Mamíferos introducidos en la provincia de Neuquén: estado actual y prioridades de manejo

, , , ,

La Patagonia alberga 84 especies de mamíferos nativos y numerosas exóticas. En este trabajo se revisa la cantidad e identidad de las especies de mamíferos introducidas en la provincia de Neuquén (NO Patagonia, Argentina) y su estado actual. Además, se describe la expansión de Cervus elaphus, Neovison vison, Oryctolagus cuniculus y Sus scrofa en la provincia. Se recopiló información proveniente de: (1) publicaciones e informes, (2) consulta a guardafaunas/guardaparques, profesionales, técnicos, (3) registros inéditos de los autores, y (4) relevamientos de campo. Se registró la introducción de 29 especies de mamíferos (62% corresponde a artiodáctilos), de las cuales siete están extintas, seis están restringidas a cotos de caza y 13 establecieron poblaciones silvestres/cimarronas. En la última década se observó un incremento del área invadida por las cuatro especies analizadas, que ya ocupan gran parte del centro y sur de la provincia. La mayor superficie invadida corresponde a O. cuniculus, seguido por S. scrofa y C. elaphus con áreas similares, y finalmente por N. vison. Se propone impulsar un plan de manejo en el NO de Neuquén con el fin de erradicar poblaciones aisladas y contener el avance hacia áreas protegidas provinciales. En el SO de Neuquén se propone un manejo coordinado entre jurisdicciones (Provincia y Administración Parques Nacionales) en la región de los parques nacionales Lanín y Nahuel Huapi. El mayor desafío ahora lo presentan la integración de las perspectivas ecológicas y técnicas con las consideraciones socioeconómicas y las diversas percepciones de los diferentes grupos sociales sobre cada proceso de invasión.


Introduced mammals in Neuquén Province: status and management priorities. Patagonia houses 84 species of native mammals and numerous exotic species. In this study we reviewed the quantity and identity of mammalian species introduced in Neuquén Province (NW Patagonia, Argentina) and their present status. We also updated the area invaded by Cervus elaphus, Neovison vison, Oryctolagus cuniculus and Sus scrofa in the Neuquén Province. We gathered information from: (1) publications and reports, (2) consultation with park rangers, professionals, technicians, (3) unpublished data of the authors, and (4) fieldwork. We recorded the introduction of 29 species of mammals (62% are Artiodactyla), seven of which are already extinct, six are restricted to hunting ranches, and 13 have established wild populations. The four analysed species show an increase in the invaded area during the last decade and already occupy most of the central and southern regions of the province. The largest invaded area corresponds to O. cuniculus, followed by S. scrofa and C. elaphus with similar areas, and finally N. vison. We promote an initiative for a management plan in NW Neuquén aiming to eradicate isolated populations and restrain the spread of exotic species into provincial protected areas. In SW Neuquén we promote a coordinated management plan between national (National Parks Administrations) and provincial (Provincial Wildlife Agencies) jurisdictions focused in the region of the National Parks Lanín and Nahuel Huapi. The largest challenge now is to integrate ecological and technical perspectives with socioeconomic considerations and the diverse perceptions of the different social groups regarding each invasion process.

Densidad, estructura social, actividad y manejo de guanacos silvestres (Lama guanicoe) en el sur del Neuquén, Argentina

, , ,

Los guanacos (Lama guanicoe) son los ungulados silvestres más abundantes y ampliamente distribuidos de Sudamérica, aunque su abundancia y rango de distribución disminuyó drásticamente en el último siglo. En Patagonia, la esquila en vivo de guanacos silvestres es promovida por organismos gubernamentales como una actividad complementaria a la ganadería que contribuiría a conservar sus poblaciones. La falta de estudios ecológicos sobre poblaciones que habitan campos privados dificulta la evaluación de posibles efectos negativos de esta actividad. Nuestro objetivo fue estimar la densidad, la estructura social y las actividades de una población de guanacos silvestres en un establecimiento ganadero y evaluar los efectos de un evento de manejo. Estimamos la densidad y la estructura social, dentro y fuera del área manejada, y analizamos las actividades individuales antes y después del manejo, entre invierno 2004 y verano 2005. La densidad fue similar en ambas épocas y el tamaño de grupos de machos decreció en primavera. Los grupos familiares fueron la estructura social más frecuente. La alimentación fue la actividad más común en ambas estaciones. La actividad «reposo» en verano se asoció positivamente con la temperatura. Nuestros resultados sobre efectos del manejo son limitados debido al bajo éxito de captura y que pocos ejemplares fueron esquilados; sin embargo, sugieren que la esquila no modificó la estructura social de la población manejada en el corto tiempo. La continuidad de estos estudios es esencial para evaluar la sustentabilidad de esta actividad y su valor potencial como herramienta de conservación de la especie.


