THE CAPYBARA

The capybara (Hydrochoerus hydrochaeris) is the largest rodent in the world. Its closest relatives are guinea pigs and rock cavies, and it is more distantly related to the agouti, chinchillas, and the coypu. Native to South America, the capybara inhabits savannas and dense forests and lives near bodies of water. It is a highly social species and can be found in groups as large as 100 individuals, but usually lives in groups of 10–20 individuals. The capybara is not a threatened species and is hunted for its meat, hide and also for a grease from its thick fatty skin which is used in the pharmaceutical trade.^[2]

Etymology

Its common name is derived from Tupi ka'apiûara, a complex agglutination of kaá (leaf) + píi (slender) + ú (eat) + ara (a suffix for agent nouns), meaning "one who eats slender leaves", or "grass-eater".^[3] The scientific name, both hydrochoerus and hydrochaeris, comes from Greek ὕδωρ (hydor = water) + χοίρος (choiros = pig, hog).^[4][5]

Play media

(video) A Capybara at a zoo.

Classification and phylogeny

The capybara and the lesser capybara belong to the subfamily Hydrochoerinae along with the rock cavies. The living capybaras and their extinct relatives were previously classified in their own family Hydrochoeridae.^[6] Since 2002, molecular phylogenetic studies have recognized a close relationship between Hydrochoerus and Kerodon^[7] supporting placement of both genera in a subfamily of Caviidae.^[4] Paleontological classifications have yet to incorporate this new taxonomy and continue to use Hydrochoeridae for all capybaras, while using Hydrochoerinae for the living genus and its closest fossil relatives, such as Neochoerus.^[8][9] The taxonomy of fossil hydrochoerines is also in a state of flux. In recent years, the diversity of fossil hydrochoerines has been substantially reduced.^[8][9] This is largely due to the recognition that capybara molar teeth show strong variation in shape over the life of an individual.^[8] In one instance, material once referred to four genera and seven species on the basis of differences in molar shape is now thought to represent differently aged individuals of a single species, Cardiatherium paranense.^[8]

Description

The capybara has a heavy, barrel-shaped body and short head, with reddish-brown fur on the upper part of its body that turns yellowish-brown underneath. Its sweat glands can be found in the surface of the hairy portions of its skin, an unusual trait among rodents.^[6] The animal lacks under hair, and guard hair differs little from over hair. Adult capybaras grow to 107 to 134 cm (3.51 to 4.40 ft) in length, stand 50 to 64 cm (20 to 25 in) tall at the withers, and typically weigh 35 to 66 kg (77 to 146 lb), with an average in the Venezuelan llanos of 48.9 kg (108 lb).^[10][11] The top recorded weights are 91 kg (201 lb) for a wild female from Brazil and 73.5 kg (162 lb) for a wild male from Uruguay.^[6][12] The dental formula is 1.1.0.01.1.3.3.^[6] Capybaras have slightly webbed feet and vestigial tails.^[6] Their hind legs are slightly longer than their forelegs; they have three toes on their rear feet and four toes on their front feet.^[13] Their muzzles are blunt, with nostrils, and the eyes and ears are near the top of their heads. Females are slightly heavier than males.

Grazing in Shepreth Wildlife Park

Its karyotype has 2n = 66 and FN = 102.^[4]

Ecology

 

Capybaras are semi-aquatic mammals^[11] found throughout almost all countries of South America (except Chile^[14]). They live in densely forested areas near bodies of water, such as lakes, rivers, swamps, ponds, and marshes,^[10] as well as flooded savannah and along rivers in tropical forest. Capybara have flourished in cattle ranches.^[6] They roam in home ranges averaging 10 hectares (25 acres) in high-density populations.^[6]
Many escapees from captivity can also be found in similar watery habitats around the world. Sightings are fairly common in Florida, although a breeding population has not yet been confirmed.^[15] In 2011, one was spotted in the Central Coast of California.^[16]

