Southwest Yukon Research Articles

Maximum June–July temperatures in the southwest Yukon over the last 300 years reconstructed from tree rings

A network of seven high-elevation white spruce tree-ring chronologies from the southwest Yukon is used to reconstruct June–July maximum temperatures ( T max) back to 1684 AD, explaining 46.6% of the climatic variation over the 1946–1995 calibration period. The chronologies are characterised by low interannual ring-width variability and display similar patterns of ring-width variation across the sample area over the last 300 years. The driving force of this common signal appears to be a tree growth response to summer temperatures across the region. The reconstruction compares well with regional records of temperature variability derived from annual ring-width and maximum density data. Periods of cooler temperatures correspond with solar minima and glacier advances, particularly during the early 18th and the early 19th centuries. The maximum reconstructed temperatures are in the 1940s with 20th century values averaging 0.46 °C higher than the 1684–1899 period. In contrast to several regional studies, there does not appear to be a reduction in the sensitivity of tree growth to temperature at these sites during the late 20th century. Instead, a slight increase in the strength of the temperature–tree growth relationship is observed during recent decades. A possible explanation for this difference is the absence of significant summer season warming in the southwest Yukon region in comparison to other areas that have demonstrated this response change. This research is part of an ongoing project aimed at assessing the spatial and temporal potential of dendroclimatic reconstructions from the Yukon Territory.

Northern Archaic Tradition Forty Years Later: Comments

Forty years have passed since the existence of Northern Archaic (NAT), a cultural tradition in northwestern Alaska distinct from Arctic traditions such as Arctic Small Tool (AST) was proposed. The usefulness and even reality of NAT as originally conceived is revisited here to see if the concept continues to have merit or if it should be abandoned altogether. Originally, NAT was thought to represent an expansion of culture northward during middle Holocene times from the more temperate and sub-arctic regions of the continent into forest/tundra-edge habitats of northwestern North America. Although evidence for the tradition came from numerous sites in Alaska and the Southwest Yukon, the concept was fully developed from findings at Onion Portage. Although the sequence demonstrated a change over time from side-notched to lanceolate points, there was a total absence of a microblade industry throughout the entire 2,000 years. Recent findings of notched points associated with microblades in other northern Alaskan sites have demonstrated a far more complex prehistory in the region than originally thought. Discussion of the “notched point” problem stresses the idea that side-notching alone need not indicate a distinct cultural tradition.

Late Quaternary Pollen Records and Vegetation History of the Southwest Yukon Territory: A Review

This paper is a summary of all known late Quaternary palynostratigraphic records from the southwest Yukon Territory. Thirty two pollen sites available by the end of 1988 are reviewed. Most pollen records in the region are of Holocene age. During the late-glacial to early Holocene, the southwest Yukon supported a herb-dominated tundra vegetation which was replaced by a birch-dominated shrub-tundra at about 10,000 yr BP. Spruce invaded the area between 9000 and 8600 yr BP at different localities, and a southward time transgression is visible in the Aishihik Basin. The current regional vegetation has been stable since 7600-8000 yr BP when dense spruce forest and/or spruce forest-tundra was established in most localities. In the Snag area, however, dense spruce forest developed only around 5700 yr BP, which is about 2000 years later than in the Aishihik Basin. The exotic pine pollen records in the region exhibit an interesting pattern, suggesting a frequent shift of the atmospheric circulation system. Anomalous records of alder pollen from the Aishihik Basin and adjacent regions suggest that alder has never been widespread in these areas due to aridity, and alder pollen is greatly overrepresented in pollen spectra. Spruce arrival dates suggest that further investigations in the Tintina Valley, Yukon River Valley, and Car-macks region might provide useful information concerning the spruce migration routes.

Linking foraging behavior to population density: An assessment of GMM models for Dall sheep

We adapted Owen-Smith's general growth-metabolism-mortality (GMM) model to estimate the abundance of a population of Dall sheep ( Ovis dalli dalli) in the southwest Yukon, Canada. Estimated sheep densities using the GMM approach (18–32 sheep/km 2) approximated long-term aerial survey data (20.2–29.6 sheep/km 2) when biologically realistic levels of parameter variation were introduced. Sheep population growth rate based on the GMM model was most sensitive to the metabolic conversion of forage into sheep biomass, rate of vegetation attrition, and mortality rate during winter. Model estimates may be improved with better estimates of metabolic conversion of forage into sheep body mass, vegetation attrition, incorporation of inter-annual variability, and stratification by sex and age classes. Overall, GMM models using mechanistic physiological and behavioral information may provide a complimentary approach to aerial censuses for estimating ungulate population abundance.

