Philantomba maxwelli (C.H. Smith, 1827)

Don E. Wilson & Russell A. Mittermeier, 2011, Bovidae, Handbook of the Mammals of the World – Volume 2 Hoofed Mammals, Barcelona: Lynx Edicions, pp. 444-779 : 708-711

231.

Maxwell's Duiker

Philantomba maxwelli

French: Céphalophe de Maxwell / German: Maxwell-Ducker / Spanish: Duiker de Maxwell

Taxonomy. Antilope maxwelli C.H. Smith, 1827 ,

Sierra Leone.

Maxwell's Duiker is sometimes included in P. monticola (particularly in historical reports), although it is now well recognized as a separate species. Reports prior to 2010 listed Maxwell’s Duiker as present from Gambia to Nigeria, but populations from Togo eastwards have been determined to be specifically distinct and are listed under Verheyen’s Duiker (FP. wal teri). Two subspecies recognized.

Subspecies and Distribution.

P. m. maxwelli C.H. Smith, 1827 — Senegal and Gambia to E Ghana (likely limited to the E by the Volta River).

P.m. danei Hinton, 1920 — Yatward and Sherbro Is, Sierra Leone.

Descriptive notes. Head-body 55-75 cm, tail 8-16 cm, shoulder height 32-42 cm; weight 7-5 kg (6:5—11-2 kg) in males and 8-6 kg (6.5-12. 6 kg) in females. Maxwells Duiker is the largest member of the genus Philantomba , although subspecies danei is notably smaller than the mainland form. Females may be up to 15% heavier than males. The body has a distinctively arched back; the forelegs are shorter than the hindlegs, and the head is often held low. The general color is dark brownish-gray, sometimes with a bluish or chestnut-red sheen, with the back darker than the sides. There is significant variation in color between and within populations; this may be age-related, as old animals tend to be paler. The belly and inner thighs are whitish, and this color may extend to the chest, but not the neck. The tail is dark above and white underneath; the lateral hairs are white and tend to grow at right anglesto the tail. The face is generally colored as the body, but the forehead is dark, approaching black in some individuals. The hair on the forehead is quite long, and extends from the crown as a short crest. Distinct pale gray stripes run from the medial corners of the eyes to the crown of the head; these are very narrow above the eyes, widening and becoming more diffuse on the forehead. The contrast between the forehead and superciliary stripes is especially pronounced in young adults, but may be faded or indistinct in old animals. A pair of swollen preorbital glandslies in front of the eyes. The glandular opening is 2-5 cm long and is surrounded by naked skin. The underside of the jaw and upper throat are white. The ears are small and rounded, with a dark brown exterior and white interior. There is a slight coronal crest. Horns are always present in males, but their presence is not consistent in females. In form, the horns are conical and ribbed at the base; the sharp tips usually curve slightly forward. Average horn length in males is 3-5—4-9 cm; maximum recorded length is 6-25 cm. When present in females, the horns are shorter. Most females of subspecies maxwelli are hornless (95% in Liberia; 81% in Ghana); females of subspecies dane: generally have horns. Dental formulais10/3,C0/1,P 3/3,M 3/3 (x2) = 32.

Habitat. Wide-ranging in both primary and secondary tropical forests in West Africa. Maxwell’s Duiker is highly adaptable and may be found in relic forest patches, gallery forests, and farmbush, where farm plots are interspersed with brushy thickets. Open fields and bamboo thickets tend to be avoided. The introduced Akyeampong weed (Chromolaena odorata ) provides a significant source of cover in disturbed areas and allows Maxwell's Duikerto live in close proximity to human settlements. This species rarely ventures more than 20-30 m from cover. In Ivory Coast, population densities in primary forest have been estimated to be 63 ind/km?; in secondary forest densities tend to be higher, approximately 79 ind/km?. In Ghana and Liberia, population densities are much lower, estimated at 10 ind/ km? even in protected areas.

Food and Feeding. Primarily frugivorous, with fleshy fruits and leguminous seeds comprising, on average, 76-9% ofthe diet (based on eight stomachs collected near Tai National Park, Ivory Coast; this averagerises to 87-9% if one outlier is excluded). Leaves and flowers are also regularly consumed; these are eaten in a significantly greater proportion during the rainy seasons when fruit is scarce. Over 78 fruiting plant species have been identified in the diet of Maxwell's Duiker in Ivory Coast. Studies performed in central Ivory Coast (near Toumodi) indicate that preferred fruiting species during the dry season include Alchornea cordifolia, Blighia sapida, Ficus capensis, Griffonia simplicifolia, Mangifera indica, Nauclea latifolia , and Phoenix reclinata; during the rainy season, fruits of Canthium vulgare, Spondias mombin, Nauclea latifolia , and Blighia sapida comprise the greatest proportion of fruits eaten. In other regions of Ivory Coast, fruits of Dialium aubrevillei and Musanga cecropioides and seeds from Turracanthus africanus are heavily utilized. Maxwell’s Duiker is unable to ingest large fruits; the maximum size that can be swallowed whole is approximately 3 cm. Larger fruits must be soft enough for the flesh to be chewed off. Browse species in the diet include Thonningia sanguinea, Landolphia owariensis, Homalium aylmeri, Canthium vulgare, and the cultivated Manihot esculenta . Blossoms are frequently consumed; fungi and bark are eaten in small quantities. Because many of these food sources are most plentiful in the forest canopy rather than at ground level, Maxwell’s Duikers will forage beneath groups of primates, picking up dropped and dislodged items. Several species of ants, particularly Paltothyreus tarsatus and Oecophylla longinoda, are opportunistically consumed.

