Pika

A pika (/ˈpaɪkə/ PY-kə; archaically spelled pica) is a small mountain-dwelling mammal found in Asia and North America. With short limbs, very round body, an even coat of fur, and no external tail, they resemble their close relative, the rabbit, but with short, rounded ears.[3] The large-eared pika of the Himalayas and nearby mountains is found at heights of more than 6,000 m (20,000 ft), among the highest of any mammal.

For other uses, see Pika (disambiguation).

Pika[1] Temporal range: Miocene–Holocene, 16.4–0 Ma[2] PreꞒ Ꞓ O S D C P T J K Pg N
American pika (Ochotona princeps)
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Lagomorpha
Family:	Ochotonidae Thomas, 1897
Genus:	Ochotona Link, 1795
Type species
Ochotona daurica Link, 1795 (Lepus dauuricus Pallas, 1776)
Species
See text

Pikas prefer rocky slopes and graze on a range of plants, mostly grasses, flowers, and young stems. In the autumn, they pull hay, soft twigs, and other stores of food into their burrows to eat during the long, cold winter.[4] The pika is also known as the "whistling hare" for its high-pitched alarm call when diving into its burrow.

The name "pika" appears to be derived from the Tungus piika,[5] and the scientific name Ochotona is from the Mongolian word ogdoi, which means pika.[6] It is used for any member of the Ochotonidae,[7] a family within the order of lagomorphs which includes the Leporidae (rabbits and hares). Only one genus, Ochotona,[7] is recognised within the family, covering 30 species.

The two species found in North America are the American pika, found primarily in the mountains of the western United States and far southwestern Canada, and the collared pika of northern British Columbia, the Yukon, western Northwest Territories, and Alaska.

Habitat

Collared pika on Hatcher Pass, Alaska

Pikas are native to cold climates, mostly in Asia, North America, and parts of Eastern Europe. Most species live on rocky mountainsides, where numerous crevices are available for their shelter, although some pikas also construct crude burrows. A few burrowing species are native to open steppe land. In the mountains of Eurasia, pikas often share their burrows with snowfinches, which build their nests there.[8] Pikas require cold temperatures to live, and can die if exposed to temperatures above 25.5 °C (77.9 °F).[9] Changing temperatures have forced some pika populations to restrict their ranges to even higher elevations.[10]

Characteristics

Ochotona sp. fossils

Pikas are small mammals, with short limbs and rounded ears. They are about 15 to 23 cm (6 to 9 in) in body length and weigh between 120 and 350 g (4 and 12 ¹⁄₂ oz), depending on species. Like rabbits, after eating, they initially produce soft, green feces, which they eat again to take in further nutrition, before producing the final, solid, fecal pellets. Some pikas, such as the collared pika, have been known to store dead birds in their burrows for food during winter.[11]

These animals are herbivores, and feed on a wide variety of plant matter, including forbs, grasses, sedges, shrub twigs, moss, and lichens. As with other lagomorphs, pikas have gnawing incisors and no canines, although they have fewer molars than rabbits; they have a dental formula of: 2.0.3.21.0.2.3

Rock-dwelling pikas have small litters of fewer than five young, while the burrowing species tend to give birth to more young, and to breed more frequently, possibly due to a greater availability of resources in their native habitats. The young are born after a gestation period between 25 and 30 days.[8]

Activity

Vegetation pile drying on rocks for subsequent storage, Little Cottonwood Canyon, Utah

American pika with mouthful of dried grass, Sequoia National Park, California

Pikas are diurnal or crepuscular, with higher-elevation species generally being more active during the daytime. They show their peak activity just before the winter season. Pikas do not hibernate, so they generally spend time during the summer collecting and storing food they will eat over the winter. Each rock-dwelling pika stores its own "haypile" of dried vegetation, while burrowing species often share food stores with their burrow mates. Haying behavior is more prominent at higher elevations. Many of the vocalizations and social behaviors that pikas exhibit are related to haypile defense.

Eurasian pikas commonly live in family groups and share duties of gathering food and keeping watch. Some species are territorial. North American pikas (O. princeps and O. collaris) are asocial, leading solitary lives outside the breeding season.

