Cercopithecinae Subfamily Mandrillus
Who is Mandrillus:
Appearance: The drill looks like a stocky, olive-brown baboon with a large head, an off-white underside, and a white ruff surrounding a hairless black face. Dense fur around the neck of the adult male greatly enlargens the look of its head and chest. The impressive pink, blue, and mauve buttocks top a bright red scrotum. A stubby tail appears above the buttocks. The hands and feet are broad and strong. The thumb of the foot is especially well developed. The chin of fully adult males is bright red.
Bioko Subspecies: Mandrillus leucophaeus poensis
Habitat and Distribution: The drill is found in the moist evergreen forests of Bioko and between the Cross and Sanaga rivers. They live in the Cameroon mountains up to 1,000 m and also in areas with both forest and Savannah components.
Social Structure and Food: Drills live in groups of up to 25. Sometimes multiple groups rendezvous forming bands of up to 200 animals. The groups consist of a single dominant adult male and multiple females and their offspring. Groups travel on the ground, but feed and sleep in the trees. Drills utter a sharp alarm bark and grunt while foraging. Other sounds include the marked crowing call for contact between groups and the croaking call of distressed juveniles. The dominant male will shake branches and bob his head as a threat display. Drills are omnivores who eat fruits, much herbaceous growth, roots, mushrooms, invertebrates (especially worms, termites, ants, and spiders) and small vertebrates. Drills have also been reported to eat giant land snails, coconuts, sea turtle eggs, and infrequently injured duikers.
Zoos: The are currently forty-six drills in zoos world wide, although most are in non-reproducing groups. In fact, only the small group of 18 drills at the Hannover, Germany zoo reproduce regularly, with several females raising their young together. (ISIS)
Status: The drill is now listed as Africa's most endangered primate. On the mainland, their range has been devastated by clear-felling and human settlement. They are hunted everywhere as bush meat and it is not uncommon for an entire group to be shot as it takes refuge in the trees. The population on the southern tip of Bioko is one of only three known remaining populations. Listed as endangered by IUCN. (Kingdom, 1997)
These species were included in the genus Papio (the baboon genus) until 1989. They have been discovered to be genetically distinct from baboons, and more akin to mangabeys. They do share many features with baboons, including, most notably, size.
As with most primates, their taxonomy is under dispute.
Drills are dark brown with a black face, white tufted beard and scarlet lower lip. They have a long muzzle with lateral ridges. Their hindquarters is naked and varies in color, which range from bright red, blue, and light purple to lilac and pink. Inner thighs are red. Males are larger and more colorful than females. Their skulls show a marked sexual dimorphism. Males average 28 inches in length and weigh around 37.5lbs. Females are normally 26 inches, 22 pounds.
Adult mandrill males are larger and more colorful than females. Their long snouts are red and blue and they have yellow-orange beards. They also have colorful rumps, which are thought to aid drills and mandrills in leading their groups through dense forests. These may also provide social and sexual signals. Males are about 40 in. long and weigh around 59 lbs., while females average 22 in. in length, 25 lbs. Adult brain weight is 5.6oz. Mandrills are the largest of all monkeys. Both drills and mandrills have very short tails. Both have cheek pouches, which enable them to store food to eat later.
Range and Diet:
Both are found only in West Africa, the drill in Nigeria, Cameroon, and the island of Bioko; the mandrill in Cameroon, Equatorial Guinea, and Gabon. They are found only in a very small area. Both live in forests and have can have group home ranges ranges of up to 5000ha. Drills have never been seen outside of forests, while mandrills may sometimes venture onto the savanna.
Both are omnivorous, eating fruit, seeds, vegetation, and small animal prey. Mandrills have been known to raid crops and plantations. They will travel long distances (5-15km) and feed most of the day. It has been suggested that mandrills live in a comparatively food-poor zone, the lower levels of the forest which are the least productive part, which accounts for their long daily travels. Their travels are similar to hamadryas baboons, which inhabit desert regions.
