Social organization, territoriality, and behavior

The pikas have two sharply contrasting forms of social organization. Those species that inhabit rocky or talus habitats are extremely unsocial. In the American pika (Ochotona princeps), males and females hold separate territories of comparable size and rarely interact. Rock-dwelling pikas in Asia tend to live in pairs on a communal territory, but they still avoid one another and engage in few social encounters. Territory size for rock-dwelling pikas is variable, and largely dependent on the quality of vegetation adjoining the talus; the lower the quality of surrounding vegetation the larger the territory. For most species territory size is large, compared to the size of its occupant(s), and average sizes range from approximately 600-2400 yd2 (500-2,000 m2). Most rock-dwelling pikas are rather pugnacious and chase conspecifics whenever they are encountered. Neighboring adult males and females suppress this aggressive urge some of the time, and adults do not always chase their own young.

In contrast, burrowing pikas are among the most social of mammals. These animals live in family burrow systems functioning as a family territory. As the summer breeding season progresses and young from sequential litters are weaned, the density on these family territories becomes high. In the plateau pika (Ochotona curzoniae) approximately 10 families occupy each hectare, and each family may be comprised of up to 30 pikas, yielding regional densities of 120 per acre (300/ha). Affiliative social interactions are frequently expressed among family members, including such behaviors as nose-rubbing, sitting-in-contact, boxing, wrestling, and grooming. Aggression, generally in the form of a long chase or fur-flying fight, is reserved for pikas that wander off of their family territory and into the domain of their neighbors.

Variability in social organization is also seen in the lep-orids. Most hares and rabbits live solitary lives and are nonterritorial. Some form temporary feeding aggregations, and the Arctic hare (Lepus arcticus) can be seen in huge herds. Territories are defended by the largely solitary European hare (L. europaeus). Most representatives of the Sylvilagus spp. occupy relatively stable overlapping home ranges of only a few acres, and several species have a male dominance hierarchy which controls the social structure of their population.

Unlike any other leporid, the European rabbit (Oryctolagus cuniculus) is extremely social. Defended territories are usually small (approximately 2.5 acres [1 ha]) and made up of a "warren"—an interconnected maze of burrows. A warren usually consists of six to 12 adults controlled by a dominant male who sits at the top of a strict linear hierarchy of dominance. Most rabbits remain in the area of their warren for life.

Communication and senses

The dominant form of communication in lagomorphs is olfactory—all species have a keen ability to detect odors. In turn, all lagomorphs have glands on their cheeks, chin, and/or groin areas that are used to rub pheromones on their coat during grooming, or to deposit scent marks on rocks or shrubs. Urine and feces are also used to transmit olfactory messages. Individual animals broadcast these pheromones to advertise their reproductive status or to demarcate their territorial boundary.

Very few lagomorphs are vocal. Some hares and rabbits communicate by thumping their big hind feet, and hares can expel a deep grumbling sound. The piercing shriek given by leporids when in distress is legendary. But, only the Zacatuche (Romerolagus diazi) and pikas (genus Ochotona) are truly vocal. Rock-dwelling pikas utter a restricted repertoire of calls, just a short call used to advertise their territory and alert neighbors of the presence of predators and a long-call (or song) given by males during the breeding season. Burrowing pikas express a rich variety of calls, including whines, trills, and muffle-like sounds, that complement their social milieu, and males also give a breeding season long-call.

While vocal communication is restricted in most lago-morphs, they still possess an acute sense of hearing. Hares in particular, but all lagomorphs, have large ears that assist in detecting predators.

Pikas have small eyes and do not seem to rely significantly on their sense of vision. On the other hand, leporids are known for their large laterally set eyes that provide a nearly circular field of vision. This arrangement provides for restricted visual acuity (which the animals do not need, as their food is sedentary), but enhances their ability to detect motion from all angles in order to avoid the approach of predators. Many leporids, in particular those living in open habitats, flash the white underside of their fluffy tails during flight to alert conspecifics of the presence of predators. Interestingly, species living in forested habitats have dark tails and do not use this form of communication.

Activity patterns

With the exception of the nocturnal steppe pika (Ochotona pusilla), all pikas are diurnally active. When temperatures are warm, pikas tend to restrict their activity to early morning and late afternoon hours.

Most leporid activity occurs at night, although many species can also be seen active during the day particularly at dawn and dusk. For example, one might classify the European rabbit (Oryctolagus cuniculus) as noctural, but its preferred feeding time is dawn.

Migratory movements

No lagomorphs migrate. The term is sometimes associated with rare mass movements of some hare species (for example the European hare) following highly unusual climatic events but these cases do not represent true migration.

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