• Seasonal diets of mink and martens: Effects of spatial and temporal changes in resource abundance

      Ben-David, Merav (1996)
      Seasonal changes in food availability and feeding habits of mink (Mustela vison) and martens (Martes americana) on Chichagof Island, Southeast Alaska, were studied through the analysis of natural abundance of stable isotopes. Dependence of the two species on marine-derived nutrients, carried to the terrestrial system via the upstream migration of spawning Pacific salmon (Onchorhynchus sp.), was investigated. Twenty-four mink and 75 martens were live-trapped repeatedly in early summer (prior to salmon runs), early autumn (post salmon runs), late winter, and in spring (during the mating season). A blood sample was obtained from each individual. In addition, 25 mink and 165 marten carcasses were obtained from trappers during late autumn 1991-1994. Concurrently, prey availability was monitored, and tissues from prey were collected. The abundance of stable isotopes in prey tissues and blood samples were compared, indicating that riverine mink depended on salmon (carcasses and fry), with little seasonal or individual variation, whereas coastal mink relied on intertidal organisms in spring and summer, but fed on salmon carcasses when they became available in autumn. In addition, analysis of blood progesterone revealed that timing of reproduction in female mink appear to be shifted, so that lactation coincided with the availability of salmon carcasses. In contrast, martens showed individual variation in their diets, with some individuals feeding exclusively on terrestrial organisms, while the diets of others include salmon carcasses. Incorporation of salmon in the diet depended largely on availability of small rodents and location of the martens home range on the landscape. Although salmon carcasses are not a preferred food item for martens, they act as a suitable alternative to maintain body condition and allow successful reproduction even in years when preferred food is not readily available.
    • Seasonal movement patterns and habitat occupancy of Kotzebue region inconnu

      Smith, Nicholas J.; Sutton, Trent; Seitz, Andrew; Zimmerman, Christian (2013-12)
      Inconnu Stenodus leucichthys are large, long-lived piscivorous whitefish harvested in subsistence and sport fisheries in Alaska. My study was conducted to describe the seasonal movements and habitat occupancy of inconnu in the Selawik and Kobuk River drainages, Alaska, from 2010 through 2012. Methods consisted of surgically implanting acoustic telemetry tags in 80 fish from both rivers in 2010 and 2011 (n = 320), and deploying a fixed array of 20 Vemco VR2W acoustic receiving stations affixed with archival tags throughout Selawik Lake and Hotham Inlet. Tagged inconnu detections revealed that Selawik and Kobuk River inconnu displayed a high degree of spatial and temporal overlap while co-located in the Hotham Inlet/Selawik Lake complex. During the winter period, tagged fish predominately occupied the northern end of Hotham Inlet. In the summer period, fish transitioned from the northern end of Hotham Inlet to Selawik Lake and also the southern end of Hotham Inlet. Average daily displacements for Selawik and Kobuk River inconnu ranged from 2,000 to 10,000 m/day. Water temperature and salinity occupancy ranged from -1.39 to 18.69°C and 0 to 31.3 psu, respectively. No stock-specific or temporal trends in temperature and salinity occupancy by inconnu from the Selawik and Kobuk rivers were detected during my study. In addition to providing a more complete account of the life history of inconnu, these results will aid managers in developing future management strategies.
    • Seasonal movements and habitat use of rainbow trout in the Susitna River basin, southcentral Alaska

      Fraley, Kevin Marshall; Falke, Jeffrey; McPhee, Megan; Prakash, Anupma (2015-12)
      Potamodromous Rainbow Trout are an important ecological and recreational resource in freshwater systems of Alaska, and increased human development, hydroelectric projects, declining Pacific salmon stocks, and climate change may threaten their populations. We used aerial and on-the-ground telemetry tracking, field-measured and remotely-sensed aquatic habitat characteristics, snorkel surveys, and resource selection and occupancy models to characterize seasonal movements and habitat use of adult Rainbow Trout (>400 mm FL) at multiple spatial and temporal scales across the large (31,221 km²) and complex Susitna River basin of southcentral Alaska during 2003-2004 and 2013-2014. We found that trout overwintered in mainstem habitats near tributary mouths from November to April. After ice-out in May, trout ascended tributaries up to 51 km to spawn, and afterward moved downstream to lower tributary reaches to intercept egg and flesh subsidies provided by spawning salmon in July and August. Trout transitioned back to mainstem overwintering habitats at the onset of autumn when salmon spawning activity waned. Fidelity to tributary of capture varied across seasons, but was high in three out of four drainages. Different habitat characteristics influenced Rainbow Trout habitat use during each season, including stream gradient and sinuosity in the winter, substrate suitability and sinuosity during spawning, mean annual flow during the pre-salmon feeding season, and Chinook salmon spawning potential after the arrival of adult salmon in freshwater. We found that during the ice-free feeding season trout responded to fine-scale (channel unit) characteristics rather than more coarse-scale (stream reach) variables. Weekly movements were significantly longer when spawning salmon were present compared to pre-arrival. We found no difference in movements and habitat use for a subset of fish for which sex was identified using genetic analysis. However, the observed sex ratio was heavily female-biased, which contrasts with what has been observed in other non-anadromous salmonid populations. As most trout undertake extensive movements within and among tributaries and make use of a variety of seasonal habitats to complete their life histories, it will be critical to take a broad and multiscale approach to their management in light of anticipated future land use and climate change.
    • Seasonal movements of arctic grayling in a small stream on the Arctic Coastal Plain, Alaska

