Geology topics

Layne G. Adams

Publications and source records attributed to Layne G. Adams.

At least 37 records · Page 2Linked to original sources

USGS2014

Climate-driven effects of fire on winter habitat for caribou in the Alaskan-Yukon Arctic

Climatic warming has direct implications for fire-dominated disturbance patterns in northern ecosystems. A transforming wildfire regime is altering plant composition and successional patterns, thus affecting the distribution and potentially the abundance of large herbivores. Caribou ( Rangifer tarandus ) are an important subsistence resource for communities throughout the north and a species that depends on terrestrial lichen in late-successional forests and tundra systems. Projected increases in area burned and reductions in stand ages may reduce lichen availability within caribou winter ranges. Sufficient reductions in lichen abundance could alter the capacity of these areas to support caribou populations. To assess the potential role of a changing fire regime on winter habitat for caribou, we used a simulation modeling platform, two global circulation models (GCMs), and a moderate emissions scenario to project annual fire characteristics and the resulting abundance of lichen-producing vegetation types (i.e., spruce forests and tundra >60 years old) across a modeling domain that encompassed the winter ranges of the Central Arctic and Porcupine caribou herds in the Alaskan-Yukon Arctic. Fires were less numerous and smaller in tundra compared to spruce habitats throughout the 90-year projection for both GCMs. Given the more likely climate trajectory, we projected that the Porcupine caribou herd, which winters primarily in the boreal forest, could be expected to experience a greater reduction in lichen-producing winter habitats (−21%) than the Central Arctic herd that wintered primarily in the arctic tundra (−11%). Our results suggest that caribou herds wintering in boreal forest will undergo fire-driven reductions in lichen-producing habitats that will, at a minimum, alter their distribution. Range shifts of caribou resulting from fire-driven changes to winter habitat may diminish access to caribou for rural communities that reside in fire-prone areas.

Alaska;Yukon↗

USGS2014

Lack of sex-biased dispersal promotes fine-scale genetic structure in alpine ungulates

Identifying patterns of fine-scale genetic structure in natural populations can advance understanding of critical ecological processes such as dispersal and gene flow across heterogeneous landscapes. Alpine ungulates generally exhibit high levels of genetic structure due to female philopatry and patchy configuration of mountain habitats. We assessed the spatial scale of genetic structure and the amount of gene flow in 301 Dall’s sheep ( Ovis dalli dalli ) at the landscape level using 15 nuclear microsatellites and 473 base pairs of the mitochondrial (mtDNA) control region. Dall’s sheep exhibited significant genetic structure within contiguous mountain ranges, but mtDNA structure occurred at a broader geographic scale than nuclear DNA within the study area, and mtDNA structure for other North American mountain sheep populations. No evidence of male-mediated gene flow or greater philopatry of females was observed; there was little difference between markers with different modes of inheritance (pairwise nuclear DNA F ST = 0.004–0.325; mtDNA F ST = 0.009–0.544), and males were no more likely than females to be recent immigrants. Historical patterns based on mtDNA indicate separate northern and southern lineages and a pattern of expansion following regional glacial retreat. Boundaries of genetic clusters aligned geographically with prominent mountain ranges, icefields, and major river valleys based on Bayesian and hierarchical modeling of microsatellite and mtDNA data. Our results suggest that fine-scale genetic structure in Dall’s sheep is influenced by limited dispersal, and structure may be weaker in populations occurring near ancestral levels of density and distribution in continuous habitats compared to other alpine ungulates that have experienced declines and marked habitat fragmentation.

