Peruvian Yellow-tailed Woolly Monkey Oreonax flavicauda (Humboldt, 1812) Peru (2000, 2006)

The Peruvian yellow-tailed woolly monkey (Oreonax flavicauda) is endemic to Peru, and is found only in a small area in the Tropical Andes. Oreonax flavicauda is known to persist only in primary premontane, montane and cloud forest between 1,500 to 2,700 m asl (Leo Luna 1982; Butchart et al. 1995; DeLuycker 2007). When O. flavicauda was first rediscovered in 1974, populations existed in the Departments of Loreto and La Libertad (Leo Luna 1980), but they have now been restricted to irregular, scattered parts of only two Departments, Amazonas and San Martín. There are no current estimates of remaining population numbers. Indiscriminate clear-cutting of primary cloud forest is the principal threat to this species, and its habitat has been largely deforested, resulting in a greatly fragmented landscape. Very little is known about the ecology and behavior of the yellow-tailed woolly monkey. Results from studies in the early 1980s indicated that the sizes of its multi-male/multi-female groups ranged from 5 to 18 individuals. Oreonax flavicauda has been seen to eat a variety of fruits, flowers, leaves, lichens, leaf bases of bromeliads, epiphyte roots and bulbs, and possibly insects (Leo Luna 1982; DeLuycker 2007). In a recent field survey, an unusually large group (17-20 individuals) was encountered in areas relatively close to agricultural plots, which may indicate that due to recent and on-going loss of habitat they are finding less suitable habitat areas. The species appears to be highly sensitive to alterations in its habitat (Leo Luna 1987; DeLuycker 2007). Due to the forest disturbance resulting from illegal logging, O. flavicauda decreases its use of the area (Leo Luna 1984), often retreating further into high-altitude forests far away from human settlement in order to use large tracts of forest. In 1981, it was estimated that O. flavicauda occurred in low densities, from 0.25 to 1 group per km² (Leo Luna 1987). It is also suspected to have a large home range (DeLuycker 2007). The species is known to be present in the Río Abiseo National Park (2,745 km²), the Alto Mayo Protected Forest (1,820 km²), and the Reserved Zone Cordillera de Colán (641 km²), which was established in 2002 with assistance from the Asociación Peruana para la Conservación de la Naturaleza (APECO). The current area occupied by O. flavicauda is unknown. In 1981, it was estimated that its potential forested habitat was at least 11,240 km² (Leo Luna 1984). It was predicted that at least 1,600 km² would be deforested for agriculture by 1991 (Leo Luna 1984). Projecting this value for 15 additional years, and using a very conservative similar rate of deforestation, this leaves an estimated 7,240 km² of potential habitat area. This estimate is probably much lower, due to a high rate of migration to the area combined with unregulated land use. In addition, much or most of this forest is now highly fragmented or isolated from other tracts of forest. Oreonax flavicauda has likely declined drastically in numbers due to a big reduction in their area of occupancy and a decrease in the quality of their habitat. Clearing the forest for agriculture continues at an alarming rate, even in the Protected Forest of Alto Mayo (BPAM). It has been estimated that between 2,300 and 2,500 ha of forest have been destroyed in BPAM (ParksWatch, Peru). The forest of the BPAM is now considerably fragmented, a result of lack of enforcement and a substantial human population living in the Protected Forest itself. The BPAM also suffers from illegal selective logging. Members of several botanical expeditions conducted within the BPAM over the last ten years reported having never seen nor heard O. flavicauda there (M. Dillon, personal comm.). Towns that were previously connected only by footpaths are now more accessible due to road construction. For example, Vista Alegre, a town in the Department of Amazonas, and where O. flavicauda has been reported, has plans to build a road in the near future; the first in the region. Additionally, O. flavicauda has been extirpated from all but the most distant and isolated forests on the eastern side of the Río Alto Mayo. Illegal hunting still occurs, and if the monkeys are encountered, they are likely shot, because of their large size, conspicuousness, and trusting behavior toward humans. The species’ velvety, thick, long fur, its skin and skull, and yellow genital hair-tuft are sought after as trophy items, and make this species a target for hunters even when they do not hunt it for subsistence. Infants taken when their mothers are shot are sold in markets as pets. There is very little information on the biology and natural history of this species, resulting mainly from the difficulties imposed by the mountainous and precipitous terrain where it lives. A complete, range-wide survey of its cloud forest habitat is urgently needed to develop plans to protect the remaining populations of Oreonax flavicauda. These surveys should also include population genetic studies, to examine genetic variability and the viability of existing populations. Urgent conservation initiatives necessary for the yellow-tailed woolly monkey’s survival include: increased protection within designated parks, reserves, and protected forests, which currently lack enforcement; the establishment of a contiguous area of protected forest, to create a biological corridor; the establishment of a national park or reserve in the semi-isolated Valle de los Chilchos area; control of illegal logging; purchase of land; the provision of alternative economic models for local communities living along buffer zones, in order to prevent further migration into the primary cloud forests; and the implementation of a strong conservation education plan. Anneke M. DeLuycker & Eckhard W. Heymann

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