Forest management in a changing climate: building the environmental information base for southwest Yukon

This paper provides an overview of a project that synthesized available information on climate change for the southwest Yukon. This was done as a first step in a longer-term process of evaluating climate impacts, assessing risks to ecosystem and community values, and developing scenarios for adaptation. The overall intent of the work was to support informed forest management decision-making for the Champagne-Aishihik Traditional Territory (CATT) in the light of climate change. The objectives of this stage of the project were to: compile and improve access to existing baseline information needed to support informed management decisions in the face of climate change; to make this information available using several communication tools for various target audiences; and to create an opportunity for scientists, government; and local residents to share observations and concerns on climate change as related to the management of forest resources within the study region. Key words: climate change, impacts, adaptation, sustainable forest management, southwest Yukon, Dendroctonus rufipennis, spruce bark beetle, Yukon Territory, champagne and Aishihik Traditional Territory

Life histories of female red squirrels and their contributions to population growth and lifetime fitness

The potential importance of life history traits to population growth rates has been well explored theoretically but has rarely been documented in wild mammals. In this study we used 18 consecutive years of data from a population of North American red squirrels (Tamiasciurus hudsonicus) in the southwest Yukon, Canada, to examine variation in female life history traits and their consequences for population growth rate. Red squirrels in this population experienced severe juvenile mortality, but survivorship beyond age 2 followed a Type I relationship where the annual survival probability decreased with age. Maximum lifespan was 8 y. Some females initiated breeding as yearlings, but most delayed first breeding until 2 y of age or in some cases even later. Annual reproduction generally involved the production of a single litter averaging 3.1 offspring (range: 1 to 7); however, some females attempted a second litter within a single breeding season, either following reproductive failure or, in rare circumstances, after a successful first breeding attempt. Life table characteristics for the 11 cohorts born between 1987 and 1997 indicated a population growth rate close to zero (r = 0.009). Elasticity analysis as well as individual population projection matrices and lifetime reproductive success data indicated that early survival and not age at first reproduction was most strongly associated with a female's contribution to population growth. Lifespan accounted for 83.9% of the variation in population growth rate and was positively correlated with age at first reproduction, such that females who bred as yearlings suffered decreased longevity. Collectively, these results emphasize the importance of female survival and not reproductive output to population growth and lifetime fitness in this system.

Crustal architecture of SW Yukon, northern Cordillera: Implications for crustal growth in a convergent margin orogen

A structural analysis of southwest Yukon based on mapping and the compilation of structural data is used to determine if convergent margin orogenesis has contributed to westward growth of North America. The crust of SW Yukon is tilted regionally to the ESE, exposing a >20 km section of crust. A down‐plunge profile is used to determine the geometry and evolution of the crust. Four lithotectonic packages are recognized. These are, from east to west, (1) the Triassic‐Jurassic Whitehorse Trough assemblage of arc and arc‐derived volcanic and sedimentary rocks, (2) the Devonian‐Mississippian continental Aishihik metamorphic assemblage, (3) the Jurassic‐Cretaceous metapelitic Kluane metamorphic assemblage, and (4) the Jurassic‐Cretaceous Dezadeash Group of arc‐marginal graywackes. The Early Jurassic Aishihik and Tertiary Coast plutonic suites are major synkinematic tabular intrusive complexes that facilitated crustal growth by subcretion of the Aishihik metamorphic assemblage beneath the Whitehorse Trough and the Kluane metamorphic assemblage and Dezadeash Group beneath Aishihik metamorphic assemblage and overlying strata, respectively. Early Jurassic crustal growth gave rise to a crust that became older and more radiogenic at depth; Tertiary growth gave rise to a crust that became younger and less radiogeneic at depth. Crustal growth by subcretion necessarily involved the removal of the lower crust and mantle of the upper plate. The lithotectonic assemblages and the tabular intrusive complexes along which they were assembled are identifiable in the seismic reflection data along Slave Northern Cordillera Lithosphere Evolution Project (SNORCLE) line 3 and are broadly imaged by a regional electromagnetic (EM) survey. The ACCRETE program to the south has documented a comparable and directly correlative crustal geometry across the Great Tonalite Sill. Our findings are inconsistent with crustal growth models of tectonic flakes being emplaced onto an autochthonous lower crust and mantle. Instead our findings support models (Lithoprobe Vancouver Island, and ACCRETE) of crustal growth at convergent margins as resulting from synmagmatic subcretion.