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Breeding. Breeding occurs throughout the year in Ghana, although in Ivory Coast most births occur during the dry seasons, from January to March and from August to September. During courtship, the male chases the female, licking or biting at her tail. As the female becomes increasingly receptive, her pace slows and the male begins to perform ritualized leg-kicking (“laufschlag”); he determines female receptivity by testing her urine with the flehmen response. Copulation is brief. Gestation is approximately 205 days (from four reliable captive records). Litter size is one, and neonates weigh 620-954 g. Births typically occur in the early morning or late afternoon. Infants andjuveniles are much darker in color than adults, with distinct white markings above the hooves. Although they can stand soon after birth, infants spend the majority of time cached in an isolated and hidden spot, usually at the base of a tree (especially between buttress roots). The mother visits regularly to nurse the infant. The same bedding spot may be used for over a month, and the infant remains immobile there unless approached within 3 m. After two weeks, the infant becomes increasingly mobile and begins nibbling on dead leaves; at four weeks, the juvenile forages daily but consistently returns to the hiding spot to spend the night. Weaning occurs around two months and the caching bed is abandoned by three months. Females may reach sexual maturity as early as eight months, although 10-12 months is more typical. In captivity, this species may live up to 18 years.

Activity patterns. Diurnal. Activity levels are highest in the early morning (06:30-08:00 h) and late afternoon (16:30-18:00 h). A general trend to lower activity levels is seen during midday (10:00-14:00 h), although 60% of observations are still of active individuals. In captivity, Maxwell's Duikeris active for 64% of daylight hours (06:30 18:00 h) and only 21% of the hours of darkness (18:30-06:00 h). Females tend to be less active than males. Night-time is spent bedded down in dense cover;if disturbed, individuals will move away and then settle down quickly. The same sleeping spotis rarely used for two consecutive nights.

Movements, Home range and Social organization. Maxwell's Duiker is a highly sedentary species, with individuals inhabiting stable home ranges that are typically 0-05 km?, but may be as small as 0-03 km?®. There is no significant difference in home range size between the sexes. Home ranges in primary forest tend to be larger than in secondary forest. Networks of paths are used within the home range. Adult males make occasional forays outside of their home range boundaries, usually returning via a circular route within 3-5 hours. Such travel is very different from the typical slow foraging within the home range and may involve reproductive or territorial activity. The basic social unit is a male-female pair; maximum recorded group size is five (one male, two adult females, and two juveniles). A bonded pair effectively shares a home range, with an overlap of approximately 80% between the two individuals. Adjacent pairs have distinct home ranges with less than 1% overlap across seasons. Home range boundaries tend to be stable across years. Borders are marked with latrine areas; males may also horn vegetation at the boundaries. Males are territorial and frequently (5-6 times/ 10 minute interval) mark boundary objects with their preorbital glands (females also mark, but at half that rate: 2-8 times/ 10 minutes). Males do nottolerate the presence of other males at the periphery of the home range. Agonistic interactions between males are brief but very intense and lack a ritualized pre-combat stage. Fights generally last less than two minutes, and involve head-to-head collisions that may result in one competitor being flipped into the air with the force of impact. Intense chases usually follow. Paired individuals often reciprocally groom and mark each other using preorbital gland secretions. In the wild, pairs account for 39% of observations; however, records of solitary animals (seen in 53% of observations) may be misleading: the second partner may not be visible to the observer. Pedal scent glands may play a role in following or locating other duikers. Night-time observations are primarily of solitary individuals resting. Despite maintaining a close association with a single partner, males will mate with other females. While walking or foraging, the tail is constantly flicked up and down,flashing the white underside; it has been suggested that this is a visual cue for paired individuals, although visibility in some habitats is too low for visual signals. When startled, Maxwell’s Duiker freezes in position, even if in mid-stride; the tail also ceasesits regular motion. Only two vocalizations are known: an alarm whistle and a loud bleat.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Maxwell's Duiker is common throughout most ofits range; the total population is estimated to be several million individuals. The adaptability ofthis species to disturbed habitats has enabled it to continue to thrive despite large tracts of original habitat being modified or destroyed. Hunting for bushmeatis the principal threat to survival.

Bibliography. Aeschlimann (1963), East (1999), Hofmann & Roth (2003), IUCN/SSC Antelope Specialist Group (2008ar), Newing (1994), Ralls (1969, 1973, 1975), Weigl (2005), Wilson (2001).

Figures

228. Bush Duiker (Sylvicapra grimmia), 228. Bush Duiker (Sylvicapra grimmia), 229. Sahel Duiker (Sylvicapra pallidior), 229. Sahel Duiker (Sylvicapra pallidior), 230. Crowned Duiker (Sylvicapra coronata), 230. Crowned Duiker (Sylvicapra coronata), 231. Maxwell's Duiker (Philantomba maxwell), 231. Maxwell's Duiker (Philantomba maxwell), 232. Verheyen’s Duiker (Philantomba walteri)

Subspecies and Distribution. P. m. maxwelli C.H. Smith, 1827 — Senegal and Gambia to E Ghana (likely limited to the E by the Volta River). P.m. danei Hinton, 1920 — Yatward and Sherbro Is, Sierra Leone .