Common opossum population density in an agroforestry system in Bolivia

The common opossum, Didelphis marsupialis thrives near human settlements. Understanding its ecology could help planning management decisions about this species, especially in anthropogenic landscapes. Yet, there are no density estimations for this species throughout its distribution range in Bolivia. We estimated the density of D. marsupialis in a rural agricultural community, where agroforestry plantations and fallows cover most of the land. We counted individuals in line transects and used DISTANCE software to calculate density. We covered a total of 70.21 km in 143 night counts, obtaining 38 records of D. marsupialis. We estimated a density of 0.30 individuals ha-1 (SE = 0.062; range: 0.20 - 0.45 individuals ha-1), with a mean encounter rate of 0.54 individuals km-1. Encounter rate varied between habitats, with mean values of 0.20 in secondary forests and 0.64 in agroforestry plantations. Our density estimate is near the lower range of previously reported values for the common opossum in other countries. We argue that our results may reflect the response to the availability of food resources and predation pressure in agroforestry plantations. (AU)

Home range and habitat use by pacas in a montane tropical forest in Bolivia / Ámbito de hogar y uso de hábitat del jochi pintado en un bosque montano tropical de Bolivia

ABSTRACT We studied the home range and habitat use of paca (Cuniculus paca) in a rural agricultural community in the Alto Beni region, in La Paz department, Bolivia, where game meat is the main source of protein for a large portion of local inhabitants. We captured and radio collared five individual paca (4 females and 1 male), which were followed for six months in 2012 to estimate home range of the individuals and assess their habitat use and selection. The total mean home range (95% Minimum Convex Polygon) was 2.26 ha (SD = 0.80), and ranged from 1.5 to 2.96 ha. The mean female home range (2.04 ha) was smaller than the male´s (2.95 ha). Pacas used two (crops and fallows) of the three available habitats (secondary forest patches), and appeared to positively select crops over the other two. The importance of crops may be linked to the type of agriculture conducted in the area (i.e. mainly cacao in agroforestry systems), which may offer more food and shelter for pacas. Given that, the importance of habitats may change seasonally; this topic should be examined in future studies. Our results suggest that agroforestry systems may be important for the species since they offer a variety of food resources throughout the year.

RESUMEN Hemos estudiado el ámbito de hogar y uso de hábitat del jochi pintado (Cuniculus paca) en una comunidad de Alto Beni en el Norte de La Paz-Bolivia, donde la carne obtenida por cacería es, como en muchas regiones de la Amazonia, una fuente principal de proteína para muchas poblaciones indígenas y campesinas. Hemos capturado y seguido con radio-collar a cinco individuos (4 hembras y 1 macho) por seis meses en 2012. El ámbito de hogar promedio de los individuos fue de 2,26 ha (ds=0,80), usando el estimador Mínimo Polígono Convexo (MPC al 95%) y los valores se encuentran entre 1,5 a 2,96 ha. El ámbito de hogar promedio de las hembras fue más pequeño (2,04 ha) que del macho (2,95 ha). Los jochis estudiados usaron 2 (cultivos y barbechos) de los 3 hábitats disponibles (parches de bosque secundario), aunque los cultivos parecen ser seleccionados positivamente respecto a los otros dos. La importancia de los cultivos podría estar ligada al tipo de cultivo que se realiza en la zona (sistemas agroforestales), que podrían estar ofreciendo mejores condiciones para ser usados por los jochis. Adicionalmente, la importancia de los hábitats podría cambiar de acuerdo a la época del año, lo cual podría ser abordado en siguientes estudios. Este trabajo es el primero en dar detalles sobre la ecología de C. paca en vida silvestre en Bolivia; sin embargo sería necesario contar con más individuos para tener más detalle sobre la ecología espacial de esta especie.