Maxwell's duikers were considered by some to be the same species as blue duikers, but are argued by others to be different species based on pelage color, the morphology of the pedal gland in the foot, which has a deeper canal in P. maxwellii, and the smaller skull size of P. monticola.
The word duiker was first used by Dutch settlers in Africa and means “diver,” referring to the animal’s propensity for diving into deep foliage when threatened. The generic name of this species, Cephalophus, derives from the Greek words kephale, meaning “head” and lophus, meaning “crest,” referring to the tuft of hair found on top of the animal’s head. Finally, the name maxwellii was given to this species to honor Colonel Charles Maxwell, who captured the P. maxwellii specimen first described by Hamilton Smith in 1827.
Of primary importance in communications among Maxwell’s duikers is the use of the suborbital gland in marking both territories and other duikers. Male duikers frequently mark their territories, when most active marking an average of 5.6 objects every ten minutes. Females mark about 2.8 objects every ten minutes. Maxwell’s duikers frequently rub heads, rubbing suborbital secretions on one another. Territorial marking and head rubbing increase when a foreign duiker is introduced into an established group. This indicates that such marking serves not only as a means of advertising territory, but also of reinforcing social relationships. Interestingly, while the behavior of Maxwell’s duikers in using the suborbital gland is well documented, little is reported concerning how Maxwell’s duikers react to these chemical markers.
In addition to suborbital secretions, Maxwell’s duikers smell or taste one another’s urine. When a male samples a female’s urine, he exhibits flehmen behavior, which is characterized by a curled upper lip and open mouth. It is hypothesized that flehmen is somehow useful in helping the animal detect pheromones in the urine. Females also sample male urine, but with less frequency.
Maxwell’s duikers make an “alarm whistle,” though it is not reported in what context these whistles are used or how other duikers react to them.
Communication Channels: tactile ; acoustic ; chemical
Other Communication Modes: pheromones ; scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Duiker populations have decreased from excessive hunting and habitat destruction. Of prime importance in the decreasing populations is the increased use of firearms by native populations in hunting these animals. While Maxwell’s duikers are not endangered, it is certain that their populations are below previous maximum levels. However, it is thought that the species will remain in abundance as long as ample habitat is available.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
There are no known adverse effects of P. maxwellii on humans.
Maxwell’s duikers are hunted by local peoples for their skins. The Mano and Gio peoples of the Mount Nimba Range in Liberia use large deadfall traps to catch these duikers. These traps can kill the animals, but duikers are also taken alive and are available for sale. In addition to being hunted and trapped for their skins, they are hunted for meat, which is available in large bushmeat markets and can provide hunters with a large and sustainable income. Maxwell’s duikers are rarely hunted for trophies due to their small size. Methods for trapping Maxwell’s duikers outside the Mount Nimba area include firearms and nets and snares placed on frequently used duiker trails.
Positive Impacts: food ; body parts are source of valuable material
Maxwell’s duikers most likely aid in the distribution of the seeds of the plants whose fruit they eat. More seeds are destroyed during digestion than are effectively disseminated in the their feces. Small seeds, however, may be effectively dispersed, and seeds of plants in the families Solanaceae and Cecropiaceae are distributed in this manner. Plants of the genus Ficus, whose fruits have small seeds and are heavily consumed by duiker are most likely dispersed this way. Some duiker spit out seeds during rumination.
Duikers are known to interact with baboons (Papio) in areas where the two species overlap. Maxwell’s duikers follow monkeys and eat fruit that the monkeys dislodge from the trees.
Several parasites are known to use P. maxwellii as a host. These include the blood parasite Theileria mutans, the nematodes Thrichuris ovis and Setaria labiata-papillosa, the cestode Avitellina centripunctata, and 8 types of tick. Maxwell’s duiker serve as food for the predators listed above.
