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Collared Pika (Ochotona collaris) is a cold-adapted Beringian species that occurs on talus slopes and is sensitive to climate warming. Collared Pikas are patchily distributed throughout the sub-Arctic mountains of northwestern Canada and Alaska; however, information on their occurrence in the northern part of their distributional range is limited. In particular, no survey information is known from the southern Richardson Mountains and the Nahoni Mountains. We conducted aerial- and ground-based surveys to document Collared Pika occurrence and general habitat suitability in northern Yukon. We flew 505 km of aerial survey (not including ferrying to targetted survey areas) and performed ground surveys at 22 sites within the Richardson Mountains (including a portion of Dàadzàii Vàn Territorial Park) and the Nahoni Mountains in and adjacent to Ni’iinlii Njik (Fishing Branch) Territorial Park. Overall, suitable habitat for Collared Pikas was patchy in the mountains of northern Yukon—talus was sparse and many patches of talus appeared to be unsuitable. Collared Pikas were detected at eight of 22 (36%) sites visited, representing important new records for the species in the northern portion of their range. Our reconnaissance provides a first approximation of habitat suitability for Collared Pikas of the mountains of northern Yukon, as well as new records for the species in the region. These data are useful in better determining the contemporary distribution of Collared Pika through species distribution modelling, and may serve to identify areas for more detailed survey and monitoring initiatives for this climate-sensitive mammal.

18. Collared Pika Ochotona collaris French: Pika a collier / German: Alaska-Pfeifhase / Spanish: Pica de collar Taxonomy. Lagomys collaris Nelson, 1893, “about 200 miles south of Fort Yukon, Alaska, near the head of the Tanana River,” USA. According to mtDNA, O. collaris belongs to subgenus Pika. It was previously included in O. princeps but was elevated to a full species based on differences in morphology, chromosomes, and, later, genetic markers. Although both species are sister taxa, genetic distance between them is quite substantial. Distribution of O. collaris and O. princeps is separated by wide gap corresponding to bigger part of Coast Mountains, in the Pacific Coast Ranges, of wstern North America. Monotypic. Distribution. SE Alaska and NW Canada (Yukon, Northwest Territories, NW British Columbia) Mts W of Mackenzie River and S to ¢.59° N. Descriptive notes. Head-body 170-190 mm, ear 17-25 mm, hindfoot 26-30 mm; weight 117-200 g. The Collared Pika is medium-sized. Dorsal fur is dull grayish brown, with light gray collar. Ventral fur is creamy white. Winterfuris longer, softer, and grayer than during other seasons. Hairs above neck gland are creamy buff. Ears are rounded, with white margins. Skull is medium-sized and stout, with incisive and palatal foramens separated. Auditory bullae are medium-sized. Condylobasal lengths are 39-43 mm, skull widths are 21-23 mm, and skull heights are 15-16 mm. Relative to the American Pika (O. princeps), the Collared Pika lacks buffy tint on belly and has light gray collar. Habitat. Talus and stone fields at elevations of 500-2000 m. Collared Pikas avoid barren stone fields without vegetation. Main stony habitats of Collared Pikas occur in meadows or tundra above timberline. The Collared Pika is a typical rock dweller. Food and Feeding. The Collared Pika feeds on green plants and stores hay in piles. It hoards most common plants in its home area but has some preferences. Hay hoarding starts in late June or early July. Mean mass of hay pile is 3-1 kg. Hay piles are usually situated under large stones or in stone crevices. Breeding. Parturition of the Collared Pika occurs from late April to late July, with the greatest number of neonates born in June. Adult Collared Pikas can breed twice per year, but success of a second breeding is unknown. Young females become fertile after c.l year of age. Each female has 1-4 embryos. Gestation is ¢.30 days; neonates are nearly hairless and born with their eyes closed. Activity patterns. The Collared Pika is diurnal and most active in morning and late afternoon. While hay hoarding, activity can be around the clock but decreases at night. Movements, Home range and Social organization. Collared Pikas move aboveground by running and leaping openly. Visible activity includes resting on rocks and feeding or hoarding. Home ranges are 700-1960 m?. Densities typically are 13-250 ind/km?, but H. E. Broadbooks in 1965 had higher estimates of 640-720 ind/km?, depending on year and habitat. Collared Pikas are vocal animals; and one type of call is known to have an individual specific pattern. Status and Conservation. Classified as Least Concern on The IUCN Red List. Bibliography. Broadbooks (1965), Franken & Hik (2004), Lanier & Olson (2009, 2013), MacDonald & Jones (1987), Morrison & Hik (2007), Morrison et al. (2009), Trefry & Hik (2010)., Published as part of Don E. Wilson, Thomas E. Lacher, Jr & Russell A. Mittermeier, 2016, Ochotonidae, pp. 28-43 in Handbook of the Mammals of the World – Volume 6 Lagomorphs and Rodents I, Barcelona :Lynx Edicions on page 39, DOI: 10.5281/zenodo.6619785

