American Pika
Encyclopedia
The American pika a diurnal
species of pika
, is found in the mountains of western North America
, usually in boulder fields at or above the tree line. They are herbivorous, smaller relatives of rabbits and hares.
s). Body size can vary among populations. In populations with sexual dimorphism
, males are slightly larger than females.
The American pika is intermediate in size among pikas. The hind legs of the pika do not seem to be much longer than its front legs and its hind feet are relatively short when compared to most other lagomorphs. It has densely furred soles on its feet except for black pads at the ends of the toes. The ears are moderately large and sub-orbicular and are hairy on both surfaces, normally dark with white margins. The pika has a tail that is "buried" and is longer relative to body size compared to other lagomorphs. Its has a slightly rounded skull with a broad and flat pre-orbital region. The fur color of the pika is the same for both sexes but varies by subspecies and season. The dorsal fur of the pika ranges from grayish to cinnamon-brown, often colored with tawny or orchraceous hues, during the summer. During winter, the fur becomes grayer and longer. The dense under-fur is usually slate-gray or lead colored. It also has whitish ventral fur.
, from central British Columbia
in Canada
to the US
states of Oregon
, Washington, Idaho
, Montana
, Wyoming
, Colorado
, Utah
, Nevada
, California
and New Mexico
.
Pikas inhabit talus fields that are fringed by suitable vegetation on alpine areas. They will also live in piles of broken rock. Sometimes, they will live in man-made substrate such as mine tailings and piles of scrap lumber. Pikas usually have their den and nest sites below rock around 0.2-1 m in diameter but often sit on larger and more prominent rocks. They generally reside in scree
near or above the tree line. Pikas are restricted to cool moist microhabitats on high peaks or watercourses. Intolerant of high diurnal temperatures, in the northern portion of their range they may be found near sea level, but in the south they are rare below 2500 metres (8,202.1 ft). Pikas rely on existing spaces in the talus for homes and do not dig burrows. However they can enlarge their home by digging.
. It eats a large variety of green plants, including different kinds of grass
es, sedge
s, thistle
s and fireweed
. Pikas can meet their water demands from the vegetation they eat. However they drink water if it is available. Pikas have two different ways of foraging. They will directly consume food (feeding) or they will cache food in haypiles to use for a food source in the winter (haying). The pika feeds throughout the year while haying is limited to the summer months. Since they do not hibernate, pikas have greater energy demands than other montane mammals. In addition, they also make 13 trips per hours to collect vegetation when haying. It seems that the timing of haying correlates to the amount of precipitation from the previous winter. Pikas will start and then quit haying earlier in years following little snow and early spring. In areas at lower elevations, haying begins before the snow has melted at high altitudes while at higher elevations, haying continues after it ends in lower elevations.
When haying, pikas harvest plants in a deliberate sequence, corresponding to their seasonal phenology. They seem to assess the nutritional value of available food and harvest accordingly. Pikas select plants that have the higher caloric, protein, lipid and water content. Forbs and tall grass tend to be hayed more than eaten directly. Haypiles tend to be stored under the talus near the talus-meadow interface although they may be constructed on the talus surface. Males generally store more vegetation than females and adults usually store more than juveniles. Pikas deposit two kinds of fecal droppings: Hard brown round pellets and caecal pellets that are soft black shiny strings that form in the caecum. Caecal pellets have more energy value than stored plant food and the pika may consume them directly or store them for later.
American pikas are diurnal
. The total area of land which an American pika uses is known as a home range. Approximately 55% of its home range is territory which the pika defends against intruders. Territory size can vary from 410-709 m² and is dependent on configuration, distance to vegetation and quality of vegetation. The home ranges of pika may overlap with the distances of the home ranges of a mating pair being shorter than that of the nearest neighbors of the same sex. Spatial distances between adults of a pair is greatest during early and mid summer and reduces during late summer and early autumn. Pikas defend their territories with aggression. Actual aggressive encounters are rare and usually occur between members of the same sex and those unfamiliar with each other. A pika may intrude on another’s territory but usually when the resident is not active. During haying, territorial behavior increases.
Adult pikas of the opposite sex with territories adjacent form mated pairs. When there is more than one male available, females will exhibit mate choice. Pikas are reflex ovulators, that is ovulation only occurs after copulation, and they are also seasonally polyestrous. A female has 2 litters per year and these litters average 3 young each. Breeding takes place one month before the snow melts and gestation lasts approximately 30 days. Parturition occurs as early as March in lower elevations but occurs from April to June at higher elevations. Lactation significantly reduces a female's fat reserves and they only nurse the second litter if the first does not survive, despite exhibiting postpartum estrus. Pikas are born slightly altricial
, being blind, slightly haired, and having fully erupted teeth. They weigh between 10 and 12 grams at birth. At around nine days, they are albe to open their eyes. Mothers forage most of the day and return to the nest once every two hours to nurse the young. Young become independent after 4 weeks, around the same time they are weaned. Young may remain in their natal or an adjoining home range. When in their home range, young occupy areas away from their relatives as much as possible. Dispersal appears to be caused by competition for territories.
