Why is the Red Uakari Population Declining in the Peruvian Amazon?

A study on the Peruvian uakari ecology in the larger Amazonian conservation context

Quyen Nguyen

Image Source: Arkive.org

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Abstract:

The bald uakari (Cacajao calvus) is a type of New World monkey found in flooded or

wooded forests in Amazonian Brazil and Peru whose population is being threatened by

various adverse human activities in Peru’s rainforests. This paper explores a few of what

those detrimental human activities are and examines the role of local communities in

protecting bald uakaris and preserving the larger Amazonian biodiversity.

Introduction/Background:

The Amazonian Ecosystem

Amazonia, especially the western portions at the foothills of the Andes, “stands out

as the largest and richest of the wilderness areas” (MacQuarrie 2001: 18), which means

good and bad news. The good news is that Amazonia still as the lungs of the earth with at

least “40,000 plants, of which 30,000 are endemic” (MacQuarrie 2001: 18), and it is home

to at least “1,120 birds (141 endemic), 356 mammals (210 endemic), 338 reptiles (at least

66 endemic), and 410 amphibians (326 endemic)” (MacQuarrie 2001: 19) which

concentrate particularly in the western edges of the massive forest. Unfortunately, this

incredibly biodiverse area has become one of the last remaining major tropical wilderness

areas due to human activity. By transforming Amazonian habitats from forests to cow

pastures, grasslands to croplands and swamps into cities (MacQuarrie 2001: 825), humans

are threatening the Amazon to the verge of extinction. In the tropical rainforests, it is

estimated that “a minimum of 3 to 4 animal or plant species are being lost each and every

day, which means that at least 1,000 to 1,500 species of plants & animals are being

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permanently removed from our planet each year” (MacQuarrie 2001: 326). This destructive

rate means that many of these endangered species are speedily dying out before we even

have the chance to find and study them, not to mention protect them.

Nguyen, Quyen. Amazonian biodiversity: white-lipped peccaries. 2013. Tambopata Research Center,

Peru.

Nguyen, Quyen. Amazonian biodiversity: Red & Blue Macaws. 2013. Tambopata Research Center,

Peru.

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Nguyen, Quyen. Amazonian biodiversity: Jaguar. 2013. Tambopata River, Peru.

Nguyen, Quyen. Amazonian biodiversity: Giant Otters. 2013. Tambopata River, Peru.

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Peruvian Uakari

The bald-headed uakari has a signature bright crimson bald face and “a short and

bushy tail which is less than half to only one third of the head and body length of the

animal” according to various studies done from 1981 to 2007 (Gron 2008). According to

Hershkovitz (1987) and Barnett (2005), the presence of blood vessels near the surface of

the skin results in a reddish appearance of the face and head in red-faced uakaris. (Gron

2008) The pelage of the Peruvian uakaris is reddish-orange but other uakaris’ color may

vary widely from “reddish to orange and buffy to whitish or pale yellow” (Gron 2008).

Taxonomy & Distribution

The scientific name of the red or bald-headed uakaris in Peru is Cacajao calvus

ucayalii, a reddish-orange New World monkey found only in Peru. The genus Cacajao has

quite limited distribution in Amazonian western forests, and Cacajao calvus, the bald-

headed uakari, is found in “regions of whitewater rivers, south of the Amazon, in Brazil and

Peru” (Kinzey 1997: 208-209). Besides the C. c. ucayalii, there are three other Cacajao

subspecies found in limited areas in Brazil and Colombia e.g. the C. c. calvus (white pelage)

is confined between the Rios Japura and Solimoes in Brazil. C. calvus ucayalii, the

subspecies we are examining, is only found in northeastern Peru, confined to the south by

the Sheshea River, to the north and west by the Amazon River and Ucayali River

respectively, and in the east by the Yavari River. (Gron 2008)

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IUCN (International Union for Conservation of Nature) 2008. Range of the Cacajao calvus ucayalli in northeastern Peru. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.1 <http://maps.iucnredlist.org/map.html?id=3416>