Dialects

Pikas have distinct calls that vary in duration. The call can either be short and quick, a little longer and more drawn out, or long songs. The short calls are an example of geographic variation. The pikas determine the appropriate time to make short calls by listening for cues for sound localization.[12] The calls are used for individual recognition, predator warning signals, territory defense, or as a way to attract the opposite sex.[13] There are also different calls depending on the season. In the spring, the songs become more frequent during the breeding season. In late summer, the vocalizations become short calls. Through various studies, the acoustic characteristics of the vocalizations can be a useful taxonomic tool.[14]

Lifespan

The average lifespan of pikas in the wild is roughly seven years. A pika's age may be determined by the number of adhesion lines on the periosteal bone on the lower jaw. The lifespan does not differ between the sexes.[15]

Species

The 30 species described are:

• Order Lagomorpha[1]
  • Family Ochotonidae: pikas
    • Genus Ochotona
      • Subgenus Pika: northern pikas
        • Alpine pika or Altai pika, O. alpina
        • Helan Shan pika or silver pika, O. argentata
        • Collared pika, O. collaris
        • Hoffmann's pika, O. hoffmanni
        • Northern pika or Siberian pika, O. hyperborea
        • Pallas's pika, O. pallasi
        • American pika, O. princeps
        • Turuchan pika, O. turuchanensis
      • Subgenus Ochotona: shrub-steppe pikas
        • Gansu pika or gray pika, O. cansus
        • Plateau pika or black-lipped pika, O. curzoniae
        • Daurian pika, O. dauurica
        • Tsing-ling pika, O. huangensis
        • Nubra pika, O. nubrica
        • Steppe pika, O. pusilla
        • Afghan pika, O. rufescens
        • Moupin pika, O. thibetana
        • Thomas's pika, O. thomasi
        • O. yarlungensis
        • O. qionglaoensis
      • Subgenus Conothoa: mountain pikas
        • Chinese red pika, O. erythrotis
        • Forrest's pika, O. forresti
        • Gaoligong pika, O. gaoligongensis
        • Glover's pika, O. gloveri
        • Himalayan pika, O. himalayana
        • Ili pika, O. iliensis
        • Koslov's pika, O. koslowi
        • Ladak pika, O. ladacensis
        • Large-eared pika, O. macrotis
        • Muli pika, O. muliensis
        • Black pika, O. nigritia
        • Royle's pika, O. roylei
        • Turkestan red pika, O. rutila
      • Subgenus Alienauroa
        • O. huanglongensis
        • O. xunhuaensis
        • O. sacraria
        • O. flatcalvariam
        • O. dabashanensis

Extinct species

Many fossil forms of Ochotona are described in the literature, from the Miocene epoch to the early Holocene (extinct species) and present (16.4-0 Ma[2]). They lived in Europe, Asia, and North America.Some species listed below are common for Eurasia and North America (O. gromovi, O. tologoica, O. zazhigini, and probably O. whartoni).

