves (Canis lupus), and their location can influence access to key resources, productivity, survivorship, and vulnerability to hunting, trapping, and control efforts. We analyzed the selection of den sites and the phenology of their use inside the Yukon-Charley River National Preserve from 1993 to 2017 to enhance our understanding of this resource. At the landscape scale, we found that wolves in east-central Alaska selected den sites that were lower in elevation, snow free earlier in the spring, exposed to greater solar radiation, and closer to water. Den sites were also associated with areas that had burned less recently and had lower terrain ruggedness at the 1 km scale. These results supported our hypothesis that wolves would den relatively close to essential resources (water and prey) and in areas that are drier (melt earlier) in the spring. At the home range scale, wolves also selected den sites at lower elevations and showed a strong selection for the center of their home range. Furthermore, the average distance between active den sites was 37.3 km, which is slightly greater than the average radius (32.5 km) of a home range of a pack. Our results support our hypothesis that dynamic social factors modulate the selection of environmental factors for den site location. Wolves den away from other packs to reduce competition and exposure to intraspecific conflict. High-quality denning habitat does not currently appear to be a limiting factor for this population. Females, on average, entered their dens on 10 May, stayed inside the den for eight days, and remained less than 1 km from the den for an additional six days after emerging. We found that wolves denning at higher elevations entered their dens later than those at lower elevations, which also supported one of our hypotheses. Lastly, we documented limited evidence of earlier denning over time. Long-term monitoring projects, such as ours, are critical in identifying these types of trends. Les tanières sont un point central du cycle biologique et de l’écologie du loup gris (Canis lupus). Leur emplacement peut influencer l’accès aux ressources principales, la productivité, la survie et la vulnérabilité à la chasse, au piégeage et aux mesures de contrôle. Afin de mieux comprendre cette ressource, nous avons analysé la sélection des emplacements de tanières et la phénologie de leur utilisation dans la réserve nationale Yukon-Charley Rivers pour les années allant de 1993 à 2017. À l’échelle du paysage, nous avons trouvé que les loups du centre-est de l’Alaska choisissaient des emplacements de tanières en moins grande altitude, plus près de l’eau, où la neige fondait plus vite au printemps et où le rayonnement solaire était plus grand. Par ailleurs, les emplacements des tanières étaient caractérisés par des secteurs brûlés moins récemment et un relief accidenté plus bas à l’échelle de 1 km. Ces résultats ont permis d’appuyer notre hypothèse selon laquelle les loups établiraient leur tanière relativement près des ressources essentielles (eau et proies), dans des endroits plus secs (fonte hâtive) au printemps. À l’échelle du domaine vital, les loups choisissaient aussi des emplacements de tanières en plus faible altitude, avec une forte propension pour le centre de leur domaine. De plus, la distance moyenne entre les tanières actives était de 37,3 km, ce qui est un peu plus grand que le rayon moyen (32,5 km) du domaine vital d’une meute. Nos résultats viennent appuyer notre hypothèse voulant que les facteurs sociodynamiques modulent la sélection de facteurs environnementaux pour l’emplacement des tanières. Les loups établissent leurs tanières à l’écart d’autres meutes afin de réduire la compétition et les possibilités de conflits intraspécifiques. En ce moment, la haute qualité de l’habitat pour l’établissement des tanières ne semble pas être un facteur limitant pour cette population. En moyenne, les femelles s’installaient dans leur tanière le 10 mai, y restaient pendant huit jours et demeuraient à moins d’un kilomètre de leur tanière pendant six autres jours après leur sortie. Nous avons remarqué que les loups optant pour des tanières en plus haute altitude s’y installaient plus tard que ceux en plus faible altitude, ce qui étayait aussi une de nos hypothèses. En dernier lieu, nous avons documenté les preuves restreintes d’établissement plus hâtif dans les tanières au fil des ans. Les projets de surveillance à long terme comme le nôtre jouent un rôle primordial dans la détermination de ces types de tendances. 

Evaluating Potential Effects of an Industrial Road on Winter Habitat of Caribou in North-Central Alaska

Worldwide, some caribou (Rangifer tarandus) populations are experiencing declines due partially to the expansion of industrial development. Caribou can exhibit behavioral avoidance of development, leading to indirect habitat loss, even if the actual footprint is small. Thus, it is important to understand before construction begins how much habitat might be affected by proposed development. In northern Alaska, an industrial road that has been proposed to facilitate mining transects a portion of the Western Arctic caribou herd’s winter range. To understand how winter habitat use might be affected by the road, we estimated resource selection patterns during winter for caribou in a study area surrounding the proposed road. We assessed the reductions of habitat value associated with three proposed routes at three distance thresholds for disturbance. High-value winter habitat tended to occur in locally rugged areas that have not burned recently and have a high density of lichen and early dates of spring snowmelt. We found that 1.5% to 8.5% (146–848 km2) of existing high-value winter habitat in our study area might be reduced in quality. The three alternative routes were only marginally different. Our results suggest that the road would have minimal direct effects on high-value winter habitat; however, additional cumulative impacts to caribou (e.g., increased access by recreationists and hunters) should be considered before the full effects of the road can be estimated.À l’échelle mondiale, certaines populations de caribous (Rangifer tarandus) connaissent des déclins partiel­lement attribuables à l’expansion industrielle. Pour des raisons de comportement, le caribou peut éviter le développement, ce qui entraîne une perte d’habitat indirecte, et ce, même si la place réellement occupée est petite. Par conséquent, il est important de comprendre, avant même que des travaux de construction ne soient amorcés, dans quelle mesure l’habitat sera touché par les travaux proposés. Dans le nord de l’Alaska, une route industrielle dont la construction a été proposée pour faciliter l’exploitation minière coupe transversalement une partie de l’aire d’hivernage du troupeau de caribous de l’ouest de l’Arctique. Afin de comprendre comment l’utilisation de l’habitat d’hivernage pourrait être touchée par la route, nous avons estimé des modèles de sélection des ressources pendant l’hiver pour le caribou se trouvant dans une aire d’étude entourant la route proposée. Nous avons évalué la diminution de la valeur de l’habitat liée à trois routes proposées à trois seuils de distance afin d’en déterminer la perturbation. Un habitat d’hivernage de grande valeur avait tendance à se manifester dans les régions locales accidentées qui n’avaient pas fait l’objet de brûlages récents, régions caractérisées par une forte densité de lichen et une fonte des neiges hâtive au printemps. Dans le cadre de notre étude, nous avons constaté que la qualité de 1,5 % à 8,5 % (146–848 km2) de l’habitat d’hivernage actuel de grande valeur pourrait être réduite. Les trois routes différaient à peine. Nos résultats suggèrent que la route aurait des effets directs minimes sur l’habitat d’hivernage de grande valeur. Cependant, il y a lieu de considérer les incidences cumulatives supplémentaires (comme l’accès accru par les amateurs de plein air et les chasseurs) afin de pouvoir estimer les effets complets de la route