Traditional concepts of the Bering Land Bridge as a zone of predominantly eastward expansion from Eurasia and a staging area for subsequent colonization of lower latitudes in North America led to early inferences regarding biogeographic histories of North American faunas, many of which remain untested. Here we apply a host–parasite comparative phylogeographical (HPCP) approach to evaluate one such history, by testing competing biogeographic hypotheses for five lineages of host-specific parasites shared by the collared pika (Ochotona collaris) and American pika (Ochotona princeps) of North America. We determine whether the southern host species (O. princeps) was descended from a northern ancestor or vice versa. Three parasite phylogenies revealed patterns consistent with the hypothesis of a southern origin, which is corroborated by four additional parasite lineages restricted toO. princeps. This finding reverses the traditional narrative for the origins of North American pikas and highlights the role of dispersal from temperate North America into Beringia in structuring northern diversity considerably prior to the Holocene. By evaluating multiple parasite lineages simultaneously, the study demonstrates the power of HPCP for resolving complex biogeographic histories that are not revealed by characteristics of the host alone.

Historically, a large number of taxonomic forms has been recognized within Nearctic pikas (Lagomorpha: Ochotonidae; Ochotona), including up to 13 species and 37 subspecies. After 1965, 2 species and 37 forms have been recognized: the monotypic O. collaris of Alaska, British Columbia, Yukon, and Northwest Territories, and O. princeps, with 36 subspecies spread throughout western Canada and the western United States. The 36 subspecies of O. princeps have been distinguished by subtle differences, particularly in pelage coloration and body size, within the highly fragmented distribution of the species on isolated “islands” of cool, rocky habitat. However, molecular phylogenetic studies (allozyme electrophoresis and sequencing of both mitochondrial and nuclear genomes) indicate the existence of 5 phylogenetic lineages within O. princeps. The cohesiveness of each lineage has been reinforced during glacial stages by introgressive hybridization among currently isolated populations within each lineage. In...

Understanding geographic call variation can resolve evolutionary and behavioural questions, yet the factors influencing divergent acoustic signals remain poorly understood in mammals. We explored call variation between collared pikas in Yukon and Alaska and American pikas in Alberta, and between individuals within a population of collared pikas. Classification trees were used to determine the extent of call divergence between populations and the elements of calls driving these differences. Pika populations had significant differences in call structure, and individual pikas were classified to their correct populations with up to 94% accuracy. To investigate possible mechanisms responsible for interspecific variability, we tested the acoustic adaptation hypothesis by using a playback experiment to explore whether American and collared pika calls transmit with less degradation across their own species' habitat than the habitat of their congener. We found no support for the acoustic adaptation hypothesis. Geographic call variation in these two species of pikas likely reflects genetic divergence, and may be a result of separate evolutionary histories. We calculated the potential for individual coding for both time and frequency measurements of calls. High frequency harmonics showed greater between- than within-individual variation, and may act as sources of information regarding individual identity.

We examined the influence of leaf size on forage selection by collared pikas (Ochotona collaris) living in alpine meadows in the Yukon Territory, Canada, by comparing the winter diets of individually recognized pikas to the available vegetation within their territories and by conducting cafeteria-style preference experiments. Pikas consistently preferred forage with larger leaves in the cafeteria trials. They also collected larger leaves from deciduous shrubs and graminoid species compared to other plant types such as lichens and evergreen shrubs for their winter diets. Pikas assessed differences in leaf size when selecting their winter diets and this appears to be an energetically efficient foraging strategy for surviving seasonal food scarcity.