Ecosystem Impact: disperses seeds
Mutualist Species:
Commensal/Parasitic Species:
Maxwell’s duikers are herbivores and mainly feed on the leaves of small forest plants such as herbs and shrubs. They rarely graze on grasses and are classified as browsers. They feed heavily on the leaves of Thonningia sanguinea, Canthium vulgare, and Alchornea cordifolia.
Maxwell’s duikers also eat fruit, which varies seasonally in abundance. Over the seasons, a total of 78 different types of fruit were eaten with an average of about 3 different species of fruit being consumed by an individual duiker at any one time. Preference varies seasonally; for example, during January and February, duikers prefer Phoenix reclinata, Griffonia simplicifolia, Nauclea latifolia, Ficus capensis, Alchornea cordifolia and Blighia sapida.
Other foods consumed by P. maxwellii are blossoms, roots, tubers, and fungi, although these foods constitute only a very small portion of the animals’ diets. Although it is speculated that ants are a natural part of the diets of many species of duikers, they have so far been found only in the stomachs of several Maxwell’s duikers. The ant species consumed were Paltothyreus tarsatus and Oecophylla longinoda. Some duikers in captivity have been seen to eat young birds, although this behavior has not been observed in the wild.
Maxwell’s duikers prefer leaves to fruit only during the dry season when tubers and flowers are also present. They show no seasonal variation in the number of species of fruit that they eat.
Animal Foods: birds; insects
Plant Foods: leaves; roots and tubers; fruit; flowers
Other Foods: fungus
Primary Diet: herbivore (Folivore , Frugivore )
Philantomba maxwellii inhabits an area of western Africa extending from Senegal and Gambia to Nigeria. Members of the species generally prefer lowland rainforests, second growth forests and forests relics found in savannas.
Biogeographic Regions: ethiopian (Native )
Maxwell’s duikers inhabit rainforest areas, relic forests in savannas, secondary growth forests and clearings in rainforests. Individual P. maxwellii are able to live in a wide variety of habitats because of their wide and adaptable food habits, which allow them to find adequate supplies of food in both primary and secondary forests as well as cleared areas.
Philantomba maxwellii individuals prefer dense foliage where they can remain concealed. Maxwell’s duikers rarely stray more than 30 m from cover. Individuals make trails through the underbrush in their respective territories.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest ; rainforest
Little information is known of the lifespan of P. maxwellii in the wild, but they are known to live as long as 10 years in captivity.
Range lifespan
Status: captivity: 10 (high) years.
Maxwell’s duikers are small antelopes, averaging about 66 cm in length and 5 to 7 kg in weight. They have short legs and an arched back and stand 35 to 38 cm tall. Females are reported to be larger in length and mass than males.
The pelage of P. maxwellii is grey or grey-brown and paler on the animal’s underside. Maxwell’s duikers are more uniform in color than closely related blue duikers, Philantomba monticola, which are more sharply bicolored and bear areas of white fur on their buttocks. Maxwell’s duikers have short, bushy tails with a fringe of white fur around the edges. Two white stripes run symmetrically down an animal's head from its horns above its eyes, to its nose. Conspicuous suborbital glands are present below each eye.
Maxwell’s duikers have small, pointed horns that extend backwards from the rear of the skull. Horns are present in both sexes and emerge in the male when it is about two and a half months old. The animals also have a small tuft of dark hair on the tops of their heads.
Philantomba maxwellii has pedal glands in its feet, which consist of a small sac in the interior of the foot that leads to the exterior via a narrow canal. This trait is useful in differentiating P. maxwellii from the related blue duiker, whose pedal glands lack the long canal.
Range mass: 5 to 7 kg.
Average length: 36-40 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger; ornamentation
Maxwell’s duikers are small, nocturnal, and skittish, making them difficult to observe in the wild. Humans avidly hunt this species but duikers have several natural predators as well. These predators include crowned eagles (Harpyhaliaetus coronatus) and leopards (Panthera pardus), as well as local species of pythons and other wild cats.
