Emperor Tamarin (Saguinus Imperator)
The emperor tamarin, (Saguinus imperator), is a species of tamarin allegedly named for its resemblance to the German emperor Wilhelm II. It lives in the southwest Amazon Basin, in east Peru, north Bolivia and in the west Brazilian states of Acre and Amazonas.
The fur of the emperor tamarin is predominantly grey colored, with yellowish speckles on its chest. The hands and feet are black and the tail is brown. Outstanding is its long, white mustache, which extends to both sides beyond the shoulders. The animal reaches a length of 23–26 centimetres (9–10 in), plus a 35–41.5 cm (13.8–16.3 in) long tail. It weighs approximately 500 grams (18 oz).
Subspecies and subfamilies
- Black-chinned emperor tamarin, Saguinus imperator imperator
- Bearded emperor tamarin, Saguinus imperator subgrisescens
The Saguinus imperator belongs to the family Callitrichidae, which is a family of New World monkeys. The Callitrichidae contains the two general species of marmosets and tamarins. There are several different Saguinus groups within the Callitrichinae subfamily, including S. midas, S. mystax, S. nigricollis, S. bicolor, S. oedipus, and S. inustus. Saguinus imperator belongs to the S. mystax group. The emperor tamarin has two subspecies: Saguinus imperator imperator and Saguinus imperator subgrisescens. The predominant difference between the two is that Saguinus imerator subgrisecens has a long white beard, giving it its customary name the “bearded emperor tamarin.”
(Saguinus imperator imperator) Black-chinned emperor tamarin
There are claws on each of the animal’s toes and fingers, aside from the great toe which has a nail. While it has a definitive long mustache, it also has almost inconspicuous white hairs on its chin. Visually, however, the saguinus imperator has a black chin. The hair on its chest and belly are a mixture of red, orange, and white hairs. On its back, the fur is dark brown. The inner side of its arms and legs are an orange-like color.
(Saguinus imperator subgrisecens) Bearded emperor tamarin
Saguinus imperator subgrisecens, the bearded emperor tamarin, typically has the same biological structure[clarification needed] as S. imperator imperator. However, its main differences lie in the variation of color on its chest, belly, and arms. Also, in addition to its long white mustache, this subspecies has a large white-haired beard, unlike S. imperator imperator, which merely has faint black whiskers upon its chin.
Aside from the color changes and visually striking beard, the two tamarins essentially have the same body structure. They are very small, compared to most other primates. Using their claws, they cling to tree branches, maintaining a consistent verticality in the jungle environment. To navigate their lush environment, which typically is in rainforests, they leap and move quickly through trees, rarely touching the forest floor. 
Habitat and ecology
Emperor tamarins occur mostly in Amazonian lowland and lower montane rain forests, as well as remnant, primary, and secondary forests.  Amazonian lowland holds an abundance of water during high sea level due the flooding by nearby water sources. This contributes to a very humid, tropical climate to occur year-round.  The lower montane forests Emperor tamarins are primarily found in are considered tropical and moist with an abundance of vegetation. During the dry season, flowering peaks and in the wet season, flowering decreases, affecting the diets of the Emperor tamarins.  Many Emperor tamarins are found in Amazonian secondary forests, which account for 40% of the forest area. Secondary forests appear to accumulate woody plant species at a relatively rapid rate but the mechanisms involved are complex and no clear pattern emerged. This process helped grow the trees in which Emperor tamarins primarily reside in when found in secondary forests.  The average size of the group tamarins live in is two to eight individuals, but it can range from four to eighteen. They reside in the form of an extended family group, usually with only one breeding female. The groups they live in usually only consist of Emperor tamarins, but occasionally can also include Saddle-back tamarins considering their food scavenging groups often join together. This is due to the fact Emperor tamarins stick to staying higher in the canopy above 10 meters, and Saddle-back tamarins usually stay below 10 meters.
