Elevation Keys Diverse Pika Population Responses to Changing Climate


Alex Wierbinski's picture

By Alex Wierbinski - Posted on 04 February 2019

SMALL SIERRA NEVADA MAMMALS

American Pika
American Pika, Ecological Society of America, Photo credit to, courtesy of, Shana Weber.
 With their sensitivity to overheating, pikas are an indicator species for how climate change may affect mountain-dwelling wildlife.
Ecological Society of America, Photo credit to, courtesy of, Shana Weber.

 

Elevation Keys Diverse Pika Population Responses to Changing Climate

Pika Survival Rates Dry Up with Low Moisture,
Ecological Society of America, February 4, 2019.

MAIN POINTS

American Pika
“Related to rabbits and hares, pikas live in cold, wet climates and high terrain, spending winters in snowy homes living off of stored grasses and other forage they have gathered, only venturing out for more when weather permits.”

The Pika Death Zone
“...they have a fairly severe sensitivity to overheating - they die if they are exposed to temperatures above 77°F for longer than six hours.”

Decreased Snow Threatens Pikas Food & Shelter
“...decreased snowpack and lower air moisture may threaten pikas more.”

How Climate is Killing the Pikas
VPD
Vapor-Pressure Deficit

Killing their Food
“VPD governs the growth of many plants that pikas depend on for food, and controls cloud formation and snow.”

Pika with Moss
American Pika with Moss, Ecological Society of America, photo credit to, courtesy of, Thomas Barlow.
Ecological Society of America, photo credit to, courtesy of, Thomas Barlow.

 

Food and Snow
“If VPD becomes higher, it will inhibit the growth of plants that pikas depend on for food, and will shrink snow packs which they use for insulation against extreme temperature.”

Record Drought of 2015
“...study period included a year with record-low snowpack and high VPD (very dry air) in winter of 2014-2015, a data point that provided valuable observations of these variables' influences on the ecosystem. The researchers further studied the dynamics across differing elevations - low, middle, and high.”

Low Elevation
Food, not Cold Problems
“...the lowest elevations, populations declined markedly.”
“...high VPD during the snow drought dried up forage plant species accustomed to moist conditions, and lack of food may have prompted malnourished pikas to forgo reproduction. Cold exposure did not appear to affect these pikas, where absence of snowpack is common because of generally warm temperatures.”

Middle Elevations
Cold Problems

“...cold stress, not dry air, that had the biggest effect.”

“...about 1200-1500 meters, pika populations lacked a strong snowpack in which to seek shelter and insulation from extreme cold.”

“...a dip in reproduction the following year, not pika mortality in a single winter, that caused the population abundance to drop.”

High Elevations
Pika Climate Lottery Winners
“Populations increased, having had sufficient snow cover for insulation despite a snow drought, and having benefitting from increased forage availability due to earlier snowmelt and a longer growth season for food.”

Fat, Warm, Well-Sexed Pikas…
“Pikas were able to consume and collect enough food to increase their health and ability to produce many offspring over the following winter.”

Pika Lives Touch Many
Healthy Pika Populations
“Pikas serve as a food source for a number of predators, including weasels, coyotes, and birds of prey. They are also ecosystem engineers - their foraging helps promote the diversity and distribution of various plant species and nutrients.

Pika Problems Spread Through Ecosystems
Consequently, pika die-offs could have many lasting dire consequences for the environment and serve as a harbinger in forecasting potential climate change impacts on animal and plant life across the greater continental US.”

 

 

 

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elevation, affects, Pika, response, climate change, global warming, warm, short, Winters

 

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