Habitat & Ecology

Generally uakaris are commonly found in or close to flooded or riparian forests. As

opposed to Cacajao melanocephalus (whose face is black with plenty of dark, blackish hair)

which is found in habitats associated with "black-water rivers,” Cacajao calvus is found in

varzea forests, which is a type of Amazonian flooded forest “drained by white-water rivers

where flooding occurs up to six months of the year, depositing new sediments and

renewing the soil.” (Gron 2008) However there has been debate about whether bald

uakaris’ habitat is fixed since they can be found in several types of habitat, including both

flooded and unflooded várzea, swamp forest, white sand soil forests, floodplains and terra

firme forest near várzea (Gron 2008). This switching in terms of habitat is a result of

seasonal migration in the dry season when uakaris are said to move from previously

flooded areas to terra firme. (Kinzey 1997: 210) They often stay within flooded areas to

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enjoy periods of fruit abundance and move to “terra firme or other habitat types when

more fruit is available outside of flooded forest” (Gron 2008).

According to Leonard & Bennett (1996), Aquino (1988) and Boubli (2002), uakaris

have been found in association with “other primates including spider monkeys (Ateles sp.),

wooly monkeys (Lagothrix sp.), sakis (Chiropotes sp.& Pithecia sp.), capuchins (Cebus sp.),

and squirrel monkeys (Saimiri sp.)” (Gron 2008). Such associations might provide predator

protection (from harpy eagles, for example) and foraging benefits (Gron 2008).

Food competition occurs among uakaris and other species with a dietary overlap such as

“macaws (Ara sp.), squirrels and sympatric primates such as squirrel monkeys and

capuchins” (Gron 2008). However the level of potential competition, according to Barnett

(2005), Barnett et al. (2005) and Barnett (2008), requires additional quantitative

assessment and is predicted to be quite low (Gron 2008).

Diet

C. calvus’ diet consists predominantly of seeds of unripe fruits (67%) followed by

other parts of fruit (10%), flowers (6%), nectar, insects (5%) and unidentified foods (4%)

(Gron 2008). “Aquino & Encarnación (1999) noted C. c. ucayaliieating 53 plant species from

20 families, of which 46% were consumed for their seeds. Of these, 67% had thick heavy

husks and were consumed in the immature state” (Gron 2008). In the dry season, Peruvian

red uakaris also move to unflooded forest to feed on palm fruit (Gron 2008).

Conservation Status and Hypotheses:

According to the IUCN Red List of Threatened Species (2008), the bald uakaris,

Cacajao Calvus, are categorized as Vulnerable. Here is a history of the IUCN’s assessment of

the C. calvus over the years (Veiga et al. 2008):

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2003 – Near Threatened (IUCN 2003)

2003 – Near Threatened

2000 – Vulnerable

1996 – Vulnerable (Baillie and Groombridge 1996)

1996 – Vulnerable

1994 – Endangered (Groombridge 1994)

1990 – Vulnerable (IUCN 1990)

1988 – Vulnerable (IUCN Conservation Monitoring Centre 1988)

1986 – Vulnerable (IUCN Conservation Monitoring Centre 1986)

1982 – Vulnerable (Thornback and Jenkins 1982)

Compared to the assessment in 1994 which put bald uakaris into the pool of endangered

animals (only two steps away from completely extinction), the 2008 status of ‘vulnerable’

is somewhat more hopeful, indicating that conservation work had been done to rectify the

dangerous drop in uakaris’ population in 1994. However, if we look at the 2003

assessment, uakaris’ have shifted closer to the extinction side of the spectrum by moving

from Near Threatened in 2003 to Vulnerable in 2008. The IUCN’s justification for this

change is that “there is reason to believe the species has declined by at least 30% over the

past 30 years (three generations) due primarily to hunting and habitat loss” (Veiga et al.

2008).

This paper explores those reasons that contribute to the uakari population decline

for the past three decades with two main hypotheses:

1. Hunters preying on uakaris for bush meat are causing their population to

decline.

2. Loggers who destroy uakaris’ arboreal habitat are depriving them of their

home and food source.

Hunting and logging are two main causes of Amazonia’s biodiversity and my hypotheses

propose that they are the dominant actors causing uakaris’ population to decrease over the

years. Biological factors such as the uakaris’ low reproductive rate (Barton 2006: 4) or

their high rate of malaria infection (Gron 2008) might contribute to their slow recovery but

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the external, human-induced effects are the more detrimental forces against uakaris’

population growth. After all, it is humans who have caused current extinction rates to

skyrocket from 100 to 1000 times the normal extinction rate in the past, making the past

two hundred years an “extinction spasm” (MacQuarrie 326) as catastrophic as the mass-

extinction of all dinosaurs 65 million years ago. While the Mesozoic period came to a close

due to an impact of a meteor collision, homo sapiens have managed to speed up our own

destructive process entirely through man-made exploitative activities (MacQuarrie 326).

