The Conservation Status of Birds on the Cordillera De Colan, Peru
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Bird Conservation International (1997) 7:181-195. © BirdLife International 1997 The conservation status of birds on the Cordillera de Colan, Peru C. W. N. DAVIES, R. BARNES, S. H. M. BUTCHART, M. FERNANDEZ and N. SEDDON Summary In July and August 1994, we surveyed two areas in the south of the Cordillera de Colan, Amazonas department, Peru, above the north bank of the rio Utcubamba. We found a high rate of deforestation, with trees being felled for timber, forest being cleared for the cultivation of cash crops, and elfin forest being burned for pasture. Most of the forest on the mountain range may have been cleared in 10 years. We recorded a number of important bird species, highlighting the significance of the area for the conservation of biodiversity; globally threatened birds included Peruvian Pigeon Columba oenops, Military Macaw Am militaris and Royal Sunangel Heliangelus regalis. Elfin forest is under particular threat in the area, but probably still holds species such as Long-whiskered Owlet Xenoglaux lowcryi. We recommend that a protected area containing areas of cloud-forest and elfin forest be established on the Cordillera de Colan. Introduction The Andean mountain chain is one of the most biologically diverse areas of the world. ICBP (1992) identified 23 Endemic Bird Areas (EBAs) in the Andes, reflecting a pattern of endemism corresponding well with data on other animal and plant groups (ICBP 1992). The tropical Andes must be considered a high priority for conservation, because of their high biodiversity and severe environmental degradation. In Peru, there are several large effectively protected areas of wet montane forest in the south and centre the country, the northernmost being Rio Abiseo National Park centred at 8°S, but the only protected area of wet montane forest in the north is the Alto Mayo Protection Forest which aims at watershed rather than biological resource conservation (INRENA 1995). The biogeography of the eastern Andes of Peru is extremely complex. Fitzpatrick et al. (1979) suggested that the island-like configurations of isolated mountain ridges may have provided conditions of reduced competition, within which relict populations persisted and differentiated. Fjeldsa (1992) noted, however, that the ranges of many local species straddle what have traditionally been considered as major biogeographic boundaries, such as the rio Maranon, and concluded that areas of long-term habitat stability may concentrate relict groups. The Cordillera de Colan (Figure 1), in Amazonas department, Peru, is an important centre of endemism, rich in relict taxa (Fjeldsa (1992). A semi-isolated mountain range to the east of the Andean chain, it is delimited by the rio Maranon to the west, the rio Utcubamba to the south, and the rio Chiriaco to the east. Fjeldsa (1992) identified it as a climatically stable area, with a correspondingly high concentration of relict groups, which may have become C. W. N. Davies et al. 182 AMAZONAS SAN MARTIN Key to Endemic Bird Areas • Ecuador-Peru East Andes (B18+B23) HiMaranon valley (B22) Andean ridge-top forrests (B24) North-east Peruvian Cordilleras (B25 Figure 1. Map of Endemic Bird Areas represented on the Cordillera de Colan. x83 extinct in areas less consistently wet over recent geological time. BirdLife International divides the Cordillera de Colan between four EBAs (Stattersfield et al. 1995): the north-east Peruvian Cordilleras, extending along the eastern side of the Andes from 5°S to io°S; the Andean Ridgetop Forests, covering low-altitude ridgetop elfin forest in southern Ecuador and northern Peru; the Maranon Valley, covering dry forest, mostly at low altitudes, in the Maranon watershed in Amazonas and Cajamarca departments; and the Ecuador-Peru East Andes, covering wet forests of foothills and lower mountain slopes of the East Andes in south-eastern Ecuador and northern Peru.At the intersection of at least four centres of endemism, the Cordillera de Colan is of immense importance for the conservation of biodiversity. The distribution of habitat types on the mountain range itself is as complex as the biogeography. The eastern slope of the range tends to be wetter than the western (INRENA 1976), because the prevailing winds in the area are moisture-laden easterlies from the Amazon basin. The highest altitudes, to 3779 m, in the north-west of the Cordillera de Colan, are capped by paramo (T. S. Schulenberg in litt. 1994). The southern and eastern parts of the Cordillera de Colan, entirely below 3000 m, are covered by montane forest in even their highest reaches. Elfin forest is probably the habitat type on the mountain range of greatest conservation