Kloss's gibbon

File:Hylobates klossii A.jpg

Kloss's gibbon

File:Mentawai Islands Map.png

The Mentawai Islands

Kloss's gibbon (Hylobates klossii), also known as the Mentawai gibbon, the bilou or dwarf siamang, is an endangered primate in the gibbon family, Hylobatidae. It is identifiable in that it is all black,<ref>Kloss Gibbon at the zoo</ref> resembling the siamang with its black fur, but is considerably smaller and lacks the siamang's distinctive throat pouch. Kloss's gibbon reaches a size Template:Convert and weigh at most Template:Convert. As is the case for all gibbons, they have long arms and no tail. Males and females are difficult to distinguish.<ref name="Whitten-1982" />

Habitat

Kloss's gibbon exclusively lives on the Mentawai Islands that lie to the west of Sumatra.<ref name=MSW3 /> The Mentawai Islands consist four main islands that are part of an island archipelago.<ref name="Yanuar-2018">Template:Cite journal</ref> These islands are hearths of biodiversity, and are the homes of many endemic species.<ref name="Yanuar-2018" /> It is a diurnal inhabitant of the rain forest that hangs in the trees from its long arms and rarely comes to the ground. Because Kloss's gibbon rarely comes out of the canopy, these gibbons use tree limbs to cross obstacles like bodies of water.<ref name="Tenaza-1975">Template:Cite journal</ref> Like all species of gibbons it lives together in pairs that stake out a territory from approximately Template:Convert of size. This area is defended vehemently against other gibbons. Its diet consists mainly of fruits, occasionally also eating different plant parts, bird eggs, insects and small vertebrates.

Communication

Kloss's gibbon are unique gibbons because the two sexes do not vocalize songs in unison.<ref name="Höing-2013">Template:Cite journal</ref> Male Kloss's gibbon sing before the sun rises and female Kloss's gibbon vocalize songs once the sun has risen.<ref name="Höing-2013" /> Female Kloss's gibbon calls are unique and have slight variations in the different stages of the call.<ref name="Haimoff-1985">Template:Cite journal</ref> The calls emitted by the females could offer other members of the species information about their position in the canopy.<ref name="Haimoff-1985" />

Reproduction

The reproductive cycle of Kloss's gibbon is similar to that of other gibbons. Every two to three years the female may give birth to a single young (with a gestation period of seven months). The young is weaned in the middle of its second year, and is fully mature in about seven years. Their life expectancy is about 25 years in the wild, and up to 40 years in captivity. Kloss's gibbons are monogamous, and male Kloss's gibbons use territory to attract and court possible mates.<ref name="Tilson-1981">Template:Cite journal</ref> Territories are often contested and Kloss's gibbons defend their territories with aggression and threats.<ref name="Tilson-1981" /> During courtship, males and females defend territory together, and mating only occurs after the females deems the male capable of defending a suitable territory.<ref name="Tilson-1981" />

Diet

Kloss's gibbon are picky eaters, and never consume over-ripened fruit.<ref name="Whitten-1982">Template:Cite journal</ref> Kloss's gibbons diet consists of fruit, leaves, shoots, and insects.<ref name="Whitten-1982" /> Kloss's gibbons favorite fruit is figs, but these gibbons do not spend a lot of time eating figs because figs are scarce on the Mentawai Islands.<ref name="Whitten-1982" />

Behavior

When Kloss's gibbons are observed by human researchers, they adapt and become less afraid, a process called habituation. Kloss's gibbons can become habituated to humans and will not flee when they are observed.<ref name="Dooley-2014">Template:Cite journal</ref> Unhabituated Kloss's gibbons sometimes exhibit a warning behavior in which they act as a lure toward people.<ref name="Dooley-2014" /> One male gibbon will produce warning calls and attract attention to himself while other members of his group make their escape.<ref name="Dooley-2014" /> Kloss's gibbons behavior help it stay cryptic, possibly to help them avoid hunting pressure.<ref name="Dooley-2014" /> Female Kloss's gibbons sing less frequently than males, and males only sing in the predawn when visibility isn't optimal for hunting.<ref name="Dooley-2014" /> Kloss's gibbons also exhibit less aggregate behavior like grooming and playing, possibly to reduce their visibility and stay hidden from hunters.<ref name="Dooley-2014" />

Conservation

Kloss's gibbon is in jeopardy of going extinct.<ref name="Höing-2013" /> Kloss's gibbon is classified as endangered by the IUCN (2021).<ref name=iucn/> Recent estimates conclude that there are around 20,000 to 25,000 Kloss's gibbons alive in the wild, and its numbers are declining.<ref name="Whittaker-2005"/> Over the last two and a half decades, the population size of Kloss's gibbon has fallen by 50%.<ref name="Whittaker-2005">Template:Cite journal</ref> There are several threats that pose significant risk to Kloss's gibbon. Kloss's gibbon has no natural predators, and humans are the main threat to the existence of this primate.<ref name="Tenaza-1975"/> Native peoples of the Mentawai Islands kill Kloss's gibbon and other endemic primates for subsistence, and also participate in poaching activities.<ref name="Yanuar-2018"/> Globalization and industrialization in the Mentawai Islands are contributing toward the degradation of high quality habitat needed by Kloss's gibbon.<ref name="Whittaker-2006">Template:Cite journal</ref> Road development and the adoption of air rifles are allowing natives to kill Kloss's gibbon easier and at higher rates.<ref name="Whittaker-2006"/> Kloss's gibbon spends the majority of its time in the tree canopy, and as a result, this species requires undisturbed, old-growth forest habitats to sustain itself.<ref name="Yanuar-2018"/> Kloss's gibbon is at risk due to habitat loss, as its homeland islands are suffering from deforestation.<ref name="Yanuar-2018"/> Conservationists focused on improving Kloss's gibbons endangered status need to protect and preserve the high quality habitat needed by these gibbons.<ref name="Yanuar-2018"/> Fragments of habitat need to be connected to allow movement without risk of exposure in highly modified areas.<ref name="Yanuar-2018"/> Local government has been cooperating with global organizations such as UNESCO to raise awareness as well as increase the amount of protected land in the Mentawai Islands.<ref name="Whittaker-2006"/>

External links

• ARKive - images and movies of the Kloss's gibbon (Hylobates klossii)
• Kloss Gibbon photos
• Kloss Gibbon songs
• Gibbon Conservation Center