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

CANEPUCCIA, A. D., A. A. FARIAS, A. H. ESCALANTE, O. IRIBARNE, A. NOVARO AND J. P. ISACCH

CANADIAN JOURNAL OF ZOOLOGY

NATL RESEARCH COUNCIL CANADA-N R C RESEARCH PRESS

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 and pampas fox Pseudalopex gymnocercus 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) the abundance of predators and their main prey, and (2) predators’ functional responses to variations in prey availability. 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 abundances and functional responses of predators, respectively. The abundance of O. geoffroyi was more affected by the inter-annual variability in flooding-induced habitat loss, particularly through its effect on waterbirds. At the same time, the abundance 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 Given that most native grasslands in elevated areas have been replaced by agriculture, the more specialized O. geoffroyi faces higher threats if current trends of climate change persist in this region.