Southeastern Peru Research Articles

ZONED TOURMALINE ASSOCIATED WITH CASSITERITE: IMPLICATIONS FOR FLUID EVOLUTION AND TIN MINERALIZATION IN THE SAN RAFAEL SN CU DEPOSIT, SOUTHEASTERN PERU

The composition of tourmaline in the San Rafael Sn–Cu lode, in southeastern Peru, provides an important record of the early evolution of the hydrothermal system that produced the world’s richest tin deposit. Many forms, colors and compositions of tourmaline, ranging from dravite to schorl, are present in the deposit, but the late tourmaline that accompanied deposition of early cassiterite has an unusual dark green color, and exhibits a strong trend of enrichment in iron. Appearance of this tourmaline in the paragenesis coincided with a marked change in the vein style, reflecting an opening of the vein system, and a dramatic change in the mineralogy of vein and alteration assemblages, evident from the precipitation of other iron-rich minerals (Fe-rich chlorite and cassiterite). This abrupt change in the plumbing of the hydrothermal system was associated with the introduction of dilute, relatively oxidizing, externally derived waters of meteoric origin that mixed with hot magmatic brines carrying high concentrations of dissolved tin and iron. The resulting sudden cooling, dilution, and oxidation of the ore fluids created the conditions required for massive precipitation of cassiterite and formation of a very large, high-grade ore deposit.

Determinants of time allocation across the lifespan : A theoretical model and an application to the Machiguenga and Piro of Peru.

This paper lays the groundwork for a theory of time allocation across the life course, based on the idea that strength and skill vary as a function of age, and that return rates for different activities vary as a function of the combination of strength and skills involved in performing those tasks. We apply the model to traditional human subsistence patterns. The model predicts that young children engage most heavily in low-strength/low-skill activities, middle-aged adults in high-strength/high-skill activities, and older adults in low-strength/high-skill activities. Tests among Machiguenga and Piro forager-horticulturalists of southeastern Peru show that males and females focus on low-strength/low-skill tasks early in life (domestic tasks and several forms of fishing), switch to higher-strength/higher-skill activities in their twenties and thirties (hunting, fishing, and gardening for males; fishing and gardening for females), and shift focus to high-skill activities late in life (manufacture/repair, food processing).

Biological Surveys and Inventories in Manu

In 1973, the Peruvian government created one of the largest and most pristine nature reserves anywhere in the world. The preserve was christened ‘‘Manu’’ after the meandering river that courses through its lower reaches. Most of the park is situated in the lowlands of the department of Madre de Dios, although its highlands lie in the adjacent department of Cuzco. The park’s origins were chronicled by Kim MacQuarrie in a beautiful book illustrated with photographs by Andre and Cornelia Bartschi (MacQuarrie, 1992, 1998). To us, it seems especially fitting that this magnificent park owes its origin to Peruvian naturalist-collector Celestino Kalinowski. Kalinowski was born and made his home in the Marcapata valley just south of Manu. He traveled widely in Peru and beyond, and he shipped specimens that he collected to major natural history museums the world over. However, his collections were especially strong from the region surrounding his home. The place names ‘‘Hacienda Cadena’’ and ‘‘Quince Mil’’ are well known to students of South America’s vertebrate faunas. So valuable were those he shipped to the bird and mammal divisions of Chicago’s Field Museum that the Museum sponsored his trip to Chicago to study his and other collections and to confer with the scientists—Colin Sanborn, Philip Hershkovitz, Melvin Traylor, and Emmet Blake—who were studying material that he sent here. Alarmed by growing commercial development in southeastern Peru in the 1960s, Kalinowski sought to secure governmental protection for the natural areas remaining in best condition. He actively lobbied governmental official Don Felipe Benavides to advocate setting aside a ‘‘reserved zone’’ consisting of the entire watershed of the Manu River. He also escorted Major Ian Grimwood, an English consultant hired to locate a national reserve in the Amazon, to Manu. Although Grimwood had earlier concluded that much of Peru’s Amazon forest had already been despoiled, Kalinowski opened his eyes to Manu’s pristine riches. A three-week trip sufficed to convince Grimwood that Manu was the place for the reserve, and he so reported his recommendation to the government. A year later, in 1968, Manu was declared a national reserve, and hunting and lumbering were prohibited. In 1973, the area became a national park, ensuring its legal status and protection. In 1977, UNESCO recognized its global status by making the national park and an adjacent reserved zone—an area of 1,881,200 hectares—Manu Biosphere Reserve. A decade later, it was named a World Heritage Site, one of only 200 areas in the world accorded this designation (MacQuarrie, 1992). Recognition of Manu’s incredible biological riches has grown hand in hand with the reference collections of its plants and animals. Seemingly, each collection made there added more species to the regional fauna; many proved to be species new to science. Despite focused biological collections in Manu for more than 50 years, this still applies today, even to the best-known vertebrate * Preferred citation: Patterson, B. D., D. F. Stotz, and S. Solari. 2006. Biological surveys and inventories in Manu, pp. 3–12. In Patterson, B. D., D. F. Stotz, and S. Solari, eds., Mammals and Birds of the Manu Biosphere Reserve, Peru. Fieldiana: Zoology, n.s., No. 110. { MacArthur Curator of Mammals, Department of Zoology, The Field Museum, 1400 South Lake Shore Drive, Chicago, IL 60506-2496, U.S.A. { Conservation Ecologist, Environmental and Conservation Programs, The Field Museum, 1400 South Lake Shore Drive, Chicago, IL 60506-2496, U.S.A. 1 Graduate Student, Department of Biological Sciences, Texas Tech University, Lubbock, TX 79409-3131, U.S.A.