• Eurasia
  • large forms
    • †Ochotona chowmincheni (China: Baode area, late Miocene)[2][16][17]
    • †Ochotona gromovi (Asia, Pliocene, see also North America)[17]
    • †Ochotona gudrunae (China: Shanxi, early Pleistocene)[2][16][17]
    • †Ochotona guizhongensis (Tibet, late Miocene)[2][17][18]
    • †Ochotona lagreli (China: Inner Mongolia, late Miocene to late Pliocene)[2][16][17][18]
    • †Ochotona magna (China, early Pleistocene)[2][17][19]
    • †Ochotona tologoica (Transbaikalia, Pliocene, see also North America)[2][17][19]
    • †Ochotona transcaucasica (Transcaucasia: eastern Georgia and Azerbaijan, Transbaikal and probably southern Europe, early to late Pleistocene)[2][16][17]
    • †Ochotona ursui (Romania, Pliocene)[2][17]
    • †Ochotona zasuchini (Transbaikalia, Pleistocene)[2][17][19]
    • †Ochotona zazhigini (Asia, Pliocene, see also North America)[2][17]
    • †Ochotona zhangi (China, Pleistocene)[2][17][19]
  • medium-sized forms
    • †Ochotona agadjianiani (Asia, Pliocene)[17]
    • †Ochotona antiqua (Moldavia, Ukraine, and the Russian Plain, Caucasus, and probably Rhodes, late Miocene to Pliocene)[2][16][17]
    • †Ochotona azerica (Transcaucasia: Azerbaijan,[20] middle Pliocene)[2][19]
    • †Ochotona lingtaica (Asia, Pliocene)[2][17]
    • †Ochotona dodogolica (Asia: western Transbaikalia, Pleistocene)[16][17]
    • †Ochotona nihewanica (China: Hebei, early Pleistocene)[2][16][17][21]
    • †Ochotona plicodenta (Asia, Pliocene)[2][17]
    • †Ochotona polonica (Europe: Poland, Germany, France, Pliocene)[2][16][17]
  • small-sized forms
    • †Ochotona bazarovi (Asia, upper Pliocene)[2][19][21]
    • †Ochotona dehmi (Germany: Schernfeld, Pleistocene)[2][17]
    • †Ochotona filippovi (Siberia, Pleistocene)[2][21]
    • †Ochotona gracilis (Asia, Pliocene)[2][17]
    • †Ochotona horaceki (Slovakia: Honce, Pleistocene)[2][17]
    • †Ochotona minor (China, late Miocene)[2][17][18]
    • †Ochotona sibirica (Asia, Pliocene)[2][17]
    • †Ochotona valerotae (France: Valerots site, Pleistocene)[2][17]
    • †Ochotona youngi (Asia, Pliocene)[17]
      and others.[2][17]
  • other examples
    • †Ochotona agadzhaniani (Transcaucasia: Armenia, Pliocene)[2]
    • †Ochotona alaica (Asia: Kyrgyzstan, Pleistocene)[2]
    • †Ochotona (Proochotona) eximia (Moldova, Ukraine, Russia, Kazakhstan, Miocene to Pliocene)[2]
    • †Ochotona (Proochotona) gigas (Ukraine, Pliocene)[2]
    • †Ochotona gureevi (Transbaikalia, middle Pliocene)[2][19]
    • †Ochotona hengduanshanensis (China, Pleistocene)[2]
    • †Ochotona intermedia (Asia, Pliocene)[2][17]
    • †Ochotona (Proochotona) kalfaense (Europe: Moldova, Miocene)[2]
    • †Ochotona (Proochotona) kirgisica (Asia: Kyrgyzstan, Pliocene)[2]
    • †Ochotona kormosi (Hungary, Pleistocene)[2][16]
    • †Ochotona (Proochotona) kurdjukovi (Asia: Kyrgyzstan, Pliocene)[2]
    • †Ochotona largerli (Georgia, Pleistocene)[2]
    • †Ochotona lazari (Ukraine, Pleistocene)[2]
    • †Ochotona mediterranensis (Turkey, Pliocene)[2]
    • †Ochotona ozansoyi (Turkey, Miocene)[2]
    • †Ochotona pseudopusilla (Ukraine and Russian Plain, Pleistocene)[2][17]
    • †Ochotona spelaeus (Ukraine, late Pleistocene)[2][22]
    • †Ochotona tedfordi (China: Yushe Basin, late Miocene)[2][16]
    • †Ochotona cf. whartoni (Irkutsk Oblast and Yakutia, Pleistocene, see also North America)[17]
    • †Ochotona zabiensis (southern Poland, early Pleistocene)[2][16]
    • †Ochotona sp. (Greece: Maritsa, Pliocene)[17]
    • †Ochotona sp. (Hungary: Ostramos, Pleistocene)[17]
    • †Ochotona sp. (Siberia, Pleistocene)[17]
    • †Ochotona sp. (Yakutia, Pleistocene)[17]
• North America
  • †Ochotona gromovi (US: Colorado, Pliocene, see also Eurasia)[2]
  • †Ochotona spanglei (US, late Miocene or early Pliocene)[2][17][21][23][24][n 1]
  • †Ochotona tologoica (US: Colorado, Pliocene, see also Eurasia)[2]
  • †Ochotona whartoni (giant pika, US, Canada, Pleistocene to early Holocene, see also Eurasia)[2][17][21][25][26][n 2]
  • †Ochotona wheatleyi (US: Alaska, Pliocene, late Pleistocene)[2]
  • †Ochotona zazhigini (US: Colorado, Pleistocene, see also Eurasia)[2]
  • extinct small pikas similar to the O. pusilla group (Pleistocene)[17][21]