importance. Particularly unusual is the presence of elfin forest down to 1500 m on the western slope of the Cordillera de Colan. This low elfin forest is almost certainly the result of a strong Massenerhebung effect (Richards 1952), by which isolated mountain ranges and parts of mountain ranges rising abruptly from lowland areas have vegetational and climatic zones at lower altitudes. High rainfall is another explanation for the unusually low elfin forest. If this were the major factor, however, elfin forest would extend lower on the wetter eastern slope of the Cordillera de Colan; the lowest known elfin forest is found on the western slopes. The fauna of the Cordillera de Colan is still poorly known; there have been only two previous biological expeditions (Mittermeier et al. 1975; T. S. Schulenberg in litt. 1994). This paper reviews the current conservation status of birds on the Cordillera de Colan, focusing on our 1994 fieldwork in the southern part of the mountain range. We will recommend a conservation policy for the Cordillera de Colan and its avifauna. Methods General field observation was our predominant means of data collection. We have opted for lucidity and present raw data: the number of individuals of each bird species recorded at each site. Birds recorded include both birds heard and seen. We carried out mist-netting using 108 m of 4-panel mist-net at five locations. Sites surveyed in 1994 We visited the Cordillera de Colan between 13 July and 31 August and carried out fieldwork in two areas on the north bank of the rio Utcubamba, east of C. W. N. Davies et al. 184 Table i. Fieldwork sites Site Dates (1994) Field- Mist-net Altitudinal hours ' hours'' range (m) d n d n lA. Comboca Village 13 July-15 July n/a n/a — — 750-1500 IB. Tesoro 15 July-22 July 219 15 129 — 1500-2150 iC. Cabanaquinta 22 Julv-6 August 286 8 319 155 2150-2650 2A. San Cristobal Village 12 August-16 August n/a n/a — — 900-1100 2B. Europa Cloud-forest 15 August-31 August 149 3 — — 1650-1850 2C. Europa Elfin forest 15 August-31 August 97 14 334 54 1650-1950 •' A "field-hour" is one hour of field observation carried out by a single person or group of people working together. '' A "mist-net hour" is the operation of a single 18 m mist-net for one hour. d, diurnal; n, nocturnal. Bagua Grande; both were on the western slope of the south-eastern extension of the Cordillera de Colan. Study Area 1, in the rfo Comboca catchment, is 30 km east of Bagua Grande; Study Area 2, in the rio Cristobal catchment, is about 20 km east of Bagua Grande (Figure 1). Forest classification follows INRENA (1976), an ecological map of Amazonas department drawn using the Holdridge system of forest classification (Holdridge et al. 1971), based on annual rainfall and temperature. Site iA: Comboca Village The only access to the village of Comboca is across the rfo Utcubamba at the village of Cerezo, which lies at 700 m about 30 km east of Bagua Grande, at 5°54'S 78°o6'W. A single mule trail leads up from the river to Comboca, a small village of approximately 100 people located at an altitude of 1250 m at 5°27'S 78°O4'W. Villagers cultivate coffee, maize, sugar cane and bananas but some patches of intact forest remain around the settlement. We did not conduct fieldwork at this site but made informal observations in dry premontane forest and scrub at 700-800 m, and in humid premontane forest at 800-1500 m, while birdwatching around Comboca village and along the trail to Cerezo. Site iB: Tesoro en la Selva Tesoro en la Selva is a single house at 1890 m, 5°49'S 78°O2'W. An area of approximately 10 hectares has been cleared for cultivation of tuber crops, sugar cane, coffee and bananas. The surrounding forest has a high concentration of fruiting and flowering trees, including Nicotiana, Salpichroa, Solanum and Cinchona, and supports correspondingly high concentrations of frugivores. Villagers from Comboca ascend daily with mules to cut mahogany Cedrella at 1500-2150 m. The use of chainsaws means that logging can proceed extremely quickly; the rate of logging appeared to be limited only by the rate of timber transport down to the rio Utcubamba by mule. We carried out fieldwork in humid lower montane forest at 1500-2150 m. Most of our fieldwork was carried out in forest-edge habitat (above 1700 m) rather than closed-canopy forest (1500-1700 m). Site iC: Cabanaquinta This site extended from the boundary with humid lower montane forest to a peak at 5°48'S 78°oi'W. The terrain was steep, with cloud-forest covering slopes of 30°-45°. Common plant genera included Ficus, Ocothca, Cccropia and Otoba. Chusquea bamboo was found in more open areas such as tree-fall clearings and land-slides. Forest on the exposed ridgetop at 2550- 2650 m was more stunted, with several dense Chusquea clumps.