Variability, contingency and rapid change in recent subarctic alpine tree line dynamics

Summary 1 Boundaries between forest and tundra ecosystems, tree lines, are expected to advance in altitude and latitude in response to climate warming. However, varied responses to 20th century warming suggest that in addition to temperature, tree line dynamics are mediated by species-specific traits and environmental conditions at landscape and local scales. 2 We examined recent tree line dynamics at six topographically different, but climatically similar, sites in south-west Yukon, Canada. Dendroecological techniques were used to reconstruct changes in density of the dominant tree species, white spruce (Picea glauca), and to construct static age distributions of willow (Salix spp.), one of two dominant shrub genera. Data were analysed to identify periods and rates of establishment and mortality and to relate these to past climate. 3 Tree line elevation and stand density increased significantly during the early to mid 20th century. However, this change was not uniform across sites. Spruce advanced rapidly on south-facing slopes and tree line rose 65–85 m in elevation. Tree line did not advance on north-facing slopes, but stand density increased 40–65%. Differences observed between aspects were due primarily to the differential presence of permafrost. Additional variability among sites was related to slope and vegetation type. Results were less conclusive for willow, but evidence for an advance was found at two sites. 4 Increases in stand density were strongly correlated with summer temperatures. The period of rapid change coincided with a 30-year period of above average temperatures, beginning in 1920. The highest correlations were obtained using a forward average of 30–50 years, supporting the hypothesis that tree line dynamics are controlled more by conditions influencing recruitment than by establishment alone. 5 The changes observed at several sites are suggestive of a threshold response and challenge the notion that tree lines respond gradually to climate warming. Overall, the results provide further evidence to support the idea that the pattern and timing of change is contingent on local, landscape, and regional-scale factors, as well as species’ biology.

Do Glaciers Listen? Local Knowledge, Colonial Encounters, and Social Imagination

Do Glaciers Listen? Local Knowledge, Colonial Encounters, and Social Imagination JULIE CRUIKSHANK UNIVERSITY OF BRITISH COLUMBIA PRESS, VANCOUVER, BC, 2005 328 PP. $32.95 PAPERBACK REVIEWED BY REBECCA K. ZARGER This fascinating book weaves together a study of memory, oral history and transformations through a series of encounters between people and glaciers in the region where the Saint Elias Mountains and the Alsek River converge in the southwest Yukon Territory and Alaska. I recently selected Cruikshank's award winning book (winner of the 2006 Julian Steward Award, given by the American Anthropological Association's Anthropology and Environment section, a 2007 Clio Award from the Canadian Historical Association and the 2006 Victor Turner Prize in Ethnographic Writing, awarded by the Society for Humanistic Anthropology) for required reading in a graduate seminar in environmental anthropology. This review is framed within the discussion and critique that emerged from the seminar, with the aim of providing not just a synopsis of the intellectual and practical contributions of the book, but its pedagogical value as well. One compelling illustration of the impact of this book is the attention that has been paid to it across a variety of disciplines, including anthropology, sociology, history, and science and area studies. Clearly Cruikshank is speaking across chasms of inquiry as she writes about of glaciers' connections to human communities and oral traditions as local people, explorers and scientists negotiate meanings in a particular, out-of-the way cultural landscape. Another reason this book was chosen for the graduate seminar was the way the author engages with the topics of local (or traditional) environmental knowledge, environmental change, and social memory. Historical documents, carefully presented Tlingit and Athapaskan oral histories, 19th century explorer's accounts, and the current politics of conservation, identities and territories are analyzed with equal intensity. As the author links these lines of evidence together (in some chapters more seamlessly than others), bridges are created between types of inquiry, voices of local elders, the human-nature divide, and local and global histories. Do Glaciers Listen? is divided into three sections. Part one, Matters of Locality situates the reader in time and space (during the Little Ice Age) as well as within current theories of the nature of knowledge and its representations. The three chapters in the first section convey, through tales of the actions of both glaciers and humans in response to one another, the distinctions between narratives of Athapaskan/Tlingit elders and geophysical scientists. Extensive passages from stories of three women, including excerpts from thirteen different shared by Kitty Smith, Annie Ned and Angela Sidney, tell us of the dangers of falling through glaciers, traveling under glacier bridges, and the imaginative power of glaciers. The second section of the book is devoted to Practices of Exploration, where the author considers the ways scientific and territorial exploration shaped alternative narratives of the Saint Elias glaciers-stories that were told around the globe in addition to local communities. The diaries and journal accounts of La Perouse, Muir, and Glave, contextualized with local oral histories of the same events, provide the opportunity to examine what the author terms the epistemological consequences of such encounters. …

