Threatened Species: Pikas

Interview with a scientist: the impact of climate change on the Pika - the first mammal to be endangered by climate change

February 2003: an interview with Dr. Erik Beever, the US Geological Survey's Forest and Rangeland Ecosystem Science Centre ecologist and lead author of the study on Pikas (Ochotona princeps).

• What are Pikas and where do they live?
• Why are Pikas susceptible to climate change?
• Are Pikas threatened by other things?
• How did you become interested in this research?
• What does a threat to Pika mean for mountain ecosystems?
  
  

What are Pikas and where do they live?

Pikas are small mammals with short, rounded ears, and an invisible ‘buried’  tail that live in higher elevations.

Although Pikas resemble hamsters, they comprise their own family and are most closely related to rabbits. Across the world, 14-26 species of Pikas occupy steppes and mountainous terrain in eastern Asia, the Middle East, and North America.

With the exception of 4 species, all species of Pikas primarily live in talus or broken rock. In North America, there are 2 species of Pikas that both live only in talus or broken rock. American Pikas (Ochotona princeps) live in cool, moist areas - often at higher elevations.

Why are Pikas susceptible to climate change?

Pikas are especially vulnerable to climate change for several reasons. In the face of increasing global temperatures, mobile vertebrates are generally predicted to move upslope or to more northern latitudes. American Pikas cannot easily move northward, as their habitat is currently restricted to small, disconnected habitat ‘islands’ in numerous mountain ranges.

Although talus within mountain ranges is often more continuous, this is not always the case; some ranges only have habitable talus (with rock diameters 0.2 - 1.0 m) at lower elevations or in broadly separated patches. Furthermore, Pikas generally do not appear to move large distances, as many individuals may spend their entire lifespan within a 1 km radius.

In addition, Pikas do not inhabit burrows (which could dampen extreme temperatures) and are highly active above ground during the hottest months of the year. In these months, they are curing vegetation for overwinter survival (Pikas are active year-round).  Earlier senescence of vegetation may mean increased stress for Pikas, and hotter temperatures during high activity periods can create direct thermal stress on the animals. Finally, Pikas are densely furred, and thus cannot dissipate heat easily.

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Dr. Eric Beever has spent years in the company of the little mammals.

I also can't deny that they have a charismatic appeal...
Dr. Erik Beever

Are Pikas threatened by other things?

Although the evidence for Pikas' vulnerability is not as strong as it is for thermal influences, models from my work with populations in the Great Basin of western North America suggests that smaller habitat area, proximity to primary roads, and long-term presence of livestock grazing at talus margins may also affect Pikas.

Proximity to roads has been shown to affect a suite of other North American mammals, and may pose a threat to Pikas because they:

• allow removal of talus habitat for other construction or landscaping projects,
• may facilitate recreational hunting of Pikas, and
• allow other disturbances to microclimates surrounding taluses (e.g., patch clearcut logging, extensive dumping of trash on taluses).
  

The amount of habitat area directly affects the number and well-being of nearly all species, and less-extensive habitat probably interacts with other threats to cause loss of local populations. Pikas are an extremely interesting counter-example to the species-habitat relationship, however, as my research documented an apparent decrease of over 25% of the Basin's Pika populations, with no change in area or spatial arrangement of talus habitat during the 20th century.

Caution is merited in implicating livestock grazing in Pika declines, as I have seen Pikas living underneath a large boulder located squarely in trails that horses used to cross taluses. However, because Pikas forage from a central place, extensive modification of vegetation at talus margins may further stress Pikas.

How did you become interested in this research?


I initially became interested in this research through a larger project on which I began work in graduate school, which investigated the relationship of persistence of 11 mammal species to land-management jurisdiction. Although I had to abandon that project, I decided to continue work with Pikas, because they represented a system that addresses many issues of current importance in conservation biology.

I also can't deny that they have a charismatic appeal, which can bring attention to changes in alpine and subalpine ecosystems. I am interested in resampling some of the populations that appear most vulnerable to future extirpation, to see how these populations vary across shorter time scales.

I am also interested in trying to decipher more clearly how management actions such as grazing, burning, and road-building, interact with temperature and habitat area to affect populations. This work would involve use of temperature-recording devices at several sites Pikas inhabit within low-elevation habitats at which they remain (e.g., Lava Beds National Monument), and at selected locations from which they appear to have been lost recently.

What does a threat to Pika mean for mountain ecosystems?

This is one of the first empirical, broad-scale cases of shifts in the distribution of a small mammal over decadal timescales. Hopefully, the research will stimulate work on other, related species.

Unfortunately, previous work on montane mammals of the Great Basin by Tim Lawlor suggests that the unique life-history and behavioural traits of each species make direct application of my work to other species a tenuous connection. Specifically, few other montane species are so obligately tied to talus habitat or are active year-round, and no other species creates anything like the Pikas' conspicuous haypiles.

Because Pikas are preyed upon by a diversity of species, none of which relies solely on Pikas for their nutrition, I suspect that their loss will not affect species ‘higher’ than Pikas in the food web, though Pikas have been suggested to act as 'ecosystem engineers' at talus margins because of their extensive haying activities.

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