Diet and predation

Foraging

Group of capybaras

Capybaras are herbivores, grazing mainly on grasses and aquatic plants,^[10][17] as well as fruit and tree bark.^[11] They are very selective feeders^[18] and will feed on the leaves of one species and disregard other species surrounding it. They eat a greater variety of plants during the dry season, as fewer plants are available. While they eat grass during the wet season, they have to switch to more abundant reeds during the dry season.^[19] Plants that capybaras eat during the summer lose their nutritional value in the winter and therefore are not consumed at that time.^[18] The capybara's jaw hinge is not perpendicular and they thus chew food by grinding back-and-forth rather than side-to-side.^[20] Capybaras are coprophagous, meaning they eat their own feces as a source of bacterial gut flora, to help digest the cellulose in the grass that forms their normal diet, and to extract the maximum protein and vitamins from their food. They may also regurgitate food to masticate again, similar to cud-chewing by a cow.^[21] As is the case with other rodents, the front teeth of capybaras grow continually to compensate for the constant wear from eating grasses;^[14] their cheek teeth also grow continuously.^[20]
Like its cousin the guinea pig, the capybara does not have the capacity to synthesize vitamin C, and capybaras not supplemented with vitamin C in captivity have been reported to develop gum disease as a sign of scurvy.^[22]
They can have a life span of 8–10 years on average,^[23] but live less than four years in the wild, as they are "a favourite food of jaguar, puma, ocelot, eagle and caiman".^[14] The capybara is also the preferred prey of the anaconda.^[24]

Natural history

The capybara male has a gland on its nose

Capybaras are very gregarious. While they do sometimes live solitarily, they are more commonly found in groups that average 10–20 individuals, with two to four adult males, four to seven adult females and the rest juveniles.^[25] Capybara groups can consist of as many as 50 or 100 individuals during the dry season,^[21][26] when the animals gather around available water sources. Males are organized in stable, linear hierarchies. The dominant male in each group is significantly heavier than any of the subordinates, but among subordinates, status is not correlated with weight.^[27] The dominant male is positioned in the center of the group while subordinates are on the periphery. These hierarchies are established early in life among the young with play fights and mock copulations.^[25] The most dominant males have access to the best resources.^[27]
Capybaras are very vocal and, when in groups, chatter with each other to establish social bonds, dominance or general group census.^[26] They can make dog-like barks^[21] when threatened or when females are herding young.^[28] Capybaras have two different scent glands; a morillo, located on the snout, and an anal gland.^[29] Both sexes have these glands, but males have much larger morillos and their anal pockets can open more easily. The anal glands of males are also lined with detachable hairs. A crystalline form of scent secretion is coated on these hairs and are released when in contact with objects like plants. These hairs have a longer-lasting scent mark and are tasted by other capybaras. A capybara marks by rubbing its morillo on an object or by walking over a scrub and marking with its anal gland. A capybara can spread its scent further by urinating. However, females usually mark without urinating and mark less frequently than males overall. Females mark more often during the wet season when they are in estrus. In addition to objects, males will also mark females.^[29]

Reproduction

Family swimming

Mother with typical litter of four pups

Skeleton

When in estrus, the female's scent changes subtly and nearby males begin pursuit.^[27] In addition, a female will alert males she is in estrus by whistling though her nose.^[21] During mating, the female has the advantage and mating choice. Capybaras mate only in water, and if a female does not want to mate with a certain male, she will either submerge or leave the water.^[21][26] Dominant males are highly protective of the females, but they usually cannot prevent all the subordinates from copulating.^[27] The larger the group, the harder it is for the male to watch all the females. Dominant males secure significantly more matings than each subordinate, but subordinate males, as a class, are responsible for more matings than each dominant male.^[27] The lifespan of the capybara's sperm is longer than that of other rodents.^[30]
Capybara gestation is 130–150 days, and usually produces a litter of four capybara babies, but may produce between one and eight in a single litter.^[6] Birth is on land and the female will rejoin the group within a few hours of delivering the newborn capybaras, which will join the group as soon as they are mobile. Within a week, the young can eat grass, but will continue to suckle—from any female in the group—until weaned at about 16 weeks. The young will form a group within the main group.^[14] Alloparenting has been observed in this species.^[26] Breeding peaks between April and May in Venezuela and between October and November in Mato Grosso, Brazil.^[6]

Activities

Though quite agile on land (capable of running as fast as a horse),^[31] Capybaras are equally at home in the water. They are excellent swimmers, and can remain completely submerged for up to five minutes,^[10] an ability they use to evade predators. Capybaras can sleep in water if need be, only keeping their noses out of the water. During midday, as temperatures increase, they wallow in water and then graze in late afternoons and early evenings.^[6] They also spend a lot of time wallowing in mud.^[13] They rest around midnight and then continue to graze before dawn.