Paleontologists have also described multiple forms of pika not referred to specific species (Ochotona indet.) or not certainly identified (O. cf. antiqua, O. cf. cansus, O. cf. daurica, O. cf. eximia, O. cf. gromovi, O. cf. intermedia, O. cf. koslowi, O. cf. lagrelii, O. cf. nihewanica). The statuses of Ochotona (Proochotona) kirgisica and O. spelaeus are uncertain.[2]

The "pusilla" group of pikas is characterized by archaic (plesiomorphic) cheek teeth and small size.[21]

The North American species migrated from Eurasia. They invaded the New World twice:

• O. spanglei during the latest Miocene or early Pliocene, followed by a roughly three-million-year-long gap in the known North American pikas record[17]
• O. whartoni (giant pika) and small pikas via the Bering Land Bridge during the earliest Pleistocene[17]

Ochotona cf. whartoni and small pikas of the O. pusilla group are also known from Siberia. The extant, endemic North American species appeared in the Pleistocene. The North American collared pika (O. collaris) and American pika (O. princeps) have been suggested to have descended from the same ancestor as the steppe pika (O. pusilla).[17]

The range of Ochotona was larger in the past, with both extinct and extant species inhabiting Western Europe and Eastern North America, areas that are currently free of pikas. Pleistocene fossils of the extant steppe pika O. pusilla currently native to Asia have been found also in many countries of Europe from the United Kingdom to Russia and from Italy to Poland, and the Asiatic extant northern pika O. hyperborea in one location in the middle Pleistocene United States.[2]

Pika Ochotona sp. fossil distribution. Extinct pikas and Ochotona indet. are red, steppe pika O. pusilla blue, northern pika O. hyperborea green, other extant pikas black.[2][27][n 3]

Fossil occurrences of leporids and ochotonids and global environmental change (climate change, C₃/C₄ plants distribution)[2]

Other genera of ochotonids (currently living only Ochotonidae) include except Ochotona (pika) extinct †Albertona, †Alloptox, †Amphilagus, †Australagomys, †Austrolagomys, †Bellatona, †Bellatonoides, †Bohlinotona, †Cuyamalagus, †Desmatolagus, †Eurolagus, †Gripholagomys, †Gymnesicolagus, †Hesperolagomys, †Heterolagus, †Kenyalagomys, †Lagopsis, †Marcuinomys, †Ochotonoides, †Ochotonoma, †Oklahomalagus, †Oreolagus, †Paludotona, †Piezodus, †Plicalagus, †Pliolagomys, †Prolagus, †Proochotona (syn. Ochotona), †Pseudobellatona, †Ptychoprolagus, †Russellagus, †Sinolagomys and †Titanomys.[2] The earliest one is Desmatolagus (middle Eocene to Miocene, 42.5–14.8 Ma[2]), usually included in the Ochotonidae, sometimes in Leporidae or in neither ochotonid nor leporid stem-lagomorphs.[28]

Ochotonids appeared in Asia between the late Eocene and the early Oligocene, and continued to develop along with increased distribution of C₃ grasses in previously forest dominated areas under the "climatic optimum" from the late Oligocene to middle Miocene. They thrived in Eurasia, North America, and even Africa. The peak of their diversity occurred during the period from the early Miocene to middle Miocene, most of them became extinct during the transition from the Miocene to Pliocene, what was accompanied by diversity increase in the leporids. It has been proposed that this switch between ochotonids and larger leporids was caused by expansion of C₄ plants (particularly the Poaceae) related to global cooling in the late Miocene, since extant pikas reveal a strong preference for C₃ plants (Asteraceae, Rosaceae,and Fabaceae, many of them C₃). Replacement of large areas of forests by open grassland first started probably in North America and is called sometimes "nature's green revolution".[2]