Eighty-eight fecal samples from 2 species of pika, Ochotona collaris and Ochotona hyperborea, collected in Alaska (N = 53) and Russia (N = 35), respectively, were examined for the presence of coccidia (Apicomplexa: Eimeriidae). Five oocyst morphotypes were observed. In O. collaris, we found Eitmeria calentinei, Eimeria cryptobarretti, and Eimeria klondikensis, whereas in O. hyperborea, we found Eimeria banffensis, E. calentinei, E. cryptobarretti, E. klondikensis, and Isospora marquardti. This study represents new geographic records for all 5 coccidia and new host records for E. cryptobarretti and I. marquardti. Only minor quantitative differences were seen between the sporulated oocysts we studied and those reported in their original descriptions.

1. Demographic analysis is essential in order to determine which factors, such as survival, fertility and other life-history characteristics, have the greatest influence on a population's rate of growth (lambda). 2. We used life-table response experiments (LTREs) to assess the relative importance of survival and fertility rates for an alpine lagomorph, the collared pika Ochotona collaris, using 12 years (1995-2006) of census data. The LTRE analysis was repeated for each of three subpopulations within the main study site that were defined by aspect (east, west and south). 3. Across the entire study site, the survival and fertility of adults contributed 35.6 and 43.5%, respectively, to the variance observed in the projected population growth rate, V(lambda), whereas juvenile survival contributed 20.9%. Adult survival and fertility contributed approximately equal amounts for each subpopulation when considered separately, although their rank order varied spatially. 4. Adult survival across the entire site was positively correlated to the Pacific Decadal Oscillation (PDO) with a time lag of 1 year, and was uncorrelated to adult density. The PDO was negatively correlated to the timing of spring snowmelt at our site, implicating the importance of earlier spring conditions and plant phenology on the subsequent winter survival of adults and therefore, population growth. 5. When subpopulations were analysed separately, survivals and fertilities were variously correlated to lagged PDO and adult densities, but the patterns varied spatially. Therefore, the mechanisms underlying V(lambda) can vary substantially over relatively short distances.

We conducted exploratory analyses to examine the relative roles played by natural and anthropogenic influences on persistence of a montane mammal. We revisited historical locations of pikas (Ochotona princeps) within the hydrographic Great Basin during summers of 1994–1999. Seven of 25 populations (28%) reported earlier in the 20th century appeared to have experienced recent extirpations. We assessed causative agents of faunal change using several alternative, but not mutually exclusive, hypotheses. Higher probability of persistence was correlated with greater area of talus habitat at local and mountain-range scales, higher elevation, more easterly longitude, more southern latitude, lack of livestock grazing, greater distance to primary roads, and wilderness management. However, only area of habitat in the mountain range, maximum elevation of talus habitat, and distance to primary roads appeared in the most parsimonious model of persistence when we used Akaike's information criterion model-select...

Summary 1 We measured leaf births, leaf deaths and leaf length of three alpine perennial species, Kobresia myosuroides, Erigeron humilis and Oxytropis nigrescens, from sites with different grazing histories (strong or weak) in response to two levels of current season grazing (present or absent) by collared pikas (Ochotona collaris), a small lagomorph, in the south-west Yukon. 2 All three species appeared to tolerate the removal of 58–61% of summer leaf production under natural conditions. Grazing history, which was defined by the location of plants located either 6 m from boulderfields with a history of occupation by pikas, was the most significant factor determining shifts in leaf births and leaf deaths following herbivory. 3 The only detectable influence of current season herbivory for any measured species was a reduction of leaf length of Kobresia. 4 A comparison of historically grazed with historically ungrazed plants indicated several changes in leaf demography and morphology. Kobresia leaves were generally shorter and had higher rates of production of new leaves. Oxytropis had higher rates of new leaf production. Erigeron had fewer leaf births throughout the summer, but showed a large and highly significant delay in the timing of leaf senescence. 5 These responses can be largely understood as strategies to avoid the predictable intensive late season foraging that is characteristic of pikas. Morphological mechanisms allow these species to tolerate and, more importantly for the herbivore, persist under heavy and chronic grazing.

