American pika

The American pika (Ochotona princeps), 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. 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 mm (6.4 to 8.5 in). Their hind feet range from 25 to 35 mm (1–1½ in). They usually weigh about 170 g (6.0 oz). 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 suborbicular and are hairy on both surfaces, normally dark with white margins. The pika's 'buried' tail is longer relative to body size compared to other lagomorphs. It has a slightly rounded skull with a broad and flat preorbital 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 underfur is usually slate-gray or lead-colored. It also has whitish ventral fur.Males are called bucks and females are called does like rabbits. The American pika can be found throughout the mountains of western North America, from central British Columbia and Alberta in Canada to the US states of Oregon, Washington, Idaho, Montana, Wyoming, Colorado, Utah, Nevada, California and New Mexico. Out of the 30 existing species of pika, it is one of only two which inhabit North America, along with the collared pika (Ochotona collaris). In relation to the distribution of the American pika, the collared pika is located farther north of those regions and is separated by a gap of about 500 miles (800 km) extending across British Columbia and Alberta. Pikas inhabit talus fields that are fringed by suitable vegetation on alpine areas. They also live in piles of broken rock. Sometimes, they 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 2,500 metres (8,200 ft). Pikas rely on existing spaces in the talus for homes and do not dig burrows. However, they can enlarge their home by digging. The American pika is a generalist herbivore. It eats a large variety of green plants, including different kinds of grasses, sedges, thistles and fireweed. Although pikas can meet their water demands from the vegetation they eat, they do drink water if it is available in their environment. Pikas have two different ways of foraging: they directly consume food (feeding) or they 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. They also make 13 trips per hour to collect vegetation when haying, up to a little over 100 trips per day. It seems that the timing of haying correlates to the amount of precipitation from the previous winter. Pikas 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.