Zanzibar Red Colobus
Encyclopedia
The Zanzibar red colobus (Procolobus kirkii) is a species
of red colobus
monkey endemic to Unguja
, the main island of the Zanzibar
archipelago, off the coast of Tanzania. It is also known as Kirk's red colobus after Sir John Kirk
(1832-1922), the British Resident
of Zanzibar who first brought it to the attention of zoological
science. It is now classified as an endangered species
and in the mid-1990s was adopted as the flagship species
for conservation
in Zanzibar. The population trend is still decreasing and because this species is only located in the archipelago, conservationists are attempting to work with local government to devise a proper, effective strategy to protect the population and habitat. The species has been reclassified twice; it was previously in the genus Colobus, and more recently in the genus Procolobus
.
has a coat that ranges from dark red to black, accented with a black stripe along the shoulders and arms, and a pale underside. Its black face is crowned with long white hair, and features a distinguishing pink mark on its lips and nose. Also, the Zanzibar red colobus has a long tail used only for balancing — it is not prehensile
. Sexual dimorphism is generally decreased in the species, meaning that females have little difference in their body size and colour from their male counterparts. Females usually outnumber the males in their groups. The species has a notably small cranium and rotund body shape, with males potentially reaching over twelve kilogram
s and females, ten kilograms. In adults, highly differentiated facial features help to distinguish each other in a group.
The word "colobus" comes from Greek
ekolobóse, meaning "he cut short", and is so named because of the significant reduction in size, or complete lack of an opposable thumb in comparison to other primates. To make up for this, they have four long digits that align to form a strong hook, allowing them to easily grasp branches and climb.
Locals on the island have called the Zanzibar red colobus "kima punju" which means "poison monkey" in Swahili
because of their strong smell unlike other monkeys. This has caused people to hold negative views against the monkey and even to say that it has an evil influence on trees that they feed on, ultimately killing the trees.
al thickets and coastal rag scrub, but can also be found in agricultural
areas and in mangrove swamps
; in which the latter provides food year-round. When found in agricultural areas, the monkey is more used to human
s and comes closer to the ground
.
There are approximately a total of 1,600 to 3,000 individuals and currently, 50% of the monkeys found on the islands live outside protected zones. The largest and most significant area of protection and habitat for the monkey is in Jozani National Park
, which provides 25 km2 of land reserve. It is located on the main island and the populations here have been greatly studied in regards to both their ecology and behavior. Even so, many groups have been found in shambas (Swahili for "farmland") within close proximity to the park. It has been reported that in these shambas adjacent to the park, there are actually higher densities of the red colobus living here in more cohesive groups, compared to inside the park reserve. The incidence of some of these monkeys living permanently outside the zone of the protected park reserve can increase the endangerment of the groups.
s and many adult female
s; typically yielding a 1:2 ratio of males to females. Young of varying ages are also incorporated in the group. The number of monkeys in a group can range from thirty to fifty individuals. The species is a very social animal, and can often be observed playing and grooming during the rest periods between meals. Unlike females, in a group, males actually maintain close bonds, acting together in defense of their group and even in grooming each other.
. They also eat leaf shoots, seed
s, flower
s, and unripe fruit
. It has also been found eating bark
, dead wood
, and soil
. It is one of the few species that do not eat ripe fruits; it has a sacculated stomach
with four chambers specific for breaking down plant materials, however it cannot digest the sugars contained in mature fruits. Because the monkey feeds on young leaves (though not limited to them), there are instances where it consumes charcoal
, which is believed to aid their digestion of the toxins (possibly phenol
ic compounds) found in the young leaves of the Indian almond tree
and mango
tree. The habit of consuming charcoal is thought to be a learned behavior
presumably passed on from the mother to her offspring. It has been noted, however, that not all populations on the islands carry out the behavior, but that it is rather mostly done by those who consume more perennial and exotic foliage.
Since some populations use mangroves as a source of food, it is natural for the monkey to consume more sodium chloride
(NaCl). Because of this, those populations have been observed to drink water directly from tree-holes, or licking water off of leaves. This innovative behavior shows the adaptation of the monkey to novel ecological and environmental circumstances.