      Heim, Kurt C.; Wipfli, Mark; Seitz, Andrew; Falke, Jeffrey (2014-08)
      In watersheds of the Arctic Coastal Plain (ACP) of Alaska, Arctic Grayling adopt a migratory life history strategy to persist in a landscape with long (~ 8 month), cold winters that cause shallow aquatic habitats to freeze solid. We investigated movement patterns of adult and juvenile Arctic Grayling in a shallow beaded stream (Crea Creek), a dominant headwater stream type on the ACP. From 2012–2013 Arctic Grayling (N = 1035) were tagged with passive integrated transponder tags and monitored using an array of stream-wide antennae. Migration into Crea Creek peaked immediately after ice break-up in the main channel of the study area. Fish caught within the stream in June were in relatively poor body condition compared to fish captured later in summer. In both years, fish entering the stream during high flow and colder temperatures swam farther upstream than those entering during low flow and warmer temperatures. Migration of adult fish out of the stream was most strongly correlated with decreasing stream discharge, whereas juvenile downstream migration occurred in two peaks and was negatively correlated to minimum stream temperature and discharge. Among juveniles, fish of larger size and higher body condition tended to emigrate earlier. These results indicate that the population level migratory response is strongly tied to seasonal changes in hydrology, though heterogeneity among individuals also influences the response to seasonal change. This work demonstrates the importance of environmental cues, and surface-water flow mediated connectivity during the open-water period, and provides information needed to identify susceptibilities of migratory fishes to climate change and petroleum development on the ACP.
    • Seasonal movements of broad whitefish (Coregonus nasus) in the freshwater systems of the Prudhoe Bay oil field

      Morris, William A. (2000-05)
      Adult broad whitefish were tagged with radio transmitters in the Little Putuligayuk and Putuligayuk rivers along the Beaufort Sea coast of the Prudhoe Bay area, Alaska. Thirty-two fish were tagged in Lake Judith, a shallow tundra lake in the Little Putuligayuk River system. An additional 5 fish were tagged in the Putuligayuk River near a suspected spawning and overwintering site. Many fish left the tundra system to overwinter in the west channel of the Sagavanirktok River, however, unexpected movements also occurred. Six (20%) of the fish found in overwintering areas moved to the east channel of the Sagavanirktok River, an area long disregarded as having much potential for overwintering fish. Additionally, 2 fish traveled west over 100 km along the coast to the Colville River. Broad whitefish in this study wintered in marginal habitat and exhibited the ability to travel between distant coastal river systems along the arctic coast of Alaska.
    • Seasonal movements of northern pike in Minto Flats, Alaska

      Albert, Matthew L.; Sutton, Trent M.; Evenson, Matthew J.; Margraf, F. Joseph; Verbyla, David (2016-08)
      Northern pike (Esox lucius) is a large, long-lived piscivorous species that are harvested in sport and subsistence fisheries in Alaska. My study described the seasonal movements of northern pike that inhabit the Minto Lakes portion (Goldstream Creek drainage) of the Minto Flats wetland complex, Alaska, from May 2008 through January 2010. Very high frequency (VHF) radio tags (n = 220) were surgically implanted in northern pike in Minto Flats in May 2007, 2008, and 2009, and fish were relocated with fixed telemetry stations and aerial- and boat-based telemetry surveys. Radio-tagged northern pike displayed a distinct spring pre-spawning migration into the Minto Lakes study area, where they remained for the duration of the open-water season. A protracted out-migration occurred between late September and early December, with downstream movements peaking in November and October of 2008 and 2009, respectively. Radio-tagged fish present in the Minto Lakes study area during the open-water season overwintered exclusively in a 26-km reach of the Chatanika River from its confluence with Goldstream Creek upstream to the Murphy Dome Road access point. Daily movement rates were greatest during May and August. In addition to providing a better understanding of northern pike life history in Minto Flats, these results will aid managers and researchers by identifying critical habitats and providing information to better design future population assessment experiments.
    • Social organization and spatial relationships in coastal river otters: assessing form and function of social groups, sex-biased dispersal, and gene flow