Responses of white spruce (Picea glauca) to experimental warming at a subarctic alpine treeline

AbstractFrom 2001 to 2004 we experimentally warmed 40 large, naturally established, white spruce [Picea glauca(Moench) Voss] seedlings at alpine treeline in southwest Yukon, Canada, using passive open‐top chambers (OTCs) distributed equally between opposing north and south‐facing slopes. Our goal was to test the hypothesis that an increase in temperature consistent with global climate warming would elicit a positive growth response. OTCs increased growing season air temperatures by 1.8°C and annual growing degree‐days by one‐third. In response, warmed seedlings grew significantly taller and had higher photosynthetic rates compared with control seedlings. On the south aspect, soil temperatures averaged 1.0°C warmer and the snow‐free period was nearly 1 month longer. These seedlings grew longer branches and wider annual rings than seedlings on the north aspect, but had reduced Photosystem‐II efficiency and experienced higher winter needle mortality. The presence of OTCs tended to reduce winter dieback over the course of the experiment. These results indicate that climate warming will enhance vertical growth rates of young conifers, with implications for future changes to the structure and elevation of treeline contingent upon exposure‐related differences. Our results suggest that the growth of seedlings on north‐facing slopes is limited by low soil temperature in the presence of permafrost, while growth on south‐facing slopes appears limited by winter desiccation and cold‐induced photoinhibition.

Cache Selection by Arctic Ground Squirrels Inhabiting Boreal-steppe Meadows of Southwest Yukon Territory, Canada

ABSTRACTWe examined food items cached by arctic ground squirrels (Spermophilus parryii) from boreal-steppe meadows of southwest Yukon Territory, Canada. Caches recovered from two sites are dominated by fruits and seeds of either northern comandra (Geocaulon lividum) or prickly rose (Rosa acicularis). These two taxa are relatively rare in the local flora at the study sites (Site 1: ≥32 available taxa, and Site 2: ≥39 available taxa), suggesting they are selectively cached as preferred items. Cache selectivity may be related to perishability, fruit size/seed abundance, and predation risk. These caches are of significantly different composition than caches from present tundra sites and Pleistocene fossil arctic ground squirrel nests and caches (middens) recovered from central Yukon. These findings suggest that although arctic ground squirrels evolved in open tundra, they can subsist on a variety of cache items and may have the ability to adapt to and select a profitable cache within a variety of boreal and tundra habitats.

Late Holocene moisture balance variability in the southwest Yukon Territory, Canada

Analyses of sediment cores from Marcella Lake, a small, hydrologically closed lake in the semi-arid southwest Yukon, provides effective moisture information for the last ∼4500 years at century-scale resolution. Water chemistry and oxygen isotope analyses from lakes and precipitation in the region indicate that Marcella Lake is currently enriched in 18O by summer evaporation. Past lake water values are inferred from oxygen isotope analyses of sedimentary endogenic carbonate in the form of algal Charophyte stem encrustations. A record of the δ 18O composition of mean annual precipitation at Jellybean Lake, a nearby evaporation-insensitive system, provides data of simultaneous δ 18O variations related to decade-to-century scale shifts in Aleutian Low intensity/position. The difference between the two isotope records, Δδ, represents 18O-enrichment in Marcella Lake water caused by summer effective moisture conditions. Results indicate increased effective moisture between ∼3000 and 1200 cal BP and two marked shifts toward increased aridity at ∼1200 and between 300 and 200 cal BP. These prominent late Holocene changes in effective moisture occurred simultaneously with changes in Aleutian Low circulation patterns over the Gulf of Alaska indicated by Jellybean Lake. The reconstructed climate patterns are consistent with the topographically controlled climatic heterogeneity observed in the coastal mountains and interior valleys of the region today.

