Eulemur macaco is considered to be quite adaptable and has been reported from a wide variety of habitats that include primary forest, secondary forest, forest-agricultural mosaics, and timber plantations. Fruits make up the bulk of the diet throughout the year, except during the dry season (May - October) when young leaves, seed pods, flowers and nectar take on greater importance, supplemented with fungi, mushrooms, bark, and invertebrates. Studies in the Lokobe Strict Nature Reserve on Nosy Be and in the forests of the Ambato Massif suggest that the Black Lemur is a significant pollinator of the Traveller's Palm (Ravenala madagascariensis) and the leguminous canopy tree species Parkia madagascariensis (Birkinshaw and Colquhoun, 1998). At Lokobe, it also appears to be the sole seed-disperser for many tree species (Birkinshaw 1999, 2001). The species is considered cathemeral (e.g. Colquhoun 1998, Andrews and Birkinshaw 1998); group size ranges from two to 15 animals. The mating season takes place in late April and May and females give birth to a single young, usually between September and November (Mittermeier et al. 2008, and references therein). Weaning occurs at 6–7 months, and sexual maturity at around two years of age (first mating by young females can occur at approximately 20 months of age, with first birthing at approximately 2 years of age).

Eulemur macaco is found in the “Sambirano” phytogeographic domain of north-western Madagascar. The Mahavavy Nord River marks the northern and north-eastern limits of its geographic distribution; the south-western/southern limit of its distribution is formed by the Andranomalaza River. The eastern limit of Black Lemur distribution is not conclusively defined, but appears to include the eastern slopes of the Tsaratanana Massif (Mittermeier et al. 2010). There are further populations in the forests of the Ampasindava Peninsula, on the off-shore islets of Nosy Be (Parc National Lokobe) and Nosy Komba, and in the coastal forests northeast of Ambanja (including the peninsula leading to Nosy Faly). It has also been introduced to the small islet of Nosy Tanikely. This species (as well as its hybrids) is sympatric with E. fulvus on the Galoko, Manongarivo, and Tsaratanana Massifs and in the Ifasy and Ramena river valleys to the west of the Tsaratanana massif (Birkinshaw et al. 2000); the Black Lemur is also sympatric with E. rubriventer on the eastern slopes of the Manongarivo Massif (Goodman and Schütz, 2000). Populations of E. macaco occur across a wide altitudinal range, from sea level up to 1,600 m (Goodman and Schütz, 2000). Tinsman and co-authors estimate that the AOO of E. macaco is declining, due primarily to habitat fragmentation and loss; bushmeat hunting within the AOO of E. macaco is also a pervasive problem (Tinsman et al. 2019).

It has been estimated that there will be a 35% reduction in the species' range from 2000 to 2080 due to climate change alone (Brown and Yoder 2015).

This species is likely affected by national trends in forest habitat loss: Madagascar lost 37% of its forest cover from 1973 to 2014, with an annual deforestation rate of 1.1%/year from 2010 to 2014. Almost half of Madagascar's forest (46%) is now located within less than 100 metres from the forest edge (Vieilledent et al. 2018).