      Blundell, Gail Marie (2001-05)
      River otters (Lontra canadensis) inhabiting marine environments are top-level predators foraging in the nearshore ecosystem and recently have been recognized as indicators of environmental health. Otters were extirpated from much of their historic distribution because of exposure to pollution and urbanization, resulting in expansive reintroduction programs that continue today. Without an understanding of the influence of factors such as social structure, mating system, or sex-biased dispersal on genetic variation and gene flow among populations, effects of local extirpation and the potential for natural recolonization (i.e., the need for reintroductions) cannot be determined. The objective of this study was to assess social organization and evaluate the importance of factors such as prey availability and kinship on formation of social groups and dispersal of individuals. Fifty-five otters were radio-tracked in three study areas in Prince William Sound, Alaska, from 1996 to 1999, to determine social organization and dispersal rates. Data from 111 individual otters (seven study areas) were obtained to assess relatedness and gene flow (with microsatellite DNA) and diet (with stable isotope analysis of ð¹³C and ð¹⁵N). DNA analysis indicated that kinship had no effect on social organization or spatial relationships among otters. Analyses of diet and home-range size indicated that social groups may be formed to facilitate cooperative foraging, enabling social otters to obtain a better-quality diet more efficiently (i.e., social otters had diets higher in schooling pelagic fishes and had smaller home ranges, compared to nonsocial otters). Male otters were more social than females, but reproductive constraints likely limited opportunities for sociality among females. Both telemetry and genetic data indicated that male and female otters had an equal, low probability of natal dispersal and male otters also exhibited breeding dispersal resulting in gene flow to nearby populations. Genetic data indicated distances for natal dispersal were bimodal; most males and some females settled nearby (within 16-30 km), but some females dispersed 60-90 km. Despite lack of geographic barriers to dispersal in a marine system, dispersal distances were relatively short, indicating that extirpation of local populations would be difficult to correct via natural recolonization unless viable otter populations were available nearby.
    • Some aspects in the ecology of the black bear (Ursus Americanus) in interior Alaska

      Hatler, David F. (1967-05)
      Research during 1964 and 1965 revealed that black bears in interior Alaska are active only 5 to 5.5 months each year. Emerging from winter dens in early May, the animals spend most of the first 3 months in river bottom and other lowland situations where green vegetation, especially Equisetum spp., composes the bulk of their diet. From the last half of July until mid-September bears are observed most commonly in alpine areas where fruits, especially Vaccinium uliginosum, are the important food. Animal food, constituting less than 15 percent (volume) of the animal's diet, is apparently taken whenever it is obtainable. Most animal food occurrences involve insects. Litter size averaged 1.73 for 30 litters observed during the 2 years studied. Litters larger than two do not seem to be common in interior Alaska. Intestinal parasites were found in 12 of 16 bears. Two heavy infestations of ascarids, 249 worms in one bear and 53 in another, were observed. Serious predation by interior Alaskan black bears upon the nests of some waterfowl has been recorded; predation upon most other wildlife species appears to be negligible. Evidence gathered during this study suggests that the rash of black bear problems experienced by interior Alaskans in 1963 was due largely to the widespread lack of blueberries during that year.
    • Spatial scales of muskox resource selection in late winter

      Wilson, Kenneth J. (1992-05)
      I examined resource selection by muskoxen in late winter on the coastal plain of the Arctic National Wildlife Refuge, Alaska, by comparing use and availability at regional, meso, local, and micro spatial scales. Use of vegetation types for feeding appears to be based on selection of areas of shallow soft snow with high cover of sedges, dead vegetation, and total vegetation, and on selection against areas of little vegetation cover or deep hardpacked snow. Muskoxen used moist sedge, tussock sedge, and Dryas terrace tundra in proportion to availability and avoided barren ground, partially vegetated, riparian shrub, and Dryas ridge tundra. Selection for areas of shallow snow occurred within vegetation types as well as between vegetation types. Occurrence of sedges and grasses in the diet was greater than availability. Feeding zones were primarily on windblown vegetated bluffs; these areas are distributed in narrow bands along creeks, rivers, and the coastline.
    • Species distribution models for Denali National Park and Preserve, Alaska

