They are considered an "evolutionary enigma" in that they are the largest of the extant species in Lemuridae, yet exhibit reproductive traits more common in small, nocturnal lemurs, such as short gestation periods (~102 days) and relatively large average litter sizes (~2–3).

Ruffed lemurs also build nests for their newborns (the only primates that do so), carry them by mouth, and exhibit an absentee parental system by stashing them while they forage.

[5] Although there is still much debate about the origins of lemurs on Madagascar, it is generally accepted that a single rafting event, similar to the one that brought New World monkeys to South America, occurred around 50–80 million years ago and allowed ancestral lemurs to cross the Mozambique Channel and colonize the island,[6][7] which had already split from Africa (while it was joined to the Indian subcontinent), approximately 160 million years ago.

Today, the endemic primate fauna of Madagascar contains over three-quarters of the extant species of the suborder Strepsirrhini, which had been abundant throughout Laurasia and Africa during the Paleocene and Eocene epochs.

Three subspecies of black-and-white ruffed lemur, which had been published decades earlier, were also recognized as variegata, editorum, and subcincta,[9] although studies have not been entirely conclusive.

Found at sites in central and southwestern Madagascar,[12] Varecia insignis and V. jullyi were very similar to modern ruffed lemurs, but more robust and assumed to be more terrestrial, and thus more prone to predation by early human settlers.

[15] Being highly arboreal and the most frugivorous of the lemurs, they thrive only in primary forest with large fruiting trees,[11] where they spend most of their time in the upper canopy.

[14] The seeds of the fruit they eat pass through their digestive tract and are propagated throughout the rainforests in their feces, helping to ensure new plant growth and a healthy forest ecosystem.

Confined to the island's seasonal eastern tropical rainforests, it is uncommon to rare throughout its range, which historically ran from the Masoala Peninsula in the northeast to the Mananara River in the south.

[11][15] Additionally, a concentrated population of black-and-white ruffed lemurs, of the subspecies Varecia variegata subcincta, can also be found on the island reserve of Nosy Mangabe in Antongil Bay.

[15] Despite this, the diet changes little between seasons, except that females will consume more high-protein, low-fiber items, such as young leaves and flowers, during pregnancy and lactation in order to offset the energy costs of reproduction.

[11] In a study done at Masoala Peninsula on red ruffed lemurs three levels of organization were identified and defined: communities, core groups, and subgroups.

[13] This suggests that although their feeding ecology is inflexible, being tied to widely distributed, patchy, and sometimes scarce fruit, ruffed lemurs instead adapt the social system in order to survive.

[20] As with all strepsirrhine primates, olfactory communication is used extensively by ruffed lemurs – scent marking in territorial defense and disputes, as well as female greeting displays.

During the hot, rainy season, the loud, raucous calls that are a hallmark of ruffed lemurs allow groups to remain in contact and maintain spacing.

[19][21] Abrupt roars are also more common during high activity and aside from alerting group members to the presence of an avian predator, they probably also help maintain contact with individuals outside of visual range or indicate an aggressive/defensive response to a disturbance.

[13] Shortly before mating season begins, females exhibit swelling of the sex skin, which reaches its peak around the middle of their 14.8 day estrous cycle.

[9][11][14][19] Starting three weeks prior to birth,[13] females begin constructing the nest from twigs, branches, leaves, and vines, locating it within her core area and 10 to 25 metres (33 to 82 ft) above ground.

[19] In order to find food, she will leave the infants alone in the nest or, after the first couple of weeks, will carry them in her mouth and stash them in concealed locations in the canopy while she forages.

[11][14] Since this early developmental period corresponds with the end of the cold, dry season, which offers the least amount of fruit, energy is conserved for lactation while travel is limited.

[11] Unlike other diurnal primates, which usually carry their infants with them,[13] ruffed lemur mothers will stash their young by concealing them in the canopy foliage, leaving them to rest and sit quietly for several hours while she forages and performs other activities.

[13] During the season when females practice infant stashing, males effectively lighten the reproductive burden of up to several mothers by guarding, huddling, grooming, travelling, playing with and feeding the young.

Completely dependent upon large fruiting trees, neither species appears to be flexible with its habitat choice,[15] with selective logging resulting in significantly lower population densities.

Historically, this species has been considered more threatened due to its highly restricted range, compared to the widely distributed black-and-white ruffed lemur.

[14] Despite this, an assessment done in 2012 and published in 2014 reinstated the critically endangered status for the red ruffed lemur, largely due to the surge in illegal logging in Masoala National Park following the 2009 Malagasy political crisis.

[13] The hardwoods that are favored for construction materials and selectively logged are also preferred by ruffed lemurs for their fruits and potentially affect their travel routes through the canopy.

[11] On this peninsula, firearms are used in addition to traditional traps, known as laly, which involve a 5 metres (16 ft) strip of cleared forest with snares set on the few remaining branches that allow the lemurs to cross.

In the United States, captive breeding is managed by the Species Survival Plan (SSP), a program developed by the Association of Zoos and Aquariums (AZA).

[30] Although reintroduction is seen as a last resort among conservationists, a combination of in situ conservation efforts, such as legal protection, public education, the spread of sustainable livelihoods, and reforestation offer hope for ruffed lemurs.

[30] So far, the results have shown some success, with 10 surviving longer than one year, 3 individuals integrating into wild groups, and 4 offspring have been born to or sired by released lemurs, all of which were parent-raised.