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, 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: sniffing each and every potential bite. Instead, the bamboo lemur will stand in one spot and visually scan the nearby foliage for that special shoot.
Adult size: 1.5 – 1.9 lbs (700 – 850 g)
Social structure: family groups of two to seven individuals
Habitat: bamboo groves in forests across Madagascar
Diet: at least 2/3rds bamboo, occasionally other leaves and fruit to supplement.
Mating: highly seasonal, October – January in Madagascar
Gestation: 140 days
Number of young: one in the wild, occasionally twins in human care
IUCN Status: vulnerable
DLC Naming theme: words that start with “Be-”
Malagasy Names: Bokombolo, Kotrika
Size and Appearance
Eastern lesser bamboo lemurs are the smallest of all the bamboo lemurs, weighing only 2 pounds (0.9 kg) and standing about 13 inches (33 cm) tall. This species has uniformly grey fur that is dense enough to keep them dry in the tropical rainforest they call home. This fur is thick enough that it often hides the lemurs’ ears, giving them a very round profile.
Bamboo lemurs will only eat a significant amount of mature bamboo leaves in the dry season when young shoots are scarce. 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.
This feeding strategy is unique due to the fact that bamboo, especially young bamboo, contains high levels of cyanide. In a day, the small bamboo lemur can consume cyanide at a concentration that could kill a human. Like pandas, bamboo lemurs have evolved to neutralize the toxins in their diet and consume a food source they do not have to share with other species in their home range.
At the Duke Lemur Center bamboo lemurs are offered fresh or frozen shoots daily with dry chow, fruits, and vegetables to supplement their diet.
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 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. If the females need to transport the infant to another location, they do so by picking it up in their mouths and carrying it. 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 to travel short distances 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. Unfortunately, lesser bamboo lemur breeding pairs have been unsuccessful in human care for years. The last successful birth of a bamboo lemur occurred in October 1998.
In the wild, the eastern bamboo lemur lives in groups ranging from three to six, and which might contain more than one female of breeding age. 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 may suggest a close taxonomic affiliation.
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, bamboo lemurs, unlike the sifaka, will move quadrupedally.
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 in Madagascar and contact calls for short and long distances. Listen to some of those vocalizations recorded at the DLC HERE.
Habitat and Conservation
The eastern lesser bamboo lemur is relatively abundant in the wild and found in primary and secondary rainforests on both coasts of Madagascar. Certain species of bamboo thrive as secondary growth, in areas where virgin rainforest has been cut down. While this may let bamboo lemurs expand their livable habitat, this species is one of the most hunted of all lemur species and their population is declining.