Animal Info - Central American Squirrel Monkey

(Other Names: Barizo Dorsirrojo, Black-crowned Central American or Red-backed Squirrel Monkey, Mono Ardilla, Mono Titi, Saïmiri à Dos Roux, Singe-écureuil à Dos Rouge or à Dos Roux)

Saimiri oerstedii (Sometimes treated as a subspecies of S. sciureus)

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, Dispersal, Diet, Behavior, Social Organization, Density and Range, Minimum Viable Population)
5. References

Profile

Pictures: Central American Squirrel Monkey #1 (67 Kb GIF) (Univ. Buf. Lib.); Central American Squirrel Monkey #2 (69 Kb JPEG) (Cummins 2003)

The Central American squirrel monkey weighs up to about 1 kg (2.2 lb). It is found in primary and secondary forests and cultivated areas. Disturbed habitats are advantageous because of their greater supply of preferred food - insects (such as grasshoppers) and fruit. The Central American squirrel monkey is arboreal and diurnal. It rarely travels on the ground and is most active in the morning and late afternoon.

Central American squirrel monkeys have large group sizes (40 - 70 individuals) in continuous forest. They are non-aggressive and egalitarian - neither males nor females appear to be dominant. Females are usually the ones who disperse to another troop.

The Central American squirrel monkey has always been restricted to the Pacific lowlands of Costa Rica and Panama. By 1983, the Central American squirrel monkey had already declined drastically due to clearing of forests. Currently, deforestation and habitat fragmentation due to agriculture and tourism development are the major causes of decline. Insecticide spraying, the pet trade and electrocution from electric power lines have also adversely affected these squirrel monkeys.

Tidbits

*** The Central American squirrel monkey rarely descends to the ground; therefore, any break in the forest, such as for roads or for telephone or electric power line rights of way, can severely fragment a troop's habitat.

*** Biologists are concerned that this shy monkey may be easily stressed by crowds of enthusiastic tourists, who throw stones and shake tree branches in an attempt to see the monkeys (Jukofsky 1996).

*** Central American squirrel monkeys travel and forage almost exclusively on branches between 1 - 2 cm (0.4 - 0.8") in diameter and rarely make horizontal leaps longer than 2 m (6.6') (Boinski et al. 1998).

Status and Trends

IUCN Status:

1970's - 1994: Endangered
1996 - 2002: Endangered (Criteria: B1+2abcde, C2a) (Population Trend: Decreasing)
2004: Endangered (Criteria: B1ab(i,ii,iii)) (Population Trend: Decreasing) (IUCN 2004)

Countries Where the Central American Squirrel Monkey Is Currently Found:

2004: Occurs in Costa Rica and Panama (IUCN 2004).

Population Estimates:

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

WORLD (Costa Rica and Panama)
- 1983: 200,000 (Boinski et al. 1998)
- 1997: 3500 - 4500 (Boinski et al. 1998)
Costa Rica
- 1996: Less than 2000 (Jukofsky 1996)
- 1996: Between 1246 and 3500 (Boinski et al. 1998)

History of Distribution:

The Central American squirrel monkey has always been restricted to the Pacific wet lowlands of Costa Rica and Panama. For more than a decade, it was thought to have become extinct in Panama until a small population was discovered in 1996.

The Central American squirrel monkey has a restricted range (1367 sq km (528 sq mi)), its distribution is fragmented, and it occurs in only a few remaining forest areas. It has lost 80% of its historic habitat. The Central American squirrel monkey includes two subspecies: S. oerstedii oerstedii is centered on the Osa Peninsula on the Pacific coast as far south as the Burica Peninsula in Panama; and S. oerstedii citrinellus has a very restricted range on the Pacific coast of Costa Rica. (IUCN 2006)

It has been argued that squirrel monkeys were probably introduced into Central America from South America by prehispanic Amerind traders. Convincing evidence now exists that S. oerstedii was present in Central America prior to the arrival of humans, and it is distinguished from squirrel monkeys in South America in numerous respects. (Boinski et al. 1998)

Distribution Map #1 (14 Kb) (InfoNatura)
Distribution Map #2 (235 Kb JPEG) (Inst. Ciên. Biol.)

Threats and Reasons for Decline:

By 1983, the Central American squirrel monkey had already declined drastically through clearing of forests. Currently, deforestation and habitat fragmentation due to agriculture (including both agribusiness and the small farmer) and tourism development are the major causes of decline. Insecticide spraying, the pet trade and electrocution from electric power lines have also adversely affected these squirrel monkeys.

Data on Biology and Ecology

Weight:

The Central American squirrel monkey weighs up to about 1 kg (2.2 lb).

Habitat:

Central American squirrel monkeys are found in primary and secondary forests and in cultivated areas. Disturbed and early successional habitats are advantageous because of their greater supply of preferred food.

The Central American squirrel monkey is found in the Mesoamerica Biodiversity Hotspot (Cons. Intl. 2005).

Age to Maturity:

3 years (female); 5 years (male).

Gestation Period:

152 - 172 days.

Dispersal:

Young Central American squirrel monkeys are independent when they are 1 year old. Females are usually the ones who disperse.

Maximum Age:

Over 12 years (captivity).

Diet:

The diet of the Central American squirrel monkey consists mainly of insects, such as grasshoppers, and small berry-like fruits. Crops are raided when nothing else is available.

Behavior:

The Central American squirrel monkey is arboreal and diurnal. It rarely travels on the ground and is most active in the morning and late afternoon. A local population of Central American squirrel monkeys probably uses only 1 or 2 trees for sleeping sites.

Social Organization:

Central American squirrel monkeys have large group sizes (40 - 70) in continuous forest. Studies of these monkeys in Costa Rica indicate that they are highly egalitarian and non-aggressive, with neither males nor females appearing to be dominant over the other sex. These studies also indicate that female dispersal predominates, with females readily changing troops with no aggression from either resident male or female troop members. (Boinski et al. 1998)

Density and Range:

Density:

130 individuals/sq km (340 individuals/sq mi) (Panama) (Nowak & Paradiso 1983)

Range:

Home ranges of 17.5 hectares (44 acres) (23 individuals) and 24 - 40 hectares (60 - 100 acres) (27 individuals) (coastal marsh) were observed in Panama. Groups of 10 - 20 individuals lived in isolated patches of forest as small as 0.8 - 2.0 hectares (2 - 5 acres) [Such populations are probably not viable. See next section.] (Nowak & Paradiso 1983)

In continuous forest, the Central American squirrel monkey has a large annual range - more than 2 sq km (0.8 sq mi) (Boinski et al. 1998)

Minimum Viable Population:

Long-term monitoring of isolated populations of Central American squirrel monkeys indicated that local extinction was almost certain when a group contained less than 15 members and had less than about 30 hectares (75 acres) of available habitat (Boinski et al. 1998).

References

Animals of the Rainforest, Boinski et al. 1998, Cons. Intl. 2005, Cummins 2003, Burton & Pearson 1987, InfoNatura, Inst. Ciên. Biol., IUCN 1994, IUCN 1996, IUCN 2000, IUCN 2003a, IUCN 2004, IUCN 2006, Jukofsky 1996, Nowak & Paradiso 1983, Univ. Buf. Lib.

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