Animal Info - Drill

(Other Name: Dril)

Mandrillus leucophaeus (Papio l.)

Status: Endangered

1. Profile (Picture)
2. Tidbits
3. Status and Trends (IUCN Status, Countries Where Currently Found, Population Estimates, History of Distribution, Threats and Reasons for Decline)
4. Data on Biology and Ecology (Weight, Habitat, Age to Maturity, Gestation Period, Birth Season, Birth Rate, Maximum Age, Diet, Behavior, Social Organization, Mortality and Survival, Density and Range)
5. References

Profile

Pictures: Drill #1 (7 Kb JPEG) (Kids Ecology Corps); Drill #2 (32 Kb JPEG) (Spec. Cons. Found.); Drill #3 (91 Kb JPEG)

The drill is a short-tailed forest baboon weighing about 15 kg (33 lb). It is found in tropical rain forest, where it subsists on a diet of fruit, seeds, fungi, roots, insects and small animals. The drill is semi-terrestrial, feeding mainly on the ground.

The drill has a flexible social organization. It lives in groups of up to about 20, consisting of a male, several females and their young. These groups may gather into super-groups of up to 200.

The drill is found within a range of less than 40,000 sq km (15,000 sq mi) in western Cameroon, southeastern Nigeria and Bioko Island (Equatorial Guinea). The major reasons for the drill's decline are hunting for food and habitat loss and fragmentation due to development, logging and agriculture.

Tidbits

*** In 1995 the IUCN rated the drill as the highest conservation priority among African primates with regard to species vulnerability and habitat value (Gadsby 1995).

*** Hunters report that it is declining in terms of group size and group density, and super-groups are rarely encountered (Gadsby 1995).

*** Other than in Korup National Park in Cameroon, there were no studies of the drill undertaken between the late 1960's and the late 1980's.

Status and Trends

IUCN Status:

1970's - 1994: Endangered
1996: Endangered (Criteria: A1acd+2cd, C1+2a)
2000 - 2004: Endangered (Criteria: A1acd+2cd) (IUCN 2004)

Countries Where the Drill Is Currently Found:

2004: Occurs in Cameroon, Equatorial Guinea (Bioko) and Nigeria. May occur in Gabon. (IUCN 2004)

Population Estimates:

[Note: Figures given are for wild populations only.]

WORLD
- 1999: As few as 3000 (AZA 1999)

History of Distribution:

Even as of 1996 the distribution of the drill was still uncertain, but it appeared to be restricted to a range of less than 40,000 sq km in western Cameroon, southeastern Nigeria and Bioko Island (Equatorial Guinea). It may occur in Gabon (IUCN 2004).

Distribution Map #1 (14 Kb GIF) (African Mammals Databank 2004)
Distribution Map #2 (31 Kb JPEG) (Spec. Cons. Found.)

Threats and Reasons for Decline:

The major reasons for the drill's decline are hunting for food and habitat loss and fragmentation due to development, logging and agriculture.

Data on Biology and Ecology

Weight:

The drill weighs about 15 kg (33 lb).

Habitat:

The drill is found in tropical rain forest.

The drill is found in both the Guinean Forests of West Africa Biodiversity Hotspot (Cons. Intl. 2005) and the Congolian Coastal Forests Global 200 Ecoregion. (Olson & Dinerstein 1998, Olson & Dinerstein 1999)

Age to Maturity:

5 years.

Gestation Period:

7.5 months.

Birth Season:

Mating apparently occurs throughout the year.

Birth Rate:

Birth rate: 0.81 infants born/year (Fa et al. 1995)

Number of female offspring/mother/year: 0.41 (Slade et al. 1998)

Maximum Age:

29 years.

Diet:

The drill eats fruit, seeds, fungi, roots, insects and small animals.

Behavior:

The drill is semi-terrestrial, feeding mainly on the ground.

Social Organization:

The drill has a flexible social organization. It lives in groups of up to about 20, consisting of a male, several females and their young. These groups may gather into super-groups of up to 200.

Mortality and Survival:

Observed average probability of surviving per year from age of first reproduction to longevity: 0.85 (Slade et al. 1998)

Density and Range:

Observed density: 6.7/sq km (17.4/sq mi) (Bioko) (Fa et al. 1995)

References

African Mammals Databank 2004, Arkive, AZA 1999, Burton & Pearson 1987, Cons. Intl. 2005, Fa et al. 1995, Gadsby 1995, Harrison 1988b, IUCN 1994, IUCN 1996, IUCN 2000, IUCN 2003a, IUCN 2004, Kids Ecology Corps, Nowak & Paradiso 1983, Oates 1996, Olson & Dinerstein 1998, Olson & Dinerstein 1999, Slade et al. 1998, Spec. Cons. Found.,

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Last modified: August 1, 2006;