Glacier-mediated streamflow teleconnections to the Arctic Oscillation

We investigated the potential for glacier- and snowmelt-fed rivers to respond differently to the Arctic Oscillation (AO) by applying nonparametric statistical techniques to standardized and deseasonalized monthly hydrometric data from eight watersheds in southwest Yukon and northwest British Columbia, Canada. We first extracted regionally coherent glacial and nival hydroclimatic signals from the station data using empirical orthogonal function analysis. The annually averaged glacial and nival principal component time series were mutually uncorrelated, suggesting a decoupling of interannual streamflow variability between the two fluvial regimes. Moreover, glacial and nival rivers showed selective teleconnectivity to the AO; the annual glacial signal was significantly positively correlated to the AO index, whereas the nival signal was not. Composite analyses of annual hydrographs, performed using data from individual hydrometric stations, were consistent with the EOF-correlation results and provided details of related changes in hydrologic seasonality. In particular, positive-phase AO events are associated with positive glacial streamflow anomalies in late spring and early summer and an earlier freshet in nival rivers with little or no net change in annual flow. Parallel composite analyses of locally available homogeneous temperature and precipitation station data suggested that the hydrologic behaviour largely arises from the combination of AO-related late spring to early summer temperature anomalies and the presence or absence of a glacial reservoir potentially available for melting. Synoptic-scale correlation mapping of sea-level pressure fields reinforced these inferences. The results provide significant additional evidence that watershed glacierization can control the fundamental nature and patterns of regional-scale spatiotemporal water resource variability resulting from low-frequency climatic forcing. Copyright © 2005 Royal Meteorological Society.

Palaeohydrology of the Southwest Yukon Territory, Canada, based on multiproxy analyses of lake sediment cores from a depth transect

Lake-level variations at Marcella Lake, a small, hydrologically closed lake in the southwestern Yukon Territory, document changes in effective moisture since the early Holocene. Former water levels, driven by regional palaeohydrology, were reconstructed by multiproxy analyses of sediment cores from four sites spanning shallow to deep water. Marcella Lake today is thermally stratified, being protected from wind by its position in a depression. It is alkaline and undergoes bio-induced calcification. Relative accumulations of calcium carbonate and organic matter at the sediment-water interface depend on the location of the depositional site relative to the thermocline. We relate lake-level fluctuations to down-core stratigraphic variations in composition, geochemistry, sedimentary structures and to the occurrence of unconformities in four cores based on observations of modern limnology and sedimentation processes. Twenty-four AMS radiocarbon dates on macrofossils and pollen provide the lake-level chronology. Prior to 10 000 cal. BP water levels were low, but then they rose to 3 to 4 m below modern levels. Between 7500 and 5000 cal. BP water levels were 5 to 6 m below modern but rose by 4000 cal. BP. Between 4000 and 2000 cal. BP they were higher than modern. During the last 2000 years, water levels were either near or 1 to 2 m below modern levels. Marcella Lake water-level fluctuations correspond with previously documented palaeoenvironmental and palaeoclimatic changes and provide new, independent effective moisture information. The improved geochronology and quantitative water-level estimates are a framework for more detailed studies in the southwest Yukon.

Hunters and Bureaucrats: Power, Knowledge, and Aboriginal-State Relations in the Southwest Yukon

Book Review| October 01 2005 Hunters and Bureaucrats: Power, Knowledge, and Aboriginal-State Relations in the Southwest Yukon By Paul Nadasdy. (Vancouver: University of British Columbia Press, 2003. 312 pp., illustrations, notes, references, index. $85.00 cloth, $29.95 paper.) Shepard Krech, III Shepard Krech, III Brown University Search for other works by this author on: This Site Google Ethnohistory (2005) 52 (4): 789–790. https://doi.org/10.1215/00141801-52-4-789 Cite Icon Cite Share Icon Share Twitter Permissions Search Site Citation Shepard Krech; Hunters and Bureaucrats: Power, Knowledge, and Aboriginal-State Relations in the Southwest Yukon. Ethnohistory 1 October 2005; 52 (4): 789–790. doi: https://doi.org/10.1215/00141801-52-4-789 Download citation file: Zotero Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search Books & JournalsAll JournalsEthnohistory Search Advanced Search The text of this article is only available as a PDF. 2005 Article PDF first page preview Close Modal Issue Section: Book Reviews You do not currently have access to this content.

