This true lemur has not been studied intensively in the wild, but it is known to be fairly social.

As with most true lemur species, newborn Sanford's Lemurs cling to the mother's chest at first and after about 2 weeks they transfer onto her back.

The blue-eyed black lemur (Eulemur flavifrons), also known as the Sclater's lemur, is a species of true lemur.

This type of behavior was first documented in the 1960s in true lemur species as well as other Lemuridae species, such as ruffed lemurs and bamboo lemurs.

The common brown lemur's mating season is May and June.

The common brown lemur's diet consists primarily of fruits, young leaves, and flowers.

Sanford's brown lemur troop sizes range from 3 to 15 individuals, numbers varying depending on location.

Previously, this species was listed as a subspecies of the common brown lemur until elevated to species status in 2001.

Features that distinguish this species from the white-fronted brown lemur are the more prominent ear and cheek tufts.

Because all lemurs, including these two brown lemur species, are only native to the island of Madagascar, they are considered to be endemic.

The most frequently seen diurnal species are Coquerel's Sifaka and the common brown lemur.

In Marojejy National Park, it is sympatric with the white-fronted brown lemur.

Ruffed lemurs, along with several species of brown lemur were once included in the genus Lemur.

Sanford's brown lemur is said to display a cathemeral activity pattern, becoming most active in the afternoon and evening with occasional bouts at night.

Sanford's brown lemur is reported to associate with the crowned lemur during the wet season, a time of greater food availability.

White-fronted Brown Lemur.

Sanford's brown lemur females also tend to have longer, bushier hair on their cheeks than do white-fronted females.

Sanford's brown lemur is considered to be Endangered, and among the rarest of the brown lemurs.

In the western part of its range, the common brown lemur overlaps that of the mongoose lemur, and the two species sometimes travel together.

Common brown lemur (Eulemur fulvus)

ARKive - images and movies of the collared brown lemur (Eulemur collaris)

Common Brown Lemur (Eulemur fulvus)

In its environment, the collared brown lemur acts as a seed disperser, and is especially critical for the dispersal of large-seeded fruiting trees within its range.

Abundant diurnal lemurs that are found here include the Coquerel's Sifaka and the Common Brown Lemur.

There is no evidence of female dominance in this species, which is unusual in the Lemuridae family but appears to be frequent in brown lemur species.

Until a taxonomic revision in 2008, it was known as the white-collared brown lemur or white-collared lemur (Eulemur albocollaris).

In the wild, the collared brown lemur's range does not overlap with other brown lemurs, so it is rarely confused with other species.

The male collared brown lemur can be distinguished by their cream-colored or rufous beards, whereas the male gray-headed lemur has a white beard.

Until 2001, the species E. rufus was considered a subspecies of the common brown lemur, E. fulvus, after which it was classified as its own species.

However, other species in the genus Eulemur are either monogamous or polygynous.

Lemur species in the Eulemur genus are known to interbreed, despite having dramatically different chromosome numbers.

Like many of the species in the Eulemur genus, the blue-eyed black lemur is sexually dichromatic.

True lemurs, also known as brown lemurs, are the lemurs in genus Eulemur.

Among primates only the prosimians, with the exception of the tarsiers and several diurnal Eulemur species, have a tapetum lucidum.

Male crowned lemurs (Eulemur coronatus), on the other hand, will only act submissively when females act aggressively towards them.

In 2001, E. fulvus was split into several separate species, including Eulemur rufus, in which this species was included.

Common Brown Lemur (Eulemur fulvus)

Red-bellied Lemur (Eulemur rubriventer)

Sclater's Lemur (Eulemur flavifrons)

In western Madagascar, sympatric ring-tailed lemurs and red-fronted lemurs (Eulemur rufifrons) have been studied together.

The trait is hitherto known only from a single primate other than humans - Sclater's Lemur (Eulemur flavifrons) of Madagascar.

Yet some or all of the brown lemurs (Eulemur) are cathemeral, which means they may be active during the day or night, depending on factors such as temperature and predation.

Consequently the common name gray-headed lemur and the scientific name Eulemur cinereiceps were resurrected to replace white-collared brown lemur and E. albocollaris respectively.

Multiple births in lemurs are normally fraternal, and are known to occur in every five to six births in species such as the ring-tailed lemur and some Eulemur.

The second major episode of diversification occurred during the Late Miocene, approximately 8 to 12 mya, and included the true lemurs (Eulemur) and the mouse lemurs (Microcebus).

Diurnal lemurs include Coquerel's Sifaka, Propithecus coquereli and Common Brown Lemur, Eulemur fulvus with another 2 - 3 species of nocturnal lemurs.

The ring-tailed lemur shares many similarities with ruffed lemurs (genus Varecia) and true lemurs (genus Eulemur), and its skeleton is nearly indistinguishable from that of the true lemurs.

In addition to providing food for humans, this plant's fruit is eaten by certain animals, such as the Red-bellied Lemur (Eulemur rubriventer) and the ruffed lemurs (Varecia) of Madagascar's eastern rainforests.

Whereas the Eulemur genus relatives may exhibit ear tufts or a furry beard, these features are absent for Eulemur rubriventer, which has thickened fur around its ears, lending a fuller facial appearance.

The only other Eulemur species that occurs within the range of the black lemur is the common brown lemur, which overlaps with the black lemur at the extreme southern and eastern edge of its range, and the red-bellied lemur, on the Tsaratanana Massif.

However, ruffed lemurs were reassigned to the genus 'Varecia' in 1962, and due to similarities between the Ring-tailed Lemur and the bamboo lemurs, particularly in regards to molecular evidence and scent glands similarities, the brown lemurs were moved to the genus 'Eulemur' in 1988 .

Originally, the species was thought to have two subspecies, Eulemur macaco macaco and Eulemur macaco flavifrons, both of which were elevated to species status by Mittermeier et al. in 2008 to Eulemur macaco and Eulemur flavifrons respectively.