This tree-dwelling primate is solely active during the daylight hours, particularly in the cooler mornings and late afternoons (2). It lives in stable troops of 2 to 15 individuals, usually consisting of an adult pair and their offspring (2). They rest huddled together at night, often in a dense tangle of vines (4), around seven to ten metres above the ground (2). Moving around its forest habitat by running along branches, up and down trunks, and leaping between trees, the pygmy marmoset feeds on fruits, buds, insects, and exudates from trees (2). Its lower canine teeth are specially suited to gouging holes in trees to enable it to feed on exudates, and within the range of each marmoset group one or more trees can be found which are riddled with holes (2). The majority of pygmy marmoset births occur in two peaks each year: between November and January, and May and June (2). In captivity, gestation lasts around 20 weeks and most of the births are of twins (2) (5). Sexual maturity is reached between 18 and 24 months and one pygmy marmoset is known to have lived for over 11 years (2).

The diminutive pygmy marmoset is the smallest monkey in the world (4). Its tiny body has greyish, black mixed with buff, or brownish-gold fur on the back, sometimes with a greenish tinge, and white, tawny or orangish fur on the underparts (2). The squirrel-like hands and feet are yellowish or orangish (2) (5), and bear sharp claw-like nails which are suited to clinging to trees (4). The tail has indistinct dark rings on a lighter background (2) (5). A longer mane of hair surrounds the face, covering the ears (5), and white marks at the edges of the mouth and a white vertical line on the nose are thought to make communication through facial expressions more conspicuous in the dim light of dense forest (4). Female pygmy marmosets are slightly heavier than males (5). It is a fairly quiet monkey, but can produce a variety of vocalisations for communicating, including a high, sharp warning whistle and a clicking sound to indicate threat (2).

Following Van Roosmalen and Van Roosmalen (1997), the Western Pygmy Marmoset C. p. pygmaea occurs in the upper Amazon basin, north of the Rio Solimões in Brazil west from the Rio Japurá, and south of the Río Caquetá in Colombia, Amazonian Ecuador and Peru, north of the Solimões-Amazonas-Marañon, and east (left bank) of the Rio Pastaza in Peru. The easternmost localities in Brazil include the Paraná do Aranapu and Paraná do Jarauá on the lower Rio Japurá. Hernández-Camacho and Cooper (1976) and Defler (2003, 2004) recorded that it is well known south of the Río Caquetá in Colombia, but that reports of its occurrence further north in the upper Río Guaviare region, remain to be confirmed. The only evidence to date is a captive specimen believed to have been obtained from Cano Morrocoy on the south bank of the Río Guaviare. Izawa (1975) reported that it is absent from the Río Peneya, north of the Río Caquetá, and during further surveys was unable to confirm its presence anywhere else north of the Río Caquetá, although in a later publication (Izawa 1979) he indicated that it may occur on the Río Orteguaza, a northern tributary of the uppermost reaches. It would evidently be the subspecies throughout the Ecuadorian Amazon (De la Torre 2000). In Peru, Aquino and Encarnación (1994a) extend the range to the west of the Río Pastaza, to the region of the Cerro Campanquiz and basin of the Río Santiago, south to the Río Mayo in the Department of San Martín, a left bank tributary of the Río Huallaga, and to both sides of Río Marañon. The range south of the Río Marañon west of the Rio Huallaga could belong to either pygmaea or niveiventris according to the distribution proposed by Van Roosmalen and Van Roosmalen (1997).

Following Van Roosmalen and Van Roosmalen’s (1997) hypothesis, the Eastern Pygmy Marmoset C. p. niveiventris would be the form south of the Rio Solimões-Amazonas-Marañon and east of the lower Río Huallaga and middle to upper Río Ucayali. Aquino and Encarnación (1994a) indicated a larger range in Peru, occupying the entire Amazonian lowlands and Andean foothills east of the Río Mayo and the Río Huallaga above the Río Mayo, and including the Río Pachitea and the Río Ucayali basins, south to the upper Río Purus and the basins of the Rió Madre de Dios, and Río de las Piedras and the Rio Tambopata. From there it extends east into northern Bolivia to the region of Cobija (Freese et al. 1982; Buchanan-Smith et al. 2000). In Bolivia, Izawa (1979) and Izawa and Bejarano (1981) confined it to the north and west of the Ríos Orthon and Manuripi, northern tributaries of the Río Madre de Dios. However, Brown and Rumiz (1986) doubt that it occurs as far south as the Río Manuripi, limiting its distribution to the north of the Río Tahuamanu. Buchanan-Smith et al. (2000) confirmed their presence south of the Río Tahuamanu along the Rio Muyumanu. The easternmost record they obtained was at Santa Rosa on the Río Abunã. Its presence in northern Bolivia indicates that it should occur in parts of eastern Acre, including the Ríos Acre and uppermost Abunã, not indicated by Hershkovitz (1977). This was confirmed by Bicca-Marques and Calegaro-Marques (1995). Van Roosmalen and Van Roosmalen (1997) observed Pygmy Marmosets between the lower Rios Purus and Madeira, and indicated a range extending south at least to the Rio Ipixuna (right bank tributary of the Rio Purus). The Río Abunã is a left bank tributary of the Rio Madeira so it is reasonable to believe that Pygmy Marmosets occur throughout the interfluvium of the Rios Purus and Madeira south to the Rio Abunã. The southernmost locality reported so far is the Manu National Park, approximately 12ºS (Soini 1988).

