Abstract:

The aim of this paper was to assess the effects of the internal and spatial (external) variables on the abundance of Mus musculus in poultry farms. The internal variables were the maintenance conditions of the farms and the number of sheds, while the external variables were related to the spatial location of each farm with respect to other farms and thus, to the probability of invasion from surrounding areas. This work was conducted on December 2004, January, September, October and December 2005 at poultry farms located at Exaltación de la Cruz, Buenos Aires Province, Argentina. If the abundance is mainly determined by the re-colonization through the displacement of the individuals, we expected the abundance of M. musculus to show an inverted relationship with the distance between farms; the abundance of M. musculus to show a positive relationship with the number of neighboring farms; as well as a correlation among the differences in abundance and the geographical distances between farms. We also expected the abundance of M. musculus to show a negative relationship with the farm maintenance condition, and a positive relationship with the number of sheds present in the farm. The only variable related to the variation in the abundance of M. musculus among farms was the maintenance condition, suggesting that the dynamics of this species in each farm is independent of the abundance in other farms, and does not depend on movements from their neighborhoods. The persistence of the population could be due to its recovery starting from the individuals who survived to the treatment that is permanently done in the farms, favored perhaps by a dense-dependent response of the reproduction or to the passive re-colonization through men.