In the dry season, one of the staple foods, Terminalia catappa
, as previously mentioned, drops its leaves and can cause the monkey to go beyond park boundaries in order to extend its feeding range. This puts the already endangered colobine at more risk.
can be easily identified because of the swelling and bright red coloration of the genital area. This signals to males that the given female is ready for mating. Moreover, just prior to mating, males will use their fingers to probe the female's genitalia. This is immediately followed by sniffing the area because estrogen
and progesterone
can be detected by this method, further helping the male conclude if the female is indeed ready to breed.
Gestation is about 6 months for colobus monkeys and one female has about 1-2 new-born every two years. Parental care is intense and often, the role is shared by multiple females of the group. It is observed that about 76% of offspring are born between September and December. Infanticide
has also been noted on occasion when a new male joins a given group that has infants.
Research has suggested that the ability for dietary expansion, which consuming charcoal partly allows, explains the higher birth rates and densities due to resource availability. Birth rates for those living in mangroves are higher than colobus monkeys living in coral rag forests.
There are higher birthing rates between October-December for colobines on Uzi Island
and then January-February for those in Kiwengwa
, located on the eastern side of the main island. Infant mortality can be significantly high with half of the infants born not reaching more than six months of age. The birth rates themselves, however, are actually decreased in comparison to mainland colobus monkeys and interbirth intervals are longer as well. Research has suggested that this is a consequence of disturbed habitats in which mainland colobi are not so affected.
species have a smaller larynx
compared to other members of the Colobinae
subfamily
. The male's call is more of an alto or soprano in contrast to the low bass of a male's in black-and-white colobus
species. The Zanzibar red colobus is non-territorial in nature and as so does not typically make loud, territorial threat calls. Zanzibar red colobus distress and warning calls are the "bark", "chist", or "wheet". One of the loudest calls from the monkey is heard when he expresses his dominance over the group and when checking the sexual status of his females.
The call heard most often by people in or near Jozani Forest
is the 'alerting signal'. This is an attention-getting call that is derived from the progression call. Chirps and grunts are made when there are changes in the surrounding environment such as changes in weather or animal movement in proximity to the group. With most arboreal animals, there are two different alerting calls, one for when a predator is on land, and another when there is an aerial predator. However, because of the lack of larger birds of prey in Zanzibar, such calls are not often witnessed. The young, on the other hand, because of their smaller size and vulnerability, do at times make such calls when they see shadows.
Because the Zanzibar red colobus is extremely social, it has a specific call for when it is alone for a certain amount of time upon which it feels vulnerable or threatened. The young are typically the ones to make such a call that sounds like a loud scream, but adults are occasionally likely (when deemed necessary) to make some variation of the call as well.
epoch
. Furthermore, it is suggested through mitochondrial analysis, that phylogenetic groups within the red colobus have been genetically isolated from another since the Pliocene
.
Examining cranial morphology has shown that Procolobus kirkii has diverged from mainland Procolobus to its own species. It has experienced an acceleration in morphological evolution of size which is suggested to be the result of insularity on the island and environmental pressures such as competition, habitat, predation and/or resource availability. There has been no evidence for population bottleneck
s in the species.
The smaller cranium of Procolobus kirkii in contrast to the mainland colobus monkey, is consistent with Foster's rule
(also known as the island rule) in which the original (larger) animal becomes smaller over time when there is limited resources. Males tend to have pedomorphic traits which include a shorter face, large orbits and an enlarged neurocranium. It is not certain how long ago and where this evolutionary change occurred.
Through molecular analyses, it is indicated that P. kirkii is more closely related to P. gordonorum compared to other red colobus species. This analysis has also placed the divergence of P. kirkii from its sister species P. godronorum at about 600,000 years ago, which actually allows for an older evolutionary age compared to the previous assumption that it had become its own species around the last glacial period.
has resulted in a significant reduction in resources and habitat; second, it is hunted for meat and pet markets. To counteract the decline in population, various attempts have been made to protect the species. In 1974, specimens were moved to Ngezi Forest on Pemba Island to try to re-establish the monkey's the population. It had been found, however, that 20 years after the translocation to the island only one group of Procolobus kirkii was found and with few sitings and interviews with locals, the population was estimated to be between 15 and 30 individuals. Researchers concluded that the group had certainly survived but did not increase in number possibly due to adverse relations with humans. Some locals in Pemba hold superstitions against the monkey because of the idea that it brings bad luck upon farmers. This may explain the reason that they have not significantly grown in population size.
