Sambirano Lesser Bamboo Lemur, Hapalemur occidentalis
SAMBIRANO LESSER BAMBOO LEMUR
Hapalemur occidentalis
Geographic Distribution and Habitat
Endemic to Madagascar, the Sambirano lesser bamboo lemur, also known as the northern bamboo lemur, western gentle lemur, western grey bamboo lemur, or western lesser bamboo lemur, can be found throughout various forest fragments, primarily in the north and northwestern parts of the island, including the Ankarana and Analamerana regions in the far north, the Sambirano region, the Ampasindava Peninsula, the Sava, Sofia, and Diana regions, and north of the Andranomalaza River in the Sahamalaza region. They prefer dry, deciduous forests (containing trees that lose their leaves after their growing season), as well as humid forests. As their name suggests, they tend to stick to areas rich with their favorite plant—bamboo!
Plagued by deforestation and climate change, it was estimated in 2000 that about 98% of the habitable regions in Madagascar would be lost by 2080. To help combat the negative impact this will have on native species, there are many protected parks and reserves within the island. Of those, the Sambirano lesser bamboo lemur has been observed in the Makira Natural Park, Masoala National Park, Farankaraina Reserve, Manongarivo Special Reserve, and Mananara-Nord National Park.
Size, Weight, and Lifespan
A lesser documented species, there is limited information regarding the size, weight, and lifespan of these lemurs. In general, the head and body length of Sambirano lesser bamboo lemurs average 11 inches (27.9 cm), with a 14.5 inch (36.7 cm) tail. They typically weigh just around 2-3 pounds (0.85-1.88 kg), with females being heavier than males.
The lifespan of the Sambirano lesser bamboo lemur is currently unknown due to limited research, but insights can be drawn from better-studied species. For example, the eastern lesser bamboo lemur has an average lifespan in captivity of 17 years for females and 12.8 years for males. The longest recorded lifespan for this species in captivity is 23 years, though the gender of that individual was not specified.
Appearance
In typical lemur fashion, this species rocks a pair of big, round eyes; generally auburn-brown in color and outlined in black, giving the appearance of stark eyeliner. If “puppy-dog eyes” worked out in the wild, I’m sure these guys would rule the island of Madagascar! Their fur colors are gray on their faces and underside, with more brown fur—sometimes tinged in a shade of green or red—covering their backsides, top of their heads, and tails. Their faces are small and rounded, with a slightly pronounced nose bridge or snout. At first glance, due to their dense coats, it would appear that these lemurs don’t typically miss any of their meals!
Diet
Could you guess what makes up a vast majority of the Sambirano lesser bamboo lemur’s diet? It’s not a trick question—it’s bamboo! If you want to get a little more specific, they gravitate toward the following species of bamboo: Dendrocalamus giganteus, Ochlandra capitata, and Phyllostachys auerea. Consumption of younger bamboo is preferred, as it is easier to digest and contains more protein. However, bamboo shoots contain the deadly chemical cyanide. Studies suggest that bamboo lemurs have a gastrointestinal tract and kidneys that absorb the cyanide, proven by cyanide being detected in their urine but seldomly in their feces. How they process the cyanide without ill effects is still unclear.
Aside from bamboo, Sambirano lesser bamboo lemurs have been observed eating fruit, liana flowers, fungi, and soil.
Behavior and Lifestyle
This species spends a significant amount of time resting, as digesting the large quantities of bamboo in their diet requires a lot of energy. Observations of these lemurs suggest that they are cathemeral creatures, meaning they are active both during the day and night time, depending upon environmental conditions and availability of resources. They, and other bamboo lemurs, may be among the smallest lemur species active during daylight hours.
Sambirano lesser bamboo lemurs are arboreal, spending most of their time in the trees, though they occasionally travel on the ground. Bamboo lemurs are known as “vertical clingers and leapers.” This means they rest on and leap from branches, using all four limbs (quadrupedally), while maintaining an upright posture.
Much research still needs to be done regarding the behavior and lifestyle of this species.
Male bamboo lemurs are one of two lemur groups that participate in a behavior known as “stink fighting!” Keep reading if you want to learn more about what this activity entails.
Though often thought of as a tree, bamboo is a species of grass!
Sambirano lesser bamboo lemurs are typically found living in groups of around six individuals, though ranges of four to 11 individuals have been observed. They are also known to be able to coexist with other lemur species.
It is likely that, like the eastern lesser bamboo lemur, females remain in their natal (birth) group, while males may leave upon reaching adulthood.
We can conjecture, based on the habits and lifestyles of Eastern lesser bamboo lemurs, that female Sambirano lesser bamboo lemurs exert dominance over the males of their troop (true for most lemur species), and are known to chase males away from a preferred feeding site. Males, however, are responsible for protecting their troops and defending their group’s territory from rival interlopers. Disputes with outside lemur groups typically occur when territories overlap. But these confrontations are rarely violent. Instead, a lot of posturing occurs. Scent marking, chasing, machismo displays, vocalizations, and “staring contests” are employed.