Pikas are vocal, using both calls and songs to communicate among themselves. A call is used to warn when a predator is lurking nearby, and a song is used during the breeding season
(males only), and during autumn (both males and females). Predators of the pika include eagle
s, hawk
s, coyote
s, bobcat
s, fox
es, and weasel
s.
elevation limits, pikas typically become inactive and withdraw into cooler talus
openings. Because of behavioral adaptation, American pikas also persist in the hot climates of Craters of the Moon
and Lava Beds
National Monuments (Idaho and California, respectively). Average and extreme maximum surface temperatures in August at these sites are 32°C (90°F) and 38°C (100°F), respectively
Recent studies suggest some populations are declining due to various factors, most notably global warming
. A 2003 study, published in the Journal of Mammalogy, showed nine of 25 sampled populations of American pika had disappeared in the Great Basin, leading biologists to conduct further investigations to determine if the species as a whole is vulnerable.
In 2010, the US government considered, then decided not to add the American pika under the US Endangered Species Act; in the IUCN Red List
it is still considered a Species of Least Concern
.
The Pikas in Peril Project , funded through the National Park Service
Climate Change Response Program, began data collection in May 2010. A large team of academic researchers and National Park Service staff are working together to address questions regarding the vulnerability of the American pika to future climate change scenarios projected for the western United States. The study is being carried out in eight parks, with results expected in 2012.
Diurnal animal
Diurnality is a plant or animal behavior characterized by activity during the day and sleeping at night.-In animals:Animals that are not diurnal might be nocturnal or crepuscular . Many animal species are diurnal, including many mammals, insects, reptiles and birds...
species of pika
Pika
The pika is a small mammal, with short limbs, rounded ears, and short tail. The name pika is used for any member of the Ochotonidae, a family within the order of lagomorphs, which also includes the Leporidae . One genus, Ochotona, is recognised within the family, and it includes 30 species...
, is found in the mountains of western North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, usually in boulder fields at or above the tree line. They are herbivorous, smaller relatives of rabbits and hares.
Description
The American pika, known in the 19th century as the "little chief hare", has a small, round, ovate body. Their body length ranges from 162 to 216 millimeters (6-8 inches). Their hind feet range from 25 to 35 mm (1-1½ in). They usually weigh about 170 grams (6 ounceOunce
The ounce is a unit of mass with several definitions, the most commonly used of which are equal to approximately 28 grams. The ounce is used in a number of different systems, including various systems of mass that form part of the imperial and United States customary systems...
s). Body size can vary among populations. In populations with sexual dimorphism
Sexual dimorphism
Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...
, males are slightly larger than females.
The American pika is intermediate in size among pikas. The hind legs of the pika do not seem to be much longer than its front legs and its hind feet are relatively short when compared to most other lagomorphs. It has densely furred soles on its feet except for black pads at the ends of the toes. The ears are moderately large and sub-orbicular and are hairy on both surfaces, normally dark with white margins. The pika has a tail that is "buried" and is longer relative to body size compared to other lagomorphs. Its has a slightly rounded skull with a broad and flat pre-orbital region. The fur color of the pika is the same for both sexes but varies by subspecies and season. The dorsal fur of the pika ranges from grayish to cinnamon-brown, often colored with tawny or orchraceous hues, during the summer. During winter, the fur becomes grayer and longer. The dense under-fur is usually slate-gray or lead colored. It also has whitish ventral fur.
Distribution and habitat
The American pika can be found throughout the mountains of western North AmericaNorth America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, from central British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
to the US
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
states of Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
, Washington, Idaho
Idaho
Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....
, Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
, Wyoming
Wyoming
Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...
, Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
, Utah
Utah
Utah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
, Nevada
Nevada
Nevada is a state in the western, mountain west, and southwestern regions of the United States. With an area of and a population of about 2.7 million, it is the 7th-largest and 35th-most populous state. Over two-thirds of Nevada's people live in the Las Vegas metropolitan area, which contains its...
, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
and New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
.