On Uzi and Vundwe Islands, P. kirkii monkeys are subject to extensive habitat destruction, particularly with coral rag forests. There is also reported poisoning, netting, and disappearance of monkeys as well as other with animals.
Various attempts have been made for conservation of the species. One project was with the World Wildlife Fund, specifically in Menai Bay
which is located just west of Uzi Island. Second, the Wildlife Conservation Society
has funded conservation projects intended for the colobine but in both cases, there has been no apparent action that was directly supportive of the monkey.
The African Convention
has played a role in the conservation of the animal by categorizing it as 'Class A.' According to the document African Convention on the Conservation of Nature and Natural Resources, 'Class A' is described as:
It has been suggested that an important way to promote conservation of the monkey is to simply spread awareness about it – that it is not a harmful animal and that it can actually be good for the region's economy because it draws tourism. This has been the case on Unguja Island. Furthermore, it would be necessary to establish and designate protected zones.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of red colobus
Red colobus
Red colobuses are Old World monkeys of the subgenus Piliocolobus in genus Procolobus. Some authors elevate Piliocolobus to a full genus, limiting Procolobus to the olive colobus. They are closely related to the black-and-white colobus monkeys and some species are often found in groups with the...
monkey endemic to Unguja
Unguja
Unguja as mentioned in The Periplus of the Erythraean Sea is the largest and most populated island of Zanzibar, in Tanzania.-Geography:...
, the main island of the Zanzibar
Zanzibar
Zanzibar ,Persian: زنگبار, from suffix bār: "coast" and Zangi: "bruin" ; is a semi-autonomous part of Tanzania, in East Africa. It comprises the Zanzibar Archipelago in the Indian Ocean, off the coast of the mainland, and consists of numerous small islands and two large ones: Unguja , and Pemba...
archipelago, off the coast of Tanzania. It is also known as Kirk's red colobus after Sir John Kirk
John Kirk (explorer)
Sir John Kirk was a Scottish physician, naturalist, companion to explorer David Livingstone, and British administrator in Zanzibar. He was born in Barry, near Arbroath, Scotland and is buried in St. Nicholas's churchyard in Sevenoaks, Kent, England. He earned his medical degree from the...
(1832-1922), the British Resident
Resident (title)
A Resident, or in full Resident Minister, is a government official required to take up permanent residence in another country. A representative of his government, he officially has diplomatic functions which are often seen as a form of indirect rule....
of Zanzibar who first brought it to the attention of zoological
Zoology
Zoology |zoölogy]]), is the branch of biology that relates to the animal kingdom, including the structure, embryology, evolution, classification, habits, and distribution of all animals, both living and extinct...
science. It is now classified as an endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
and in the mid-1990s was adopted as the flagship species
Flagship species
The concept of flagship species is a surrogate species concept with its genesis in the field of conservation biology. The flagship species concept holds that by raising the profile of a particular species, it can successfully leverage more support for biodiversity conservation at large in a...
for conservation
Conservation biology
Conservation biology is the scientific study of the nature and status of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction...
in Zanzibar. The population trend is still decreasing and because this species is only located in the archipelago, conservationists are attempting to work with local government to devise a proper, effective strategy to protect the population and habitat. The species has been reclassified twice; it was previously in the genus Colobus, and more recently in the genus Procolobus
Procolobus
Procolobus is the genus of the red colobus monkeys and the olive colobus. Some authorities restrict the genus Procolobus to the olive colobus, placing the remaining in Piliocolobus. They are found in Africa where almost entirely restricted to forests...
.
Description
This Old World monkeyOld World monkey
The Old World monkeys or Cercopithecidae are a group of primates, falling in the superfamily Cercopithecoidea in the clade Catarrhini. The Old World monkeys are native to Africa and Asia today, inhabiting a range of environments from tropical rain forest to savanna, shrubland and mountainous...
has a coat that ranges from dark red to black, accented with a black stripe along the shoulders and arms, and a pale underside. Its black face is crowned with long white hair, and features a distinguishing pink mark on its lips and nose. Also, the Zanzibar red colobus has a long tail used only for balancing — it is not prehensile
Prehensile tail
A prehensile tail is the tail of an animal that has adapted to be able to grasp and/or hold objects. Fully prehensile tails can be used to hold and manipulate objects, and in particular to aid arboreal creatures in finding and eating food in the trees...