Notes

1. Ochotona spanglei in the Paleobiology Database.[24][pdb 1][pdb 2][pdb 3]
2. Ochotona whartoni in the Paleobiology Database.[26][pdb 4][pdb 5][pdb 6][pdb 7][pdb 8][pdb 9][pdb 10]
3. The coordinates of additional fossils not listed in the xls file attached to Ge and all paper[2] were taken from the Paleobiology Database.[27][pdb 11][pdb 12][pdb 13][pdb 14][pdb 15][pdb 16][pdb 17][pdb 18][pdb 19][pdb 20][pdb 6][pdb 7][pdb 21][pdb 22][pdb 5][pdb 23][pdb 24][pdb 25][pdb 26][pdb 27][pdb 28][pdb 29][pdb 30]

References

1. Hoffman, R.S.; Smith, A.T. (2005). "Order Lagomorpha". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 185–193. ISBN 978-0-8018-8221-0. OCLC 62265494.
2. Ge, Deyan; Wen, Zhixin; Xia, Lin; Zhang, Zhaoqun; Erbajeva, Margarita; Huang, Chengming; Yang, Qisen (April 3, 2013). "Evolutionary History of Lagomorphs in Response to Global Environmental Change". PLoS ONE. 8 (4:e59668): e59668. Bibcode:2013PLoSO...859668G. doi:10.1371/journal.pone.0059668. PMC 3616043. PMID 23573205. Table_S1.xls Archived 2014-05-22 at the Wayback Machine
3. Melissa Breyer (2 September 2016). "Meet the 'mouse-bunny' that could vanish from the US". treehugger.
4. Walters, Martin (2005). Encyclopedia of animals. Parragon. p. 203. ISBN 978-1-40545-669-2.
5. Harper, Douglas. "pika". Online Etymology Dictionary.
6. General pika information Archived 2017-05-10 at the Wayback Machine. twycrosszoo.org
7. Lydekker, Richard (1911). "Pica" . In Chisholm, Hugh (ed.). Encyclopædia Britannica. 21 (11th ed.). Cambridge University Press. p. 575.
8. Kawamichi, Takeo (1984). Macdonald, D. (ed.). The Encyclopedia of Mammals. New York: Facts on File. pp. 726–727. ISBN 978-0-87196-871-5.
9. "American Pika". U.S. Fish and Wildlife Service. Retrieved 2018-11-18.
10. Erb, Liesl P; Ray, Chris; Guralnick, Robert (2011-09-01). "On the generality of a climate-mediated shift in the distribution of the American pika (Ochotona princeps)". Ecology. 92 (9): 1730–1735. doi:10.1890/11-0175.1. PMID 21939069.
11. Leininger, Charlene (2009) Ochotona collaris Archived 2013-06-28 at the Wayback Machine. Animal Diversity Web
12. Conner, Douglas A. (1982-02-25). "Geographic Variation in Short Calls of Pikas (Ochotona princeps)". Journal of Mammalogy. 63 (1): 48–52. doi:10.2307/1380670. JSTOR 1380670.
13. Trefry, Sarah A.; Hik, David S. (2009). "Variation in pika (Ochotona collaris, O. princeps) vocalizations within and between populations". Ecography. 33 (4): 784–795. doi:10.1111/j.1600-0587.2009.05589.x.
14. Somers, Preston (1973). "Dialects in southern Rocky Mountain pikas, Ochotona princeps (Lagomorpha)". Animal Behaviour. 21: 124–137. doi:10.1016/S0003-3472(73)80050-8.
15. Barker, Jennifer M; Boonstra, Rudy; Schulte-Hostedde, Albrecht I (2003-10-01). "Age determination in yellow-pine chipmunks (Tamias amoenus): a comparison of eye lens masses and bone sections". Canadian Journal of Zoology. 81 (10): 1774–1779. doi:10.1139/z03-173.
16. Fostowicz-Frelik, Łucja; Frelik, Grzegorz; Gasparik, Mihály (October 2010). "Morphological phylogeny of pikas (Lagomorpha: Ochotona), with a description of a new species from the Pliocene/Pleistocene transition of Hungary". Proceedings of the Academy of Natural Sciences of Philadelphia. 159: 97–117. doi:10.1635/053.159.0107. JSTOR 41446115.