Conservation and human interaction

Capybaras are not considered a threatened species;^[1] their population is stable throughout most of their South American range, though in some areas hunting has reduced their numbers.^[10][14]
Capybaras are hunted for their meat and pelts in some areas,^[32] and otherwise killed by humans who see their grazing as competition for livestock. In some areas, they are farmed, which has the effect of ensuring the wetland habitats are protected. Their survival is aided by their ability to breed rapidly.^[14]
Capybaras can be found in many areas in zoos and parks,^[20] and may live for 12 years in captivity.^[14] Capybaras are gentle and will usually allow humans to pet and hand-feed them.
The European Association of Zoos and Aquaria (EAZA) tasked Drusillas Park in Alfriston, Sussex to keep the studbook for Capybaras, to monitor captive populations in Europe. The studbook includes information about all births, deaths and movements of capybaras, as well as how they are related.^[33]
Capybaras are farmed for meat and skins in South America.^[34] The meat is considered unsuitable to eat in some areas, while in other areas it is considered an important source of protein.^[6] In parts of South America, especially in Venezuela, capybara meat is popular during Lent and Holy Week as the Catholic Church previously gave a special dispensation that allows for its consumption while other meats are generally forbidden.^[35]
Although it is illegal in some states,^[36] capybaras are occasionally kept as pets in the United States.^[37]



 



 

THE PORCUPINES

Porcupines are rodents with a coat of sharp spines, or quills, that defend them from predators. They are indigenous to the Americas, Southern Asia, Europe, and Africa. Porcupines are the third largest of the rodents, behind the capybara and the beaver. Most porcupines are about 25–36 in (64–91 cm) long, with an 8–10 in (20–25 cm) long tail. Weighing 12–35 lb (5.4–15.9 kg), they are rounded, large and slow. Porcupines come in various shades of brown, gray, and the unusual white. Porcupines' spiny protection resembles that of the unrelated erinaceomorph hedgehogs and monotreme echidnas.
The common porcupine is an herbivore. It eats leaves, herbs, twigs and green plants like clover and in the winter it may eat bark. The North American porcupine often climbs trees to find food. The African porcupine is not a climber and forages on the ground.^[1] It is mostly nocturnal,^[2] but will sometimes forage for food in the day. Porcupines have become a pest in Kenya and are eaten as a delicacy.^[3] A male porcupine urinates on a female porcupine prior to mating, spraying the urine at high velocity. ^{[4][5][6][7][8]}
The name porcupine comes from Middle French porc espin (spined pig).^[9] A regional American name for the animal is quill pig.^[10]

  

Species

Old World porcupine

A porcupine is any of 29 species of rodent belonging to the families Erethizontidae (genera: Coendou, Sphiggurus, Erethizon, Echinoprocta, and Chaetomys) or Hystricidae (genera: Atherurus, Hystrix, and Trichys). Porcupines vary in size considerably: Rothschild's Porcupine of South America weighs less than a kilogram (2.2 lb); the Crested porcupine found in Italy, Sicily, North Africa and sub-Saharan Africa can grow to well over 27 kg (60 lb). The two families of porcupines are quite different, and although both belong to the Hystricognathi branch of the vast order Rodentia, they are not closely related.
The eleven Old World porcupines tend to be fairly big, and have spikes that are grouped in clusters.
The two subfamilies of New World porcupines are mostly smaller (although the North American Porcupine reaches about 85 cm or 33 in in length and 18 kg or 40 lb), have their quills attached singly rather than grouped in clusters, and are excellent climbers, spending much of their time in trees. The New World porcupines evolved their spines independently (through convergent evolution) and are more closely related to several other families of rodent than they are to the Old World porcupines. Porcupines have a relatively high longevity and had held the record for being the longest-living rodent,^[11] until it was recently broken by the naked mole-rat.^[12]

Quills

Quills come in varying lengths and colors, depending on the animal's age and species.

