Hapalemur griseus has no less than three widely used common names: the eastern lesser bamboo lemur, the gray gentle lemur, and the gray bamboo lemur. To avoid confusion, any discussion of bamboo lemurs, eastern lesser bamboo lemurs, or gray gentle lemurs on this website, unless otherwise specified, refers to the variety of bamboo lemur housed at the Lemur Center: the eastern lesser bamboo lemur, Hapalemur griseus.
Bamboo lemurs appear to have greater manual dexterity and superior hand-eye coordination than other lemurs. More than likely this is due to their preference for small but tasty bamboo shoots. While foraging through a thick stand of bamboo, searching for these tender bits, the bamboo lemur simply doesn’t have time for the typical lemur food searching strategy which is to sniff each and every potential bite. Instead, the bamboo lemur will stand in one spot, and visually scan the nearby foliage for that special shoot.
Like sifaka, bamboo lemurs are, in general, vertical clingers and leapers. They prefer to maintain an upright position when traveling through the trees, and will do so by quickly jumping from one vertical bamboo stalk to another as they make their way through the forest. However, when on the ground, or a horizontal tree branch, the bamboo lemurs, unlike the sifaka, will move quadrupedally, galloping along like small cats.
The bamboo lemurs have a rich vocal repertoire, which includes an unusual call the females make as they are entering their yearly estrous period. They also have separate calls for aerial and ground predators and contact calls for short and long distances. Far from the complex rainforest environment of Madagascar, in the context of a captive environment where the only social group is the small family group necessary for carefully managed captive breeding, it is difficult to determine the full meaning of this, or any other lemur vocalization.
Only in the winter, when shoots are scarce, will the bamboo lemur eat a significant amount of mature bamboo leaves. At certain times of the year, bamboo accounts for 90% of their diet. At other times of the year berries, grass stems and other young leaves supplement this lemur’s diet.
In captivity, the bamboo lemur will avidly feed on monkey chow, fruits and vegetables, with bamboo only necessary as an enrichment supplement to the diet.
In the rainforests of Madagascar, the greater bamboo lemur and the golden bamboo lemur are much more selective in choosing which species of bamboo they will feed on, and this certainly accounts for their extremely limited distribution. Both species prefer feeding on Madagascar’s endemic giant bamboo which is not at all common. However, to avoid feeding competition when occupying the same forest, which these two species sometimes do, each lemur feeds on a different part of the giant bamboo. The golden bamboo lemur prefers leaf petioles and new shoots, while the greater bamboo lemur is highly selective towards the tender inner pith, and will literally shred the toughest and most mature stalks to get access to the tasty pith within.
Bamboo lemur females come into estrus once a year, typical for a diurnal lemur. Single infants, and very rarely twins, are born after a gestation of some 140 days, longer than average for a lemur. Infant care is highly unusual in this species. Rather than carry the infant, as is typical of most lemur mothers, or keep the infant in a nest, as ruffed lemur and aye-aye mothers do, the bamboo lemur mother does something else entirely.
From the day of birth the mother might “park” the infant on a small branch in the middle of the bamboo grove while she goes off foraging, returning periodically to groom and nurse the infant. The fact that the middle of a bamboo grove is a dense thicket protected from predators surely has aided in the evolution of this strategy. In captivity, the mother might park the infant on the side of a cage, a protective heat lamp basket, or a small branch. If the females need to transport the infant to another location, they do so by picking it up in their mouths and carrying it via this method. Mouth carrying is seldom seen after the infants get to be two weeks old, however, as by this age the infants are becoming surprisingly mobile and may not stay put if parked in a given location.
Infants older than a couple of weeks will also often hop onto the mother’s neck and travel short distances thusly, but some mothers are extremely reluctant to transport their infants in this manner, and will nip at the infant until it hops off. In those cases, the mobile infant, especially when frightened, will simply jump onto the nearest group member, whether it is a sibling or its father. In fact, bamboo lemur juveniles and fathers play a more active role in infant care than is typical in lemurs. After a surprisingly short period of time, however, the infants are navigating around completely on their own.
Unfortunately, lesser bamboo lemur breeding pairs have been unsuccessful at producing infants at the Lemur Center for years. The last successful birth of a bamboo lemur occurred in October, 1998. Current DLC population is down to 2 individuals with little hope for future increases.
In the wild, the gray gentle lemur lives in groups ranging from three to six, and which in some instances might contain more than one female of breeding age. Home range size ranges from 8 ha to 15 ha depending on the quality of the habitat. As is true of most lemur species, females are dominant over males, and in the wild as well as in captivity they will invest some energy in chasing the males away from choice feeding sites.
Scent marking is an important method of communication for bamboo lemurs. Surprisingly, the male bamboo lemur is equipped with a set of scent glands exactly like those found on male ring-tailed lemurs, but not found on any other type of lemur. Like ring-tailed males, male bamboo lemurs engage in “stink fights” where the tail is repeatedly drawn through the animal’s brachial scent gland to anoint it, and then waved over the head in the direction of a rival. Although not as showy a display due to their drabber coloration, the similarity in these two species suggests a close taxonomic affiliation.
Habitat & Conservation
The eastern lesser bamboo lemur is relatively abundant in the wild. Certain species of bamboo thrive as secondary growth, in areas where virgin rainforest has been cut down. In other words, as virgin rainforest in Madagascar falls to the axe, the bamboo lemur might benefit! In fact, this type of bamboo lemur is one of the few lemurs whose livable habitat may actually be expanding and whose wild population might subsequently be increasing. However, it is one of the most hunted of all the lemur species, and it is frequently kept as a pet. This lemur is protected in three National Parks, four Nature Reserves, and five Special Reserves.
Unfortunately the conservation picture for the more endangered varieties of bamboo lemur is grim. The lake Alaotra bamboo lemur’s habitat in Madagascar is vanishing at an alarming rate. Found only around Madagascar’s Lake Alaotra, and living in the reed and papyrus beds and marshes surrounding the lake, it is the only lemur which might swim in the course of day to day foraging (although this is by no means the preferred method of locomotion!) This lemur has the most restricted habitat of any, and as the reed beds surrounding the lake are continually being cut and burned by the local villagers, it is shrinking rapidly. The JWPT in the UK has an excellent breeding program for this species.
The golden bamboo lemur was only discovered in 1985 in Ranomafana National Park in Madagascar. Although it occurs in two protected areas (it is also found in Andringitra Nature Reserve in southeastern Madagascar), the range of this lemur is very small, and its habitat requirements are very strict. This species is not found in captivity.
The greater bamboo lemur is by far the largest species of bamboo lemur, with adult males weighing more than five pounds. It has an extremely limited range, and although it is found in two protected areas, the population continues to be threatened by slash and burn agriculture and is considered critically endangered, along with the golden bamboo lemur.