Findings:

HUNTING

Uakaris are susceptible to hunting due to its primary range close to rivers (varzea

forests). Aquino (1988) has suggested that uakari populations “close to the Ucayali and

Amazon Rivers have been greatly reduced and in some areas exterminated, caused by

hunting and habitat disturbance” (Veiga et al. 2008). Due to their riparian habitat, uakaris

are prone to hunters, either preferentially hunted or taken when other primates are

unavailable (Barnett and Brandon-Jones 1997).

Hunted for Meat

Sightings in 2003 of C. c. ucayalii on the Quebradas Tangarana and Tahuaillo in Peru

show that the local C. c. ucayalii populations were frequently hunted. “On the Quebrada

Blanco, we met a local hunter carrying a dead female that he had shot an hour’s walk from

our camp,” Ward and Chism (2003) report. “Later, two tourists informed us that they met a

hunter carrying two dead red uakaris at the same campsite. […] A Jivaro Indian at Neuvo

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Jerusalem [told] us he had shot three (a male and two females, one with an infant) while

hunting the previous week.” (Ward and Chism 2013: 21)

In Amazonia, according to Peres (1990), subsistence hunting has always played an

important role in indigenous peoples’ lifestyle (Ward and Chism 2003: 21). The locals

strongly prefer larger cebids to smaller New World monkeys for their higher quantity and

quality of meat, making them cost-effective to hunt (Ward and Chism 2003: 21). During the

later half of the twentieth century, as the Peruvian population increased as urbanization

took place, dried or smoked monkey meat became a common food source for the protein

hungry frontier village and town dwellers. (Soini 1972: 26) Attractive to local hunters as

they are, large cebids’ populations are therefore prone to becoming locally extirpated.

Their slow reproductive rates also lowers recovery chances. Populations of the larger

primates in the Río Tapiche basin and the Quebrada Blanco-Río Yavari corridor are

reported to have declined dramatically (Ward and Chism 2003: 21).

As soon as the once stable stocks of larger monkeys have been depleted, the flesh of

smaller monkeys will automatically enter the market. (Soini 1972: 26) Ward and Chism

also came to a similar prediction that red uakaris will experience the same fate as larger

primates due to “being ‘next in line’” in terms of body mass after the woolly (Lagothrix

sp.), spider (Ateles sp.), and howler (Alouatta sp.) monkeys. At least around the

Reserva Comunal Tamshiyacu-area in northearstern Peru, sightings of only one troop of

woolly monkeys and no howler or spider monkeys have convinced researchers that the C.

c. ucayalii are the next potential victims of local hunters (Ward and Chism 2003: 21).

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Non-human primate species of Manu; for more information see Pacheco et al. (1993). Neotropical Primates. 13(2): 31–36. 2005. doi: http://dx.doi.org/10.1896/1413-4705.13.2.31

Harvested for other purposes

Since the time of pre-Columbian Indians, Amazonian monkeys were already much

exploited by man for not just food but also household pets (Soini 1972: 26). Red uakaris in

Peru to this day still suffer from this irrational human demand for monkey pets. At Jaldar

Village on the Rio Yarapa, an area in Peru where high density of uakaris are found, an

employee at Tahuayo Lodge and a villager each possessed a female infant as pets, as

observed by a group of researchers (Ward and Chism 2013: 21). “Four male C. C. ucayalii,

two subadults and two juveniles housed at a lodge on the Rio Yarapa, were all obtained as

infants when their mothers were killed by Jivaro Indian hunters on the Rio Tahuayo”

(Ward and Chism 2013: 21).

LOGGING

Deforestation

The reduced region of uakari habitat can be seen in Conservation International’s

map (below) displaying the original range of Peruvian uakaris in and how it had shrunken

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by 1986. According to Bowler (2007), logging concessions designated in 2004 in

northeastern Peru cover around one-third of the geographic range of Cacajao c. ucayalii,

furthering the extension of human activity and reducing uakaris’ intact habitat even more

dramatically. While the selective removal of low-density, high-value timber species may

not have a great impact on populations of Cacajao c. ucayalii, Bowler proposes that the

logging operations increase human populations and bushmeat hunting in remote parts of

the range (Veiga et al. 2008).