Porcupines' quills, or spines, take on various forms, depending on the species, but all are modified hairs coated with thick plates of keratin, and they are embedded in the skin musculature. Old World porcupines (Hystricidae) have quills embedded in clusters, whereas in New World porcupines (Erethizontidae), single quills are interspersed with bristles, underfur and hair.
Quills are released by contact with them, or they may drop out when the porcupine shakes its body. New quills grow to replace lost ones. From ancient times, it was believed that porcupines could throw their quills at an enemy, but this has long been refuted.^[13][14]

Uses

Porcupines are only occasionally eaten in western culture, but are very popular in Southeast Asia, particularly Vietnam, where the prominent use of them as a food source has contributed to significant declines in their populations.^[15][16][17]
More commonly, their quills and guardhairs are used for traditional decorative clothing. For example, their guardhairs are used in the creation of the Native American "porky roach" headdress. The main quills may be dyed, and then applied in combination with thread to embellish leather accessories such as knife sheaths and leather bags. Lakota women would harvest the quills for quillwork by throwing a blanket over a porcupine and retrieving the quills it left stuck in the blanket.^[18]
Porcupine quills have recently inspired a new type of hypodermic needle. Thanks to backward-facing barbs on the quills, when used as needles, they are particularly good at two things – penetrating the skin and remaining in place.^[19]

Habitat

A pair of North American porcupines in their habitat in Quebec

Porcupines occupy a short range of habitats in tropical and temperate parts of Asia, Southern Europe, Africa, and North and South America. Porcupines live in forests, deserts, rocky outcrops and hillsides. Some New World porcupines live in trees, but Old World porcupines stay on the rocks. Porcupines can be found on rocky areas up to 3,700 m (12,100 ft) high. Porcupines are generally nocturnal but are occasionally active during daylight.

Hunting Porcupine near the town of Cassem, The Book of Wonders by Marco Polo (first book), illumination stored at the French national library (manuscript 2810)

Classification

A North American porcupine

North American porcupine eating grass and clover

Porcupines are distributed into two evolutionary independent groups of the order Rodentia, suborder Hystricomorpha.^{[20][21][22][23][24][25][26][27]}



 

THE SOUTHERN ELEPHANT SEALS

The southern elephant seal (Mirounga leonina) is one of the two extant species of elephant seals. It is both the largest pinniped and member of the order Carnivora living today, as well as the largest Antarctic seal. The seal gets its name from its great size and the large proboscis of the adult males, which is used to make extraordinarily loud roaring noises, especially during the mating season. Rather larger at average than the male northern elephant seal (which is 40% lighter) and male walrus (the average North Pacific bull, of the larger race, is 2.5 times lighter), the adult bull southern elephant seal is without rival the largest carnivoran alive.^[3][4][5] An average adult male southern elephant seal weighs six to seven times more than the largest terrestrial carnivorans, the polar bear and Kodiak bear.^[6][7]

