GOLDEN BAMBOO LEMUR

Hapalemur aureus

Geographic Distribution and Habitat
Golden bamboo lemurs, bokombolomena in Malagasy, are endemic to Madagascar, where they live in the southeastern bamboo-laden tropical forests and marshes. They occupy lowland and montane forests and they inhabit primary rainforests within a couple different protected areas, such as Ranomafana National Park and Andringitra National Park, which are actually connected by a forest corridor that is becoming increasingly fragmented. Their altitude range is from 2,624 to 4,265 ft (800–1300 m).

Golden bamboo lemur range, IUCN 2020

Size, Weight, and Lifespan
Golden bamboo lemurs have an average adult weight of 2.7 to 3.7 lbs (1.25–1.7 kg) with a body length of approximately 13.3 inches (34 cm). Their nonprehensile tail adds an additional 16 inches (41 cm), for a total length of 29.3 inches (74.4 cm).

The lifespan of golden bamboo lemurs has not been studied, though it is likely theirs is similar to some sister species like the eastern lesser bamboo lemur (Hapalemur griseus), which can live on average to 17.1 years (females) or 12.8 years (males). In captivity, the eastern lesser bamboo lemur has lived until age 23.

Appearance
Golden bamboo lemurs are dark grayish-brown with an underlying orange pelage on their stomach, their lower face, and the underside of their tails. They have wide, round eyes the color of desert pottery and black, furry snub faces with pink noses. Their fingers are long, used for gripping bamboo, and their tail is thick and nonprehensile.

As strepsirrhines, golden bamboo lemurs possess a tooth-comb used for grooming, but they also have additional cusps on the upper fourth premolars that are thought to help in crushing the tough, fibrous plant material they regularly consume. Each tooth has a serrated cutting edge, except for the molars (again, thought to help with their nearly exclusive bamboo diet).

Female and male golden bamboo lemurs are sexually monomorphic; that is, there are no physical differences between the two sexes other than their genitalia. Females only have one pair of mammae (mammary glands), which is located pectorally. Golden bamboo lemurs are significantly larger than most other bamboo lemur species.

Photo credit: Charles J Sharp/Creative Commons

What Does It Mean?

Arboreal:
Physically adapted to living primarily or exclusively in trees.

Crepuscular:
​Most active during twilight hours.

Diurnal:
Active during daylight hours.

Gene flow:
The transfer of genes from one population into another through breeding.

Gestation Period:
The time of pregnancy from conception until birth. 

Habitat fragmentation:
The process by which a large, continuous stretch of habitat gets divided into smaller, disjointed patches of habitat.

Infant parking:
Refers to mothers leaving their young in the nest at night.

Monogamous:
Having only one sexual partner. 

​Nonprehensile: 
​Incapable of grasping or gripping (opposite of prehensile: capable of grasping).

Pectorally:
Related to the breast or chest.

​Quadruped:
A being who walks on all fours.

Slash and burn agriculture:
​A method of unsustainable farming where farmers clear land by cutting and burning flora in order to create an empty field—a “swidden”—for cultivation. Such practices are detrimental to local ecosystems.

Sympatric: 
Occurring or living in the same area; overlapping in distribution.
​   ​
Tooth-comb:
The incisors on the lower front jaw of some animals are grouped as if to form a comb. The tooth-comb is used by these animals to groom and clean their fur or hair.

Visit the Glossary for more definitions

Diet
A golden bamboo lemur restaurant would have the least diversified menu out there—there would be about four different options, and most of them would be tall, hollow, and tannish-brown. Their name pretty much gives it away: golden bamboo lemurs eat . . . bamboo!

They eat the stuff year round with a whopping 78% of their diet allotted to Madagascar giant bamboo, though they have also been observed eating other bamboo grasses (10%), bamboo foliage (3%), fruit (4%), and other foods (5%). They are opportunistic frugivores.

When it is seasonally available, golden bamboo lemurs prefer to consume young giant bamboo and to discard the mature growth because new growth has a lower energy cost, is easier to digest, and has a higher concentration of protein. When young giant bamboo is not in season, they will consume varying parts of the mature growth. Golden bamboo lemurs ingest about 1.1 pounds (500 g) of bamboo daily.

Ironically, the most protein-rich part of giant bamboo is also the most deadly; giant bamboo shoots contain high amounts of cyanide. In the 1 pound of bamboo that golden bamboo lemurs eat daily, they consequently consume twelve times the lethal dose of cyanide in comparable mammals. Studies suggest that golden bamboo lemurs’ gastrointestinal tract and kidneys absorb the cyanide, as it has tested positive in urine but rarely in fecal matter.