Most lesser bamboo lemurs only venture out of their home range when food sources are scarce.
Bathroom etiquette is a thing in the jungle, at least with these lemurs. Known as “latrine behavior,” Sambirano lesser bamboo lemurs stand in queues and take turns defecating in a single, centralized location.
Researchers studying the Sambirano lesser bamboo lemurs have recorded them making vocalizations throughout the nighttime. Bamboo lemurs are known to have a wide range of vocal calls, from nervous-sounding chatters and clucking to more aggressive growls and alarm calls. These different types of calls are unique and each carries its own specific meaning, from communicating submissiveness to signaling a warning if a predator is near.
Scent marking is another key way in which these lemurs communicate. Male bamboo lemurs possess a specific type of scent glands that they use to carry out “stink fights.” To do this, they continuously run their tails along scent glands on their arms before waving their tails over their heads in the direction of their opponent. Male ring-tailed lemurs and bamboo lemurs are the only lemur species known to exhibit this behavior.
The birthing season for the Sambirano lesser bamboo lemur runs from October to January, with females giving birth after a 137- to 140-day gestation period. Mating occurs one day out of the year, during the 24 hours that females are sexually receptive.
Only one infant is birthed at a time, aside from a rare case of twins, with mothers generally delivering every other year. Female Sambirano lesser bamboo lemurs take their parental duties very seriously, carrying their baby by mouth during its first few weeks of life until it is strong enough to hold onto the mother’s back. After a series of months, the mothers eventually feel comfortable to “park” their infant somewhere for a short period of time, when they need to forage.
In general, lemurs are known to positively contribute to their ecosystem by serving as seed dispersers and pollinators. Sambirano lesser bamboo lemurs have been known to eat various fruits and liana flowers. Not only will they drop seeds in the process of eating, but seeds also found in their fecal droppings have a higher chance of reaching germination due to the natural fertilization their feces create.
Bamboo lemurs have been known to help keep the bamboo populations under control in regions where the fast-growing plant tended to overpopulate, though this is less important now due to the deforestation happening in Madagascar.
Lastly, these smaller lemurs serve as prey to many of the natural predators that share the island with them, like hawks, boa constrictors, and fossa, Madagascar’s largest carnivore.
The Sambirano lesser bamboo lemur is classified as Vulnerable (IUCN, 2018) by the International Union for Conservation of Nature, appearing on the IUCN Red List of Threatened Species. Habitat loss, largely caused by slash-and-burn agriculture to clear land for livestock and other human activities, is the biggest threat to this species and many other animals in Madagascar. Additionally, illegal timber harvesting, mining, and hunting further endanger these lemurs. Hunting is often carried out using slingshots and snare traps, with motives ranging from capturing lemurs for food or pet trade to protecting crops. Their adaptability to fragmented forests and human-occupied areas sometimes leads farmers to target them as crop pests.
Sambirano lesser bamboo lemurs are listed in Appendix I of the Convention on International Trade in Endangered Species (CITES), an international agreement between governments whose goal is to ensure that international trade in specimens of wild animals and plants does not threaten their survival. There are a number of national parks and protective reserves that are home to this species.
The IUCN has made several recommendations to further bolster conservation efforts. These include developing a targeted strategy to preserve bamboo-rich areas outside protected parks and reserves, ensuring the survival of lemurs living there. They also emphasize addressing the food security crisis in remote villages near the lemurs’ habitats to reduce hunting pressure.
- https://www.iucnredlist.org/species/9678/115565375
- https://animalia.bio/western-lesser-bamboo-lemur?category=1
- https://neprimateconservancy.org/eastern-lesser-bamboo-lemur/
- https://lemur.duke.edu/engage/virtual-programs/subscription/03-2022-ll1/#:~:text=Lemurs%2C%20however%20are%20monomorphic%2C%20with,food%20and%20safe%20sleeping%20spots.
- https://lemur.duke.edu/discover/meet-the-lemurs/eastern-lesser-bamboo-lemur/
- https://www.lemurreserve.org/lemurs/northern-bamboo-lemur/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC5550550/#Sec13
- https://wilderinstitute.org/conservation/lemurs/#:~:text=Lemurs%20play%20critical%20ecological%20roles,is%20critical%20to%20lemur%20conservation.
- https://lemur.duke.edu/discover/meet-the-lemurs/eastern-lesser-bamboo-lemur/#:~:text=Surprisingly%2C%20the%20male%20bamboo%20lemur,recorded%20at%20the%20DLC%20HERE.
- https://www.youtube.com/watch?v=x3O-f6uPs_w
Written by Hannah Broadland, November 2024