RESURRECTION OF STENOCERCUS TORQUATUS BOULENGER, A SPINY-TAILED IGUANID LIZARD (SQUAMATA: IGUANIA) FROM PERU

We resurrect and redescribe Stenocercus torquatus from the Andes of central Peru in departamentos Junín and Pasco at elevations between 800 and 1800 m. This species was erroneously synonymized with Stenocercus crassicaudatus, which occurs allopatrically in the Andes of southeastern Peru, departamento Cusco. In addition to several scale counts, Stenocercus torquatus differs from S. crassicaudatus in having a black antehumeral collar, two black transverse bands anterior to the antehumeral collar, a shorter tail, the ability to change color, and an arboreal life-style.

PARROT NESTING IN SOUTHEASTERN PERU: SEASONAL PATTERNS AND KEYSTONE TREES

Parrots that inhabit tropical lowland forests are difficult to study, are poorly known, and little information is available on their nesting habits, making analysis of community-wide nesting patterns difficult. I present nesting records for 15 species of psittacids that co-occur in southeastern Peru. The psittacid breeding season in this area lasted from June to April, with smaller species nesting earlier than larger species. Why smaller species bred earlier is uncertain, though it may be related to interspecific competition for nest sites or variations in food availability. This study identified two keystone plant resources used by nesting parrots: Dipteryx micrantha (Fabaceae) and Mauritia flexuosa (Arecaceae). Local threats to these plant species are discussed.

New Species of Telmatobius (Anura: Leptodactylidae) from Humid Paramo of Peru and Bolivia

A new species of Telmatobius is described from humid paramo of southeastern Peru and western Bolivia. Males of the new species differ from those of Telmatobius sanborni, the only other species of Telmatobius in the area, mainly by lacking hypertrophied forearms and having smaller nuptial spicules; in addition, color patterns are different. The apparent low diversity of forest Telmatobius in southern Peru may be an artifact of lack of research on this group of frogs in this region.

BOLIVIAN ECTOPARASITES: A NEW SPECIES OF LAELAPINE MITE (ACARI: PARASITIFORMES, LAELAPIDAE) FROM THE RODENT NEACOMYS SPINOSUS

Laelaps neacomydis n. sp. is described from the pelage of the rodent Neacomys spinosus collected in Bolivia. Collection records from northern Brazil, southeastern Peru, and central Bolivia indicate its wide distribution across Amazonas associated with rodents of the genus Neacomys. The formal taxonomic description and illustrations are derived from the adults (female and male). Two larger species of laelapine mites, Gigantolaelaps intermedius and L. boultoni, infest the same hosts at the same localities.