Quantitative analysis of freshwater ostracode assemblages in southwestern Yukon Territory, Canada

Relations between modern ostracode assemblages and environmental variables from lakes in the southwest Yukon and northern British Columbia were explored. A total of 29 freshwater species representing 8 genera were identified from the sediments of 36 lakes, with the number of species ranging between 3 and 8 per lake. Species widespread throughout the study area include Cyclocypris ampla, Candona candida, Cypria turneri, Cypria ophtalmica, and Candona protzi. The Mg/Ca ratio is an important factor determining the ostracode species composition of a lake. Species richness is at a maximum when the lake water has intermediate values of conductivity. Lakes in which one species clearly dominates the assemblage (‰>‰70% relative abundance) have water saturated with respect to CaCO3. Mg/Ca ratio, depth and Sr are the environmental factors that are most highly correlated with species distributions in this region.

Hunters and Bureaucrats: Power, Knowledge, and Aboriginal-State Relations in the Southwest Yukon

Hunters and Bureaucrats: Power, Knowledge, and Aboriginal-State Relations in the Southwest Yukon

Modern Chironomid Assemblages and Their Relationship to Physical and Chemical Variables in Southwest Yukon and Northern British Columbia Lakes

Modern chironomid assemblages consisting of 68 taxa were extracted from the sediments of 39 lakes in southwest Yukon and northern British Columbia, Canada. Important factors accounting for the distribution of the chironomid taxa include sediment organic matter (LOI; weight-loss-on-ignition), total phosphorus, bottom water temperature, and lake alkalinity. The results show the importance of organic matter, which is associated with water depth and lake productivity, in affecting chironomid community composition. Tanytarsus sp. C, Tanytarsus pallidicornis type, Allo/Mesopsectrocladius, Polypedilum, and Procladius were associated with lakes having high LOI values and shallow lake depths, while Paratanytarsus, Sergentia, and Corynocera oliveri type were more prevalent in deeper lakes with more minerogenic sediments. Surprisingly, Chironomus was most abundant in deeper lakes with low LOI values, which might be partially explained by low oxygen levels. Contrary to some findings, Tanytarsus lugens group was common in shallow, productive lakes in this region.

Hunters and bureaucrats: power, knowledge, and aboriginal-state relations in the southwest Yukon

Illustrations Acknowledgments Introduction 1. Aboriginal-State Relations in Kluane Country: An Overview 2. Not Really 'Knowledge' at All, It's More a Way of Life 3. The Politics of TEK: Power and the Integration of Knowledge 4. Counting Sheep: The Ruby Range Sheep Steering Committee and the Construction of Knowledge 5. Knowledge-Integration in Practice: The Case of the Ruby Range Sheep Steering Committee 6. Just Like Whitemen: Property and Land Claims in Kluane Country Conclusion Notes References Index

Interannual Variation in Timing of Parturition and Growth of Collared Pikas (Ochotona collaris) in the Southwest Yukon

The length of the snow-free season has a significant influence on reproduction and growth in northern alpine environments, and these life history traits may provide sensitive indicators of the responses of organisms to climate change. We examined growth rates and timing of parturition of collared pikas (Ochotona collaris) from 1995-2002 in the Ruby Range, Yukon Territory, Canada. Growth rates were best described using a Gompertz model, in which the asymptotic mass, determined from the average male and female weights, was 157 g, the growth rate constant (K) was 0.0557, and the age at inflection (I) was 18.12 days, for a birth weight of 10 g. The maximum growth rate for North American pikas (O. collaris and O. princeps) increased with latitude, with maximum growth rates being approximately one-third greater in northern populations where the snow-free season is less than three months long. The mean parturition date varied significantly among years from 3 June to 3 July, and delayed parturition was correlated with indices of high snow accumulation and, to a lesser extent, late spring snowmelt. However, parturition date did not significantly affect the subsequent over-winter survival of juveniles in this population, suggesting that pikas are able to adjust to seasonal uncertainty associated with highly variable spring conditions.