Problemas de conservación para una concentración inusual de huemules (Hippocamelus bisulcus) en la zona del lago La Plata, provincia de ChubutJo Anne M. Smith-Flueck, Werner T. Flueck
Se estudió al huemul (Hippocamelus bisulcus) en verano en la zona del lago La Plata, Chubut, recolectando grupos de heces y restos de animales muertos para posterior análisis. Al norte del lago se encontraron 10.23 grupos de heces por hombre/día (H/D) con 1% de las heces frescas, mientras la zona sur resultó en 9.83 grupos de heces por H/D con 44% de las heces frescas. La proporción baja de heces frescas al norte se relaciona al fácil acceso a tal zona y su uso intenso por el humano durante el verano. En dicha zona se encontraron restos de 18 huemules muertos que fue 25 veces mayor por H/D que en la zona sur y en otros estudios. Esta concentración alta de restos se relaciona al uso intensivo de esta zona como invernada, mientras que los huemules al sur tienen acceso a valles bajos en Chile. El lago merece pertenecer a una reserva, pero ni siquiera posee un plan de manejo, y actualmente hay varios grupos de interés para explotar la zona, incluyendo turismo, pesca, caza, forestal y minería. La presencia de huemul, particularmente por tratarse de una población de las más intactas, debería ser determinante en el desarrollo de un plan de manejo, también debido a tener el estado de Monumento Natural (provincial y nacional). Sin embargo, la falta de una planificación coordinada y de la participación de expertos está ejemplificada en una importante tala reciente de lengas en zonas con huemul. Por falta de garantía de compatibilidad entre la presencia del huemul y las diversas actividades propuestas, y dado el conocimiento existente sobre tales efectos en situaciones semejantes, es indispensable avanzar con una planificación coordinada regionalmente que debería basarse en el Principio de Precaución.
Conservation problems for an unusual concentration of huemul (Hippocamelus bisulcus) by Lago La Plata, province of Chubut. Huemul (Hippocamelus bisulcus) is a native deer threatened by extinction. There are less than 700 remaining in Argentina, and 1000–2000 including Chilean deer: numeric reduction in the past has been estimated at 99%. We studied the area of Lago La Plata in Chubut during the summers between 1993–1999. Vegetation is characterized by mature deciduous hardwood forests starting at lake level (950 m) and covering surrounding mountains to about 1500 m. June–August are the coldest months with average temperatures between -2 and -4EC and 300–400 mm of precipitation as snow. We surveyed for feces pellet groups and remains of dead deer. An area of 50 m around each remain was searched and all material found was collected. Pellet groups considered less than 2 weeks old (fresh) were used as an index of seasonal habitat use. North of the lake we found 10,23 pellet groups per Man-Day (MD) with 1% fresh, whereas south of the lake, groups averaged 9,83 groups per MD with 44% fresh. This difference in summer use was related to more intense use of the northern area by people (fishing, camping, logging) due to road access, causing a greater proportion of deer to move to higher elevations. Compared to other studies with the same approach it can be deduced that the density of huemul on both sides of the lake was at least 1,5–1,6 deer/100 ha which is high for this species. However, eighteen remains of huemul were found north of the lake which was 25 times more per MD than in the south or compared to any other studies. All remains were found within 100 m of the lake shore and were judged to have originated within the previous 3–4 years, excluding the possibility of a sudden catastrophic event. We suggest that areas near the northern shore represent crucial winter habitat for deer. Although they may have migrated to lower laying steppe habitat to the east in the past, as is known for other regions, those areas have been altered substantially through ranching, fire wood cutting and human settlements. Deer species often concentrate in winter, which is generally the time of high mortality rates; this may explain the high concentration of remains on the north side. Populations on the south side have easy access to valleys which drop down to 250 m of elevation with evergreen forests, explaining why few remains were found near the lakeshore region. Thus, the quality of winter habitat for the northern population is crucial for deer survival, and being mature old growth forest, it appears to be the selected habitat; this has also been shown for other cervids in similar habitat in Alaska. Unfortunately, although the area deserves to be a national park or nature reserve, a management plan does not even exist. Little interest in the area until recently allowed huemul to persist, however, there are now several groups with different interests to exploit the area, including tourism, hunting, fishing, mining, and forestry. Although there are national and provincial laws, which provide huemul and its habitat special protection, they have not yet been applied. Recently, the lack of a coordinated approach to develop a regional management concept led to a clear-cut of an important section of mature forest in an area particularly inhabited by huemul in winter. Application of existing laws should favor the implementation of the Precautionary Principle and an eco-regional approach. The latter is important because the circumstances of the area do not permit the application of a multiple-use concept, which has generally been shown to be an outdated practice.