. Sexual dimorphism is generally decreased in the species, meaning that females have little difference in their body size and colour from their male counterparts. Females usually outnumber the males in their groups. The species has a notably small cranium and rotund body shape, with males potentially reaching over twelve kilogram
Kilogram
The kilogram or kilogramme , also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram , which is almost exactly equal to the mass of one liter of water...
s and females, ten kilograms. In adults, highly differentiated facial features help to distinguish each other in a group.
The word "colobus" comes from Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
ekolobóse, meaning "he cut short", and is so named because of the significant reduction in size, or complete lack of an opposable thumb in comparison to other primates. To make up for this, they have four long digits that align to form a strong hook, allowing them to easily grasp branches and climb.
Locals on the island have called the Zanzibar red colobus "kima punju" which means "poison monkey" in Swahili
Swahili language
Swahili or Kiswahili is a Bantu language spoken by various ethnic groups that inhabit several large stretches of the Mozambique Channel coastline from northern Kenya to northern Mozambique, including the Comoro Islands. It is also spoken by ethnic minority groups in Somalia...
because of their strong smell unlike other monkeys. This has caused people to hold negative views against the monkey and even to say that it has an evil influence on trees that they feed on, ultimately killing the trees.
Habitat
The Zanzibar red colobus is found in three forests of the Zanzibar archipelago. It displays a wide habit tolerance, but it is mainly an arboreal species and prefers drier areas over wet ones. Habitats include places such as coastCoast
A coastline or seashore is the area where land meets the sea or ocean. A precise line that can be called a coastline cannot be determined due to the dynamic nature of tides. The term "coastal zone" can be used instead, which is a spatial zone where interaction of the sea and land processes occurs...
al thickets and coastal rag scrub, but can also be found in agricultural
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
areas and in mangrove swamps
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
; in which the latter provides food year-round. When found in agricultural areas, the monkey is more used to human
Human
Humans are the only living species in the Homo genus...
s and comes closer to the ground
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
.
There are approximately a total of 1,600 to 3,000 individuals and currently, 50% of the monkeys found on the islands live outside protected zones. The largest and most significant area of protection and habitat for the monkey is in Jozani National Park
Jozani Chwaka Bay National Park
The Jozani Chwaka Bay National Park is a national park of Tanzania located on the island of Zanzibar. It is the only national park in Zanzibar....
, which provides 25 km2 of land reserve. It is located on the main island and the populations here have been greatly studied in regards to both their ecology and behavior. Even so, many groups have been found in shambas (Swahili for "farmland") within close proximity to the park. It has been reported that in these shambas adjacent to the park, there are actually higher densities of the red colobus living here in more cohesive groups, compared to inside the park reserve. The incidence of some of these monkeys living permanently outside the zone of the protected park reserve can increase the endangerment of the groups.
Behavior
The groups consist of up to four adult maleMale
Male refers to the biological sex of an organism, or part of an organism, which produces small mobile gametes, called spermatozoa. Each spermatozoon can fuse with a larger female gamete or ovum, in the process of fertilization...
s and many adult female
Female
Female is the sex of an organism, or a part of an organism, which produces non-mobile ova .- Defining characteristics :The ova are defined as the larger gametes in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon, is produced by the male...
s; typically yielding a 1:2 ratio of males to females. Young of varying ages are also incorporated in the group. The number of monkeys in a group can range from thirty to fifty individuals. The species is a very social animal, and can often be observed playing and grooming during the rest periods between meals. Unlike females, in a group, males actually maintain close bonds, acting together in defense of their group and even in grooming each other.
Feeding
Feeding is also a group activity. It begins to feed in the morning, and is more active during the cooler parts of the day. Loud calls from males indicate the group is ready to move to another tree to feed. This monkey is mainly a foliovore, and on average, half of the leaves consumed are young leavesLeaves
-History:Vocalist Arnar Gudjonsson was formerly the guitarist with Mower, and he was joined by Hallur Hallsson , Arnar Ólafsson , Bjarni Grímsson , and Andri Ásgrímsson . Late in 2001 they played with Emiliana Torrini and drew early praise from the New York Times...