17. Erbajeva, Margarita A.; Mead, Jim I.; Alexeeva, Nadezhda V.; Angelone, Chiara; Swift, Sandra L. (2011). "Taxonomic diversity of Late Cenozoic Asian and North American ochotonids (an overview)" (PDF). Palaeontologia Electronica: 1–9. Archived (PDF) from the original on April 14, 2014. Retrieved April 13, 2014.
18. Cai, Baoquan (1989). "Fossil Lagomorpha from the Late Pliocene of Yangyuan and Yuxian counties, Hebei Province" (PDF). Vertebrata PalAsiatica. XXVII (3): 170–181. Archived (PDF) from the original on March 5, 2016. Retrieved May 20, 2014. Translated by Will Downs Department of Geology Bilby Research Center Northern Arizona University October, 1990
19. Erbajeva, Margarita A.; Zheng, Shaohua (30 June 2005). "New data on Late Miocene – Pleistocene ochotonids (Ochotonidae, Lagomorpha) from North China" (PDF). Acta Zoologica Cracoviensia. 48A (1–2): 93–117. doi:10.3409/173491505783995734. Archived (PDF) from the original on May 10, 2017. Retrieved May 20, 2014.
20. Čermák, Stanislav; Obuch, Ján; Benda, Petr (2006). "Notes on the genus Ochotona in the Middle East (Lagomorpha: Ochotonidae)" (PDF). Lynx. 37: 51–66. ISSN 0024-7774. Archived from the original (PDF) on May 22, 2014. Retrieved May 22, 2014.
21. Erbajeva, Margarita A.; Mead, Jim I.; Swift, Sandra L. (2003). "Evolution and development of Asian and North American ochotonids" (PDF). Occasional Papers in Earth Sciences No. 5: 33–34. Archived from the original (PDF) on March 31, 2014. Retrieved April 13, 2014. 3rd INTERNATIONAL MAMMOTH CONFERENCE, 2003: PROGRAM AND ABSTRACTS, Edited by John E. Storer
22. Rekovets, Leonid (2003). "Mammoth (Mammuthus primigenius) in the periglacial faunas of Ukraine" (PDF). Occasional Papers in Earth Sciences No. 5: 130–131. Archived from the original (PDF) on March 31, 2014. Retrieved April 13, 2014. 3rd INTERNATIONAL MAMMOTH CONFERENCE, 2003: PROGRAM AND ABSTRACTS, Edited by John E. Storer
23. Shotwell, J. Arnold (1956). "Hemphillian mammalian assemblage from northeastern Oregon". Geological Society of America Bulletin. 67 (6): 717–738. doi:10.1130/0016-7606(1956)67[717:HMAFNO]2.0.CO;2.
24. "Ochotona spanglei Shotwell 1956". The Paleobiology Database. Archived from the original on April 15, 2014.
25. Guthrie, R.D.; Matthews, John V. Jr. (1971). "The Cape Deceit fauna—Early pleistocene mammalian assemblage from the Alaskan arctic". Quaternary Research. 1 (4): 474–510. Bibcode:1971QuRes...1..474G. doi:10.1016/0033-5894(71)90060-3.
26. "Ochotona whartoni Guthrie and Matthews, Jr. 1971 (pika)". The Paleobiology Database. Archived from the original on April 14, 2014.
27. "Ochotona Link 1795 (pika)". The Paleobiology Database.
28. Hordijk, Kees (2010). Perseverance of pikas in the Miocene : interplay of climate and competition in the evolution of Spanish Ochotonidae (Lagomorpha, Mammalia). Geologica Ultraiectina. 333. Departement Aardwetenschappen. hdl:1874/197550. ISBN 978-90-5744-194-3. document type Dissertation full text

