White-Nosed Saki, Chiropotes albinasus
WHITE-NOSED SAKI
Chiropotes albinasus
Geographic Distribution and Habitat
Also more aptly known as the red-nosed saki, white-nosed sakis are found in the Brazilian Amazon in the higher ground between the Madeira and Xingu Rivers (known as an interfluvium). They are mostly found in dry terra firma forests in the higher elevations of their range but have also been found in the transitional zones between forest and savanna. They prefer large unbroken forest ranges with high fruit production, but they have been reported in forests fragmented by habitat loss as well.
Some researchers have noted that the common name of bearded saki assigned to the Chiropotes genus is confusing alongside the common name of saki used for the Pithecia genus. To combat this confusion, these researchers have suggested changing the common name of the Chiropotes genus to cuxiú, which is used by the people of the Brazilian Amazon, making an alternate name for the white- (or red-) nosed saki the white- (or red-) nosed cuxiú.
Size, Weight, and Lifespan
Like other bearded sakis, white-nosed sakis are slightly sexually dimorphic. Females weigh around 5.5 lb (2.5 kg), while males may weigh up to 8.15 lb (3.7 kg). Female head-body length is around 16.5 inches (41.8 cm) and male head-body length is on average 16.8 inches (42.7 cm).
The exact lifespan of white-nosed sakis in the wild is unclear, but in captivity, bearded sakis have been known to live into their late teens.
Appearance
As the name of the bearded saki implies, both male and female white-nosed sakis share the big beautiful beards that their “cousins” also have (although the white-nosed saki’s beard is slighter and smaller than those of other bearded sakis). Their beards are fully grown once they reach maturity at about three years of age. Despite the title of white-nosed saki, their noses are actually red in color, which stands out against their black fur. Similar to other bearded sakis, they have temporal swellings and long bushy tails.
Diet
White-nosed sakis are highly frugivorous, with fruit making up 90% of their diet. Specifically, they like the seeds from fruit the best and, along with other saki and bearded saki monkeys, are known for eating more seeds than any other group of primates. They are equipped with large flared canines that help them crack into larger seeds. White-nosed sakis are known to go for underripe fruits more often than ripe fruit, which scientists think helps avoid feeding competition with other fruit-eaters. Immature, unripe fruit is also more often available than ripe fruit, making it a more dependable food choice. Scientists have also observed white-nosed sakis eating insects and spiders and noted that they also prefer fruit infested with insect larvae. Because unripe fruit is more difficult to absorb nutrients from, scientists think that insects help supplement the white-nosed saki’s diet.
Behavior and Lifestyle
White-nosed sakis are most active during the day, making them diurnal. They move quickly on top of the branches of the upper forest canopy on all fours (meaning they are quadrupedal) and leap between trees.
They are mostly preyed on by raptors such as Harpy eagles, and black hawk-eagles. When threatened by potential predators, white-nosed sakis have several defenses to rely on. Most often, alarm calling to ruin the raptors’ element of surprise is executed, followed by group members fleeing from the nearby area and/or hiding in vegetation. Should a raptor come too close, the group may team up against the predator and mob them by charging and even attacking the threat as a group. Mostly this is carried out by males when necessary.
White-nosed sakis live in large groups ranging from 19 to over 50 individuals. Details about their social structure are unclear due to their wide ranges and fast travel high in the trees where observing them is difficult. These factors make it difficult for researchers to keep track of individual monkeys which is necessary for understanding group dynamics. We do have some idea that they form fairly loose fission-fusion social structures, where individuals frequently shift between social groups.
Their home ranges may be 0.77 square miles (200 ha) to over 3.86 square miles (1000 ha) and they travel 1.5 – 2.1 miles (2.5 – 3.5 km) in a day. White-nosed sakis can be found in the same habitat with many other monkey species, including: black-and-gold howler monkeys, Emilia’s marmosets, Vieira’s titi monkeys, the bearded capuchin, Spix’s red-handed howler, white-cheeked spider monkey, Azara’s night monkey, red-bellied titi monkey, tufted capuchin, silvery marmoset, common squirrel monkey, and Humboldt’s white-fronted capuchin.
Detailed studies have yet to be done on white-nosed sakis’ methods of communication. We do have some descriptions of how they warn each other of potential dangers. When a potential predator is present, they alert other group members with a high-pitched whinny alarm call. These calls may be accompanied by wagging their tail while it’s arched over their head, which is also done under other stressful or exciting circumstances and seems to indicate some level of agitation.
White-nosed sakis are not known to scent mark but may exchange olfactory signals through body contact like hugging.
Due to the same restrictions on observing social structure in white-nosed sakis, little is known about their reproduction. Female bearded sakis are known to display sexual swellings when ready to mate, where their genitals swell and become very pink or red in color. Gestation typically lasts for about five months. Once born, females will carry infants ventrally (on their chest) for the first two months, after which babies will switch to piggyback rides until reaching five months, when they begin to move more independently. Infants are typically weaned off of their mothers’ milk after two years of age. Males are not known to take part in parental care.
Although they prefer unripe fruit that hasn’t fully matured, the seeds dropped by white-nosed sakis will still start to grow into new trees. Because white-nosed sakis, like many primates, like to eat while on the move, seeds dropped while feeding often fall much farther away from the source tree than they would have been able to travel on their own. This results in greater likelihood that the seed will germinate and reforest.
White-nosed sakis may also provide some pest control for the fruiting plants they feed on by eating infested fruits and managing insect populations.
The white-nosed saki is classified as Vulnerable by the International Union for Conservation of Nature (IUCN, 2020), appearing on the IUCN Red List of Threatened Species. The main threat faced by white-nosed sakis is deforestation due to logging, as well as conversion to farmland, cattle pastures, and infrastructural developments. Deforestation does not always knock out large swathes of forest immediately and will often result in patchy forest fragments where small sections of forest become cut off from each other. This makes things difficult for the animals that remain in the forest fragments as they are restricted in their options for food sources and mating opportunities. While some primates have proven able to adapt to these limited landscapes, it presents a more difficult challenge for white-nosed sakis with their large group sizes. White-nosed sakis are also hunted for bushmeat.
White-nosed sakis 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 currently no specific efforts toward the conservation of white-nosed sakis specifically, but they do occur in a number of protected areas throughout their range. White-nosed sakis also benefit from conservation efforts targeted towards other species they share habitat with. Otherwise, further research and a better understanding of the species will be the initial steps in future conservation efforts for white-nosed sakis.
- https://www.iucnredlist.org/species/4685/191702783
- https://cites.org/eng/app/appendices.php
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Written by Lina Rademacher, December 2024