Alaska↗

USGS2014

Changing Arctic ecosystems: resilience of caribou to climatic shifts in the Arctic

The U.S. Geological Survey (USGS) Changing Arctic Ecosystems (CAE) initiative strives to inform key resource management decisions for Arctic Alaska by providing scientific information and forecasts for current and future ecosystem response to a warming climate. Over the past 5 years, a focal area for the USGS CAE initiative has been the North Slope of Alaska. This region has experienced a warming trend over the past 60 years, yet the rate of change has been varied across the North Slope, leading scientists to question the future response and resilience of wildlife populations, such as caribou ( Rangifer tarandus ), that rely on tundra habitats for forage. Future changes in temperature and precipitation to coastal wet sedge and upland low shrub tundra are expected, with unknown consequences for caribou that rely on these plant communities for food. Understanding how future environmental change may affect caribou migration, nutrition, and reproduction is a focal question being addressed by the USGS CAE research. Results will inform management agencies in Alaska and people that rely on caribou for food.

Alaska↗

USGS2012

Range overlap and individual movements during breeding season influence genetic relationships of caribou herds in south-central Alaska

North American caribou ( Rangifer tarandus ) herds commonly exhibit little nuclear genetic differentiation among adjacent herds, although available evidence supports strong demographic separation, even for herds with seasonal range overlap. During 1997–2003, we studied the Mentasta and Nelchina caribou herds in south-central Alaska using radiotelemetry to determine individual movements and range overlap during the breeding season, and nuclear and mitochondrial DNA (mtDNA) markers to assess levels of genetic differentiation. Although the herds were considered discrete because females calved in separate regions, individual movements and breeding-range overlap in some years provided opportunity for male-mediated gene flow, even without demographic interchange. Telemetry results revealed strong female philopatry, and little evidence of female emigration despite overlapping seasonal distributions. Analyses of 13 microsatellites indicated the Mentasta and Nelchina herds were not significantly differentiated using both traditional population-based analyses and individual-based Bayesian clustering analyses. However, we observed mtDNA differentiation between the 2 herds (F STM = 0.041, P < 0.001). Although the Mentasta and Nelchina herds exhibit distinct population dynamics and physical characteristics, they demonstrate evidence of gene flow and thus function as a genetic metapopulation.

Alaska↗

USGS2012

Diversity of nitrogen isotopes and protein status in caribou: implications for monitoring northern ungulates

Nutritional condition is an important determinant of productivity and survival in caribou (Rangifer tarandus). We used samples of excreta (n = 1,150) to estimate diet composition from microhistology and 2 isotopic proxies of protein status for 2 ecotypes of caribou in 4 herds in late winter (2006–2008). Isotopes of nitrogen (δ 15 N in parts per thousand [‰]) from excreta samples (urea, diet, and body N) were used to estimate indexes of protein status: the proportion of urea N derived from body N (p-UN) and the difference between the δ15N of the body and urinary urea (Δbody-urea). We examined dietary and terrain characteristics, δ 15 N, p-UN, and Δ body-urea by ecotype, herd, year, and foraging site. Multiple regression and an information-theoretic approach were used to evaluate correlates of protein status at each foraging site. The dietary and terrain characteristics of foraging sites did not vary by ecotype or herd (P > 0.108); diets were dominated by lichens (68% ± 14.1% SD). The δ 15 N of urea, diet, body N, p-UN, and Δ body-urea varied among foraging sites within each herd (P < 0.001). Although highly variable, the δ 15 N of urinary urea was typically low (−4.68‰ ± 2.67‰ SD). Dietary N also had low δ 15 N (−4.18‰ ± 0.92‰ SD), whereas body N was generally heavier in 15 N (2.20‰ ± 1.56‰ SD) than urinary urea or the diet. Both measures of protein status were similarly diverse between ecotypes and among herds, which limited their applicability to monitor protein status at the population level. Although we observed limitations to interpreting estimates of p-UN from highly vagile ungulates, the Δbody-urea may prove to be a useful index of protein status at smaller spatial and temporal scales. Indeed, a portion of the observed variance (r 2 = 0.26) in Δbody-urea at each foraging site was explained by the proportion of shrubs in the winter diet. There remains potential in using δ 15 N in excreta as a noninvasive tool for evaluating protein status in northern ungulates; however, considerable analytical and sampling challenges remain for applying these isotopic approaches at large scales.