Pygmy marmosets can be found in the Upper Amazon of South America. Its range includes western Brazil, southeastern Colombia, eastern Ecuador and Peru, as well as northern Bolivia.

Biogeographic Regions: neotropical (Native )

The pygmy marmoset inhabits the Amazon basin (5). Two subspecies are recognised: Cebuella pygmaea pygmaea is found in the state of Amazonas, Brazil, (north of the Rio Solimões), eastern Peru (north of the Río Maranõn), southern Colombia, northern Bolivia and north-eastern Ecuador. Cebuella pygmaea niveiventris also occurs in the state of Amazonas, Brazil, eastern Peru, and as far south as northern Bolivia, but is found south of the Rio Solimões and Río Maranõn (1).

Pygmy marmosets are the smallest living monkeys. Their head and body range in length from 130 to 370mm. The tail ranges from 150 to 420mm. The fur is fine, soft, and dense. The head and neck are generally dark brown to gray, while the back is black to gray with bluff mixed in. The under side is often orangish, but can range from white to tawny. The head and chest of this species have long tufts of hair, giving the appearance of a mane. The tail is not prehensile. Their forelimbs are shorter than their hind limbs. Pygmy marmosets have claws on all of their digits except the great toe, which has a flat nail. They have only two molars as opposed to the three in most other monkeys. Their canines are only slightly longer than their incisors; this condition is referred to as "short-tusked." Males and females are outwardly nearly indistinguishable; except for genitalia, they exibit no secondary sex characteristics (MacDonald 1984, Rathbun 1990, Nowak 1991, www.cris., www.philly).

Average mass: 124 g.

Average basal metabolic rate: 0.599 W.

Habitat and Ecology

Systems

• Terrestrial

Pygmy marmosets occupy trees and shrubs in tropical and floodplain forests. They also move farther into the forests, although their numbers are fewer there. Pygmy marmosets have also been known to use secondary forest habitats if there is suitable food available (MacDonald 1984, Rathbun 1990, www.philly).

Terrestrial Biomes: rainforest

This tiny primate inhabits lowland, tropical evergreen forests, most often on river floodplains (5), showing a preference for areas which are flooded for more than three months of the year (4). It seems able to tolerate disturbed habitats (4).

Pygmy marmosets gouge holes in trees and feed primarily on sap, gum, and latex. They also add spiders and insects, which are attracted to the sap from the tree, to their diet. Fruit is also eaten on rare occasions (MacDonald 1984, Rathbun 1990, Nowak 1991, www.fonz., www.philly).

Animal Foods: insects; terrestrial non-insect arthropods

Plant Foods: fruit; sap or other plant fluids

Primary Diet: herbivore (Eats sap or other plant foods)

Average lifespan

Status: captivity: 18.6 years.

Maximum longevity: 18.6 years (captivity) Observations: In captivity, these animals have been known to live up to 18.6 years (Richard Weigl 2005).

This monkey lives in small groups, thought to be family groups, in which only one female per group breeds per season. Some investigators have reported pygmy marmosets to be monogamous, others claim that females mate with several males (Nowak 1991).

Mating System: monogamous ; polyandrous

A baculum is present in males. The females have two mammae. Gestation lasts approximately 130 to 150 days. The female generally gives birth to fraternal twins. The offspring become sexually mature at 12 to 18 months. They reach adult size by the age of two. The life span in the wild is not known, but they have lived up to 16 years in capitivity (MacDonald 1984, Rathbun 1990, Nowak 1991, www.philly).

Average number of offspring: 2.

Range gestation period: 130 to 150 days.

Average weaning age: 3 months.

Range age at sexual or reproductive maturity (female): 12 to 18 months.

Range age at sexual or reproductive maturity (male): 12 to 18 months.

Key Reproductive Features: iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Average birth mass: 16 g.

Average number of offspring: 2.

The male assists in the birth and later care of the offspring. At birth the young weigh approximately 15g. The offspring are altricial and require constant care for the first two weeks. The other individuals in the group, the father and other adults, help care for the offspring. The father generally carries the young on his back and returns them to the mother for nursing. The young are nursed for up to three months.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Male)

Marmosets may become threatened due to habitat loss. Pygmy marmosets, however may be able to save themselves through their adaptability to the secondary forest (Rathbun 1990, www.philly, www.cris.).

IUCN Red List of Threatened Species: least concern

Classified as Least Concern (LC) on the IUCN Red List 2007 (1) and listed on Appendix I of CITES (3).

Population

Population Trend

Major Threats

The pygmy marmoset faces no significant threats and is therefore classified as Least Concern on the IUCN Red List (1). Despite significant habitat destruction occurring in some parts of its range, this does not seem to have affected pygmy marmoset numbers (4). However, some populations, such as in the Putumayo region of Colombia, may be impacted by collection for the pet trade (2), and those inhabiting areas visited heavily by tourists exhibited slightly different behaviour, which has raised some concern that this may affect their reproductive capabilities (4).

Conservation Actions

The pygmy marmoset is listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning that any international trade in this species should be carefully monitored (3). To reduce habitat degradation and human disturbances, there have been some efforts to raise awareness in local communities. For example, a programme in Ecuador was initiated to educate children in the importance of conserving primates (4). Such efforts are vital if the pygmy marmoset it to remain globally unthreatened.