Identifying the genetic structure of a species and the factors that drive it is an important first step in modern population management, in part because populations evolving from separate ancestral sources may possess potentially different characteristics. This is especially true for climate-sensitive species such as pikas, where the delimitation of distinct genetic units and the characterization of population responses to contemporary and historical environmental pressures are of particular interest. We combined a restriction site-associated DNA sequencing (RADSeq) data set containing 4156 single nucleotide polymorphisms with ecological niche models (ENMs) of present and past habitat suitability to characterize population composition and evaluate the effects of historical range shifts, contemporary climates and landscape factors on gene flow in Collared Pikas, which are found in Alaska and adjacent regions of northwestern Canada and are the lesser-studied of North America's two pika species. The results suggest that contemporary environmental factors contribute little to current population connectivity. Instead, genetic diversity is strongly shaped by the presence of three ancestral lineages isolated during the Pleistocene (~148 and 52 kya). Based on ENMs and genetic data, populations originating from a northern refugium experienced longer-term stability, whereas both southern lineages underwent population expansion – contradicting the southern stability and northern expansion patterns seen in many other taxa. Current populations are comparable with respect to generally low diversity within populations and little-to-no recent admixture. The predominance of divergent histories structuring populations implies that if we are to understand and manage pika populations, we must specifically assess and accurately account for the forces underlying genetic similarity.

[EN] Interactions among herbivores can shape the structure of their communities and drive their dynamics. However, detecting herbivore interactions can be challenging when they are deferred in space or time. Moreover, interactions among distantly related groups of herbivores, such as vertebrates and invertebrates, are poorly understood. We investigated the effect of invertebrate herbivory on the subsequent foraging choices of a small alpine-dwelling vertebrate, the collared pika (Ochotona collaris). We carried out a field experiment within pika territories, by presenting them with a choice of foraging sites following manipulation of invertebrate (caterpillar) herbivory. Pikas actively selected areas with increased, recent invertebrate herbivory. While the underlying mechanisms behind this interaction remain unknown, our results demonstrate a positive effect of invertebrate herbivores on subsequent vertebrate foraging preferences for the first time. Even among distantly related taxa, such interactions where one herbivore is cueing on the foraging of another, could drive the creation of herbivory hotspots, with cascading consequences for ecosystem processes. © 2013 The Author(s) Published by the Royal Society.

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.

THE FORAGING DECISIONS MADE BY HERBIVORES influence population dynamics through their effects on energy gain, energy expenditure, and ultimately, survival (McNamara and Houston, 1997). In turn, foraging by herbivores may influence the amount of vegetation available for the future. Therefore, herbivores and vegetation often are coupled in a strong reciprocal relationship: the abundance of one affects the abundance of the other through time (e.g., Caughley, 1976). This interaction is particularly important for herbivores living in seasonal environments where food abundance and quality vary dramatically between growing and winter seasons. Herbivores must adapt their foraging behaviour to contend with these changes and survive until the following growing season (Owen-Smith, 2002). In addition to seasonal effects, daily foraging decisions are constrained by a number of other factors, which may be classified as either internal (such as energetic or nutritional needs), or external (such as predation risk or interspecific interactions). These constraints limit the availability of food items to the herbivore and explain why most species exhibit some degree of diet selectivity. Most species, therefore, must balance trade-offs associated with these constraints such as obtaining enough food while minimizing predation risk (Lima and Dill, 1990), or decisions about selecting species with differing degrees of nutritional value (Stephens and Krebs, 1986). I am using a combination of descriptive and experimental methodologies, combined with modelling techniques, to increase our understanding of plant-herbivore interactions and their influence on herbivore population dynamics, using the collared pika (Ochotona collaris) as a model species. Pikas are small (~160 g) lagomorphs that live in alpine talus slopes. Pikas are asocial and each individual collects vegetation for two distinct diets: a summer diet that is consumed immediately, and a winter diet that is stored in haypiles under boulders (Millar and Zwickel, 1972; Conner, 1983). Because of predation risk, pikas rarely venture more than 10 m from talus into meadows to collect vegetation (Holmes, 1991), and this behaviour creates a strong gradient of grazing pressure, with most foraging activity occurring within 3 m of talus (Huntly, 1987; McIntire and Hik, 2005). Insatiable hoarders of vegetation (McKechnie et al., 1994), pikas provide an opportunity to test experimentally hypotheses regarding diet selection as a function of various constraints. Since 1995, most individuals (> 95%) within the study area have been captured, weighed, sexed, and marked with uniquely coloured ear tags. This detailed, long-term demographic dataset will provide context for this study and a means of validating population models. The objectives for this project are 1) to determine how collared pikas make foraging decisions with respect to predation risk and forage quality, 2) to incorporate these constraints into a plant-herbivore modelling approach to determine their effects on population dynamics, and 3) to compare the plant-herbivore model to spatial demographic models of population dynamics.