. They also eat leaf shoots, seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s, flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
s, and unripe fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
. It has also been found eating bark
Bark
Bark is the outermost layers of stems and roots of woody plants. Plants with bark include trees, woody vines and shrubs. Bark refers to all the tissues outside of the vascular cambium and is a nontechnical term. It overlays the wood and consists of the inner bark and the outer bark. The inner...
, dead wood
Wood
Wood is a hard, fibrous tissue found in many trees. It has been used for hundreds of thousands of years for both fuel and as a construction material. It is an organic material, a natural composite of cellulose fibers embedded in a matrix of lignin which resists compression...
, and soil
Soil
Soil is a natural body consisting of layers of mineral constituents of variable thicknesses, which differ from the parent materials in their morphological, physical, chemical, and mineralogical characteristics...
. It is one of the few species that do not eat ripe fruits; it has a sacculated stomach
Stomach
The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...
with four chambers specific for breaking down plant materials, however it cannot digest the sugars contained in mature fruits. Because the monkey feeds on young leaves (though not limited to them), there are instances where it consumes charcoal
Charcoal
Charcoal is the dark grey residue consisting of carbon, and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen...
, which is believed to aid their digestion of the toxins (possibly phenol
Phenol
Phenol, also known as carbolic acid, phenic acid, is an organic compound with the chemical formula C6H5OH. It is a white crystalline solid. The molecule consists of a phenyl , bonded to a hydroxyl group. It is produced on a large scale as a precursor to many materials and useful compounds...
ic compounds) found in the young leaves of the Indian almond tree
Terminalia catappa
Terminalia catappa is a large tropical tree in the Leadwood tree family, Combretaceae. The tree has been spread widely by humans and the native range is uncertain. It has long been naturalised in a broad belt extending from Africa to Northern Australia and New Guinea through Southeast Asia and...
and mango
Mango
The mango is a fleshy stone fruit belonging to the genus Mangifera, consisting of numerous tropical fruiting trees in the flowering plant family Anacardiaceae. The mango is native to India from where it spread all over the world. It is also the most cultivated fruit of the tropical world. While...
tree. The habit of consuming charcoal is thought to be a learned behavior
Behavior
Behavior or behaviour refers to the actions and mannerisms made by organisms, systems, or artificial entities in conjunction with its environment, which includes the other systems or organisms around as well as the physical environment...
presumably passed on from the mother to her offspring. It has been noted, however, that not all populations on the islands carry out the behavior, but that it is rather mostly done by those who consume more perennial and exotic foliage.
Since some populations use mangroves as a source of food, it is natural for the monkey to consume more sodium chloride
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...
(NaCl). Because of this, those populations have been observed to drink water directly from tree-holes, or licking water off of leaves. This innovative behavior shows the adaptation of the monkey to novel ecological and environmental circumstances.
In the dry season, one of the staple foods, Terminalia catappa
Terminalia catappa
Terminalia catappa is a large tropical tree in the Leadwood tree family, Combretaceae. The tree has been spread widely by humans and the native range is uncertain. It has long been naturalised in a broad belt extending from Africa to Northern Australia and New Guinea through Southeast Asia and...
, as previously mentioned, drops its leaves and can cause the monkey to go beyond park boundaries in order to extend its feeding range. This puts the already endangered colobine at more risk.
Reproduction
Males usually reach sexual maturity at about 3-3.5 years old, while females reach it at about two years old. Females approaching estrousEstrous cycle
The estrous cycle comprises the recurring physiologic changes that are induced by reproductive hormones in most mammalian placental females. Estrous cycles start after puberty in sexually mature females and are interrupted by anestrous phases or pregnancies...
can be easily identified because of the swelling and bright red coloration of the genital area. This signals to males that the given female is ready for mating. Moreover, just prior to mating, males will use their fingers to probe the female's genitalia. This is immediately followed by sniffing the area because estrogen
Estrogen
Estrogens , oestrogens , or œstrogens, are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal...
and progesterone
Progesterone
Progesterone also known as P4 is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species...
can be detected by this method, further helping the male conclude if the female is indeed ready to breed.
