, Volume 134, Issue 3, pp 343–349 | Cite as

Habitat-specific demography: evidence for source-sink population structure in a mammal, the pika

  • M. P. KreuzerJr.Email author
  • N. J. Huntly
Population Ecology


Theory suggests that populations may persist in sink habitats that cannot support replacement-level birth rates. Although it is commonly believed that organisms that can actively select habitat should rarely occur in sinks, the frequency of use of sinks in free-ranging species is not well-documented. We found that a population of American pikas (Ochotona princeps, Lagomorpha) inhabiting distinct alpine habitats (meadow and snowbed) in Wyoming, USA, had habitat-specific demographic rates that produced a source-sink population structure. Population size increased in both habitats in summer and declined in both habitats in winter, with populations in snowbeds increasing more during summer and decreasing more over winter. Birth rates were consistently higher in meadows and populations in meadows had a consistently higher finite rate of increase (λ, from life tables) than did those in snowbeds, for which λ was far below that needed for replacement. Patterns of immigration, population structure, and temporal variation in population size were as expected if meadows were functional sources and snowbeds functional sinks. Patterns of snowmelt differed between habitats, predicted the critical difference in birth rates between habitats, and are a likely primary cause of the differences in habitat-specific birth rates that we observed. This study provides a clear example of source-sink population structure for a mammal.


Habitat use Niche Ochotona princeps Population dynamics 



We thank J Roach, F Stevens, WC Witt, J Kreuzer, D Gentry, S Relyea, A Ray, and M Sanford for help with fieldwork, R van Kirk and T Peterson for mathematical and statistical advice, and the National Science Foundation (DEB 9972608), the American Society of Mammalogists, the Graduate Student Research and Scholarship Committee at Idaho State University, and the NERC Centre for Population Biology (UK) for support. All work followed guidelines for study and use of mammals as set forth by the American Society of Mammalogists and United States Department of Agriculture and was approved by the Idaho State University IACUC.


  1. Caswell, H (2001) Matrix Population Models: Construction, Analysis, and Interpretation, 2 edn. Sinauer, Sunderland, Mass.Google Scholar
  2. Chesson P, Huntly N (1989) Short-term instabilities and long-term community dynamics. Trends Ecol Evol 4:293–298Google Scholar
  3. Chesson P, Huntly N (1997) The roles of harsh and fluctuating conditions in the dynamics of ecological communities. Am Nat 150:519–553CrossRefGoogle Scholar
  4. Dearing MD (1997) The function of haypiles of pikas ( Ochotona princeps). J Mammal 78:1156–1163Google Scholar
  5. Dias PC (1996) Sources and sinks in population biology. Trends Evol Ecol 11:326–330CrossRefGoogle Scholar
  6. Diffendorfer JE (1998) Testing models of source-sink dynamics and balanced dispersal. Oikos 81:417–433Google Scholar
  7. Doncaster CP, Clobert J, Doligez B, Gustafsson L, Danchin E (1997) Balanced dispersal between spatially varying local populations: an alternative to the source-sink model. Am Nat 150:425–445CrossRefGoogle Scholar
  8. Golian SC, Whitworth MR (1985) Growth of pikas (Ochotona princeps) in Colorado. J Mammal 66:367–371Google Scholar
  9. Gotelli NJ (1995) A primer of ecology. Sinauer, Sunderland, MassGoogle Scholar
  10. Hall ER (1981) The mammals of North America, 2nd edn. Wiley, New YorkGoogle Scholar
  11. Holmes RT, Marra PP, Sherry TW (1996) Habitat-specific demography of breeding black-throated blue warblers (Dendroica caerulescens): implications for population dynamics. J Anim Ecol 65:183–195Google Scholar
  12. Holt RD (1985) Population dynamics in two-patch environments: some anomalous consequences of an optimal habitat distribution. Theor Popul Biol 28:181–208Google Scholar
  13. Huntly NJ, Smith AT, Ivins BL (1986) Foraging behavior of the pika (Ochotona princeps) with comparisons of grazing versus haying. J Mammal 67:139–148Google Scholar
  14. Johnson P L, Billings WD (1962) The alpine vegetation of the Beartooth Plateau in relation to cryopedogenic processes and patterns. Ecol Monogr 32:105–135Google Scholar
  15. Kreuzer MP (2001) Evidence and potential mechanisms for source-sink population structure: a study of pikas (Ochotona princeps) on the Beartooth Plateau. PhD Dissertation. Idaho State University, PocatelloGoogle Scholar
  16. Millar JS (1974) Success of reproduction in pikas, (Ochotona princeps Richardson). J Mammal 55:527-542PubMedGoogle Scholar
  17. Millar JS, Zwickel FC (1972) Determination of age, age structure, and mortality of the pika (Ochotona princeps Richardson). Can J Zool 50:229–232Google Scholar
  18. Morris DW (1991) On the evolutionary stability of dispersal to sink habitats. Am Nat 137:907-911CrossRefGoogle Scholar
  19. Peacock MM, Ray C (2001) Dispersal in pikas (Ochotona princeps): combining genetic and demographic approaches to reveal spatial and temporal patterns. In: Clobert J, Dhondt A, Danchin E, Nichols J (eds). The evolution of dispersal. Oxford University Press, Oxford, pp 43-56Google Scholar
  20. Pulliam HR (1988) Sources, sinks and population regulation. Am Nat 132:652–661CrossRefGoogle Scholar
  21. Pulliam HR (2000) On the relationship between niche and distribution. Ecol Lett 3:349–361CrossRefGoogle Scholar
  22. Pulliam HR, Danielson BJ (1991) Sources, sinks and habitat selection: a landscape perspective on population dynamics. Am Nat137:S50-S66Google Scholar
  23. Shmida A, Ellner S (1984) Coexistence of plant species with similar niches. Vegetatio 58:29–55Google Scholar
  24. Smith AT (1978) Comparative demography of pikas (Ochotona): effect of spatial and temporal age-specific mortality. Ecology 59:133-139Google Scholar
  25. Smith AT, Ivins BL (1983a) Colonization in a pika population: dispersal versus philopatry. Behav Ecol Sociobiol 13:37–47Google Scholar
  26. Smith AT, Ivins BL (1983b) Reproductive tactics of pikas: why have two litters? Can J Zool 61:1551–1559Google Scholar
  27. Smith AT, Weston ML (1990) Ochotona princeps. Mammal Spec 352Google Scholar
  28. Tilman, D (1997) Community invasibility, recruitment limitation, and grassland biodiversity. Ecology 78:81-92Google Scholar
  29. Van Horne B (1983) Density as a misleading indicator of habitat quality. J Wildl Manage 47:893–901Google Scholar
  30. Winker K, Rappole JH, Ramos MA (1995) The use of movement data as an assay of habitat quality. Oecologia 101:211-216Google Scholar

Copyright information

© Springer-Verlag 2003

Authors and Affiliations

  1. 1.Department of Biological Sciences and Center for Ecological Research and EducationIdaho State UniversityPocatelloUSA

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