Description

Skeleton of a southern elephant seal

Close-up of juvenile southern elephant seal, showing face and mouth detail

The southern elephant seal is distinguished from the northern elephant seal (which does not overlap in range with this species) by its greater body mass and a shorter proboscis. The southern males also appear taller when fighting, due to their tendency to bend their backs more strongly than the northern species. This seal shows extreme sexual dimorphism in size, seemingly the largest of any mammal by mass, with the males typically five to six times heavier than the females.^[8] In comparison, in two other very large marine mammals with high size sexual dimorphism, the northern elephant seal and the sperm whale, the males weigh on average about three times as much as the females, and only more than four times as heavy in exceptionally heavy bull specimens.^[9] While the females southern elephant seal typically weighs 400 to 900 kg (880 to 1,980 lb) and measures 2.6 to 3 m (8.5 to 9.8 ft) long, the bulls typically weigh 2,200 to 4,000 kg (4,900 to 8,800 lb) and measure from 4.2 to 5.8 m (14 to 19 ft) long.^[10][11] An adult female averages 771 kg (1,700 lb) in mass, while a mature bull averages about 3,175 kg (7,000 lb).^[12][13] Studies have indicated elephant seals from South Georgia are around 30% heavier and 10% longer on average than those from Macquarie Island.^[8] The record-sized bull, shot in Possession Bay, South Georgia, on 28 February 1913, measured 6.85 m (22.5 ft) long and was estimated to weigh a hulking 5,000 kg (11,000 lb), although it was only partially weighed peacemeal.^[7][14] The maximum size of a female is 1,000 kg (2,200 lb) and 3.7 m (12 ft).^[7] The eyes are large, round, and black. The width of the eyes, and a high concentration of low-light pigments, suggest sight plays an important role in the capture of prey. Like all seals, elephant seals have hind limbs whose ends form the tail and tail fin. Each of the "feet" can deploy five long, webbed fingers. This agile dual palm is used to propel water. The pectoral fins are used little while swimming. While their hind limbs are unfit for locomotion on land, elephant seals use their fins as support to propel their bodies. They are able to propel themselves quickly (as fast as 8 km/h (5.0 mph)) in this way for short-distance travel, to return to water, to catch up with a female, or to chase an intruder.
Pups are born with fur and are completely black. Their coats are unsuited to water, but protect infants by insulating them from the cold air. The first moulting accompanies weaning. After moulting, the coats may turn grey and brown, depending on the thickness and moisture of hair. Among older males, the skin takes the form of a thick leather which is often scarred.
Like other seals, the vascular system of elephant seals is adapted to the cold; a mixture of small veins surround arteries, capturing heat from them. This structure is present in extremities such as the hind legs.

Range and population

The world population was estimated at 650,000 animals in the mid-1990s,^[1] and was estimated in 2005 at between 664,000 and 740,000 animals.^[15] Studies have shown the existence of three geographic subpopulations, one in each of the three oceans.
Tracking studies have indicated the routes traveled by elephant seals, demonstrating their main feeding area is at the edge of the Antarctic continent. While elephant seals may come ashore in Antarctica occasionally to rest or to mate, they gather to breed in subantarctic locations.

Southern elephant seal harem on a beach on the Kerguelen Islands

The largest subpopulation is in the South Atlantic, with more than 400,000 individuals, including about 113,000 breeding females on South Georgia;^[16] the other breeding colonies of the Atlantic subpopulation are located on the Falkland Islands and Valdes Peninsula in Argentina (the only continental breeding population).
The second subpopulation, in the south Indian Ocean, consist of up to 200,000 individuals, three-quarters of which breed in the Kerguelen Islands and the rest in the Crozet Islands, Marion and Prince Edward Islands, and Heard Island. Some individuals also breed on Amsterdam Island.

King penguins and southern elephant seal at South Georgia Island

The third subpopulation of about 75,000 seals is found in the subantarctic islands of the Pacific Ocean south of Tasmania and New Zealand, mainly Macquarie Island.
Colonies once existed in Tasmania, Saint Helena, and the Juan Fernández Islands off the coast of Chile. Some individuals at the time of moulting have been found in South Africa or Australia. Lost animals have also been reported from time to time on the shores of Mauritius, with two reports from the Río Guayas estuary area in Ecuador.^[15]
After the end of large-scale seal hunting in the 19th century, the southern elephant seal recovered to a sizable population in the 1950s; since then, an unexplained decline in the subpopulations of the Indian Ocean and Pacific Ocean has occurred. The population now seems to be stable; the reasons for the fluctuation are unknown. Suggested explanations include a phenomenon of depression following a rapid demographic rebound that depletes vital resources, a change in climate, competition with other species whose numbers also varied, or even an adverse influence of scientific monitoring techniques.^{[citation needed]}

Lifestyle

Social behavior and reproduction

Bull elephant seals fighting

Elephant seals are among the seals that can stay on land for the longest periods of time, as they can stay dry for several consecutive weeks each year. Males arrive in the colonies earlier than the females and fight for control of harems when they arrive.^[17] Large body size confers advantages in fighting and the agonistic relationships of the bulls gives rise to a dominance hierarchy with access to harems and activity within harems, being determined by rank.^[18] The dominant bulls (“harem masters”) establish harems of several dozen females. The least successful males have no harems, but may try to copulate with a harem male's females when the male is not looking. The majority of primiparous females and a significant proportion of multiparous females mate at sea with roaming males away from harems.^[19]