(Bowler et al. 2009: 36)

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Bowler, Mark. Lago Preto Map. 2008. <http://www.mbowler.mistral.co.uk/lagopreto/images/Lago%20Preto%20location%20map%20(from%20Bowler%20et%20al.%202008).jpg>

Mongabay News. Deforestation in Peru. 2013. <http://news.mongabay.com/2013/0613-peru-deforestation-tracking-system.html>

Looking at Peru’s deforestation rate in the graph above, we see that since 2009 it

has reduced in terms of intensity, yet the deforestation rate in Loreto (northeastern Peru

where uakaris are found) has stayed consistently high in proportion to other areas. No

Deforesta on&Non-TimberForestExtrac on

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tests have been performed to show the direct causal effects of deforestation to uakari

population decline but it is undeniable that the process of deforestation enables human

activity, especially hunting, to occur more easily.

Aguaje extraction

As mentioned above, uakaris’ diet consists of mostly seeds from immature fruits,

especially from aguaje (Mauritia flexuosa) palm fruits. Barton (2006) has done a study to

show that aguaje seeds account for 22.4% of uakaris’ entire diet list (see below.)

However, as aguaje fruits become more in demand, unsustainable extraction practices

threaten to deplete Peru’s aguaje resource and deprive the animals that feed on aguaje of

their food source. According to the National Geographic, aguaje fruits generate $4.6 million

every year in the markets of Iquitos, “more than any other indigenous fruit from the

Peruvian Amazon” (Rutger 2008). Not only consumed as a local fruit, aguaje fruits are also

used in “ice cream, popsicles and cold drinks, and is the richest natural source of vitamin A

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yet known (Pacheco Santos, 2005)” (Manzi 2009: 510). Recent advertisements of aguaje as

the new “superfruit” for women as it contains Phytoestrogens, a “natural estrogen,” are

being widely distributed online through commercial websites such as curvyfruit.com are

also boosting the demand for aguaje even though the information advertised is by no

means endorsed by the FDA or any legitimate organizations.

Nguyen, Quyen. Aguaje palm trees in swamp forests. 2013. Tambopata Research Center, Peru.

“Recent estimates suggest that residents of Iquitos, the largest city in the region,

consume approximately 148.8 metric tons of aguaje fruit per month, the vast majority of

which is harvested by felling and killing adult female trees” (Gilmore et al. 2013). Although

aguaje has brought in in a significant amount of income for rural families (see graph below),

how it is traditionally extracted threatens to considerably reduce aguaje availability for future

extraction. Since the aguaje palms are naturally tall – it could get over 30m high (Manzi 2009:

510) – locals tend to “fell the female palm to secure the fruit” (Manzi 2009: 510) since it is

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difficult and dangerous to climb the trees. This practice makes aguaje extraction in Peru doubly

unsustainable because people are not only cutting down an entire tree to extract short-term

fruits but also killing off a disproportionate amount of female trees which might result in

genetic erosion among the aguaje trees. To resolve this issue, in 2001 a palm-climbing device

was developed by two brothers from the community of Parinari in order to introduce an

alternative method of extracting aguaje fruits (Manzi 2009: 512). This proved to be a great

device for aguaje extraction and easy to use. The price of the device, however was $75, which

was too expensive for an average household. Communities end up having to share these

devices and reserving them for the most advanced climbers (Manzi 2009: 513). The use of the

climbing device did lead to the protection of 40ha of aguaje in Roca Fuerte (Manzi 2009: 513)

but had the devices been designed to be cheaper, even more hectares of aguaje might have

been saved.