Behavior and Social Structure:
Drills live in harem groups. One male can can as many as 20 females in his group. During the dry season several groups may come together to form one large group. As many as 200 individuals together have been observed. Males will emigrate and also can remain solitary. Mandrills normally form large multimale-multifemale groups with a distinct hierarchy. However, harem groups are not unheard of, as mandrill competition can be fierce. Dominant male mandrills are more colorful than lower ranked males. Group size can vary from 2 to over 200 individuals.
Both drills and mandrills are diurnal quadrupeds and can be arboreal or terrestrial. Adult males tend to be more terrestrial than females than females and juveniles, perhaps because of their larger size. Male drills forage at the rear of the group and herd the group away from danger. Mandrills will sleep in trees, in a different location each night.
Drills rely on visual and vocal communication, while mandrills also use scent marking. They are one of the few Old World monkeys to have cutaneous glands. Alpha males scent mark the most frequently. Drills have a series of deep grunts used for close contact communication, to get their group together, and to begin movement. Their loud, high-pitched "crowing call" is used contact subgroups that have separated for foraging. Juveniles alarm bark more than the others. Male mandrills have a 2-phase grunt or roar to round up their group. Drills have a "threat jerk," which consists of abruptly thrusting their heads forward, retracting eyelids, puckering lips, and raising the medial crest on their heads. Mandrills will "head bob" as a threat; and, like baboons, will yawn to display tension and warning. They greet each other (and others known and liked by them, like their favored zoo keepers) with a facial expression akin to a smile. This expression can be interpreted as a threat by some inexperienced observers who note the display of the mandrills' large teeth. Despite their fierce appearance, mandrills can be quite pleasant personalities and have also demonstrated impressive cognitive abilities.
Reproduction and Lifespan:
Drills reach sexual maturity at about 42mos. Females have an estrus cycle of 35 days and gestation length of around 174 days. Birth interval is generally 15 months. Lifespan is about 29 years.
Mandrills live longer, an average of 46 years. They are sexually mature a bit earlier also, at about 30 months. Female estrus cycle is 33 days, and they display a small swelling betwen their callosities. Gestation is 220 days with a birth interval of 17 months. Mandrills also have mating seasons which fall between July and October. This is dry season in Gabon. In captive studies higher ranking mandrills have greater access to estrus females and, according to DNA tests, fathered the most infants.
Drills have been classified as Endangered by the USESA. Both are hunted for meat. Drills' habit of "standing their ground" during an attack has made them preferred game in Nigeria, because several can be shot at one time. These are found in small, isolated patches of forest.
Interesting Drill and Mandrill Facts:
Because their deep forest habitat makes them difficult research subjects, and because they are wary of humans, Mandrillus have never been successfully studied in their native habbit.
AZA 1999/2000 Report on Conservation & Science
DRILLS & MANDRILLS
(Mandrillus leucophaeus & M. sphinx)
Species Coordinator: Cathleen Cox, Ph.D., Los Angeles Zoo International Drill (M. leucophaeus) Co-Studbook KeepersCathleen Cox, Ph.D., Los Angeles Zo& Andreas Knieriem, DVM, Hannover ZRegional Mandrill (M. sphinx) Studbook Keeper: Erik Terdal, Tulsa Zoo & Living Museum
Introduction: Drills. In response to a notable decline in reproduction among captive drills and a substantial decrease in the size of the wild population, the Drill SSP was established in 1988. At that time the drill had been identified as one of five African primates to be given highest priority for in situ conservation measures by the IUCN Primate Specialist Group. The initial master planning session for drills took place in June 1989, followed by a second master planning session held in September 1991. Since that time SPMAG analyses have been done on an annual basis.In 1989 the number of founders with living descendants in the SSP drill population ranged between 5 and 21, depending on whether or not individuals with unknown parentage were treated as founders. In recent years the drill studbook has been updated with each quarterly distribution of the ISIS Specimen CD-ROM. The management version of the studbook utilizes historical data together with several conservative but pragmatic assumptions. In particular, wild parentage is assigned to the drills listed in the international studbook which have unknown parentage and unknown birth location that first appear in years in which there were no captive births that were lost to follow-up. With these assumptions the number of founders becomes 20. Much of the genetic diversity that the 20 founders represented had already been lost by 1989 and the management group agreed on the goal of maintaining 80% of the genetic diversity for 100 years. Assuming N~IN = 0.35, the minimum viable population size is 97 animals.