Density, social structure, activity and management of wild guanacos (Lama guanicoe) in southern Neuquén Province, Argentina. Guanacos (Lama guanicoe) are the most abundant and widespread wild South American ungulate though both their abundance and range distribution have drastically decreased in the last century. In Patagonia, live-shearing of wild guanacos is being promoted by wildlife agencies as a complementary activity for sheep farmers that may help to conserve populations of guanacos. The lack of ecological studies of guanaco populations inhabiting private ranches hinders the evaluation of possible negative effects of live-shearing. Our objective was to estimate the density, social structure and activities on a free-ranging guanaco population within a livestock ranch and to assess the effect of a shearing event. We estimated population density and social structure, inside and outside of an area being managed and analysed individual behaviour, before and after shearing, between winter 2004 and summer 2005. Density was similar in both seasons and male group size decreased in spring. Family groups were the most frequent social structure. Foraging was the most common activity in both seasons. Resting activity in summer was positively associated with temperature. Our results on the effects of management are limited because capture success was low and few guanacos were sheared; however, our results suggest that live-shearing did not modify the social structure of the managed population in the short-term. The continuity of these studies is essential for a long-term evaluation of sustainability of this activity and its potential value as a conservation tool for the species.

Variaciones morfológicas y diagnosis de la ardilla de vientre rojo, Callosciurus erythraeus (Pallas, 1779), en Argentina

,

La ardilla de vientre rojo (Callosciurus erythraeus) es originaria del sudeste asiático y desde 1973 ha establecido una población silvestre en la provincia de Buenos Aires, Argentina. En este trabajo describimos características generales y morfométricas de las ardillas, particularmente variaciones en su coloración (ejemplares con vientre amarillo-cremoso y banda negra del lomo ausente) en seis sitios del partido de Luján. También identificamos caracteres diagnósticos distintivos respecto a las especies nativas de ardilla Sciurus aestuans y S. ignitus: (1) las características del báculo o hueso peniano, (2) el número de septos transbulares y otras características craneanas, y (3) el número de mamas.


Morphological variations and diagnosis of the Red-Bellied Squirrel, Callosciurus erythraeus (Pallas, 1779), in Argentina. The Red-Bellied Squirrel Callosciurus erythraeus, native to South-East Asia, has established a wild population in the province of Buenos Aires (Argentina) since 1973. In this study we describe general characteristics and morphometry of the squirrels, in particular pelage color variability (individuals with yellow-creamy underparts and no black stripe on their backs) at six sites in the County of Luján. In addition, we established three diagnostic characters to distinguish them from the two native squirrel species Sciurus aestuans and S. ignitus: (1) characteristics of the baculum, (2) number of transbullar septa and other skull features, and (3) number of functional mammae.

Expansión poblacional de una especie introducida en la Argentina: la ardilla de vientre rojo Callosciurus erythraeus

, ,

Population expansion of an exotic mammal in Argentina: the Red-Bellied Squirrel Callosciurus erythraeus. Biological invasions are one of the major threats to biodiversity and ecosystem functioning, and they provoke economic losses to productive systems. A wild population of the Red-Bellied Squirrel Callosciurus erythraeus, native to South-east Asia, has established in the Province of Buenos Aires (Argentina) since 1973. The objective of this study is to assess the spatial distribution of the Red-Bellied Squirrel and describe the opinion of local inhabitants regarding the presence of this exotic species. We conducted 312 interviews in the district of Luján (original release site of this species) and other neighbouring districts, between August 2003 and March 2004. The area of the range distribution of squirrels was calculated using the minimum convex polygon method in a geographical information system. The present distribution of the Red-Bellied Squirrels (the only squirrel species present in this region) covers an area of approximately 680 km2. The increment of the radial distribution of squirrels was larger during the last five years (1999–2004: 1.6 km/year) than in a previous period (1973–1999: 0.3 km/year). While some inhabitants and local producers reported that the squirrels caused economic damages (e.g. in fruit plantations, afforestations, electric and irrigation systems), other inhabitants enjoy the presence of this species given its ornamental value, as a pet and even as a tourist attraction. The latter may encourage the transport of squirrels creating new invasive points, as has already occurred in the province of Córdoba (Argentina), and generating one of the major difficulties to prevent further expansion of this species.

Uso de trampas de pelo y caracterización de los pelos de la ardilla de vientre rojo Callosciurus erythraeus

, ,

Use of hair tubes and hair characterization of the Red-Bellied Squirrel Callosciurus erythraeus. The Asiatic Red-Bellied Squirrel has been introduced into the Pampas Region, where a wild population has now been established and is colonizing new areas. Hair tubes have been successfully used to assess the presence/absence of other species of squirrel through the identification of the collected hairs. The objectives of this study were to characterize the hairs of the Red-Bellied Squirrel and to test the use of hair tubes to detect the presence of this species. The study was conducted in the province of Buenos Aires, Argentina, from January to July 2004. Hairs from the back, head and tail have dark and light stripes while hairs from the belly are uniformly reddish brown. A multi-seriated medullar pattern was observed in the hairs of the back, head and belly, while the tail’s hairs showed a different medullar pattern that can be described as overlapped dark rings. Cuticle scales patterns corresponded to the normal mosaic type in the hairs of the tail, back, head and belly, and for the last three regions a different pattern was observed next to the hair bulb. Hair tubes were made of PVC tubes (25 × 6 cm) opened at both extremes. The tubes had an adhesive tape attached at both extremes and bait (peanuts and nuts) was offered in the centre. Given the arboreal habits of this squirrel, traps were placed on tree branches and inspected weekly. The hair tubes were successful in collecting hairs of the Red-Bellied Squirrel that can be distinguished from those of other mammals inhabiting the same area. Because this is quite a simple and inexpensive technique, we consider it an appropriate method to evaluate the presence of this alien species in the region.