Permanent and well-supported museum or natural history collections provide a solid foundation for the process of systematics research through creation of an empirical record which validates our understanding of the biosphere. We explore the role of museums in ongoing studies of the complex helminth fauna characteristic of pikas (Ochotona spp.) in the American west. These studies address the taxonomy for pinworms of the Labiostomatinae and the problems associated with the absence of adequate type series and vouchers and with misidentifications in original descriptions. We demonstrate that the types for Labiostomum (Labiostomum) coloradensis are identical to some specimens in the syntype series representing L. (Eugenuris) utahensis, although the published descriptions are in disagreement. Both are identical to L. (Eugenuris) talkeetnaeuris and, as a consequence, are reduced as junior synonyms. Only 2 species of large pinworms, namely L. (Labiostomum) rauschi and L. (Eugenuris) talkeetnaeuris, are widely distributed in Ochotona collaris and O. princeps. Although this serves to clarify the taxonomy for species in these genera, prior records remain confused, as representative voucher specimens from all major surveys in North America were never submitted to museum collections. We strongly suggest that type and voucher series should not be held in private or personal collections, where such are eventually lost, discarded, or destroyed through neglect due to inattention and the absence of curation. The potential to accumulate meaningful baselines for assessment of environmental change is jeopardized if materials from survey and inventory are not routinely submitted to museum collections. The capacity of museum repositories, as a focus for systematics, ecology, and evolutionary studies and for the development of resources for biodiversity informatics, continues to be undervalued and poorly utilized by a cadre of scientists who are dependant on accurate and definitive information that transcends specific disciplines.

Food hoarding is a behavioral adaptation of some herbivores to manage food availability through time and space. In strongly seasonal environments, where summer growing seasons are short relative to winter, an earlier start to hoarding should increase the amount of vegetation stored for winter and improve subsequent sur- vival. We examined hoarding behavior ('haying') and its impact on survival for a small alpine lagomorph, the col- lared pika (Ochotona collaris) in Yukon, Canada. We used a combination of video surveillance, haypile measure- ments, and survival data from marked individuals of known age and sex. Annual haypile initiation was strongly influ- enced by age and year. Adult pikas began haying an average of 16 days earlier in 2004 relative to 2005, whereas young of the year (juveniles) did not vary in the timing of haypile initiation. The mean haying rate per hour increased monthly from 3.7 ± 0.7 trips in June to 6.6 ± 0.8 trips in August. Simulation analysis estimated the median haypile mass (dry weight) by mid-September to be 5.5 kg. At least 75% of simulated haypiles had a min- imum of 90 days (3 months) of food reserves, and 50% of simulated haypiles had a minimum of 177 days (5.9 months) of food reserves by mid-September, sup- porting the hypothesis that haypiles serve as the primary source of food during winter. Survival was greatest for pikas in 2005 when they began haying prior to 31 July, but the benefits of earlier accumulation of vegetation on sur- vival also varied between years. The implications of earlier spring snowmelt are discussed with respect to pika foraging and overwinter survival.

