• Bald eagle (Haliaeetus leucocephalus alaskanus) nesting related to forestry in southeastern Alaska

      Corr, Patrick O. (1974-05)
      There were 136 nests located by aerial survey along 225 miles of beach in six logged plots and six virgin plots. Nest densities during the three years were 0.20, 0.23, and 0.20 active nests per beach mile. Islets present within 2 miles of a logged main shore provided nesting territories for eagles not able to find suitable nest sites along the logged shore. Spatial distribution of active nests indicated a 1.25 mile territory radius per nesting pair. Statistical comparison (Mann and Whitney U test) of mean territory size found in logged versus virgin plots showed no significant difference in territory size between the two plot types. Nests located in beach fringe timber remaining after harvesting were utilized frequently because of the lack of alternate nest sites in the immediate vicinity; these nest sites were highly susceptible to wind throw. Storm damage resulted in the loss of 20 per cent of the known nests during winter 1968-1969. It is recommended that buffer zones (10 chain radius - 660 feet) around eagle nests be maintained during harvesting, and that logging activity in the vicinity of nesting eagles be curtailed during April and May. Also, smaller, scattered timber sales should be promoted to ensure that extensive beach strip logging does not remove potential nest sites along miles of shoreline.
    • Beaver population ecology in interior Alaska

      Boyce, Mark S. (1974-05)
      The ecology of beaver (Castor canadensis Kuhl) populations along two streams in interior Alaska was studied in 1972 and 1973. The two study areas were similar in most respects, except for the history of human trapping intensity. The heavily trapped population exhibited the following contrasts to the essentially unexploited population: (1) higher mortality among adult age classes, (2) higher survivorship of the prereproductives, (3) a sex ratio with a preponderance of females, (4) decreased age at first breeding and consequently, (5) a smaller average size at maturity. Males appear to expend lower effort for parental activities than do females, and consequently exhibit higher survivorship than their mates. Population regulating mechanisms, management implications, and the evolution of an optimal life history strategy are discussed. The distribution and abundance of beaver colonies were related to habitat types and characteristics of the physical environment by multiple linear regression analysis.
    • Bird use of arctic tundra habitats at Canning River Delta, Alaska

      Martin, Philip D. (1983-12)
      Seasonal patterns of abundance of shorebirds and Lapland Longspur were studied at the Canning River delta. Study plots with differing habitat characteristics were examined: upland, mesic, and lowland tundra, and coastal saline flats. Nesting density was greatest in the mesic plot, but the lowland received intense use by late summer transients; use of the saline habitat was consistently high. Cold weather in July, 1980 probably reduced prey availability. Aquatic habitats, especially polygon troughs, produced a high proportion of the adult insect biomass. Comparison of energetic requirements of birds with the energetic value of their prey supply suggests that food could have limited reproductive success. Availability of both aquatic and terrestrial insects may contribute to high breeding bird density in structurally diverse habitats. Heavy use of wet/flooded tundra by late summer migrants probably reflects abundance of midge (Diptera: chironomidae) larvae in pond sediments.
    • Black bear denning ecology and habitat selection in interior Alaska

      Smith, Martin E.; Follmann, Erich; Dean, Fred; Hechtel, John; Bowyer, Terry (1994-12)
      To identify conflicts between existing black bear (Ursus americanus) management and human activity on Tanana River Flats, Alaska, we monitored 27 radio-collared black bears from 1988-1991. We compared denning chronology, den characteristics, den-site selection, and habitat selection across sex, age, and female reproductive classes. Mean den entry was 1 October and emergence was 21 April, with females denned earlier and emerging later than males. Marshland and heath meadow habitats were avoided, and willow-alder was selected for den-sites. Eighty-three percent of dens were excavated, 100% contained nests, 18% were previously used, and 29% had flooded. Black bears selected black spruce-tamarack and birch-aspen significantly more, and marshland and heath meadow significantly less than available. Marshland and birch-aspen were used significantly more in spring than autumn. Marshland was used less than available by all bears in all seasons. Special habitat or den-site requirements are not critical for management of Tanana River Flats black bears.
    • Blood profile of grizzly bears in central and northern Alaska