      Ritter, Joy L. (2007-05)
      The objective of this study is to explore the use of existing data to model the distribution of four species in Denali National Park; caribou, moose, grizzly bear, and wolf. Radiolocation data consisting of 1331 locations collected over three years for female caribou, 1329 locations collected over three years for female moose, 6579 locations collected over ten years for grizzly bears, and 2686 locations collected over three years for wolves were obtained from park biologists. A geographic information system was used to derive landscape characteristics associated with the animal locations and random locations placed in the same area. Caribou models were developed at three spatial scales with three different algorithms. Classification tree models showed a high prediction success, correctly classifying 75 to 94 percent of randomly withheld animal locations. Fall models for female caribou had the poorest prediction ability while summer models for female grizzly bears performed best. Topographic landscape characteristics such as elevation and terrain ruggedness were important classifiers for most of my prediction models. Distribution maps were developed for individual and multiple species during different seasons. Areas of moderate elevation along the north side of the Alaska Range are important for all our study animals.
    • Stopover ecology of semipalmated sandpipers (Calidris pusilla) at coastal deltas of the Beaufort Sea, Alaska

      Churchwell, Roy Thomas; Powell, Abby; Gens, Rudiger; Dunton, Kenneth; Blanchard, Arny; Hundertmark, Kris; Hollmen, Tuula (2015-12)
      Avian migration is one of the wonders of the natural world. Stored fats are the main source of nutrients and fuel for avian migration and it is assumed the fat deposition at stopover sites is a critical component of a successful migration. Stopover sites are crucial in the successful migration of many birds, but particularly for arctic-breeding shorebirds that migrate long distances from breeding to wintering grounds. Despite the importance of stopover sites, it is often difficult to determine the importance of these sites to migrating shorebirds. I investigated three aspects of stopover ecology of Semipalmated Sandpipers (Calidris pusilla) foraging at coastal deltas on the Beaufort Sea coast, Alaska. First, I quantified the spatial and temporal distribution and abundance of the benthic macroinvertebrate community living within the mudflats. I found that there were two ecological groups of macroinvertebrates using river deltas, one originated in terrestrial freshwater habitats and most importantly could withstand freezing in delta sediments over the winter, and the other originated from the marine environment, could not withstand freezing and had to migrate to intertidal habitats each summer from deeper water areas that did not freeze over the winter. Stable isotope analysis allowed me to describe the origin of carbon consumed by invertebrates in intertidal habitats. I predicted freshwater invertebrates would consume terrestrial carbon, and marine invertebrates would consume marine carbon, but I found that both groups utilized the same carbon, which was a mixture of terrestrial and marine sources. My second research question determined the importance of delta foraging habitat for fall migrating Semipalmated Sandpipers. I mapped the temporal distribution and abundance of birds and quantified this relationship to invertebrate distribution and abundance. I researched fattening rates of shorebirds by measuring triglycerides in the blood of shorebirds I captured. I hypothesized that triglyceride levels would be correlated with invertebrate abundance and related to habitat quality; however, I found no relationship. Next, I determined shorebird dependence on marine invertebrates using the stable isotope signature of invertebrates and shorebird plasma. I found that shorebird abundance was associated with invertebrate abundance, and that shorebirds did feed almost exclusively on invertebrates from the mudflats later in the season. I did not find a significant difference in habitat quality among the deltas, although more birds were counted at the Jago Delta than at the other two deltas. Finally, I researched the question of how change in water levels due to lunar tides and storm surge events impacted the availability of foraging habitat. I assessed the phenology of Semipalmated Sandpiper migration and how this related to the availability of forage based on abundance, distribution, and accessibility of macroinvertebrates. There was a significant decline in the calories available for forage when there was a lunar tide and when there was a storm surge event. The most foraging habitat was available late in the migration period, while the peak in Semipalmated Sandpiper migration was early in the period. Late in the season there is also a greater chance of a storm surge event occurring due to the lack of sea ice during that period. In summary, I found Beaufort Sea deltas were more diverse than I expected both in macroinvertebrate community and in how shorebirds use the available foraging habitat. After completing this research I feel this habitat is critical to Semipalmated Sandpiper migration; however, there is a real risk of extensive change to these deltas due to future warming with negative consequences for shorebirds.
    • Successional changes in the hydrology, water quality, primary production, and growth of juvenile Arctic grayling of blocked Tanana River sloughs, Alaska