Mean household total income by source, January–December 2002, Roca Fuerte, Peru. Notes: mean household total income measures household total annual production (i.e., consumption and market income). ‘Other Extraction’ measures income from all other aquatic and terrestrial extractive activities besides aguaje palm fruit extraction (i.e., paiche fishing, aquarium fish collection, timber, firewood, and heart of palm extraction, chonta, etc.). Gini coefficient measures income distribution across households. A low Gini coefficient indicates more equal income distribution, whereas a high Gini coefficient indicates more unequal distribution. (Manzi 2009: 510)

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Climbing of aguaje palm and harvesting of fruit, Roca Fuerte, 2003. Note: aguaje harvesting comprises the following steps: (a) using the stirrup to ascend; (b) sliding the upper strap upward and tightly clutching the strap around the palm; (c) sliding the lower strap upward while sitting in the harness and tightly clutching the strap around the palm; (d) locating one foot in the stirrup and repeating steps (a)–(d) until reaching the crown; (e) cutting down the racemes with the machete or saw; (f) stripping the fruit from each raceme (desgranar) and filling the sacks; (g) transporting the sacks. (Manzi 2009: 512)

To return to the connection between Peruvian uakaris and aguaje palms, we have

seen uakaris’ clear dependency on aguaje as a food source and how the unsustainable

extraction of aguaje will lead to the depletion of aguaje trees and hence, a reduction in

uakaris’ favorite seeds. In 2006 Bowler took notice of this striking connection between

uakaris and aguaje trees and predicted that “in certain parts of the red uakaris range the

removal of this non-timber resource will have a more serious impact on uakari populations

than logging. A paper discussing these findings is currently in preparation” (Bowler 2006:

1). The promised paper has not been published and we still do not have a concrete

argument that excessive aguaje extraction is responsible for the uakaris’ population

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decline. However, considering that the aguaje palm is a keystone species that not only

offers food for various animals but also provides “food, fiber, oil, medicinals, materials for

construction and fishing equipment” for humans (Manzi 2009: 510), sustainable

approaches to aguaje extraction should be developed and implemented as soon as possible.

Conclusion & Recommendation:

In conclusion, we have established that uakaris are susceptible to hunting for its

meat and also as pets. They are the next-in-line target for bushmeat hunters to prey upon

once the larger primates in the area have been depleted. In order to stop the bushmeat

trade from thriving, more research needs to done to find out what other affordable protein-

rich food can be cultivated to replace bushmeat for local communities. Also the lack of

knowledge about Amazonian ecosystems also perpetuates the locals’ indiscriminate

hunting without considering their action’s long-term consequences. This is where non-

profits and the government need to step in to increase the locals’ awareness of how

important uakaris (or any other species) is to an ecosystem like the Amazon, which

Vandermeer and Perfecto have compared to a highly connected web of multiple strong

connections (Vandermeer and Perfecto 2005: 18). A simple example of the interconnected

nature of an ecosystem is how the uakaris’ search for aguaje seeds leads to a cascade of

aguaje fruits down to the forest floor, which then become food for other animals like tapirs,

76% of whose diet comes from aguaje fruits (Torres 2013: 8).

In terms of logging and non-timber extraction, we predict that deforestation may

not directly harm uakaris’ arboreal habitat but it certainly opens doors to hunters and

other human activities such as mining or highway construction to occur closer to the

uakaris’ range. Similarly, the extraction of aguaje fruits has not been shown to explicitly

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hurt uakaris’ population but since we know uakaris rely majorly on aguaje fruits for their

seeds, it is recommended that aguaje trees should be extracted sustainably so as to keep its

number growing. Besides making palm-climbing devices more affordable to local climbers,

integrating aguaje cultivation into local communities’ agroforestry agenda has also yielded

positive results, an example of which is the “dwarf” aguaje recently cultivated in Peru: Due

to the trunk’s shorter height, this type of aguaje fruit can be extracted without felling or

even climbing the trees (Torres 2013: 49). Sustainable agroforestry such as the aguaje

cultivation in northeastern Peru not only provides low-income families with a more steady

income but also contributes to the positive reconciliation of the tension between

conserving Amazonian biodiversity (uakari population, in this case) and acknowledging

local communities’ dire economic needs.

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Vandermeer, John H., and Ivette Perfecto. Breakfast of biodiversity: the political ecology of rain forest destruction. 2nd ed. Oakland, Calif.: Food First Books ;, 2005. Print. Veiga, L.M., Bowler, M., Silva Jr., J.S., Queiroz, H.L., Boubli, J.-P. & Rylands, A.B. 2008.Cacajao calvus. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.1. <www.iucnredlist.org>. Downloaded on 14 October 2013. Ward, Nancy, and Janice Chism. "A Report on a New Geographic Location of Red Uakaris (C. c. ucayalii) on the Quebrada Tahuaillo in Northeastern Peru." NEOTROPICAL PRIMATES 11 (2003): 19-22. Print.