Maxwell’s duikers issue an “alarm whistle,” but can also make a bleating noise when in danger, such as when confronted and cornered by another duiker or handled by a human. When Maxwell’s duikers are nervous or threatened, they freeze as they are, sometimes in mid-stride.
Known Predators:
Anti-predator Adaptations: cryptic
A male duiker forms bonds and mates exclusively with one female, even when a surplus of females is present.
Male duikers smell or lick the urine of females and demonstrate flehmen, which is a behavior in which the animal retracts its upper lip and opens its mouth. This behavior is considered to somehow aid the animal in sensing pheromones and ascertaining the sexual status of females.
Male Maxwell’s duikers engage in a simple courtship wherein the male chases and bites the female. After a period of chasing, the male and female circle one another, after which the male approaches the female from behind, kicking its foreleg between the hindlegs of the female. Copulation ensues shortly thereafter.
Mating System: monogamous
Female P. maxwellii breed about once a year and give birth to a single young. Duikers time their mating so that young are born in the dry season (January to March) or the “little dry season” (August to September).
The gestation period is about 120 days. Labor for this species lasts 20 to 30 minutes. After the infant duiker is born, the mother cleans it thoroughly with its tongue and eats any membranous material clinging to it. Newborns are capable of standing and walking within hours of birth, and one was reported as being able to run within 25 minutes of birth. Newborn Maxwell's duikers are "hiders" and generally remained concealed. A young duiker gains about 50 g per day by drinking its mother’s milk. Female duikers nursing their young must drink ample quantities of water. After about 2 weeks, young Maxwell’s duikers are able to begin foraging on their own. Weaning follows soon afterwards, although young duiker continue to nurse occasionally until 2 months of age. Full maturity is reached in about three years.
Breeding interval: Maxwell's duikers breed about once a year.
Range number of offspring: 1 to 1.
Range gestation period: 4 (low) months.
Average gestation period: 4 months.
Average weaning age: 0.47 months.
Average age at sexual or reproductive maturity (female): 3 years.
Average age at sexual or reproductive maturity (male): 3 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Maxwell’s duikers provide little in terms of parental care. Young duikers usually spend their time in concealed areas and seek out their mothers only for nursing; female duikers were not witnessed to seek out their offspring even to nurse them. Maxwell’s duikers nurse with mother and young antiparallel to one another. Soon after a young Maxwell's duiker begins foraging on its own, at about 2 weeks of age, its mother begins to discourage it from nursing. Female duikers lick their infants as a method of grooming them.
Parental Investment: altricial ; female parental care ; pre-hatching/birth (Provisioning: Female); pre-weaning/fledging (Provisioning: Female)
The Maxwell's duiker (Philantomba maxwellii) is a small antelope found in western Africa.
Maxwell's duiker
Phylogenetic relationships of Maxwell's duiker, including Walter's duiker[4]The scientific name of Maxwell's duiker is Philantomba maxwelli. It is classified in the genus Philantomba along with the blue duiker (P. monticola) and Walter's duiker (P. walteri). It was first described by English naturalist Charles Hamilton Smith in 1827.[5][6] The species is sometimes treated as a species of Cephalophus,[2][7] another genus of duikers, although Philantomba has been recognised as a genus by zoologists such as Peter Grubb and Colin Groves.[8] Theodor Haltenorth has considered this species to be a race of the blue duiker due to their identical features.[5][6]
In 2012, Anne R. Johnston (of the University of Orleans) and colleagues constructed a cladogram of the subfamily Cephalophinae (duiker), that includes the three genera Cephalophus, Philantomba and Sylvicapra, based on mitochondrial analysis. Philantomba was shown to be monophyletic. It is sister to the rest of the subfamily, from which it diverged nearly 8.73 million years ago (in the late Miocene). Maxwell's duiker split from blue duiker 2.68 to 5.31 million years ago.[9] This cladogram, however, did not include the newly discovered Walter's duiker. Marc Colyn (of the University of Rennes 1) and colleagues, who had discovered this species in 2010, had prepared a similar cladogram that included it.[4]