      Wuttig, Klaus G. (1997-08)
      A comparative stream study was conducted to assess the influence of development and blockage on the hydrology, water quality, primary production, and Arctic grayling of Badger Slough, Alaska. Data collected showed that Badger Slough exhibited stable, clear flows throughout the summer, and higher total and total dissolved phosphorus, orthophosphate, alkalinity, pH, conductivity, and average temperatures, and lower winter dissolved oxygen concentrations than both Piledriver and 23-Mile Sloughs. Mean algal biomass (3.3 mg m-3) and primary production (6.9 g O2 m-2 d-1) are greater than that recorded for any other interior Alaska streams and percent fines in riffle substrates have increased. However, growth of age-0 grayling remains high. Badger Slough has eutrophied due to increased nutrients and stable flows, and the quality of rearing habitat for age-0 fish remains good. However, an annual flushing flow of 8.0 m3 s-1 is recommended for controlling accumulations of fines and maintenance of grayling habitat.
    • Summer ecology of the Teshekpuk caribou herd

      Parrett, Lincoln Scott (2007-05)
      The summer range of the Teshekpuk Caribou (Rangifer tarandus granti) Herd is currently undergoing the initial stages of petroleum exploration and development. Pre-development baseline information is necessary to interpret post-development distribution and habitat selection of caribou and to develop mitigation measures. We estimated bi-weekly distributions, diet and habitat selection by caribou during the summers, 2002-2004, based on aerial relocations of 21-49 radio-collared females. Little or no habitat selection was detected when comparing used locations to habitat available within bi-weekly utilization distributions. Habitat selection was much stronger when comparing bi-weekly utilization distributions to the remaining area of summer use. At the latter scale of analysis, there were dynamic temporal patterns in resource selection by caribou. High air temperature was strongly avoided throughout July. Tussock tundra was avoided early in the summer, but selected during August. Wet sedge was selected in June and from late-August through September. Estimates of dietary nitrogen content indicated that high nitrogen concentrations are available only for a short period in early summer, and declined well before forage biomass. Predicted dietary nitrogen concentration appeared to be much lower for the Teshekpuk Caribou Herd than for the Porcupine Caribou Herd. Successful mitigation measures for petroleum development in NPR-A will need to be spatially and temporally tailored to observed dynamic patterns in caribou resource selection. Future work should estimate the performance of caribou (e.g., survival or weight gain) in relation to habitat quality and use in order to confirm the value of selected habitats and to enhance the robustness of mitigation measures.
    • TEST College of Engineering & Mines 9/25/17

      CHISUM (2017-09)
      TEST College of Engineering & Mines 9/25/17
    • The Ecology Of Marten In Southcentral Alaska

      Buskirk, Steven William (1983)
      The ecology of marten in the upper Susitna Basin, southcentral Alaska was studied from January 1980 to June 1982. Data were gathered on home range and movements, seasonal food habits, habitat use and winter energetic strategies. Radio telemetry was used to obtain a total of 560 locations for 17 marten. Mean home range sizes of marten along the Susitna River were 3.71 km('2) for females, 6.82 km('2) for males and 6.75 km('2) for adult males (2+ years). Marten were found to be nocturnal in autumn and to show strong variability in their diel activity patterns in late winter. Marten tended to move upward in elevation during spring and downward in autumn, contrary to the prevailing views of trappers. Analyses of marten scats and colon contents collected during four seasons showed the most important foods to be microtine rodents, squirrels, fruits and birds. Major foods showed strong seasonal variation in utilization. Microtines were most important in autumn and showed declining use over winter. Northern red-backed voles were the most important microtine species. Sciurids were most important in spring and appeared to be a nonpreferred alternative food. Marten made little use of shrews, snowshoe hares, porcupines or insects. Carrion and human foods were highly preferred and consumed when available. Habitat utilization was studied through the use of aerial transects and snow tracking and by identifying resting sites. Marten foraged for microtines more frequently than expected in vegetation types dominated by black spruce. Marten rested in winter primarily in active red squirrel middens in stands dominated by old-growth white spruce. Fat depot and organ weights and total body fat of marten were measured to find an indicator to total body fat. Marten were found to have extremely low body fat ratios which did not show a significant change over winter.