A new species of tree frog from the Andes of southeastern Peru (Anura: Hylidae: Hyla)

AbstractA new species of Hyla is described from cloud forests of the Cosñipata Valley in southern Peru. The new species lacks webbing in hands and has vestigial webbing between toes III and IV, is readily distinguished from any other species of Andean Hyla, and is not clearly assignable to any species group. The new species seems to be a secretive, bromeliad-dweller.

Avian Geophagy and Soil Characteristics in Southeastern Peru

ABSTRACTWe observed ten species of psittacids, three species of columbids, and two species of cracids consuming soil from banks of the lower Tambopata River in southeastern Peru. Our study used observations and soil analyses from eight exposed riverbank sections to test the predictions of three models to determine why birds consume clay: mechanical aid to digestion (grit), adsorption of dietary toxins, and mineral supplementation. We found that preferred soils were deficient in particles large enough to aid in the mechanical breakdown of food and help digestion. Percent clay content and cation exchange capacity (CEC), both predicted to correlate with adsorption of toxins, did not differ between used and unused sites as had been found in a similar study. Instead, preferred soils were more saline and had higher concentrations of exchangeable sodium. This suggests that the choice of soils at our site was based primarily on sodium content. Birds may be using the heavy, plastic texture of soils rich in clays and high in exchangeable sodium as a proximal cue for soil selection. Our findings suggest that avian soil selection decisions depend on the range of available soil characteristics.RESUMENObservamos diez especies de Psittasidos, trés especies de Columbidos, y dos especies de Cracidos consumiendo suelo de los bancos del bajo Rio Tambopata en el sureste del Perú. Nuestro estudio utiliza observaciones de aves y análisis de suelos de ocho secciones expuestas de los bancos de rio para probar las predicciones de tres modelos de porque las aves consumen arcilla: ayuda mecánica para la digestión (arena triturada), adsorción de toxinas en la dieta, y suplemento mineral. Encontramos que los suelos preferidos eran deficientes en particulas lo suficientemente grandes como para ayudar en la trituración mecánica del alimento y ayudar a la digestión. El porcentaje de contenido de arcilla y la capacidad de intercambio catiónico (CIC), ambos esperados para correlacionar con la adsorción de toxinas, no varió entre sitios usados y no usados como ha sido encontrado en un estudio similar. En cambio, los suelos preferidos fueron más salinos y con mayor concentracion de sodio intercambiable. Esto sugiere que la selección de suelos en nuestro sitio de estudio está basado principalmente en el contenido de sodio. Las aves pueden estar usando las texturas densas y plásticas de los suelos ricos en arcillas con alto contenido de sodio intercambiable como una señal próxima para la selección del suelo. Nuestros resultados sugieren que las decisiones de selección de suelos por las aves depende del rango de caracteristicas de suelos disponibles.

Geographic Distribution, Ecology, and Phylogenetic Affinities ofThyroptera lavaliPine 1993

Thyroptera lavali (Chiroptera: Thyropteridae) is a rare Neotropical species that until now has been recorded from only five localities in the Amazonian rainforests of Peru, Ecuador, Venezuela, and Brazil. Fewer than 10 specimens of T. lavali exist and, accordingly, little is known about its distribution, natural history, and phylogenetic affinities. We report new records for the species from southeastern Peru. Together with other recently published records, these expand the known range of the species considerably, as well as increase our knowledge of its ecology. Thyroptera lavali seems to prefer primary forest near swamps, and probably roosts in palms; its reproductive pattern is similar to that of other Neotropical insectivorous bats, with parturition at the beginning of wet season. Finally, we used two different data matrices to assess its phylogenetic relationships: one of discrete morphological characters, the other of DNA sequences of mitochondrial genes. Both data sets support a sister relationship between T. lavali and T. tricolor, with T. discifera as the basal member of the genus Thyroptera.