Additional references of the Paleobiology Database

1. Shotwell, J. A. (1956). "Hemphillian mammalian assemblage from Northeastern Oregon". Geological Society of America Bulletin. 67 (6): 717. doi:10.1130/0016-7606(1956)67[717:hmafno]2.0.co;2. [J. Alroy/J. Alroy]
2. Voorhies, M. R. (1990). Gustavson, T. C. (ed.). Bureau of Economic Geology Guidebook. [J. Alroy/J. Alroy]
3. Additional contributors to utilized records of Paleobiology Database (authorizers supplying these records) include John Alroy.
4. Guthrie, R. D.; Matthews, Jr., J. V. (1971). "The Cape Deceit fauna—Early pleistocene mammalian assemblage from the Alaskan arctic". Quaternary Research. 1 (4): 474–510. Bibcode:1971QuRes...1..474G. doi:10.1016/0033-5894(71)90060-3. [J. Alroy/J. Alroy]
5. Jopling, A. V.; et al. (1981). "Stratigraphic, Sedimentological and Faunal Evidence for the Occurrence of Pre-Sangamonian Artefacts in Northern Yukon". Arctic. 34 (1). doi:10.14430/arctic2499. [J. Alroy/J. Alroy]
6. Harington, C. R. (1978). "Quaternary vertebrate faunas of Canada and Alaska and their suggested chronological sequence". Syllogeus. 15. [J. Alroy/J. Alroy]
7. Harington, C. R. (1990). "Vertebrates of the last interglaciation in Canada: A review" (PDF). Geographie Physique et Quaternaire. 44 (3): 375. doi:10.7202/032837ar. [J. Alroy/J. Alroy/M. Uhen]
8. Storer, J. E. (2004). "A Middle Pleistocene (late Irvingtonian) mammalian fauna from Thistle Creek, Klondike Goldfields region of Yukon Territory, Canada". Paludicola. 4 (4): 137–150. [J. Alroy/J. Alroy]
9. Tedford, R. H.; Wang, X; Taylor, B. E. (2009). "Phylogenetic Systematics of the North American Fossil Caninae (Carnivora: Canidae)". Bulletin of the American Museum of Natural History. 325: 1–218. doi:10.1206/574.1. hdl:2246/5999. [J. Marcot/J. Marcot]
10. Additional contributors to utilized records of Paleobiology Database (authorizers supplying these records) include John Alroy, Jonathan Marcot.
11. Barnosky, A. D.; Rasmussen, D. L. (1988). "Middle Pleistocene arvicoline rodents and environmental change at 2900-meters elevation, Porcupine Cave, South Park, Colorado". Annals of Carnegie Museum. 57 (12): 267–292. [J. Alroy/J. Alroy]
12. Belyaeva, E. I. (1948). Catalogue of Tertiary Fossil Sites of the Land Mammals in the U.S.S.R. [M. Uhen/M. Uhen]
13. Bonifay, M. F. (1973). "Principaux gisements paleontologiques Francais du Pleistocene Moyen: Essai de classification". Le Quaternaire: 41–50. [A. Turner/H. O'Regan/H. O'Regan]
14. Cai, B. (1987). "A preliminary report on the Late Pliocene Micromammalian fauna from Yangyuan and Yuxian, Hebei". Vertebrata PalAsiatica. 25 (2): 124–136. [A. Turner/H. O'Regan/H. O'Regan]
15. Deng, T.; Wang, X.; Fortelius, M.; Li, Q.; Wang, Y.; Tseng, Z. J.; Takeuchi, G. T.; Saylor, J. E.; Säilä, L. K.; Xie, G. (2011). "Out of Tibet: Pliocene woolly rhino suggests high-plateau origin of Ice Age megaherbivores". Science. 333 (6047): 1285–1288. Bibcode:2011Sci...333.1285D. doi:10.1126/science.1206594. PMID 21885780. [J. Alroy/J. Alroy/J. Alroy]
16. Erbaeva, M. A. (1986). "The Late Cenozoic Faunistic complexes of Transbaikalia with special reference to the micromammalia". Quatarpalaontologie. 6: 25–28. [A. Turner/H. O'Regan/H. O'Regan]
17. Frazier, M. K. (1977). "New Records of Neofiber leonardi (Rodentia: Cricetidae) and the Paleoecology of the Genus". Journal of Mammalogy. 58 (3): 368–373. doi:10.2307/1379335. JSTOR 1379335. [M. Uhen/M. Shalap]