Emperor tamarins consume a wide range of specimens in their daily dietary routine. They eat fruits and flowers, many of which are readily available due to their flourishing vegetational habitats.  They also eat the exudes of plants such as gums and saps, easily gouged from the trees they are living in. Many also choose to consume animal prey, such as insects and frogs, depending upon what type of forest they are located in. Emperor tamarins have been reported to engage in mixed species associations with Weddell’s saddle-back tamarins(S. fuscicollis weddelli), spending up to 20% of their day foraging in these mixed species troops. Emperor tamarin society is based on a dominance hierarchy led by a dominant female and her mate. It is the dominant emperor tamarins who form these foraging troops, forming these mixed species groups is beneficial to the emperor tamarins and their ability to find quality food resources. Some speculated at one point that females of the species were the primary scavengers of food, specifically fruit and flowers, because of their enhanced abilities over the males in the form of stronger visual cues. Upon research, it was found that males and females possess the same abilities to locate food patches. Though it does not discriminate between the two species, females do tend to be the more dominate hunters, which led to the speculation.  Weddell’s saddle-back tamarins are better and faster at locating food resources. S.fuscicollis are a smaller bodied species of tamarins and are able to move fast through the canopy, saddle-back tamarins often arrive to the food resources before the emperor tamarins. The emperor tamarins follow the saddle-back tamarins to food patches using their larger size to intimidate the feeding Weddell’s saddle-back tamarins into leaving the feeding tree. This foraging strategy is beneficial to both species, the mixed species troops provide more vigilance for predator protection. Observations of tamarins foraging in mixed species troops using feeding platforms and monitoring fruiting trees show that these troops spend less time foraging in smaller patches of fruiting trees with limited amounts of fruiting resources. 
Reproduction and infant care
The age of first reproduction in emperor tamarins is around 16-20 months old, with a gestation period of up to 6 months. Tamarins are seasonal breeders, breeding is based around food availability, most births occur during the wet season when food resources are in abundance.
Tamarin species were once thought to be a monogamous species, but observations of emperor tamarins in the wild prove show that they have a polyandrous mating system, with one dominant female mating with multiple males. This mating system works to insure paternal investment in offspring, if a female mates with multiple males and give birth to a litter, males are more likely to invest because of the possibility that one off the infants will carry their genes onto the next generation. Due to high rates of twinning or multiple births in Emperor tamarins parental care and paternal investment is important to infant survival. Previously the only knowledge of tamarin infant care came from captive studies on Cotton-top tamarins (S. oedipus), which demonstrated that infant survival is dependent on helpers. Helpers are either older female offspring of the dominant female that have remained in their natal group or the males that most frequently interact with the dominant female. Infant carrying has a high energetic cost due to the relatively large fetal weight of infants to the weight of adults. Helpers provide the extra support to remove some of the cost of caring for multiple infants. Male emperor tamarins have been observed to spend the most time with infants often carrying both infants while the dominant female forages. Male emperor tamarins are reported to be more observant of the infants and more protective, they are known to react faster to infant distress calls then females. Infant mortalityin the wild is at its most highest during the first 5-15 weeks of their lives when the begin to first move around and explore on their own, this is because one of the greatest threats to infant survival is falling from the canopy. 
According to Bairrao, Saguinus imperator can be found in Peru; places in Brazil and Bolivia that are parts of the southwest Amazon Basin; east of the upper Purus river; between the Purus river and Rio Acre; east of the upper Juruá river to the Tarauacá river and Juruparí river; west to the Urubamba river and Inuya river; and south of Tahuamanú river. 
According to Buchanan’s research, the subspecies of S. Imperator, S. i. imperator, are rarely found in Los Campos and Buena Vista, which are located near the left bank of the Rio Acre; and in the basin of the São Pedro River. 
Lastly, according to Buchanan and Bairrao, the subspecies, S. i. subgrisescens, can be found on the upper banks of the Juruá River; south the of Tahuamanú river and along the banks of the Muyumanu river. 
More Info in WIKIPEDIA