Fe-Ti-P Oxide Melts Generated through Magma Mixing in the Antauta Subvolcanic Center, Peru: Implications for the Origin of Nelsonite and Iron Oxide-Dominated Hydrothermal Deposits

Commingling and mixing of K-rich basaltic (absarokitic) and partially crystallized, strongly peraluminous, S-type monzogranitic-rhyodacitic magmas have been documented in the 23.8 Ma Antauta hypabyssal complex of the Picotani Group, Puno, southeastern Peru. Magma mixing generated intermediate, andesitic rocks hosting small volumes of SiO2-poor (>8.4 wt %), Fe oxide-rich melt, with TiO2 (>30 wt %) and P2O5 (>23 wt %) contents corresponding to those of the genetically problematic nelsonite ore type. Microscopic spheres of this composition are embedded in rhyolitic glass surrounding both extensively melted, sieve-textured plagioclase xenocrysts derived from the rhyodacitic magma and cognate orthopyroxene phenocrysts exhibiting replacive Fe-rich mantles. The andesites also contain up to 15 modal percent of strongly resorbed, granite-derived, quartz xenocrysts with glass-orthopyroxene-clinopyroxene coronas. Intense, quasipervasive silicification of the fractionating mafic magma is inferred to have displaced the hybridized melt composition into the stable liquid immiscibility region of the Na2O+K2O+MgO+Al2O3-FeO+TiO2+MnO+CaO+P2O5 - SiO2 - H2O system. Some Fe-Ti-P–rich bodies have 30 to ca. 55 wt percent SiO2 and exhibit broadly linear trends of major oxides versus SiO2, but the more SiO2-deficient spheres exhibit extreme compositional scatter, implying the existence of complex immiscibility fields within the parental, protonelsonitic melt domain. In contrast, the predominant, apparently conjugate, silicate glass (70–78 wt % SiO2) is relatively consistent in composition and equivalent to a syenogranite and/or rhyolite. The extreme local variability in the composition of the oxide-rich melt bodies may directly reflect their formation in a magma-mixing environment in which temperature varied over at least 200° to 300°C. Such a compositional range, also apparent in large-scale nelsonite occurrences, indicates that strong fractionation of mafic melts under conditions precluding ferroan spinel crystallization may not be a prerequisite for oxide-silicate immiscibility, and hence nelsonite formation. Specular hematite is widely disseminated in the glassy andesites, commonly clustered around resorbed quartz xenocrysts, and microscopic bodies of illite-montmorillonite-chlorite occur in contact with unaltered glass in unveined andesites, implying endogenous sources of, respectively, iron and hydrothermal fluid. Moreover, the Upper Paleozoic clastic sedimentary envelope of the Antauta center at Pucacancha hosts hydrothermal breccias and veins rich in hematite, barite, quartz, chalcedony, and epidote, with lesser anhydrite and traces of U-, Th-, REE-rich allanite, chalcopyrite, and molybdenian scheelite. This unambiguously hydrothermal mineralization is analogous to that of the iron oxide-copper-gold clan, and we propose that the development of some deposits of this type may have been triggered by the formation and subsequent vesiculation of immiscible Fe-rich oxide melt during the mixing of mafic and felsic magmas.

A new species of Monodelphis (Didelphimorphia: Didelphidae) from southeastern Peru

Summary A new species of short-tailed opossum ( Monodelphis ) is described from the lowland forest of southeastern Peru. The new species is similar and more related to Monodelphis adusta Thomas, 1897, but is comparatively larger, and lighter in color. Other species known to occur in the area ( M.emiliae and M.glirina ) have no closer resemblance to the new species. Other characters useful to distinguish this new species are a heavy, broad, and extremely flattened skull, with a conspicuous sagittal crest. The premaxilla is short and the upper incisor rows are wide apart. During the comparisons of the new species with M.adusta , it became clear that two subspecies of the latter could be recognized and morphologically diagnosed: Monodelphis a.adusta and M.a.peruviana . Their distributions are limited to the south and to the north, respectively, by the Amazon River. The name M.melanops , described from Panama is a junior synonym of M.a.adusta , but M.osgoodi , described from the highlands of Bolivia is a valid species, and probably has no close relationships to either M.adusta or the new species here described.