Alaska↗

USGS2011

Characteristics of foraging sites and protein status in wintering muskoxen: insights from isotopes of nitrogen

Identifying links between nutritional condition of individuals and population trajectories greatly enhances our understanding of the ecology, conservation, and management of wildlife. For northern ungulates, the potential impacts of a changing climate to populations are predicted to be nutritionally mediated through an increase in the severity and variance in winter conditions. Foraging conditions and the availability of body protein as a store for reproduction in late winter may constrain productivity in northern ungulates, yet the link between characteristics of wintering habitats and protein status has not been established for a wild ungulate. We used a non‐invasive proxy of protein status derived from isotopes of N in excreta to evaluate the influence of winter habitats on the protein status of muskoxen in three populations in Alaska (2005–2008). Multiple regression and an information‐theoretic approach were used to compare models that evaluated the influence of population, year, and characteristics of foraging sites (components of diet and physiography) on protein status for groups of muskoxen. The observed variance in protein status among groups of muskoxen across populations and years was partially explained (45%) by local foraging conditions that affected forage availability. Protein status improved for groups of muskoxen as the amount of graminoids in the diet increased (−0.430 ± 0.31, β± 95% CI) and elevation of foraging sites decreased (0.824 ± 0.67). Resources available for reproduction in muskoxen are highly dependent upon demographic, environmental, and physiographic constraints that affect forage availability in winter. Due to their very sedentary nature in winter, muskoxen are highly susceptible to localized foraging conditions; therefore, the spatial variance in resource availability may exert a strong effect on productivity. Consequently, there is a clear need to account for climate–topography effects in winter at multiple scales when predicting the potential impacts of climatic shifts on population trajectories of muskoxen.

Oikos↗

USGS2011

Fire, grazing history, lichen abundance, and winter distribution of caribou in Alaska's taiga

In the early 1990s the Nelchina Caribou ( Rangifer tarandus ) Herd (NCH) began a dramatic shift to its current winter range, migrating at least an additional 100 km beyond its historic range. We evaluated the impacts of fire and grazing history on lichen abundance and subsequent use and distribution by the NCH. Historic (prior to 1990) and current (2002) winter ranges of the NCH had similar vascular vegetation, lichen cover ( P = 0.491), and fire histories ( P = 0.535), but the former range had significantly less forage lichen biomass as a result of grazing by caribou. Biomass of forage lichens was twice as great overall ( P = 0.031) and 4 times greater in caribou selected sites on the current range than in the historic range, greatly increasing availability to caribou. Caribou on the current range selected for stands with >20% lichen cover ( P < 0.001), greater than 1,250 kg/ha ( P < 0.001) forage lichen biomass and stands older than 80 yr postfire ( P < 0.001). After fires, forage lichen cover and biomass seldom recovered sufficiently to attract caribou grazing until after ≥60 yr, and, as a group, primary forage lichen species did not reach maximum abundance until 180 yr postfire. Recovery following overgrazing can occur much more quickly because lichen cover, albeit mostly fragments, and organic substrates remain present. Our results provide benchmarks for wildlife managers assessing condition of caribou winter range and predicting effects of fires on lichen abundance and caribou distribution. Of our measurements of cover and biomass by species, densities and heights of trees, elevation, slope and aspect, only percentage cover by Cladonia amaurocraea , Cladina rangiferina , Flavocetraria cuculata , and lowbush cranberry ( Vaccinium vitis‐idaea ) were necessary for predicting caribou use of winter range.

