Differential responses of marsh predators to rainfall-induced habitat loss and subsequent variations in prey availability

CANEPUCCIA ALEJANDRO D; FARÍAS ARIEL; ESCALANTE ALICIA H; IRIBARNE OSCAR O; NOVARO ANDRES ; ISACCH JUAN P

CANADIAN JOURNAL OF ZOOLOGY

National Research Council Canada

Año: 2008 vol. 86 p. 407 - 418

0008-4301

Rainfall has increased in many regions during recent decades, but most information is from dry-land ecosystems, which prevent generalizations on its ecological consequences. We explored the effects of increased flooding on Geoffroy`s cat Oncifelis geoffroyi  D´Orbigny and Gervais, 1844 and pampas fox Pseudalopex gymnocercus  Fisher ,1814 exposed to an abnormally rainy period in marshes at Mar Chiquita (37° 32’ to 37° 45’S, 57° 19’ to 57° 26’W, Argentina). Particularly we assessed the effects of flooding on: (1) habitat use by Geoffroy`s cats and Pampas foxes (2) abundance of the main prey, and then, (3) the functional responses of predators to variations in prey abundance. Overall, simple regression analysis identified negative effects of flooding on prey abundance (rodents, waterbirds and arthropods), but structural equation modeling and logistic generalized linear models identified differential effects of rainfall on the habitat use and functional responses of predators, respectively. The habitat use of O. geoffroyi was more negatively affected by the inter-annual variability in flooding-induced habitat loss, particularly through its effect on waterbirds. At the same time, the habitat use of P. gymnocercus was less affected, likely because it was less dependent on prey from flooded areas and used higher elevation habitats. Given that most native grasslands in elevated areas have been replaced by agriculture, the more specialized O. geoffroyi faces higher threats if current trends of climate change persist in this region.