We studied an alpine herbivory gradient established by collared pikas, a small central place foraging lagomorph, to examine the effects of multiple grazing levels on above-ground live biomass (AGB) and species richness (SR) in alpine tundra. The effects of within-season (four sampling periods), multi-season (across three summers) and longer-term dynamics (inferred from spatial location of vegetation with respect to pika haypiles) were examined. Along the grazing gradient, we found support for and against hypotheses that propose biphasic, increasing, or decreasing responses to herbivory, both in terms of AGB and SR. Our results suggest that plant-herbivore predictability is still weak. To further examine the impact of herbivory, we experimentally removed pikas using mesh exclosures placed at increasing distance from the edge of talus occupied by pikas. AGB after the second consecutive year of herbivore exclusion increased by 125% compared to control plots in highly grazed areas adjacent to talus (1 m). In more lightly grazed sites at distances 1-6 m from talus, AGB increased by more than 40% after pikas were removed. No differences were observed in the ungrazed sites6 m from talus. AGB was highest in meadow patches previously grazed by pikas compared to those with little grazing history, but this response was only observed after two seasons following release from herbivory. Grazed sites at distances of 1-6 m had the highest SR. These results indicate that multi-year measurements of growth are particularly relevant in ecosystems dominated by long-lived perennials in regions where productivity is low. Infrequent herbivore vacancies may provide local short-term release from pika grazing, thereby contributing to the persistence of productive, highly palatable vegetation.

Ochotona collaris (Nelson, 1893). Proc. Biol. Soc. Washington, 8:117. TYPE LOCALITY: "about 200 miles south of Fort Yukon, Alaska near the head of the Tanana River." [USA]. DISTRIBUTION: WC Mackenzie, S Yukon, NW British Columbia (Canada); SE Alaska (USA). STATUS: Not significantly threatened (MacDonald and Jones, 1987). SYNONYMS: Monotypic. COMMENTS: Broadbooks (1965) and Youngman (1975) considered collaris and princeps conspecific. Corbet (1978c), following Argyropulo (1948) and Gureev (1964), included collaris in alpina. A statistical réévaluation of craniometric data by Weston (1981) indicated that collaris, princeps and alpina are separate species; Hall (1981:286) also recognized collaris as a distinct species. O. collaris and O. princeps share similar chromosome numbers that differ sharply from those of alpina and hyperborea (Vorontsov and Ivanitskaya, 1973). Reviewed by MacDonald and Jones (1987, Mammalian Species, 281)., Published as part of Robert S. Hoffmann, 1993, Order Lagomorpha, pp. 807-827 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 808, DOI: 10.5281/zenodo.7353088, {"references":["MacDonald, S. O., and C. Jones. 1987. Ochotona collaris. Mammalian Species, 281: 1 - 4.","Broadbooks, H. E. 1965. Ecology and distribution of the pikas of Washington and Alaska. American Midland Naturalist, 73: 299 - 335.","Youngman, P. M. 1975. Mammals of the Yukon Territory. National Museum of Natural Sciences (Ottawa), Publications in Zoology, 10: 1 - 192.","Corbet, G. B. 1978 c. The mammals of the Palaearctic region: A taxonomic review. British Museum (Natural History), London, 314 pp.","Argyropulo, A. I. 1948. Obzor retsentnykh vidov cem. Lagomyidae Lilljeb., 1886 (Lagomorpha, Mammalia) [A review of Recent species of the family ...]. Trudy Zoologicheskovo Instituta, Akademiya Nauk, Leningrad, 7: 124 - 128 (in Russian).","Gureev, A. A. 1964. Fauna SSSR, Mlekopitayushchie, tom. 3, vyp. 10, Zaitseobraznye (Lagomorpha) [Fauna of the USSR, mammals, vol. 3, pt. 10, Lagomorpha]. Nauka, Moscow-Leningrad, 276 pp. (in Russian).","Weston, M. L. 1981. The Ochotona alpina complex: A statistical re-evaluation. Pp. 73 - 89, in Proceedings of the world lagomorph conference (K. K. Myers and C. D. MacInnes, eds.). Guelph University Press, Guelph, Ontario, 983 pp.","Hall, E. R. 1981. The mammals of North America. Second ed. John Wiley and Sons, New York, 1: 1 - 600 + 90, 2: 601 - 1181 + 90.","Vorontsov, N. N., and E. Yu. Ivanitskaya. 1973. Comparative karyology of north Palaearctic pikas (Ochotona, Ochotonidae, Lagomorpha). Caryologia, 26: 213 - 223."]}