Pikas inhabit talus fields that are fringed by suitable vegetation on alpine areas. They will also live in piles of broken rock. Sometimes, they will live in man-made substrate such as mine tailings and piles of scrap lumber. Pikas usually have their den and nest sites below rock around 0.2-1 m in diameter but often sit on larger and more prominent rocks. They generally reside in scree
Scree
Scree, also called talus, is a term given to an accumulation of broken rock fragments at the base of crags, mountain cliffs, or valley shoulders. Landforms associated with these materials are sometimes called scree slopes or talus piles...
near or above the tree line. Pikas are restricted to cool moist microhabitats on high peaks or watercourses. Intolerant of high diurnal temperatures, in the northern portion of their range they may be found near sea level, but in the south they are rare below 2500 metres (8,202.1 ft). Pikas rely on existing spaces in the talus for homes and do not dig burrows. However they can enlarge their home by digging.
Diet
The American pika is a generalist herbivoreHerbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
. It eats a large variety of green plants, including different kinds of grass
Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...
es, sedge
Cyperaceae
Cyperaceae are a family of monocotyledonous graminoid flowering plants known as sedges, which superficially resemble grasses or rushes. The family is large, with some 5,500 species described in about 109 genera. These species are widely distributed, with the centers of diversity for the group...
s, thistle
Thistle
Thistle is the common name of a group of flowering plants characterised by leaves with sharp prickles on the margins, mostly in the family Asteraceae. Prickles often occur all over the plant – on surfaces such as those of the stem and flat parts of leaves. These are an adaptation that protects the...
s and fireweed
Fireweed
Epilobium angustifolium, commonly known as Fireweed , Great Willow-herb , or Rosebay Willowherb , is a perennial herbaceous plant in the willowherb family Onagraceae...
. Pikas can meet their water demands from the vegetation they eat. However they drink water if it is available. Pikas have two different ways of foraging. They will directly consume food (feeding) or they will cache food in haypiles to use for a food source in the winter (haying). The pika feeds throughout the year while haying is limited to the summer months. Since they do not hibernate, pikas have greater energy demands than other montane mammals. In addition, they also make 13 trips per hours to collect vegetation when haying. It seems that the timing of haying correlates to the amount of precipitation from the previous winter. Pikas will start and then quit haying earlier in years following little snow and early spring. In areas at lower elevations, haying begins before the snow has melted at high altitudes while at higher elevations, haying continues after it ends in lower elevations.
When haying, pikas harvest plants in a deliberate sequence, corresponding to their seasonal phenology. They seem to assess the nutritional value of available food and harvest accordingly. Pikas select plants that have the higher caloric, protein, lipid and water content. Forbs and tall grass tend to be hayed more than eaten directly. Haypiles tend to be stored under the talus near the talus-meadow interface although they may be constructed on the talus surface. Males generally store more vegetation than females and adults usually store more than juveniles. Pikas deposit two kinds of fecal droppings: Hard brown round pellets and caecal pellets that are soft black shiny strings that form in the caecum. Caecal pellets have more energy value than stored plant food and the pika may consume them directly or store them for later.
Life history
Diurnal
Diurnal may refer to:* Diurnal cycle, any pattern that recurs daily** Diurnality, the behavior of animals and plants that are active in the daytime* Diurnal motion, the apparent motion of stars around the Earth...
. The total area of land which an American pika uses is known as a home range. Approximately 55% of its home range is territory which the pika defends against intruders. Territory size can vary from 410-709 m² and is dependent on configuration, distance to vegetation and quality of vegetation. The home ranges of pika may overlap with the distances of the home ranges of a mating pair being shorter than that of the nearest neighbors of the same sex. Spatial distances between adults of a pair is greatest during early and mid summer and reduces during late summer and early autumn. Pikas defend their territories with aggression. Actual aggressive encounters are rare and usually occur between members of the same sex and those unfamiliar with each other. A pika may intrude on another’s territory but usually when the resident is not active. During haying, territorial behavior increases.
Adult pikas of the opposite sex with territories adjacent form mated pairs. When there is more than one male available, females will exhibit mate choice. Pikas are reflex ovulators, that is ovulation only occurs after copulation, and they are also seasonally polyestrous. A female has 2 litters per year and these litters average 3 young each. Breeding takes place one month before the snow melts and gestation lasts approximately 30 days. Parturition occurs as early as March in lower elevations but occurs from April to June at higher elevations. Lactation significantly reduces a female's fat reserves and they only nurse the second litter if the first does not survive, despite exhibiting postpartum estrus. Pikas are born slightly altricial
Altricial
Altricial, meaning "requiring nourishment", refers to a pattern of growth and development in organisms which are incapable of moving around on their own soon after hatching or being born...