Southern elephant seal (females): one is giving birth

An elephant seal must stay in his territory to defend it, which could mean months without eating, having to live on his blubber storage. Two fighting males use their weight and canine teeth against each other. The outcome is rarely fatal, and the defeated bull will flee; however, bulls can suffer severe tears and cuts. Some males can stay ashore for more than three months without food. Males commonly vocalize with a coughing roar that serves in both individual recognition and size assessment.^[18] Conflicts between high-ranking males are more often resolved with posturing and vocalizing than with physical contact.^[18]
Generally, pups are born rather quickly in the breeding season.^[20] After being born, a newborn will bark or yap and its mother will respond with a high-pitched moan.^[21] The newborn begins to suckle immediately. Lactation lasts an average of 23 days. Throughout this period, the female fasts. Newborns weigh about 40 kg (88 lb) at birth, and reach 120 to 130 kg (260 to 290 lb) by the time they are weaned. The mother loses significant weight during this time. Young weaned seals gather in nurseries until they lose their birth coats. They enter the water to practice swimming, generally starting their apprenticeship in estuaries or ponds. In summer, the elephant seals come ashore to moult. This sometimes happens directly after reproduction.

Feeding and diving

Southern elephant seal (just weaned pup): first bath

Satellite tracking revealed the seals spend very little time on the surface, usually a few minutes for breathing. They dive repeatedly, each time for more than 20 minutes, to hunt their prey —squid and fish— at depths of 400 to 1,000 m (1,300 to 3,300 ft). They are the deepest diving air-breathing non-cetaceans and have been recorded at a maximum of 2,133 m (6,998 ft) in depth.^[22]

Southern elephant seal (young males): collective mudbath during moulting

As far as duration, depth, and the sequence of dives, the southern elephant seal is the best performing seal. In many regards, they exceed even most cetaceans. These capabilities result from nonstandard physiological adaptations, common to marine mammals, but particularly developed in elephant seals. The coping strategy is based on increased oxygen storage and reduced oxygen consumption.
In the ocean, the seals apparently live alone. Most females dive in pelagic zones for foraging, while males dive in both pelagic and benthic zones.^[23] Individuals will return annually to the same hunting areas. Due to the inaccessibility of their deep-water foraging areas, no comprehensive information has been obtained about their dietary preferences, although some observation of hunting behavior and prey selection has occurred.^[24]
While hunting in the dark depths, elephant seals seem to locate their prey, at least in part, using vision; the bioluminescence of some prey animals can facilitate their capture. Elephant seals do not have a developed system of echolocation in the manner of cetaceans, but their vibrissae (facial whiskers), which are sensitive to vibrations, are assumed to play a role in search of food. When at the subantarctic or Antarctic coasts, the seals can also consume molluscs, crustaceans, nothothens,^[25] lanternfish,^[25] krill, cephalopods^[26] or even algae. Weaned pups may be prey for killer whales (orcas) and (rarely) by leopard seals, while juveniles may also fall prey to orcas.^[27]

Conservation

Play fight

After their near extinction due to hunting in the 19th century, the total population was estimated at between 664,000 and 740,000 animals in 2005,^[15] but as of 2002, two of the three major populations were declining.^[28] The reasons for this are unclear, but are thought to be related to the distribution and declining levels of the seals' primary food sources.^[28] Most of their most important breeding sites are now protected by international treaty, as UNESCO World Heritage Sites, or by national legislation.

Minazo

One of the most famous southern elephant seals is Minazo, which lived in Japan's Enoshima Aquarium from when he was a half-year old until his death in 2005 at age 11.^[29] Minazo became popular for his signature bucket-holding, tongue-lolling pose. In 2006, Minazo was memorialized by the Japanese noise musician Masami Akita, also known as Merzbow, in a two-volume album,^[30][31] with artwork by Jenny Akita showing Minazo holding his beloved bucket.
In 2007, Minazo became the subject of an image macro similar to lolcat called "lolrus". In his liner notes, Masami Akita suggested Minazo's frequent and demanding performances left him exhausted, contributing ultimately to his death.^{[citation needed]} Akita's intention in celebrating Minazo was to highlight the plight of captive animals used for performance before public audiences.^[29] Minazo has also featured on several t-shirt designs.