Environmental factors associated with rodent infestations in Argentine poultry farms

1. Seasonal variations in rodent infestations were studied at poultry farms in central Argentina as well as the environmental factors associated with rodent infestations at poultry farms. 2. During the summer and winter of 1998 rodent infestation was monitored at 10 poultry farms by means of tracking stations, and 21 environmental varia bles were selected that a priori could be related with the extent of rodent infestation. 3. There was a higher rodent infestation in winter than in summer. 4. Species detected by rodent sightings at the poultry farms included Akodo n azarae, Calomys spp. (C. laucha and possibly C. musculinus) and Mus muscu lus. 5. In summer, rodent infestation was positively associated with the perimet er of the farm, whereas there was an inverse relationship with the maintena nce conditions of the sheds. In winter, rodent infestation was positively a ssociated with the percentage of the borders of the farm covered with veget ation, and with the amount of plant cover, especially the amount of plant c over which was above 20 cm in height. 6. There was no significant relationship between rodent infestation and the time lag since the last application of rodenticide (first-generation antic oagulant) at the farms. 7. These results suggest that strategies for controlling rodents based sole ly on chemical methods may not be good enough for efficient rodent control. Farms which are properly managed, with a better control of vegetation grow th at both the perimeter and within the internal area, in addition to a hig her maintenance of sheds have appreciably lower rodent infestations.