Gestation is about 6 months for colobus monkeys and one female has about 1-2 new-born every two years. Parental care is intense and often, the role is shared by multiple females of the group. It is observed that about 76% of offspring are born between September and December. Infanticide
Infanticide
Infanticide or infant homicide is the killing of a human infant. Neonaticide, a killing within 24 hours of a baby's birth, is most commonly done by the mother.In many past societies, certain forms of infanticide were considered permissible...
has also been noted on occasion when a new male joins a given group that has infants.
Research has suggested that the ability for dietary expansion, which consuming charcoal partly allows, explains the higher birth rates and densities due to resource availability. Birth rates for those living in mangroves are higher than colobus monkeys living in coral rag forests.
There are higher birthing rates between October-December for colobines on Uzi Island
Uzi Island
Uzi Island is an island in the south of Zanzibar, connected by causeway to the main island of Unguja. It is located immediately to the south of the main island's Unguja Ukuu ruins. The island contains the small town of Uzi, and is six kilometres in length, making it the second largest of the...
and then January-February for those in Kiwengwa
Kiwengwa
Kiwengwa is a village on the Tanzanian island of Unguja, part of Zanzibar. It is located on the northeast coast between the villages of Pongwe and Pwani Mchangani. It is also connected by road to Kinyasini, which lies eight kilometres to the west.-References:...
, located on the eastern side of the main island. Infant mortality can be significantly high with half of the infants born not reaching more than six months of age. The birth rates themselves, however, are actually decreased in comparison to mainland colobus monkeys and interbirth intervals are longer as well. Research has suggested that this is a consequence of disturbed habitats in which mainland colobi are not so affected.
Communication
The red colobusRed colobus
Red colobuses are Old World monkeys of the subgenus Piliocolobus in genus Procolobus. Some authors elevate Piliocolobus to a full genus, limiting Procolobus to the olive colobus. They are closely related to the black-and-white colobus monkeys and some species are often found in groups with the...
species have a smaller larynx
Larynx
The larynx , commonly called the voice box, is an organ in the neck of amphibians, reptiles and mammals involved in breathing, sound production, and protecting the trachea against food aspiration. It manipulates pitch and volume...
compared to other members of the Colobinae
Colobinae
Colobinae is a subfamily of the Old World monkey family that includes 59 species in 10 genera, including the skunk-like black-and-white colobus, the large-nosed proboscis monkey, and the gray langurs. Some classifications split the colobine monkeys into two tribes, while others split them into...
subfamily
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
. The male's call is more of an alto or soprano in contrast to the low bass of a male's in black-and-white colobus
Black-and-white colobus
Black-and-white colobuses are Old World monkeys of the genus Colobus, native to Africa. They are closely related to the brown colobus monkeys of genus Piliocolobus. The word "colobus" comes from Greek κολοβός kolobós , and is so named because its thumb is a stump.Colobuses are herbivorous, eating...
species. The Zanzibar red colobus is non-territorial in nature and as so does not typically make loud, territorial threat calls. Zanzibar red colobus distress and warning calls are the "bark", "chist", or "wheet". One of the loudest calls from the monkey is heard when he expresses his dominance over the group and when checking the sexual status of his females.
The call heard most often by people in or near Jozani Forest
Jozani Chwaka Bay National Park
The Jozani Chwaka Bay National Park is a national park of Tanzania located on the island of Zanzibar. It is the only national park in Zanzibar....
is the 'alerting signal'. This is an attention-getting call that is derived from the progression call. Chirps and grunts are made when there are changes in the surrounding environment such as changes in weather or animal movement in proximity to the group. With most arboreal animals, there are two different alerting calls, one for when a predator is on land, and another when there is an aerial predator. However, because of the lack of larger birds of prey in Zanzibar, such calls are not often witnessed. The young, on the other hand, because of their smaller size and vulnerability, do at times make such calls when they see shadows.
Because the Zanzibar red colobus is extremely social, it has a specific call for when it is alone for a certain amount of time upon which it feels vulnerable or threatened. The young are typically the ones to make such a call that sounds like a loud scream, but adults are occasionally likely (when deemed necessary) to make some variation of the call as well.
Evolution
The P. kirkii population on Zanzibar, represents a population of red colobus that is believed to have been isolated on the island after sea levels rose toward the end of the PleistocenePleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
epoch
Epoch (geology)
An epoch is a subdivision of the geologic timescale based on rock layering. In order, the higher subdivisions are periods, eras and eons. We are currently living in the Holocene epoch...