REDISCOVERY OF THE SELVA CACIQUE (CACICUS KOEPCKEAE) IN SOUTHEASTERN PERU WITH NOTES ON HABITAT, VOICE, AND NEST

Abstract Two new locations, vocalizations, and the nest of the little known Selva Cacique (Cacicus koepckeae, Icteridae) are described from southeastern Peru. Similarities between the vocalizations of Selva and Ecuadorian caciques (C. sclateri) indicate that the two species may be closely related. The Selva Cacique may be ecologically restricted to narrow rivers and headwater regions, where found in river margin habitats and nearby transitional forest. Its occurrence from an elevation of 300 m at the type locality to ≤575 m at the headwaters of the Rio Manu Chico, 240 km from the type locality, indicates that it may occur in small numbers over a much larger area than was previously known.

New Species of Drymoluber (Reptilia: Squamata: Colubridae) from Southeastern Peru

Abstract A new species of colubrid snake, genus Drymoluber, is described from three localities (1920–3300 m elevation) in southeastern Peru (Departamento de Apurimac). The characteristics of the new species include dorsal scales smooth with two apical pits, in 13 rows throughout body; 14–16 maxillary teeth; one preocular; two postoculars; one anterior and two posterior temporals; anal plate entire; ventrals 158–182; subcaudals 82–92; and a dorsal pattern of transverse blackish blotches (1.0–1.5 scales wide) and narrower hazelnut brown interspaces (2.0–2.5 scales wide) in juveniles, whereas adults are dorsally uniform olive-grey and ventrally yellowish-grey. The new species differs from all species of the genus in number of dorsal scales, number of temporals, number of maxillary teeth, and in several aspects of coloration and pattern.

Succession and Micro‐elevation Effects on Seedling Establishment of Calophyllum brasiliense Camb. (Clusiaceae) in an Amazonian River Meander Forest1

ABSTRACTI investigated the effects of successional stage and micro‐elevation on seedling establishment of Calophyllum brasiliense (Clusiaceae), a common canopy tree of seasonally flooded lowland forest along the Manú River meander zone in southeastern Peru. To compare seedling establishment between microhabitat types, I planted C. brasiliense seeds in a fully crossed experimental design of three successional stages (early, mid, and mature) and two micro‐elevations (levees and backwaters). Seedling establishment success in this study was affected by both successional stage and micro‐elevation, but micro‐elevation was most important in mid‐successional habitats. In general, seedlings in early succession experienced better conditions than in mature forest; light levels were higher, herbivory lower, and seedling growth higher. In mid‐successional forest, micro‐elevation determined habitat quality; backwaters had higher light levels, lower herbivory, and higher seedling growth and survival than levees. Mid‐successional backwaters were similar in quality to early successional forest for seedling establishment, while levees in that same successional stage were the poorest microhabitats for establishment. Although mid‐successional backwaters are similar to early succession for seedling establishment, in the long run, seedlings that establish in mid‐succession have a lower chance of reaching reproductive size before their habitat ages to mature forest than members of their cohort that established in early succession. I hypothesize that successful recruitment for C. brasiliense in the Manú River meander system requires dispersal to early successional habitat.

Porphyry-Style Alteration and Mineralization of the Middle Eocene to Early Oligocene Andahuaylas-Yauri Belt, Cuzco Region, Peru