      Brannon, Robert D. (1983-05)
      Blood from 151 grizzly bears (Ursus arctos) captured between 1973 and 1982 in the Brooks Range, Alaska, and the Alaska Range was examined for 7 hanatological, 24 serum chemistry, and 6 protein electrophoretic determinations. Differences in these characteristics between samples collected one hour apart indicate a response to stress during capture. Location differences in leukocyte count, erythrocyte count, hemoglobin, hematocrit, and cortisol suggest that Alaska Range bears were more stressed by capturing than Brooks Range bears. Sodium, creatinine, and urea nitrogen were negatively correlated with capture date, suggesting varied diet reinstatement and regained renal function as time from den emergence increased. Calcium, phosphorous, and alkaline phosphatase were negatively correlated with age, reflecting increased osteoblast activity and bone formation in young bears. Males had higher values than females for erythrocyte count, hematocrit, glucose, creatinine, calcium, phosphorous, and alkaline phosphatase, while glutamic-oxalacetic and glutamic-pyruvic transaminases were higher in females.
    • Body Condition And Food Resources Of White-Tailed Deer On Anticosti Island, Quebec

      Huot, Jean (1982)
      A study was conducted on relationships between seasonal variation in body condition of white-tailed deer (Odocoileus virginianus borealis) and food resources on Anticosti Island, Quebec. Results of the vegetation surveys show that food resources are extremely limited in abundance and variety as snow covers the ground vegetation in winter. Excluding Picea spp., Abies balsamea is by far the most available browse species, accounting for approximately 95% of the available browse biomass in February and March. Analysis of rumen contents suggests that this species accounts for 98.5% of the browse eaten by inland deer between February and mid-April. Lichens account for 9.5% of the dry weight of the rumen content at that time. During the snow-free period, forbs dominate the diet. Both sexes and all age classes show a well defined pattern in body composition with maximum fat levels occurring between September and mid-December and minimum levels between mid-April and mid-June. Fat reserves (ether extraction) in fawns vary from a maximum of 15.3% in fall to a minimum of 0.2% in spring as they lose 41% of their ingesta-free body weight. Composition of the winter body weight loss varies according to sex and age, fat represents 31.7% to 58.9% of the loss and protein 17.8% to 23.0%, water is inversely correlated with fat and ash is a minor part of the loss. The caloric content of the weight loss on an ingesta-free weight basis is lowest in 3-year-old males (3.95 kcal/g) and highest in 2-year-old females (6.86 kcal/g). It is concluded that in association with their low productivity in summer, Anticosti deer must base their winter survival strategy primarily on energy conservation and secondarily on food acquisition during that season.
    • Breeding ecology and fasting tolerance of scaup and other ducks in the boreal forest of Alaska

      Martin, Kate H. (2007-08)
      Information on the breeding ecology of boreal forest ducks is lacking, despite management concern for species such as the lesser scaup (Aythya affinis), whose population has declined markedly since the 1980s. The mechanisms impacting population growth of scaup, and which component of their population dynamics is most affected, are unknown. Previous investigators hypothesized that food deprivation in the spring may reduce breeding success. My objectives were to: 1) examine reproductive parameters of lesser scaup and other ducks on the Yukon Flats in interior Alaska, and 2) measure the tolerance of captive scaup to fasting, in comparison to sympatric Northern shovelers (Anas clypeata) and American wigeon (Anas americana). Although breeding probability of paired females was assumed to be 1.0, the breeding probability of paired female scaup was between 0.12 (SE = 0.05, n=67) to 0.68 (SE = 0.08, n=37), and was positively related to body mass. These results suggest that managers may overestimate the productivity of boreal ducks using traditional survey methods. In addition, captive female scaup completely recovered from a loss of 11% body mass in only four days, suggesting that mass loss can be rapidly reversed, and may be able to obtain the body condition required for reproduction, if food supplies are adequate.
    • Breeding ecology of Smith's longspurs (Calcarius pictus) in the Brooks Range, Alaska