Mandrills: While the status of the drill in captivity and in the wild remains marginal, the status of the mandrill, the sole congener of the drill, appears considerably better. One hundred forty-two mandrills reside in 33 AZA accredited institutions and 21 additional mandrills are held by private owners. Mandrills reproduce readily and it appears that the likelihood of developing a self-sustaining captive population is much greater for mandrills than for drills. Current year
In 1998 the WCMC approved the formation of the Mandrillus SSP which is to manage both drills and mandrills and replaces the Drill SSP. The mandrill is much better known than the drill and information gained through mandrill management promises to be a valuable asset in improving reproduction in the drill population. The draft of the first mandrill master plan was circulated in April 2000. The goal of the management group is to maintain 90% of mandrill genetic diversity for 50 years. Assuming that the Ne/N = 0.40, that we are in the initial year of the program, and that we will increase lambda to 1 .25, we will need space for 208 mandrills. Recommendations for 20 mandrill pairings were made in the master plan. Four of the reconunended pairings were already in place and the transfers needed for six of the recommended pairings have subsequently been made. Preparations for the transfers needed for three additional recommended pairings are currently underway.
Population Status in the Wild: Drills. This endangered baboon is found in a limited range of the west coast of Africa but the forest dwelling primates are rarely seen. One subspecies ranges from eastern Nigeria southward to the Sanaga river in Cameroon, another resides on the island of Bioko, Equatorial Guinea. Despite local regulations, both subspecies are hunted as “bush meat* which provides a short-term source of revenue for local residents. Hunting together with deforestation and the accompanying fragmentation of the remaining habitat are the major causes of the continuing decline in the drill population.
The drill is identified as the single species to be given highest priority in in situ conservation efforts in the IUCNISSC Action Plan for African Primate Conservation that was updated in 1996.
Field researchers Liza Gadsby and Peter Jenkins estimated that fewer than 3,000 drills remained in the wild in 1996. This estimate was based on the assumption that there were 500 drills on Bioko. However, in March of 1998 field researcher Gail Hearn reported a further decline in the number of drills on Bioko; Dr. Hearn now .believes that there may be as few as 100 remaining on the island.
Mandrills: This striking baboon is believed to be allopatric with the drill and its range lies to the southeast. The area occupied by mandrills is approximately four times larger than that occupied by drills and extends from the Sanaga River in Cameroon through Rio Muni, Gabon and into the southern portion of the Congo. Deforestation and hunting are on the rise in the mandrill*s range and it has been categorized as endangered by USFWS and “at risk” by the IUCN Primate Specialist Group. At this time there are no accurate censuses that provide an estimate of the number of mandrills in the wild.
Demographic Trends: Drills. As of 30 June, 2000 there were a total of 144 (62.80.2) drills in captivity: 18 (7.11) in North America, 37 (15.21.1) in Europe, 10 (5.5) in Japan, and 79 (35.43.1) in Africa held under the auspices of Pandrillus which includes the Drill Rehabilitation and Breeding Center (DRBC) in Nigeria. At this time, more than one-half (31.38) of the captive population is held by DRBC and that is where most of the reproduction is taking place. At DRBC 14 drills were born and 4 confiscated drills were accepted between 1 July 1999 and 30 June 2000. In contrast, just a few females held elsewhere are capable of reproducing and this substantially limits the rate at which the North American, European and Asian captive populations can expand. Without additional imports, the founder base of these populations will deteriorate as the older animals pass away. Historically, drills in captivity have been maintained in pairs or in small groups with one male and one or more females; in both cases reproduction has been marginal. In contrast, the core group of drills housed at DRBC consists of 3 adult males, 7 adult females and numerous juveniles. Reproduction has proven quite successful in the large multi-male group, which has caused the SSP to re-evaluate the manner in which North American drills are housed. San Diego Wild Animal Park is now planning to construct a large field pen which will hold a multi-male group of drills which would be provided as a loan from the Nigerian government and DRBC.