Journal of Wildlife Management↗

USGS2011

An isotopic approach to measuring nitrogen balance in caribou

Nutritional restrictions in winter may reduce the availability of protein for reproduction and survival in northern ungulates. We refined a technique that uses recently voided excreta on snow to assess protein status in wild caribou ( Rangifer tarandus ) in late winter. Our study was the first application of this non‐invasive, isotopic approach to assess protein status of wild caribou by determining dietary and endogenous contributions of nitrogen (N) to urinary urea. We used isotopic ratios of N (δ 15 N) in urine and fecal samples to estimate the proportion of urea N derived from body N ( p ‐UN) in pregnant, adult females of the Chisana Herd, a small population that ranged across the Alaska‐Yukon border. We took advantage of a predator‐exclosure project to examine N status of penned caribou in April 2006. Lichens were the primary forage (>40%) consumed by caribou in the pen and δ 15 N of fiber tracked the major forages in their diets. The δ 15 N of urinary urea for females in the pen was depleted relative (−1.3 ± 1.0 parts per thousand [‰], ${\bar {x}}\pm {\rm SD}$ ) to the δ 15 N of body N (2.7 ± 0.7‰). A similar proportion of animals in the exclosure lost core body mass (excluding estimates of fetal and uterine tissues; 55%) and body protein (estimated by isotope ratios; 54%). This non‐invasive technique could be applied at various spatial and temporal scales to assess trends in protein status of free‐ranging populations of northern ungulates. Intra‐ and inter‐annual estimates of protein status could help managers monitor effects of foraging conditions on nutritional constraints in ungulates, increase the efficiency and efficacy of management actions, and help prepare stakeholders for potential changes in population trends.

Journal of Wildlife Management↗

USGS2010

Ranking Alaska moose nutrition: Signals to begin liberal antlerless harvests

We focused on describing low nutritional status in an increasing moose ( Alces alces gigas ) population with reduced predation in Game Management Unit (GMU) 20A near Fairbanks, Alaska, USA. A skeptical public disallowed liberal antlerless harvests of this moose population until we provided convincing data on low nutritional status. We ranked nutritional status in 15 Alaska moose populations (in boreal forests and coastal tundra) based on multiyear twinning rates. Data on age-of-first-reproduction and parturition rates provided a ranking consistent with twinning rates in the 6 areas where comparative data were available. Also, short-yearling mass provided a ranking consistent with twinning rates in 5 of the 6 areas where data were available. Data from 5 areas implied an inverse relationship between twinning rate and browse removal rate. Only in GMU 20A did nutritional indices reach low levels where justification for halting population growth was apparent, which supports prior findings that nutrition is a minor factor limiting most Alaska moose populations compared to predation. With predator reductions, the GMU 20A moose population increased from 1976 until liberal antlerless harvests in 2004. During 1997–2005, GMU 20A moose exhibited the lowest nutritional status reported to date for wild, noninsular, North American populations, including 1) delayed reproduction until moose reached 36 months of age and the lowest parturition rate among 36-month-old moose (29%, n = 147); 2) the lowest average multiyear twinning rates from late-May aerial surveys ( x̄ = 7%, SE = 0.9%, n = 9 yr, range = 3–10%) and delayed twinning until moose reached 60 months of age; 3) the lowest average mass of female short-yearlings in Alaska ( x̄ = 155 ± 1.6 [SE] kg in the Tanana Flats subpopulation, up to 58 kg below average masses found elsewhere); and 4) high removal (42%) of current annual browse biomass compared to 9–26% elsewhere in boreal forests. When average multiyear twinning rates in GMU 20A (sampled during 1960–2005) declined to <10% in the mid- to late 1990s, we began encouraging liberal antlerless harvests, but only conservative annual harvests of 61–76 antlerless moose were achieved during 1996–2001. Using data in the context of our broader ranking system, we convinced skeptical citizen advisory committees to allow liberal antlerless harvests of 600–690 moose in 2004 and 2005, with the objective of halting population growth of the 16,000–17,000 moose; total harvests were 7–8% of total prehunt numbers. The resulting liberal antlerless harvests served to protect the moose population's health and habitat and to fulfill a mandate for elevated yield. Liberal antlerless harvests appear justified to halt population growth when multiyear twinning rates average ≤10% and ≥1 of the following signals substantiate low nutritional status: <50% of 36-month-old moose are parturient, average multiyear short-yearling mass is <175 kg, or >35% of annual browse biomass is removed by moose.