. Furthermore, it is suggested through mitochondrial analysis, that phylogenetic groups within the red colobus have been genetically isolated from another since the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
.
Examining cranial morphology has shown that Procolobus kirkii has diverged from mainland Procolobus to its own species. It has experienced an acceleration in morphological evolution of size which is suggested to be the result of insularity on the island and environmental pressures such as competition, habitat, predation and/or resource availability. There has been no evidence for population bottleneck
Population bottleneck
A population bottleneck is an evolutionary event in which a significant percentage of a population or species is killed or otherwise prevented from reproducing....
s in the species.
The smaller cranium of Procolobus kirkii in contrast to the mainland colobus monkey, is consistent with Foster's rule
Foster's rule
Foster's rule is a principle in evolutionary biology stating that members of a species get smaller or bigger depending on the resources available in the environment. This is the core of the study of island biogeography. For example, it is known that pygmy mammoths evolved from normal mammoths on...
(also known as the island rule) in which the original (larger) animal becomes smaller over time when there is limited resources. Males tend to have pedomorphic traits which include a shorter face, large orbits and an enlarged neurocranium. It is not certain how long ago and where this evolutionary change occurred.
Through molecular analyses, it is indicated that P. kirkii is more closely related to P. gordonorum compared to other red colobus species. This analysis has also placed the divergence of P. kirkii from its sister species P. godronorum at about 600,000 years ago, which actually allows for an older evolutionary age compared to the previous assumption that it had become its own species around the last glacial period.
Conservation
A number of factors have contributed to the monkey's endangered status. First, an increase in deforestationDeforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....
has resulted in a significant reduction in resources and habitat; second, it is hunted for meat and pet markets. To counteract the decline in population, various attempts have been made to protect the species. In 1974, specimens were moved to Ngezi Forest on Pemba Island to try to re-establish the monkey's the population. It had been found, however, that 20 years after the translocation to the island only one group of Procolobus kirkii was found and with few sitings and interviews with locals, the population was estimated to be between 15 and 30 individuals. Researchers concluded that the group had certainly survived but did not increase in number possibly due to adverse relations with humans. Some locals in Pemba hold superstitions against the monkey because of the idea that it brings bad luck upon farmers. This may explain the reason that they have not significantly grown in population size.
On Uzi and Vundwe Islands, P. kirkii monkeys are subject to extensive habitat destruction, particularly with coral rag forests. There is also reported poisoning, netting, and disappearance of monkeys as well as other with animals.
Various attempts have been made for conservation of the species. One project was with the World Wildlife Fund, specifically in Menai Bay
Menai Bay
Menai Bay is located in the south-west of Zanzibar in Tanzania. It is home to nineteen villages with a total population of around 17,000.- External links :***...
which is located just west of Uzi Island. Second, the Wildlife Conservation Society
Wildlife Conservation Society
The Wildlife Conservation Society based at the Bronx Zoo was founded in 1895 as the New York Zoological Society and currently manages some of wild places around the world, with over 500 field conservation projects in 60 countries, and 200 scientists on staff...
has funded conservation projects intended for the colobine but in both cases, there has been no apparent action that was directly supportive of the monkey.
The African Convention
African Convention
African Convention was a political party in French West Africa. The CA was formed at a meeting in Dakar on 11 January 1957. The CA constisted of the Senegalese Popular Bloc of Léopold Sédar Senghor, the African Popular Movement of Nazi Boni in Upper Volta and the Nigerien Democratic Front of...
has played a role in the conservation of the animal by categorizing it as 'Class A.' According to the document African Convention on the Conservation of Nature and Natural Resources, 'Class A' is described as:
species in Class A shall be totally protected throughout the entire territory of the Contracting States; the hunting, killing, capture or collection of specimens shall be permitted only on the authorization in each case of the highest competent authority and only if required in the national interest or for scientific purposes.
It has been suggested that an important way to promote conservation of the monkey is to simply spread awareness about it – that it is not a harmful animal and that it can actually be good for the region's economy because it draws tourism. This has been the case on Unguja Island. Furthermore, it would be necessary to establish and designate protected zones.