Originally known for its Fe-Cu skarn mineralization, the Andahuaylas-Yauri belt of southeastern Peru is rapidly emerging as an important porphyry copper province. Field work by the authors confirms that mineralization in the belt is spatially and temporally associated with the middle Eocene to early Oligocene (~48–32 Ma), calc-alkaline Andahuaylas-Yauri batholith, a composite body with an areal extent of ~300 × 130 km emplaced into clastic and carbonate strata (e.g., Yura Group and Ferrobamba Formation) of Jurassic to Cretaceous age. Batholith emplacement included early-stage, mafic, cumulate gabbro and diorite between ~48 and 43 Ma, followed by pulses of granodiorite and quartz monzodiorite at ~40 to 32 Ma. Coeval volcanic rocks make up the middle Eocene to early Oligocene Anta Formation, a sequence of >1,000 m of andesite lava flows and dacite pyroclastic flows with interbedded volcaniclastic conglomerate. Sedimentary rocks include the red beds of the Eocene to early Oligocene San Jeronimo Group and the postmineralization late Oligocene to Miocene Punacancha and Paruro formations. Eocene and Oligocene volcanic and sedimentary rocks are interpreted to have accumulated largely in both transtensional and contractional synorogenic basins. New and previously published K-Ar and Re-Os ages show that much of the porphyry-style alteration and mineralization along the belt took place during the middle Eocene to early Oligocene (~42–30 Ma). Thus, batholithic magma emplacement, volcanism, and sedimentation are inferred to have accompanied a period of intense deformation, crustal shortening, and regional surface uplift broadly synchronous with the Incaic orogeny. Supergene mineralization is inferred to have been active since the Pliocene on the basis of geomorphologic evidence and a single K-Ar determination (3.3 ± 0.2 Ma) on supergene alunite. The belt is defined by 31 systems with porphyry-style alteration and mineralization, including 19 systems grouped in 5 main clusters plus 12 separate centers, and by hundreds of occurrences of magnetite-rich, skarn-type Fe-Cu mineralization. Porphyry copper stocks are dominated by calc-alkaline, biotite- and amphibole-bearing intrusions of granodioritic composition, but monzogranitic, monzonitic, quartz-monzonitic, and monzodioritic stocks occur locally. Hydrothermal alteration includes sericite-clay-chlorite, and potassic, quartz-sericitic, and propylitic assemblages. Calcic-potassic and advanced argillic alteration associations are locally represented, and calc-silicate assemblages with skarn-type mineralization occur where carbonate country rocks predominate. Porphyry copper deposits and prospects of the belt range from gold-rich, molybdenum-poor examples (Cotabambas), through deposits carrying both gold and molybdenum (Tintaya, Los Chancas), to relatively molybdenum-rich, gold-poor end members (Lahuani). Gold-only porphyry systems are also represented (Morosayhuas). Gold-rich porphyry copper systems are rich in hydrothermal magnetite and display a positive correlation between Cu and Au in potassic alteration. The bulk of the hypogene Cu (-Au, -Mo) mineralization occurs in the form of chalcopyrite and bornite, in intimate association with early-stage potassic alteration which, in many deposits and prospects, is variably overprinted by copper-depleting sericite-clay-chlorite alteration. Most porphyry copper systems of the belt lack economically significant zones of supergene chalcocite enrichment. This is due primarily to their relatively low pyrite contents, the restricted development of quartz-sericitic alteration, and the high neutralization capacities of both potassic alteration zones and carbonate country rocks as well as geomorphologic factors. Leached cappings are irregular, typically goethitic, and contain copper oxide minerals developed by in situ oxidation of low-pyrite, chalcopyrite (-bornite) mineralization. Porphyry copper-bearing stocks emplaced in the clastic strata of the Yura Group and certain phases of the Andahuaylas-Yauri batholith may develop appreciable supergene chalcocite enrichment in structurally and lithologically favorable zones. A model for the region suggests that the calc-alkaline magmas of the Andahuaylas-Yauri batholith and subsequent porphyry-style mineralization were generated during an event of subduction flattening which triggered the crustal shortening, tectonism, and uplift assigned to the Incaic orogeny. Shortening of the upper crust would have impeded rapid magma ascent favoring storage of fluid in large chambers which, at the appropriate depth in the uppermost crust, would have promoted large-scale porphyry copper emplacement. Geodynamic reconstructions of the late Eocene to early Oligocene period of flat subduction in the central Andes suggest that emplacement of the Andahuaylas-Yauri batholith took place at an inflection corridor in the subduction zone broadly coincident with the position of the present-day Abancay deflection. Similarly, evidence from southeastern Peru suggests that the Andahuaylas-Yauri belt may be continuous with the late Eocene to early Oligocene porphyry copper belt of northern Chile and that the process of subduction flattening in southern Peru also may have taken place in northern Chile between ~45 and 35 Ma.