Journal of Wildlife Management↗

USGS2010

Wolves will not provide small-scale ecological restoration

Licht and colleagues (BioScience 60: 147–153) proposed a paradigm shift in wolf management to include the introductions of small, highly manipulated groups of wolves ( Canis lupus ) to confined natural areas to facilitate ecosystem recovery. Certainly, reductions or losses of apex predators from many regions worldwide have had profound effects on ecosystem characteristics (Soulé et al. 2003). Numerous efforts to restore or enhance predator populations through policy change or reintroductions have occurred, often with the intent to restore ecosystem function (Breitenmoser et al. 2001). However, in addition to the gargantuan technological and political challenges inherent in Licht and colleagues' proposal, we contend that intensively managed wolves will not restore natural ecosystem processes given the disparity in scale between these proposed actions and the ecosystem processes that wolves foster. Further, we note that predator-prey relationships are more complex than Licht suggested.

BioScience↗

USGS2009

Population-level resource selection by sympatric brown and American black bears in Alaska

Distribution theory predicts that for two species living in sympatry, the subordinate species would be constrained from using the most suitable resources (e.g., habitat), resulting in its use of less suitable habitat and spatial segregation between species. We used negative binomial generalized linear mixed models with fixed effects to estimate seasonal population-level resource selection at two spatial resolutions for female brown bears ( Ursus arctos ) and female American black bears ( U. americanus ) in southcentral Alaska during May–September 2000. Black bears selected areas occupied by brown bears during spring which may be related to spatially restricted (i.e., restricted to low elevations) but dispersed or patchy availability of food. In contrast, black bears avoided areas occupied by brown bears during summer. Brown bears selected areas near salmon streams during summer, presumably to access spawning salmon. Use of areas with high berry production by black bears during summer appeared in response to avoidance of areas containing brown bears. Berries likely provided black bears a less nutritious, but adequate food source. We suggest that during summer, black bears were displaced by brown bears, which supports distribution theory in that black bears appeared to be partially constrained from areas containing salmon, resulting in their use of areas containing less nutritious forage. Spatial segregation of brown and American black bears apparently occurs when high-quality resources are spatially restricted and alternate resources are available to the subordinate species. This and previous work suggest that individual interactions between species can result in seasonal population-level responses.

Polar Biology↗

USGS2008

Stochastic and compensatory effects limit persistence of variation in body mass of young caribou

Nutritional restriction during growth can have short- and long-term effects on fitness; however, animals inhabiting uncertain environments may exhibit adaptations to cope with variation in food availability. We examined changes in body mass in free-ranging female caribou ( Rangifer tarandus ) by measuring mass at birth and at 4, 11, and 16 months of age to evaluate the relative importance of seasonal nutrition to growth, the persistence of cohort-specific variation in body mass through time, and compensatory growth of individuals. Relative mean body mass of cohorts did not persist through time. Compensatory growth of smaller individuals was not observed in summer; however, small calves exhibited more positive change in body mass than did large calves. Compensation occurred during periods of nutritional restriction (winter) rather than during periods of rapid growth (summer) thus differing from the conventional view of compensatory growth.