, being blind, slightly haired, and having fully erupted teeth. They weigh between 10 and 12 grams at birth. At around nine days, they are albe to open their eyes. Mothers forage most of the day and return to the nest once every two hours to nurse the young. Young become independent after 4 weeks, around the same time they are weaned. Young may remain in their natal or an adjoining home range. When in their home range, young occupy areas away from their relatives as much as possible. Dispersal appears to be caused by competition for territories.
Pikas are vocal, using both calls and songs to communicate among themselves. A call is used to warn when a predator is lurking nearby, and a song is used during the breeding season
Estrous cycle
The estrous cycle comprises the recurring physiologic changes that are induced by reproductive hormones in most mammalian placental females. Estrous cycles start after puberty in sexually mature females and are interrupted by anestrous phases or pregnancies...
(males only), and during autumn (both males and females). Predators of the pika include eagle
Eagle
Eagles are members of the bird family Accipitridae, and belong to several genera which are not necessarily closely related to each other. Most of the more than 60 species occur in Eurasia and Africa. Outside this area, just two species can be found in the United States and Canada, nine more in...
s, hawk
Hawk
The term hawk can be used in several ways:* In strict usage in Australia and Africa, to mean any of the species in the subfamily Accipitrinae, which comprises the genera Accipiter, Micronisus, Melierax, Urotriorchis and Megatriorchis. The large and widespread Accipiter genus includes goshawks,...
s, coyote
Coyote
The coyote , also known as the American jackal or the prairie wolf, is a species of canine found throughout North and Central America, ranging from Panama in the south, north through Mexico, the United States and Canada...
s, bobcat
Bobcat
The bobcat is a North American mammal of the cat family Felidae, appearing during the Irvingtonian stage of around 1.8 million years ago . With twelve recognized subspecies, it ranges from southern Canada to northern Mexico, including most of the continental United States...
s, fox
Fox
Fox is a common name for many species of omnivorous mammals belonging to the Canidae family. Foxes are small to medium-sized canids , characterized by possessing a long narrow snout, and a bushy tail .Members of about 37 species are referred to as foxes, of which only 12 species actually belong to...
es, and weasel
Weasel
Weasels are mammals forming the genus Mustela of the Mustelidae family. They are small, active predators, long and slender with short legs....
s.
Conservation and decline
As they live in the high and cooler mountain regions, they are very sensitive to high temperatures, and are considered to be one of the best early warning systems for detecting global warming in the western United States. Temperature increases are suspected to be one cause cause of American pikas moving higher in elevation in an attempt to find suitable habitat, as well as cooler temperatures. American pikas, however, cannot easily migrate in response to climate change, as their habitat is currently restricted to small, disconnected habitat "islands" in numerous mountain ranges. Pikas can die in six hours when exposed to temperatures above 25.5°C (77.9°F) if individuals cannot find refuge from heat. In warmer environments, such as during midday sun and at lowerelevation limits, pikas typically become inactive and withdraw into cooler talus
Scree
Scree, also called talus, is a term given to an accumulation of broken rock fragments at the base of crags, mountain cliffs, or valley shoulders. Landforms associated with these materials are sometimes called scree slopes or talus piles...
openings. Because of behavioral adaptation, American pikas also persist in the hot climates of Craters of the Moon
Craters of the Moon National Monument and Preserve
Craters of the Moon National Monument and Preserve is a national monument and national preserve located in the Snake River Plain in central Idaho, U.S.A. It is along US 20 , between the small cities of Arco and Carey, at an average elevation of above sea level...
and Lava Beds
Lava Beds National Monument
Lava Beds National Monument is located in northeastern California, in Siskiyou and Modoc Counties. The Monument lies on the northeastern flank of the Medicine Lake Volcano, with the largest total area covered by a volcano in the Cascade Range....
National Monuments (Idaho and California, respectively). Average and extreme maximum surface temperatures in August at these sites are 32°C (90°F) and 38°C (100°F), respectively
Recent studies suggest some populations are declining due to various factors, most notably global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
. A 2003 study, published in the Journal of Mammalogy, showed nine of 25 sampled populations of American pika had disappeared in the Great Basin, leading biologists to conduct further investigations to determine if the species as a whole is vulnerable.
In 2010, the US government considered, then decided not to add the American pika under the US Endangered Species Act; in the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
it is still considered a Species of Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
.
The Pikas in Peril Project , funded through the National Park Service
National Park Service
The National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...
Climate Change Response Program, began data collection in May 2010. A large team of academic researchers and National Park Service staff are working together to address questions regarding the vulnerability of the American pika to future climate change scenarios projected for the western United States. The study is being carried out in eight parks, with results expected in 2012.