      Craig, Heather Rebekah; Powell, Abby; Kendall, Steve; O'Brien, Diane (2015-08)
      Alaska's Arctic ecosystem provides critical habitat for nesting songbirds. However, within this region climate change projections indicate a shrubbier future, as well as major shifts in summer weather patterns. The polygynandrous Smith's Longspur (Calcarius pictus) is a little known species that is closely tied to treeless tundra habitat in northern Alaska. I evaluated Smith's Longspur dispersal ability and annual survival rates using seven years of banding data, as well as breeding habitat requirements and reproductive success in two populations in the Brooks Range. Most adults (88%; n = 34) returned to nest in the same breeding neighborhood as previous years, and dispersal distance (x ± SE = 301 ± 70 m) did not differ between sexes. Only 4% of juvenile birds were resighted as adults and dispersal distance (x = 1674 ± 500 m; n = 6) was significantly greater for juveniles than for adults. From 674 capture-recapture histories, I evaluated annual survival and found that adult female survival (50-58%) was only slightly lower than for males (60-63%); juvenile survival was 41%, but was also paired with a low (13%) encounter probability. I examined nest-site selection patterns by comparing habitat measurements from 86 nests to paired random points within the nest area. Nests were typically found in open low shrub tundra and never among tall shrubs (height of tallest shrub x = 26.8 ± 6.7 cm). However, the only predictor of nest location I found was variation in willow height, which was slightly lower at nests than at random points. Daily nest survival rates were estimated from 257 nests and found to be relatively high (0.97-0.99) and consistent across years, and the best approximating model indicated that nest survival was negatively related to the numbers of days below freezing and season date. Despite dispersal ability and resilience to harsh conditions, Smith's Longspurs' response to climate change is unknown. The lack of sex-bias in dispersal and the low sex bias in survival, as well as the weak nest-site selection, may be attributed to the species' social mating system. Unlike most songbirds, multiple inter-mated individuals exist within each breeding neighborhood, altering social dynamics and likely demographic patterns. This is the first study to investigate the breeding biology of Smith's Longspurs at the western extent of their range and provides important conservation information as Arctic regions change.
    • Breeding ecology of whimbrels (Numenius phaeopus) in Interior Alaska

      Harwood, Christopher M.; Powell, Abby N.; Verbyla, David; Gill, Robert E. Jr. (2016-12)
      Whimbrels Numenius phaeopus breed in tundra-like habitats, both beyond treeline and within the boreal forest of interior Alaska. Despite their widespread distribution and designation as a species of conservation concern, their ecology has been particularly understudied in Alaska. During 2008--2012, I initiated the first dedicated study of Whimbrel breeding ecology in Alaska, and the first such study of any boreal-breeding shorebird in the state. Within a habitat mosaic of forest, woodlands, muskeg, scrub, and ponds within the floodplain of the Kanuti River in north-central Alaska, Whimbrels bred in the three largest (of nine) patches of discontinuous tussock tundra. These Whimbrels exhibited a compressed annual breeding schedule with the first birds arriving about 6 May and nests hatching about 17 June. Evidence for clustered and synchronous nesting, which may aid in predator defense, was equivocal. Most (69%) Whimbrels nested in mixed shrub-sedge tussock bog. I modeled nest-site selection at multiple spatial scales for 39 nests; however, the only variables important in the models were at the finest scale around the nest, namely that nests tended to be located on hummocks and exhibited lateral cover. Model results for nest survival of 67 nests over 4 years revealed a considerable difference in nest success (92% vs. 41%) at the two largest patches studied; this site effect was largely unexplained. To investigate Whimbrel ecology more broadly in the boreal biome, in 2013 I designed and conducted a Whimbrel-specific survey comprising 279 point counts within 28 transects along the road system of interior Alaska. I detected Whimbrels on just 32% of transects and 11% of count points. Although I detected Whimbrels at 3 sites where they had not been reported previously, I failed to detect them at several historically occupied sites. Dwarf shrub meadow was the most commonly observed habitat for all points visited. I modeled Whimbrel presence based on coarse habitat and avifaunal community features; no models were well supported. Between the local and regional surveys, my results tended to reinforce several widespread, but not necessarily investigated, descriptions about the breeding ecology of Whimbrels. My studies supported the premises that Whimbrels are patchily distributed on the landscape and often breed in clusters. Breeding of individuals and occupancy of some patches may be annually variable. Despite analyses of multiple habitat features at multiple spatial scales, I mostly observed a lack of specificity in where they bred among tundra-like patches, and where they nested specifically within such patches. This suggests that Whimbrels are tundra habitat generalists on their breeding grounds. Such phenotypic plasticity may be particularly adaptive in the dynamic, wildfire-prone landscape of interior Alaska.
    • Breeding ecology of white-winged scoters on the Yukon Flats, Alaska