Journal of Mammalogy↗

USGS2006

Simulating the influences of various fire regimes on caribou winter habitat

Caribou are an integral component of high‐latitude ecosystems and represent a major subsistence food source for many northern people. The availability and quality of winter habitat is critical to sustain these caribou populations. Caribou commonly use older spruce woodlands with adequate terrestrial lichen, a preferred winter forage, in the understory. Changes in climate and fire regime pose a significant threat to the long‐term sustainability of this important winter habitat. Computer simulations performed with a spatially explicit vegetation succession model (ALFRESCO) indicate that changes in the frequency and extent of fire in interior Alaska may substantially impact the abundance and quality of winter habitat for caribou. We modeled four different fire scenarios and tracked the frequency, extent, and spatial distribution of the simulated fires and associated changes to vegetation composition and distribution. Our results suggest that shorter fire frequencies (i.e., less time between recurring fires) on the winter range of the Nelchina caribou herd in eastern interior Alaska will result in large decreases of available winter habitat, relative to that currently available, in both the short and long term. A 30% shortening of the fire frequency resulted in a 3.5‐fold increase in the area burned annually and an associated 41% decrease in the amount of spruce–lichen forest found on the landscape. More importantly, simulations with more frequent fires produced a relatively immature forest age structure, compared to that which currently exists, with few stands older than 100 years. This age structure is at the lower limits of stand age classes preferred by caribou from the Nelchina herd. Projected changes in fire regime due to climate warming and/or additional prescribed burning could substantially alter the winter habitat of caribou in interior Alaska and lead to changes in winter range use and/or population dynamics.

Ecological Applications↗

USGS2006

Evaluation of aerial survey methods for Dall's sheep

Most Dall's sheep ( Ovis dalli dalli ) population-monitoring efforts use intensive aerial surveys with no attempt to estimate variance or adjust for potential sightability bias. We used radiocollared sheep to assess factors that could affect sightability of Dall's sheep in standard fixed-wing and helicopter surveys and to evaluate feasibility of methods that might account for sightability bias. Work was conducted in conjunction with annual aerial surveys of Dall's sheep in the western Baird Mountains, Alaska, USA, in 2000–2003. Overall sightability was relatively high compared with other aerial wildlife surveys, with 88% of the available, marked sheep detected in our fixed-wing surveys. Total counts from helicopter surveys were not consistently larger than counts from fixed-wing surveys of the same units, and detection probabilities did not differ for the 2 aircraft types. Our results suggest that total counts from helicopter surveys cannot be used to obtain reliable estimates of detection probabilities for fixed-wing surveys. Groups containing radiocollared sheep often changed in size and composition before they could be observed by a second crew in units that were double-surveyed. Double-observer methods that require determination of which groups were detected by each observer will be infeasible unless survey procedures can be modified so that groups remain more stable between observations. Mean group sizes increased during our study period, and our logistic regression sightability model indicated that detection probabilities increased with group size. Mark–resight estimates of annual population sizes were similar to sightability-model estimates, and confidence intervals overlapped broadly. We recommend the sightability-model approach as the most effective and feasible of the alternatives we considered for monitoring Dall's sheep populations.

Alaska↗

USGS2005

Evaluation of wolf density estimation from radiotelemetry data

Density estimation of wolves ( Canis lupus ) requires a count of individuals and an estimate of the area those individuals inhabit. With radiomarked wolves, the count is straightforward but estimation of the area is more difficult and often given inadequate attention. The population area, based on the mosaic of pack territories, is influenced by sampling intensity similar to the estimation of individual home ranges. If sampling intensity is low, population area will be underestimated and wolf density will be inflated. Using data from studies in Denali National Park and Preserve, Alaska, we investigated these relationships using Monte Carlo simulation to evaluate effects of radiolocation effort and number of marked packs on density estimation. As the number of adjoining pack home ranges increased, fewer relocations were necessary to define a given percentage of population area. We present recommendations for monitoring wolves via radiotelemetry.