18. Gidley, J. W. (1913). "Preliminary report on a recently discovered Pleistocene cave deposit near Cumberland, Maryland". Proceedings of the United States National Museum. 46 (2014): 93–102. doi:10.5479/si.00963801.46-2014.93. hdl:2027/hvd.32044107347718. [M. Uhen/M. Shalap/M. Shalap]
19. Grady, F.; Garton, E. R. (2000). "Paleontology and historic field trip of the John Guilday Cave Preserve (Trout Rock)". Bulletin – West Virginia Speleological Survey. 14: 241–244. [M. Uhen/M. Shalap/M. Shalap]
20. Guilday, J. E. (1979). "Eastern North American Pleistocene Ochotona (Lagomorpha: Mammalia). Carnegie Museum of Natural History". Annals of Carnegie Museum. 48 (24). [J. Alroy/J. Alroy]
21. Janossy, D. (1970). "Ein neuer Eomyide (Rodentia, Mammalia) aus dem Ältestpleistozän ("Oberes Villafrankium", Villanyium) des Osztramos (Nordostungarn); (A new Eomyid (Rodentia, Mammalia) from the lowermost Pleistocene (upper Villafranchian) from Osztramos mountain (Northeastern Hungary)". Annales Historico-Naturales Musei Nationalis Hungarici. 62: 99–113. [J. Alroy/S. Kuemmell/S. Kuemmell]
22. Janossy, D. (1986). Pleistocene vertebrate faunas of Hungary. Developments in Palaeontology and Stratigraphy. 8. Amsterdam: Elsevier. ISBN 978-0-444-99526-1. [A. Turner/H. O'Regan/H. O'Regan]
23. Kurten, B.; Anderson, E. (1980). Pleistocene mammals of North America. ISBN 978-0231037334. [J. Alroy/J. Alroy/J. Alroy]
24. Mead, J. I.; Grady, F. (1996). "Ochotona (Lagomorpha) from late Quaternary cave deposits in eastern North America". Quaternary Research. 45 (1): 93–101. Bibcode:1996QuRes..45...93M. doi:10.1006/qres.1996.0009. [J. Alroy/J. Alroy/J. Alroy]
25. Qiu, Z. (1987). "Neogene micromammals of China". Whyte, P., Ed. Paleoenvironment of East Asia from the Mid-Tertiary, Second International Conference on the Paleoenvironment of East Asia. 77 (1–2): 834–848. [W. Clyde/J. Finarelli/W. Clyde]
26. Rasmussen, D. L. (1974). "New Quaternary mammal localities in the upper Clark Fork River valley, western Montana". Northwest Geology. 3: 62–70. [M. Uhen/C. Peredo]
27. Sotnikova, M.V.; Dodonov, A.E.; Pen'kov, A.V. (1997). "Upper Cenozoic bio-magnetic stratigraphy of Central Asian mammalian localities". Palaeogeography, Palaeoclimatology, Palaeoecology. 133 (3–4): 243–258. Bibcode:1997PPP...133..243S. doi:10.1016/s0031-0182(97)00078-3. [A. Turner/H. O'Regan/H. O'Regan]
28. Terzea, E. (1996). "Biochronology of the Pleistocene deposits at Betfia (Bihor, Romania)". Acta Zoologica Cracovensia. 39 (1): 531–540. [A. Behrensmeyer/H. O'Regan/H. O'Regan]
29. Winkler, A. J.; Grady, F. (1990). "The middle Pleistocene rodent Atopomys (Cricetidae: Arvicolinae) from the eastern and south-central United States". Journal of Vertebrate Paleontology. 10 (4): 484–490. doi:10.1080/02724634.1990.10011831. [J. Alroy/J. Alroy]
30. Additional contributors to utilized records of Paleobiology Database (authorizers supplying these records) include John Alroy, Anna Behrensmeyer, Will Clyde, Alan Turner, Mark Uhen.

Further reading

• Orr, Robert Thomas (1977). The Little-known Pika (illustrated ed.). New York: Macmillan. ISBN 9780025939608.

External links

• The trek of the pika, by Michael Morris, Parks Canada, Mount Revelstoke and Glacier National Parks. (includes sound file)