      Safine, David Elliot (2005-08)
      Breeding bird surveys indicate a long-term decline in the numbers of scoters (Melanitta sp.) in North America. My objectives were to estimate survival of nests, ducklings, and adult female White-winged Scoters (Melanitta fusca) breeding on the Yukon Flats National Wildlife Refuge, Alaska, 2002-2004, within their primary breeding range. I measured habitat variables at nest sites and random sites in the study area to characterize nest habitat selection, and investigated breeding incidence with a laboratory analysis of circulating concentrations of the plasma yolk precursors vitellogenin (VTG) and very-low density lipoprotein (VLDL). The low hen and nest survival rates I observed combined with the substantial proportion of non-breeders on the breeding ground (up to 28%) may be responsible for the observed declines in abundance if annual survival rates are not high enough to maintain stable populations. Scoters avoided nesting in graminoid habitat, but nested in all other scrub or forested plant communities in proportion to their availability, selecting sites with more cover, higher variability of cover, and closer to edge and water than random sites. At the nest habitat scale, scoters are generalists, which may reduce the foraging efficiency of nest predators.
    • Calving ground habitat selection: Teshekpuk Lake and Western Arctic caribou herds

      Kelleyhouse, Rebecca A. (2001-12)
      Barren-ground caribou (Rangifer tarandus granti) exhibit relative fidelity to calving grounds each spring. The Western Arctic Herd (WAH) and Teshekpuk Lake Herd (TLH) calve separately on Alaska's north slope, each selective of the dominant vegetation type. The WAH consumed mostly sedges, though the TLH diet varied. Despite differing snow conditions between the calving grounds, both herds were selective of the lowest snow cover class. Rugged terrain was avoided by both herds. While the TLH selected a high rate of increase in biomass, the WAH selected high biomass at calving and at peak lactation. Climate trends (1985-2001) were variable. There was a warming trend on the WAH calving ground, though no significant trends were present on the TLH calving ground, as expressed by median NDVI on 21 June. These herds have similar winter ranges and population trends, yet they differ in respect to habitat composition, selection and climate patterns during calving.
    • Carbon exchange and permafrost collapse: implications for a changing climate

      Myers-Smith, Isla Heather (2005-05)
      With a warmer climate, the wetlands of Interior Alaska may experience more frequent or extensive stand-replacing fires and permafrost degradation. This, in turn may change the primary factors controlling carbon emissions. I measured carbon exchange along a moisture transect from the center of a sphagnum-dominated bog into a burned forest (2001 Survey Line Fire) on the Tanana River Floodplain. Both the bog and the surrounding burn were sinks for CO₂, and the bog was a CH₄ source in the abnormally dry summer of 2004. Thermokarst and subsiding soils were observed on the margin of the bog in the three years since the fire, increasing the anaerobic portion of the soil landscape. I observed the greatest variation in carbon fluxes in this portion of the transect. I conclude that permafrost collapse is altering the pattern of emissions from this landscape. I tracked historical changes in vegetation, hydrology and fire at this site through macrofossil, charcoal and diatom analysis of peat cores. The paleoecological record suggests that fire mediates permafrost collapse in this system. This study indicates that future changes in temperature and precipitation will alter carbon cycling and vegetation patterns across this boreal landscape.
    • Characteristics of the Sulukna River spawning population of inconnu, Yukon River drainage, Alaska