Mandrills: As of 30 June 2000 there were a total of 142 (56.84.2) mandrills in AZA accredited institutions. Mandrill managers have tended to limit the number of births in recent years, which has resulted in a decrease in the number of immature animals as well as overall population size. Now that mandrills are being managed under an SSP, lambda will be increased to 1.25 and 18 to 20 pairs will be recommended for breeding each year.
Population Genetics: Drills. Analysis of the management smdbook shows
that 15 unrelated individuals have contributed to the current North American drill population. Despite the number of founders, our current FGE is just 4.90. Bringing in additional founders into North America would substantially improve the outlook for establishing a self-sustaining population and drill holders are being encouraged to exchange one or more of their animals with those held in other regions. Such regional exchanges will benefit all programs and there is a need to improve the degree of communication between institutions on different continents that are holding drills. The Mandrillus SSP gives full support to the development of a formal global management plan under the IUCN.
Mandrills: In the management version of the mandrill studbook the assumption is made that all individuals of unknown parentage who came into the population prior to 1960 were actually wild caught animals. Excluding the living animals with unknown parentage as well as privately held mandrills from the analysis shows that the current population is derived from 21 founders and there are no potential founders remaining. The present FGE is 8.629 and the potential FGE is 13.747. There are still many individuals in the population whose lineage is not clear; in order to minimize the impact of these mandrills on the future population anyone whose genome is less than 50% known are not to be recommended for breeding.
Special Concerns: At present breeding is occurring at just one of the four facilities that hold drills. The lack of breeding results from both female reluctance to accept male approaches and from a paucity of males willing to approach. For the past two years the suitability of techniques used for assisted reproduction in other species has been explored with little success. In the meantime, three transfers have been recommended that will bring unfamiliar animals into contact and, it is hoped, increase the number of females producing young. A second area of concern is the possibility that drills in captivity vary in subspecific origin and this issue needs further clarification. It has been determined that the two subspecies which are very similar in appearance can be distinguished on the basis of their mitochondrial DNA. We now need to identify the subspecific make-up of each drill in North America and determine if pairings between subspecies are less likely to result in viable births.
Progress Towards Goals: 1) The draft of the first mandrill master plan has been circulated and includes 20 breeding recommendations. The transfers needed to make possible 13 of the recommended parings possible have taken place or are in progress.
2) Three transfers of drills have been made or are in progress that are expected to result in an increase in thenumber of productive females.
3) San Diego is working to import new founders for the drill population from Nigeria.
4) At the Bronx Zoo further work is underway to further refine techniques for distinguishing between the 2 subspecies of drill; when complete the techniques are to be used to determine the subspecific composition of the North American drill population.
Field Conservation: The SSP continues to encourage the establishment of in situ captive breeding facilities and contributes funds to the DRBC. DRBC*s permanent facility has been built in the Afi River Forest Reserve, the only major drill habitat area in Nigeria that is not included in Cross River National Park. The permanent facility promises to enhance wildlife conservation efforts in Nigeria and may serve as a model for similar facilities in Cameroon and on Bioko. Ultimately, such programs may lead to the exchange of genetic material between captive populations, increasing the viability of each.
Financial Report: The SSP encourages participating zoos to contribute to projects that benefit captive breeding as well as field conservation of drills. During the past year Los Angeles contributed funds to assist with the local education program being administered by DRBC in Nigeria. San Diego and Los Angeles are contributing funds as well as information to assist with improvements in the physical plant and educational endeavors of Limbe Conservation Center in Cameroon where 10 drills are being held. Each zoo makes their own contributions directly to the projects identified and an account specifically for the Mandrillus
SSP has not been needed.
Short-term Goals for the Upcoming Year: 1) Facilitate the production of a current version of the mandrill studbook.
2) Update the drill master plan.
3) Determine the subspecifie composition of the North American drill population.
4) Assess the success of assisted reproduction efforts to date and make recommendation concerning future work inthis area.
5) Provide information and seek funding to support in situ studies and in situ captive breeding facilities.
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