SPECIES IDENTITY IN THE GENUS ADENOMERA (ANURA: LEPTODACTYLIDAE) IN SOUTHEASTERN PERU

The genus Adenomera has been a difficult group for systematic studies because the species are similar and geographically variable. Two species have been reported from the Peruvian Amazon Basin: Adenomera andreae and Adenomera hylaedactyla. However, acoustic recordings from the Tambopata National Reserve in southeastern Peru reveal four sympatric advertisement call types that are distinctive in acoustic parameters and to the human ear. Some subtle morphological differences are also present. We conclude that there are at least four sympatric species at Tambopata and that Adenomera has a greater species diversity than currently acknowledged.

Avifauna of the Pilón Lajas Biosphere Reserve and Communal Lands, Bolivia

Pilón Lajas Biosphere Reserve and Communal Lands (Pilón Lajas) ranges from 300 m to 1,400 m altitude in the departments of Beni and La Paz, Bolivia. It is located in the Bolivian and Peruvian lower yungas Endemic Bird Area (054) and within one of the regions of highest conservation priority in the Neotropics. Pilón Lajas includes primary evergreen tropical lowland forest, foothill forest, and lower montane forest. Vegetation heterogeneity forms the basis for the high species richness of the area. A population of approximately 600 Chiman, Moseten and Tacana indigenous people live within the reserve. Little has been published regarding the avifauna of Pilón Lajas. Here we present the results of visual observations and tape recordings of 22 ornithological surveys, recording 502 bird species. Serranía Pilón is the most intensively studied and species-rich mountain range with 332 species, 48 of which have been recorded only in this area within Pilón Lajas. We present 26 new departmental records and evidence of breeding for 42 species. The reserve protects three globally Vulnerable and three globally Near Threatened species, four species of High Conservation Priority and 32 of Medium Conservation Priority. Together with Madidi National Park and the adjacent Bahuaja Sonene National Park in south-eastern Peru, Pilón Lajas forms a unique protected area system of more than 3.5 million ha and plays an important role in the establishment of biological corridors along the eastern Andean slope in Bolivia.

Frugivores at a fruiting Ficus in south-eastern Peru

In neotropical forests, 50–90% of the canopy trees bear fruits adapted for animal dispersal whereas close to 100% of the shrubs and sub-canopy trees produce fleshy fruits (Howe & Smallwood 1982). It has been suggested that during periods of fruit scarcity, some plant species perform a critical role in the forest ecosystem by sustaining frugivorous animals that are important dispersal agents for seeds of many other trees during other seasons of the year (Howe 1984, Terborgh 1986a). Loss or absence of those seed dispersers would have strong negative consequences for tree species, thereby affecting the health of the entire ecosystem, over time. For that reason, plant species that sustain frugivores (= seed dispersers) during periods of resource scarcity have been called ‘keystone species’ (Gilbert 1980, Howe 1984, Terborgh 1983, 1986a, b; van Schaik et al. 1993). For example, in the tropical rain forest of Manu National Park, Peru, Terborgh (1983) found that figs, palm nuts and nectar are resources of great importance for the primate community during periods of fruit scarcity. During that season, three species of fig were identified as keystone resources maintaining nearly 40% of the animal biomass in the ecosystem (Terborgh 1983).

Population densities of some nocturnal raptor species (Strigidae) in southeastern Peru

Abstract Line transects based on distance sampling methodology were used to census nocturnal raptor species in three different primary lowland forest habitats in the Tambopata region, southeastren Peru. Density estimates were calculated for five owl species in these forest habitats. In general, species were more abundant in primary old floodplain or primary middle/upper floodplain forests than in primary seasonally flooded swamp forest. Density estimates were also higher than those calculated from traditional spot-mapping methods in other lowland forest sites in southeastern Peru and French Guiana. There was no significant difference in the number of individual owls recorded during nights with different cloud cover or during different phases of the moon. Problems of distance estimation at night and unfamiliarity with a range of vocalizations, particularly with Strix owls, may be overcome by conducting a practice period before surveys are undertaken, with transect routes and distance markers adequately set...