A monitoring program for Patagonian foxes based on power analysis

ALEJANDRO TRAVAINI; ALEJANDRO RODRIGUEZ; DIEGO PROCOPIO; SONIA CRISTINA ZAPATA; JUAN IGNACIO ZANÓN; ROLANDO MARTÍNEZ-PECK

European Journal of Wildlife Research

Springer-Verlag

Lugar: Berlin; Año: 2010 vol. 56 p. 421 - 433

1612-4642

Culpeo fox (Pseudalopex culpaeus) and gray fox (Pseudalopex griseus) are heavily culled in Patagonia. Fox populations seem to persist thanks to spatial refuges from which hunted areas are repopulated, following a source–ink dynamics. Sustainable use of Patagonian foxes arrants the design of a monitoring program in nature serves and areas subjected to predator control. During  years, we used visitation indices to bait stations in a ational park and neighboring sheep ranches of southern rgentina. We operated bait stations during three consecutive ights and calculated seven indices of relative bundance. For each fox species, we compared the power f different monitoring designs and scenarios that combined isitation indices, effort (number of bait station lines and urvey frequency) while controlling for type I error, and agnitude of population change during a given period. We ooked at the combinations that produced high power â¡Ü0.24). The operation of bait stations during several ights markedly increased statistical power. Index 7 recording visits 72 h after activation) exhibited the lowest ariation and improved expected power to detect a opulation trend. Both fox species could be monitored imultaneously, with power >0.76 in the short term 5 years), activating 24 bait station lines. We conclude that onitoring programs for culpeo fox and gray fox based on ait stations are able to detect marked declines but are less seful to reliably detect moderate increases in abundance, specially in sheep ranches.