Three subspecies are identified:[5][7][10]
Maxwell's duiker is a small antelope, as are the others in its genus. It is characterised by a slightly elevated back, short legs, a small head and short, round ears. According to measurements by Haltenorth, the head-and-body length is typically between 63 and 100 centimetres (25 and 39 in), and between 55 and 90 centimetres (22 and 35 in) excluding the head. It reaches 35–38 centimetres (14–15 in) at the shoulder, and weighs around 8–10 kilograms (18–22 lb). The tail, 8–10 centimetres (3.1–3.9 in) long, is bushy and lined with white.[7][11] The species exhibits sexual dimorphism, as the females are slightly larger than the males.[10] The coat is grayish brown, sometimes with a bluish tinge; the colour varies with individuals. A short tuft of hair circles the base of the horns and covers the area between them. The underbelly, in contrast with the dorsal parts, is generally white. Four teats are present.[7]
Males, and sometimes females, possess straight, short, spiky horns. Heavily ringed and thick at the base, these measure 3.5–6 centimetres (1.4–2.4 in) in length.[7][11] The length of the horns of the subspecies P. m. maxwelli rises from east to west, though this is not apparent in Ghana and the longest horns are observed in the western extremes of the range. The proportion of horned females reduces sharply from 100 percent in Nigeria and Togo to 5 out of 80 in Liberia.[12] P. m. libriensis females generally lack horns; in populations where female grow horns, the males are observed to have longer horns.[7] The broad skull, with a narrow, bare muzzle, is nearly 12.7 centimetres (5.0 in) long and 6.4 centimetres (2.5 in) wide.[13] In P. m. maxwelli, the skull measurements tend to increase from east to west between Togo and Liberia, though this trend is not observed in the eastern and western extremes of the range.[12]
The blue duiker bears a striking resemblance to Maxwell's duiker. However, the latter is nearly twice as large and heavier as the former, with a larger skull. While colouration is more uniform in Maxwell's duiker, the blue duiker shows two different colourations - there is a marked transition from the dorsal parts and the flanks to the rump. Another point of difference is the pedal gland (in the hooves), which has a simpler opening in the blue duiker.[7][10][12]
The Maxwell duiker prefers areas with fresh and dense growth of shrubs and other plants. It inhabits the warm, moist lowland forests prevalent in western African countries such as Benin, Burkina Faso, Côte d'Ivoire, Ghana, Guinea, Guinea-Bissau, Liberia, Nigeria, Senegal, Sierra Leone and Togo. The habitat also includes forest fringes, secondary, scrub and gallery forests and farmlands. The western limits of the range lie in southwestern Senegal and western Gambia, from where it extends as far east as the Cross River in Nigeria.[2][14]
The Maxwell duiker's diet mostly consists of fruits, seeds, secondary vegetation and shrubs. Maxwell's duiker and other duikers present in the same geographical area were found to have similar diets. Diets are subject to seasonal changes, with a shift towards vegetation and parts of flowers at the beginning of winter.
The animal's small size is reflected in its food choices. Due to its smaller mouth, body anatomy, and masseter muscle, it tends to concentrate on food items up to 3 cm in diameter, while larger species eat items up to 6 cm in diameter.[15]
Maxwell's duiker has a preorbital gland known to be used for marking objects and members of the same species, especially by dominant males. It was one of the first animals observed using its preorbital gland for scent marking. It was shown that scent marking is also associated with individual recognition or social appeasement as male and females will often press these glands together on both sides of each other's faces.[16]
Calves are born mainly during the two dry seasons in Africa. Females birth a single calf once per year, after a gestation period of 120 days. Offspring usually weigh around 1/10 the weight of their mother and are similar in color to calves from other duiker species. Maxwell's duikers can survive up to 10 years in captivity.[17]
Maxwell's duiker is listed as Least Concern, though with the population trend decreasing, by the International Union for Conservation of Nature and Natural Resources (IUCN).
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