Daily and seasonal behavior in relation to local climate was analyzed for two populations of pikas, (Ochotona princeps), representing the extremes of the altitudinal range of the species in the Sierra Nevada of California. The goal of this work was to determine the relationship of a propagule to its environment at the time of dispersal, in order to evaluate the probability of successful colonziation in different parts of the species range. Pikas at the high-altitude site (3,400 m) were active throughout the day, whereas at the warmer low- altitude site (2,550 m) they concentrated their activity in the morning and late afternoon. Field experiments suggest that when pikas are deprived of the opportunity to retreat to favorable microclimates in rockslides, they are unable to tolerate the high diurnal tempera- tures found at lower elevations. Thus, high environmental temperatures apparently constitute a major stress on dispersing individuals at low altitudes. The onset of hay storage, vocalization, and parturition, three measures of seasonality, occurred about 6 wk earlier at the low-altitude site. The timing of haying and vocalization there was correlated with the amount of precipitation during the previous winter: during dry years with little snow and an early spring pikas began and terminated their haying earlier than in wet years with a late spring. The reproductive season appeared to remain the same from year to year at the same site. The timing of dispersal of juveniles is related to the reproductive season. Most juveniles at the low-altitude site disperse during midsummer when temperatures are high and their chance of success is low. Also, during dry years most of the period suitable for gathering hay ends before a majority of the juveniles can disperse. Temperature and seasonality ap- parently have little effect on the dispersal of pikas at high altitude. At high altitude the pikas are wider ranging than at low altitude, and they occupy a greater proportion of available sites.

Ochotona collaris (Nelson, 1893). Proc. Biol. Soc. Wash., 8: 117. TYPE LOCALITY: U.S.A., Alaska, near head of Tanana River. DISTRIBUTION: W.C. Mackenzie, S. Yukon, N. W. British Columbia (Canada); S.E. Alaska (U.S.A.). COMMENT: Broadbooks, 1965, Am. Midi. Nat., 73:299-335, and Youngman, 1975, Mammals of the Yukon Terr., Nat. Mus. Nat. Sci. (Ottawa), Publ. Zool. 10, 192 pp, considered collaris and princeps conspecific. Corbet, 1978, following Gureev, 1964, included collaris in alpina. A statistical re-evaluation of craniometric data by Weston, 1981, in Myers, Proc. World Lagomorph Conf., indicated that collaris, princeps, and alpina are separate species. Hall, 1981:286, recognized collaris as a distinct species. ISIS NUMBER: 5301409001001002001., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Lagomorpha, pp. 595-604 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 595, DOI: 10.5281/zenodo.7353003, {"references":["Broadbooks, H. E. 1965. Ecology and distribution of the pikas of Washington and Alaska. American Midland Naturalist, 73: 299 - 335.","Youngman, P. M. 1975. Mammals of the Yukon Territory. National Museum of Natural Sciences (Ottawa), Publications in Zoology, 10: 1 - 192.","Gureev, A. A. 1964. Fauna SSSR, Mlekopitayushchie, tom. 3, vyp. 10, Zaitseobraznye (Lagomorpha) [Fauna of the USSR, mammals, vol. 3, pt. 10, Lagomorpha]. Nauka, Moscow-Leningrad, 276 pp. (in Russian).","Weston, M. L. 1981. The Ochotona alpina complex: A statistical re-evaluation. Pp. 73 - 89, in Proceedings of the world lagomorph conference (K. K. Myers and C. D. MacInnes, eds.). Guelph University Press, Guelph, Ontario, 983 pp.","Hall, E. R. 1981. The mammals of North America. Second ed. John Wiley and Sons, New York, 1: 1 - 600 + 90, 2: 601 - 1181 + 90."]}