Wildlife Society Bulletin↗

USGS2003

Winter habitat use by female caribou in relation to wildland fires in interior Alaska

The role of wildland fire in the winter habitat use of caribou ( Rangifer tarandus ) has long been debated. Fire has been viewed as detrimental to caribou because it destroys the slow-growing climax forage lichens that caribou utilize in winter. Other researchers argued that caribou were not reliant on lichens and that fire may be beneficial, even in the short term. We evaluated the distribution of caribou relative to recent fires (<50 years old) within the current winter range of the Nelchina caribou herd in east-central Alaska. To address issues concerning independence and spatial and temporal scales, we used both conventional very high frequency and global positioning system telemetry to estimate caribou use relative to recent, known-aged burns. In addition, we used two methods to estimate availability of different habitat classes. Caribou used recently burned areas much less than expected, regardless of methodologies used. Moreover, within burns, caribou were more likely to use habitat within 500 m of the burn perimeter than core areas. Methods for determining use and availability did not have large influences on our measures of habitat selectivity.

Canadian Journal of Zoology↗

USGS2003

Demography of Dall's sheep in northwestern Alaska

Dall’s sheep in northwestern Alaska declined in the early 1990s following the severe 1989-90 and 1990-91 winters. In the Baird Mountains of Noatak National Preserve, estimates of adult sheep declined by 50% from 800 in 1989 to under 400 in 1991. Population counts remained low throughout 1991 to 1996, reaching a minimum of 244 adult sheep in 1996. Few lambs were observed during annual midsummer aerial surveys in 1991 to 1994. We suspect that these declines resulted from a combination of poorer nutritional condition and increased vulnerability of sheep to predation resulting from severe winter conditions. As a result of these declines, both subsistence and sport hunting seasons were closed by emergency order in 1991, resulting in substantial management controversy. The affected publics, although willing to accept the closures, questioned the validity of the sheep survey data and strongly emphasized their interest in restoring harvests as soon as populations increased sufficiently. In 1995 the Northwest Arctic Regional Advisory Council, the local advisory committee for the Federal Subsistence Board, passed a motion supporting efforts to initiate research on sheep populations in the region to better understand the factors limiting sheep populations and to evaluate sheep survey methodologies. Currently estimates of Dall’s sheep population size and composition in the western Brooks Range are based on intensive fixed-wing aerial surveys conducted annually since 1986 in areas including the Baird Mountains. The annual variation in recent Baird Mountains aerial counts cannot be explained with reasonable assumptions about reproduction and survival, suggesting that there is some variability in the proportion of the population observed each year or that a substantial number of sheep move during the survey. Prior to our research, no attempt had been made to estimate visibility bias or precision for these surveys. Our understanding of Dall’s sheep population biology comes largely from studies in central or southern Alaska and the southern Yukon. However, sheep in northwestern Alaska are at the northwestern extreme of their range and live in a less hospitable environment characterized by short growing seasons and long, severe winters. We expect patterns of productivity and survival for sheep in Noatak National Preserve to differ from the more southerly populations. To adequately manage sheep harvests in northwestern Alaska, we need a better understanding of sheep demography. Along with unbiased population estimates, understanding the dynamics of sheep populations in the region will allow population models to be developed that can provide focus for a useful dialog on management goals and strategies and facilitate a cooperative strategy for managing sheep harvests in northwestern Alaska.

Alaska↗

USGS2001

Serologic survey for canine coronavirus in wolves from Alaska

Wolves ( Canis lupus ) were captured in three areas of Interior Alaska (USA). Four hundred twenty-five sera were tested for evidence of exposure to canine coronavirus by means of an indirect fluorescent antibody procedure. Serum antibody prevalence averaged 70% (167/240) during the spring collection period and 25% (46/185) during the autumn collection period. Prevalence was 0% (0/42) in the autumn pup cohort (age 4-5 mo), and 60% (58/97) in the spring pup cohort (age 9-10 mo). Prevalence was lowest in the Eastern Interior study area. A statistical model indicates that prevalence increased slightly each year in all three study areas. These results indicate that transmission occurs primarily during the winter months, antibody decay is quite rapid, and reexposure during the summer is rare.

Alaska↗