This remnant forest has a unique composition of flora and fauna, internationally renowned for both its diversity and rarity. Although physically isolated from the Andes, Bilsa possesses species also encountered in the western Andean middle elevation cloud forests 100 km to the southwest, as well as species endemic to the Choco, a pluvial forest of southern coastal Colombia, and species common to the generally dryer Tumbesian Bio-region.

The region’s rugged topography (300 to 800 meters) and the coastal climate create a dense fog which shrouds all of Bilsa’s steeper ridges. Rare animals found at the reserve include the Jaguar, several small cat species, the Long-Wattled Umbrella Bird, the Giant Anteater and abundant populations of the threatened Mantled Howler Monkey. The reserve’s bird species diversity (about 330 species) is among the highest of any coastal site in Ecuador. Bilsa also harbours several threatened bird species, and contains isolated populations of 9 bird species never before recorded outside the Andes. The ongoing botanical inventory at Bilsa has uncovered 30 plant species new to science.

Unique Wildlife

The Bilsa Biological Station’s biodiversity credentials are certainly impeccable. Two thousand different plant species have been documented, including 30 species completely new to science. Abundant animal and bird populations indicate an intact ecosystem. To date, 24 mammal species are known to live in Bilsa, five of which are on international threatened species lists. Apart from the jaguar, these are the jaguarundi, oncilla, giant anteater and troupes of mantled howler monkeys.

More than 300 species of birds have been documented, amongst the highest totals for any Western coastal forest in Ecuador. But once again, it is the uniqueness of many of the birds which makes Bilsa so special. It is listed as a key area for the protection of birds in both the Choco and Tumbesian endemic bird areas (confined respectively to Ecuador and Colombia and Ecuador and Peru), which between them hold 96 species of birds found nowhere else in the World.

Approximately 95% of this reserve is primary forest and the remainder is secondary forest of various ages. It provides additional space for all the organisms of the rainforest that receives pressure from the road on the Northern side of the Jatun Sacha Reserve along the Napo River. In particular it provides important habitat for jaguars and mountain lions that occasionally cross the Arajuno River to the Jatun Sacha side for hunting.

Because of the previous owner’s eco-tourism interests, he was in partnership with the local provincial works commissioner to construct a road to his block of forest through the Jatun Sacha Reserve. Indeed, the Jatun Sacha Foundation recently had to fight the two partners all the way to the Ecuadorian Supreme Court to stop the planned road – an expensive legal fight which the Foundation eventually won.

On a broader front, the 19-year development of the Jatun Sacha Biological Station has had a very positive effect in the area, as numerous local Non-Government Organisations have developed their own private reserve initiatives along the Jatun Sacha peninsula, starting projects based on the Jatun Sacha model.

Monkey Business – Protecting Habitat

The common, or Humboldt’s, Woolly Monkey (Lagothrix lagotricha), one of the chunkiest and heaviest New World primates, lives in the rainforests of the Western Amazon river basin, including the CTF supported Reserves at the Guaybero-Cocodrilo Reserve, La Macarena in Colombia and Jatun Sacha in Eastern Ecuador.

Reserves such as these are critical for the survival of these monkeys. They inhabit river edge gallery forest; palm woodland; seasonally flooded varzea and dry terra firma primary forest; and high altitude cloud forest. They prefer mature, continuous, undisturbed humid tracts – and will not live in secondary woodland which has re-grown after logging.

Covered in short, dense fur, they have large, round heads with a bare black or brown face. Their bodies are thick, with sturdy limbs, and their protruding bellies have given them the Portuguese name ‘barrigudo’ or ‘big belly’. They average 16–24 inches in length (40–60 cms), excluding their thick and prehensile tail.

They are active during the day – and gregarious – living in social groups of 10 to 70, often in company with capuchins, howlers and other species of monkeys. Rather slow moving, they generally travel on all fours, but often swing by their hands, feet and tail – or by the tail alone. On the ground, they can stand erect using their tail for support, but they are happiest in the forest mid-canopy at 7–12 metres (22–38 feet).

Their principal food is ripe fruit, supplemented by leaves, seeds and some insects. Seeds are most important early in the rainy season when ripe fruit is not readily available. Most intensively hunted Females reach maturity at 6–8 years and males any time after 5 years. Females bear single young after a 7–8 months gestation period and feed their babies for 9–12 months. The young are carried for the first month or so on the abdomen of the mother and climb onto her back after 6 weeks.

It is at this time that woolly monkeys are at their most vulnerable. They are the most intensively hunted primate species in South America – a mother normally being killed so that her infant can be sold on the pet market. Tragically, it is estimated that ten mothers are sacrificed for every live individual infant that actually reaches the market.

Groups of young woollies are very playful in the wild, while grooming is a common activity within a social group. Adult males receive the most grooming, whilst adult females are usually groomed by their juvenile daughters. Communication is by voice, facial expression and other visual behaviour and woollies can show subtle changes in mood and intention by employing a variety of expressions.

Restricted to the Western Amazon basin of Northern South America, common woolly monkeys occur in the upper Magdalena River valley in Colombia; throughout much of the upper Amazon basin of Colombia, Ecuador, Peru and Bolivia; in Brazil west of the Rio Negro; and in the foothills and Eastern slopes of the Andes up to 3,000 metres.