Behavior and Lifestyle
Golden bamboo lemurs are arboreal and diurnal or crepuscular (depending on who you ask; there’s a debate among scientists about which category they fit into), with a defined rest period between mid-morning and early afternoon. Much of their waking hours are spent with their group while resting (50%), eating and foraging for bamboo (41%), and traveling (8%).

Golden bamboo lemurs are vertical clingers and leapers that always land feet-first, but they are quadrupeds on horizontal surfaces. Though they are not often found on the ground, like all bamboo lemurs, they are capable of running quickly.

Another bamboo lemur species, the eastern lesser bamboo lemur, is known to exhibit latrine behavior, where groups defecate repeatedly at specific sites; it is possible that golden bamboo lemurs also perform this action.

Fun Facts

The golden bamboo lemur was first discovered in 1985 in Ranomafana National Park; it was first described in 1987.

Golden bamboo lemur adults eat enough cyanide daily to kill an animal its size twelve times over.

Daily Life and Group Dynamics 
Golden bamboo lemurs live in small family groups with up to four individuals that consist of one adult male, one adult female, and smaller, younger adults or juveniles (so essentially, a monogamous pair and their offspring). The home range of a golden bamboo lemur is approximately 64 acres (26 hectares), but they travel generally less than 1,197.5 ft (365 m) a day.

At Ranomafana National Park, golden bamboo lemurs are sympatric with the eastern lesser bamboo lemur, brown mouse lemurs, greater dwarf lemurs, sportive lemurs, eastern avahis, aye-ayes, greater bamboo lemurs, red-fronted lemurs, red-bellied lemurs, and Milne-Edwards’s sifakas.

Luckily, despite the fact that eastern lesser bamboo lemurs and golden bamboo lemurs live together in the same habitat and consume the same general foods, they eat different parts (i.e., shoots vs. leaves), so they avoid competition by eating different parts of the same plants.

Communication
Golden bamboo lemurs are highly vocal with at least two distinct calls. They make a “hard grunt” sound, which is likely a contact call between family members that is sometimes responded to or mimicked. They also make a loud, sharp, honking call at night that is produced by a single individual of a group that is thought to act as a territorial display.

Golden bamboo lemurs secrete a fatty substance from their brachial glands, which is likely rubbed onto their tails for scent dispersal.

Reproduction and Family
Golden bamboo lemurs are monogamous and mating takes place from July to August. The gestation period lasts for approximately 138 days (4.6 months) and births occur once per year between November and December.

Mothers rarely give birth to more than a single infant at a time and they do not take their parental duties lightly—they are known to nest in sheltered and dense vegetation with their young for their first 10 to 14 days of life. Infants will then require another several months of maternal care and lactation, but at least mom can start to move around freely; golden bamboo lemurs practice infant parking and oral transport. Infants can be left alone while the mother forages distances no more than 820 feet (250 m) away for up to 200 minutes on average. Weaning occurs at 6 to 8 months of age, but young golden bamboo lemurs stay in a family group until they are about 3 years old.

Photo credit: Rachel Kramer/Creative Commons

Ecological Role
The golden bamboo lemur’s ecological role has not been extensively studied (for instance, there is nothing to prove their diet of bamboo has any real ecological consequences), so it could be stated that their ecological role consists of the inherent part they play in the fascinating and unique lemur fauna of Madagascar.

Conservation Status and Threats
The International Union for Conservation of Nature lists the golden bamboo lemur as Critically Endangered (IUCN, 2020). Their population is in decline due to habitat loss and hunting; it was estimated to be 5,916 in 2005, but now it is likely that only 630 individuals remain (250 of which are mature). In Ranomafana National Park, the estimated population is 69.

Golden bamboo lemurs have a small range with a heavily fragmented habitat, which acts as a barrier to migration and gene flow. Slash-and-burn agriculture and harvesting for bamboo both contribute to habitat loss—even protected areas like national parks are under threat from illegal logging and other types of exploitation.

These lemurs are also hunted for subsistence and the pet trade.

Conservation Efforts
The golden bamboo lemur is listed on Appendix I of the Convention on International Trade in Endangered Species (CITES) and they are known to occur in protected areas like national parks—namely Andringrita and Ranomafana. There is a proposal to form a forest corridor between the aforementioned parks as a conservation effort in conjunction with efforts to propagate and re-establish stands of bamboo varieties for the golden bamboo lemurs to subsist on.

​References:

  • https://animaldiversity.org/accounts/Hapalemur_aureus/
  • https://www.iucnredlist.org/species/9672/16119513
  • http://animalia.bio/golden-bamboo-lemur
  • https://thewebsiteofeverything.com/animals/mammals/Primates/Lemuridae/Hapalemur/Hapalemur-aureus/
  • http://www.animalinfo.org/species/primate/hapaaure.htm​
  • ​http://pin.primate.wisc.edu/factsheets/entry/bamboo_lemur/taxon

Written by Rachel Heim, January 2020