      Esse, David Andrews; Margraf, F. Joseph; Sutton, Trent M.; Brown, Randy J. (2011-12)
      Inconnu Stenodus leucichthys are large migratory whitefish harvested in subsistence and sport fisheries in Alaska. Research on the Sulukna River spawning population of inconnu was conducted in September and early October from 2007 to 2009. Samples were collected to verify maturity and spawning readiness, and to determine age distributions of mature males and females. Spawning abundance was estimated and post-spawning migration timing was identified. Otoliths were analyzed optically to determine age and chemically to determine amphidromy. Maturity sampling indicated that all sampled fish were in spawning condition or had recently spawned. Abundance estimates were 2,079 and 3,531 inconnu in 2008 and 2009, respectively. Post-spawning downstream migration timing was nearly identical between years, with the majority of fish moving downstream between September 30 and October 9. In both years, migrating inconnu displayed a nocturnal migration pattern, with 96% migrating between 10:00 pm and 9:00 am hours daily. Age estimates ranged between 6 and 26 years. Chemical analysis indicated that some Sulukna River inconnu were amphidromous, making migrations of over 1,300 km to the sea. This information indicates that the Sulukna River spawning population of inconnu has a large and variable abundance, in which amphidromy is facultative.
    • Characterization of muskox habitat in northeastern Alaska

      O'Brien, Constance Marsha (1988-12)
      In northeastern Alaska, muskoxen have been most often found in riparian habitats and proximate uplands. Vegetation was studied in nine adjacent river drainages; six of the drainages are regularly used by muskoxen. Twenty-two vegetation/land cover types were described using aerial photographs, point-intercept sampling, and ocular cover estimates. The proportion of each cover type was estimated for each drainage and compared among drainages by MANOVA. There was no significant difference among non-muskox drainages in the average proportion of cover types. A marginally significant difference was found among muskox drainages. There were no significant differences in the proportions of each vegetation type in non-muskox drainages versus muskox drainages. Five vegetation types associated with high forage quality and availability and low snow accumulation were often used by muskoxen. Four of these five vegetation types typically had <7% cover in the nine drainages and are critical habitat components in northeastern Alaska.
    • Climate, embryonic development, and potential for adaptation to warming water temperatures by Bristol Bay sockeye salmon

      Sparks, Morgan McKenzie; Falke, Jeffrey; Westley, Peter; Adkison, Milo; Quinn, Thomas (2016-08)
      Rapidly warming water temperatures associated with climate change represent a substantial disturbance to the habitat of aquatic ectothermic organisms. For salmonid fishes (family Salmonidae), early life history survival and timing of reproduction and development are closely tied to temperature, such that altered thermal regimes could alter patterns of survival or shift phenology into a mismatch with the environment. Because temperature is the dominant driver of developmental rates, empirical statistical models have been developed to predict the timing of hatching and fry emergence based on incubation temperature. In this thesis I explored how the timing of hatching and emergence may shift in response to warming temperatures and how spawning timing across an Alaskan landscape is shaped by incubation temperatures experienced by sockeye salmon (Oncorhynchus nerka) embryos and alevin. Additionally, I quantified the relative roles of genetics and environmentally induced plasticity on the timing of hatching in two populations of sockeye salmon from the Iliamna Lake system, Alaska by rearing them in common garden conditions in the laboratory. To meet these goals I reformulated a widely cited developmental model to incorporate variability in natural regimes and use it to predict hatching timing over the course of the spawning duration for 25 populations of Bristol Bay sockeye salmon. Additionally, I hind- and forecasted lake temperature based off historical and predicted air temperatures to estimate and predict hatching for a single population. I found that predicted hatching timing for wild populations varied between 58 and 260 days, and was largely variable as a result of habitat thermal heterogeneity and parental spawn time. I also predicted a three-week decrease in hatching timing over the course of the next century for a single beach spawning population, which was just beyond historic variability. Counter to expectations, for a subset of populations hatching and emergence timing variability exceeded that of spawning timing, indicating the relationship between spawning timing and incubation temperature may be weaker than expected. The results of the common garden experiment revealed indistinguishable differences between populations in hatching timing across five temperature scenarios, but strong plasticity as timing differed between 74 and 189 days in the warmest to coolest treatment. Furthermore, I detected family-specific differences in hatching timing both within and among treatments consistent with heritable developmental rates and gene by environment interactions in days to hatch, where the interaction between treatment and family was as high as 10 days difference in hatching. Population or family-specific survival in this experiment did not differ in response to temperature suggesting a lack of thermal adaptation in this regard during this life stage in these populations. Alevin mass and length upon hatching varied little among treatments (<10%), but did significantly decrease with cooling temperatures. Taken as a whole this study indicates that the effects of climate change during the early life history stages may be buffered by phenotypic plasticity and variability in populations and habitats will be important for maintaining diversity in the face of climate change.